essay about ocean current

Understanding Global Change

Discover why the climate and environment changes, your place in the Earth system, and paths to a resilient future.

Ocean circulation

The ocean covers 71% of Earth’s surface and is constantly in motion. Large masses of water that move together, called ocean currents, transport heat , marine organisms, nutrients , dissolved gasses such as carbon dioxide and oxygen , and pollutants all over the world.  Climate and ecosystems everywhere on Earth, even those far from the ocean, are affected by the ocean circulation.

On this page:

What is ocean circulation, earth system models about ocean circulation, how human activities influence ocean circulation, explore the earth system, investigate, links to learn more.

For the classroom:

• Teaching Resources

Global Change Infographic

Ocean circulation is an essential part of How the Earth System Works.  Click the image on the left to open the Understanding Global Change Infographic . Locate the ocean circulation icon and identify other Earth system processes and phenomena that cause changes to, or are affected by, ocean circulation.

Graphic courtesy of SAGE

Ocean circulation patterns, the movement of large masses of water both at and below the surface, are determined by atmospheric circulation patterns, variation in the amount of sunlight absorbed with latitude, and the water cycle . Surface currents, also called horizontal currents, are primarily the result of wind pushing on the surface of the water, and the direction and extent of their movement is determined by the distribution of continents . Currents, like winds in the atmosphere, do not move in straight lines because of the spin of the Earth, which causes the Coriolis effect.

Currents that move up and down in the water column, also called vertical currents, are created by differences in the density of water masses, where heavier waters sink and lighter waters rise.  This type of ocean circulation is called thermohaline circulation (therme=heat, halos=salt) because the vertical movement is caused by differences in temperature and salinity (the amount of salt in water).  Adding heat decreases the density of water, while adding salt increases the density of water. Thermohaline circulation occurs because winds move warm surface waters from the equator towards the poles, where the water cools and increases in density. Some of this water gets so cold that it freezes, leaving its salt behind in the remaining water, further increasing the density of this water.  This cold, salty water near the poles (primarily in the North Atlantic and near Antarctica) sinks and spreads along the bottom and eventually rises back towards the surface of the ocean. It takes about 1000 years for water to circulate around what is called the global conveyor belt that moves water three dimensionally throughout the world’s ocean basins.

Graphic courtesy of NASA/JPL

This model shows some of the cause and effect relationships among components of the Earth system related to ocean circulation. While this model does not depict the ocean circulation patterns that results from atmospheric wind and density differences in water masses, it summarizes the key concepts involved in explaining this process. Hover over the icons for brief explanations; click on the icons to learn more about each topic. Download the Earth system models on this page.

The model below shows some of the additional phenomena that ocean circulation patterns affect. Ocean circulation is such an important process in the Earth system because currents transport heat , oxygen , nutrients , and living organisms . Most of the sunlight absorbed by water on Earth’s surface gets stored in our oceans as heat, and heat from the atmosphere is also absorbed by the ocean, which increases the ocean’s temperature. This heat is then transported by currents and re-radiated, influencing regional air temperatures and climates all over the globe. For example, the Gulf Stream in the Atlantic Ocean brings heat from near the equator to Europe, making it much warmer than other areas at similar latitudes. Hover over the icons for brief explanations; click on the icons to learn more about each topic.

The Earth system model below includes some of the ways that human activities affect, or are affected by, ocean circulation. As the world warms due to increased levels of greenhouse gases in the atmosphere from human activities, changes in ocean and atmospheric circulation patterns will alter regional climate and ecosystems around the globe. Hover over or click on the icons to learn more about these human causes of change and how they influence, or are influenced by, ocean circulation.

Click the icons and bolded terms (e.g. nutrient levels, atmospheric circulation, etc.) on this page to learn more about these process and phenomena. Alternatively, explore the Understanding Global Change Infographic and find new topics that are of interest and/or locally relevant to you.

To learn more about teaching ocean circulation, visit the Teaching Resources page.

Learn more in these real-world examples, and challenge yourself to construct a model that explains the Earth system relationships.

• Global change drove the evolution of giants
• NOAA: Ocean currents
• NOAA: How does the ocean affect climate and weather on land?
• UCAR: Ocean on the move: Thermohaline circulation
• NASA: Thermohaline Circulation
• NOAA: What is upwelling?

• school Campus Bookshelves
• menu_book Bookshelves
• perm_media Learning Objects
• login Login
• how_to_reg Request Instructor Account
• hub Instructor Commons

Margin Size

• Download Page (PDF)
• Download Full Book (PDF)
• Periodic Table
• Physics Constants
• Scientific Calculator
• Reference & Cite
• Tools expand_more
• Readability

selected template will load here

This action is not available.

8.4: Ocean Currents

• Last updated
• Save as PDF
• Page ID 12701

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

\( \newcommand{\Span}{\mathrm{span}}\)

\( \newcommand{\id}{\mathrm{id}}\)

\( \newcommand{\kernel}{\mathrm{null}\,}\)

\( \newcommand{\range}{\mathrm{range}\,}\)

\( \newcommand{\RealPart}{\mathrm{Re}}\)

\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

\( \newcommand{\Argument}{\mathrm{Arg}}\)

\( \newcommand{\norm}[1]{\| #1 \|}\)

\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

\( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

\( \newcommand{\vectorC}[1]{\textbf{#1}} \)

\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

Ocean water is constantly in motion (Figure 14.7). From north to south, east to west, and up and down the shore, ocean water moves all over the place. These movements can be explained as the result of many separate forces, including local conditions of wind, water, the position of the moon and Sun, the rotation of the Earth, and the position of land formations.

Figure 14.7 : Ocean waves transfer energy through the water over great distances.

Lesson Objectives

• Describe how surface currents form and how they affect the world’s climate.
• Describe the causes of deep currents.
• Relate upwelling areas to their impact on the food chain.

Surface Currents

Wind that blows over the ocean water creates waves. It also creates surface currents , which are horizontal streams of water that can flow for thousands of kilometers and can reach depths of hundreds of meters. Surface currents are an important factor in the ocean because they are a major factor in determining climate around the globe.

Causes of Surface Currents

Currents on the surface are determined by three major factors: the major overall global wind patterns, the rotation of the Earth, and the shape of ocean basins.

When you blow across a cup of hot chocolate, you create tiny ripples on its surface that continue to move after you’ve stopped blowing. The ripples in the cup are tiny waves, just like the waves that wind forms on the ocean surface. The movement of hot chocolate throughout the cup forms a stream or current, just as oceanic water moves when wind blows across it.

But what makes the wind start to blow? When sunshine heats up air, the air expands, which means the density of the air decreases and it becomes lighter. Like a balloon, the light warm air floats upward, leaving a slight vacuum below, which pulls in cooler, denser air from the sides. The cooler air coming into the space left by the warm air is wind.

Because the Earth’s equator is warmed by the most direct rays of the Sun, air at the equator is hotter than air further north or south. This hotter air rises up at the equator and as colder air moves in to take its place, winds begin to blow and push the ocean into waves and currents.

Wind is not the only factor that affects ocean currents. The ‘Coriolis Effect’ describes how Earth’s rotation steers winds and surface currents (Figure 14.14). The Earth is a sphere that spins on its axis in a counterclockwise direction when seen from the North Pole. The further towards one of the poles you move from the equator, the shorter the distance around the Earth. This means that objects on the equator move faster than objects further from the equator. While wind or an ocean current moves, the Earth is spinning underneath it. As a result, an object moving north or south along the Earth will appear to move in a curve, instead of in a straight line. Wind or water that travels toward the poles from the equator is deflected to the east, while wind or water that travels toward the equator from the poles gets bent to the west. The Coriolis Effect bends the direction of surface currents.

The third major factor that determines the direction of surface currents is the shape of ocean basins (Figure 14.15). When a surface current collides with land, it changes the direction of the currents. Imagine pushing the water in a bathtub towards the end of the tub. When the water reaches the edge, it has to change direction.

Figure 14.15 : This map shows the major surface currents at sea. Currents are created by wind, and their directions are determined by the Coriolis effect and the shape of ocean basins.

Effect on Global Climate

Surface currents play a large role in determining climate. These currents bring warm water from the equator to cooler parts of the ocean; they transfer heat energy. Let’s take the Gulf Stream as an example; you can find the Gulf Stream in the North Atlantic Ocean in Figure 14.15. The Gulf Stream is an ocean current that transports warm water from the equator past the east coast of North America and across the Atlantic to Europe. The volume of water it transports is more than 25 times that of all of the rivers in the world combined, and the energy it transfers is more than 100 times the world’s energy demand. It is about 160 kilometers wide and about a kilometer deep. The Gulf Stream’s warm waters give Europe a much warmer climate than other places at the same latitude. If the Gulf Stream were severely disrupted, temperatures would plunge in Europe.

Deep Currents

Surface currents occur close to the surface of the ocean and mostly affect the photic zone. Deep within the ocean, equally important currents exist that are called deep currents . These currents are not created by wind, but instead by differences in density of masses of water. Density is the amount of mass in a given volume. For example, if you take two full one liter bottles of liquid, one might weigh more, that is it would have greater mass than the other. Because the bottles are both of equal volume, the liquid in the heavier bottle is denser. If you put the two liquids together, the one with greater density would sink and the one with lower density would rise.

Two major factors determine the density of ocean water: salinity (the amount of salt dissolved in the water) and temperature (Figure 14.16). The more salt that is dissolved in the water, the greater its density will be. Temperature also affects density: the colder the temperature, the greater the density. This is because temperature affects volume but not mass. Colder water takes up less space than warmer water (except when it freezes). So, cold water has greater density than warm water.

Figure 14.16 : Thermohaline currents are created by differences in density due to temperature (thermo) and salinity (haline). The blue arrows are deep currents and the red ones are surface currents.

Figure 14.17 : Surface and deep currents together form convection currents that circulate water from one place to another and back again. A water particle in the convection cycle can take 1600 years to complete the cycle.

More dense water masses will sink towards the ocean floor. Just like convection in air, when denser water sinks, its space is filled by less dense water moving in. This creates convection currents that move enormous amounts of water in the depths of the ocean. Why is the water temperature cooler in some places? Water cools as it moves from the equator to the poles via surface currents. Cooler water is more dense so it begins to sink. As a result, the surface currents and the deep currents are linked. Wind causes surface currents to transport water around the oceans, while density differences cause deep currents to return that water back around the globe (Figure 14.17).

As you have seen, water that has greater density usually sinks to the bottom. However, in the right conditions, this process can be reversed. Denser water from the deep ocean can come up to the surface in an upwelling (Figure 14.18). Generally, an upwelling occurs along the coast when wind blows water strongly away from the shore. As the surface water is blown away from the shore, colder water from below comes up to take its place. This is an important process in places like California, South America, South Africa, and the Arabian Sea because the nutrients brought up from the deep ocean water support the growth of plankton which, in turn, supports other members in the ecosystem. Upwelling also takes place along the equator between the North and South Equatorial Currents.

Figure 14.18 : An upwelling forces denser water from below to take the place of less dense water at the surface that is pushed away by the wind.

Lesson Summary

• Ocean waves are energy traveling through the water.
• The highest portion of a wave is the crest and the lowest is the trough.
• The horizontal distance between two wave crests is the wave’s length.
• Most waves in the ocean are wind generated waves.
• Ocean surface currents are produced by major overall patterns of atmospheric circulation, the Coriolis Effect and the shape of each ocean basin.
• Ocean surface circulation brings warm equatorial waters towards the poles and cooler polar water towards the equator.
• Deep ocean circulation is density driven circulation produced by differences in salinity and temperature of water masses.
• Upwelling areas are biologically important areas that form as ocean surface waters are blown away from a shore, causing cold, nutrient rich waters to rise to the surface.

Review Questions

• What factors of wind determine the size of a wave?
• Define the crest and trough of a wave.
• What is the most significant cause of the surface currents in the ocean?
• How do ocean surface currents affect climate?
• What is the Coriolis Effect?
• Some scientists have hypothesized that if enough ice in Greenland melts, the Gulf Stream might be shut down. Without the Gulf Stream to bring warm water northward, Europe would become much colder. Explain why melting ice in Greenland might affect the Gulf Stream.
• What process can make denser water rise to the top?
• Why are upwelling areas important to marine life?
• Provided by : Wikibooks. Located at : http://en.wikibooks.org/wiki/High_School_Earth_Science/Ocean_Movements . License : CC BY-SA: Attribution-ShareAlike

Ocean Currents Map

Why are ocean currents important, types of ocean currents.

Ocean currents are driven by a variety of factors, including tides, winds, and changes in water density. These factors work together to create a complex system that has a significant impact on our weather, marine travel, and oceanic ecosystems. Tides, which are caused by the gravitational pull of the moon and the sun, play a role in driving ocean currents. The rising and falling of tides create a rhythmic movement of water, contributing to the flow of currents. Winds also have a strong influence on ocean currents. Global wind systems, driven by the uneven heating of the Earth's surface, transfer heat from the tropics to the polar regions. This heat transfer creates pressure differences in the atmosphere, which in turn generate winds. These winds, known as surface winds, push the surface waters of the ocean, creating surface currents. In addition to tides and winds, changes in water density contribute to the formation of ocean currents. Variations in temperature and salinity, both of which affect water density, play a crucial role. This process, known as thermohaline circulation, drives deep ocean currents. In cold regions like the North Atlantic Ocean, differences in water density caused by variations in temperature and salinity are particularly important. It is important to note that ocean currents are not solely influenced by abiotic factors. Biological factors also come into play. The distribution of food and nutrients in the ocean can be influenced by ocean currents, which in turn affects marine ecosystems. In conclusion, the driving forces behind ocean currents are diverse and interconnected. Tides, winds, and changes in water density all contribute to the complex system of currents that shape our planet's climate system and support marine ecosystems.

Surface Currents

Deep ocean currents, tidal currents.

Ocean Currents Map PDF

The Great Pacific Garbage Patch

This collection of litter (composed mostly of tiny pieces of plastic) is located in the north pacific. the trash is collecting in the calm center of the north pacific subtropical gyre. a gyre is a large system of swirling ocean currents. the north pacific subtropical gyre is made of four separate currents: the california current, the north equatorial current, the kuroshio current, and the north pacific current. these four currents are moving large amounts of trash towards the great pacific garbage patch — helping it grow ever larger., to understand ocean currents, it's best to start with understanding the waves. and how it plays a large role in creating energy..

The five major oceans wide gyres are the North Atlantic, South Atlantic North Pacific South Pacific, Indian Ocean, Ocean gyres and world map pacific of plastic pollution. The currents we see at the beach are called coastal currents that can affect land and wave formations. Currents travel around 5.6 miles per hour in warmer waters of the northern hemisphere and in the North Pacific moves much slower in cold water at 0.03 to 0.06 miles per hour.

Connected One World Ocean

Currents & marine organisms.

Ocean currents exist both on and below the surface. Some currents are local to specific areas, while others are global. And they move a lot of water. The largest current in the world, the Antarctic Circumpolar Current, is estimated to be 100 times larger than all the water flowing in all the world’s rivers! All of this moving water helps more stationary species get the food and nutrients they need. Instead of going looking for food, these creatures wait for the currents to bring a fresh supply to them. Currents also play a major role in reproduction. The currents spread larvae and other reproductive cells. Without currents many of the ocean’s ecosystems would collapse.

What Can You Do?

Cleaning up the Great Pacific Garbage Patch is a challenge. It is not close to any coastline, which means no one country or organization has stepped up to take responsibility for its cleanup. However, many ocean conservation organizations, such as Ocean Blue Project, one of the best Ocean cleanup organizations removing 1 million pounds of plastic by 2025. Help save our blue economy by making a one time donation to help remove plastic pollution from a beach near you.  

The best way to support this effort — reduce your use of single-use plastics. If less plastic is being used, then less of it will end up in our oceans.

What are the Five Oceans of the World?

"the five bodies of water and the global ocean produces more then half oxygen humans breath.", historically the ocean was thought of having 4 oceans the pacific, atlantic, indian, and arctic. today we have five bodies of water and our one world ocean or five oceans aka ocean 5, and two seas covering over 71 percent of the earths surface and over 97 percent of the earth’s water. only 1% of earths water is freshwater and percent or two is part of our ice glaciers. with sea level rise just think of our ice melting and how a percent of earth would so be under water. the oceans of the world host over 230,000 marine animals species and more could be discovered as humans learn ways to explore the deepest sections of the ocean. we all share the same ocean our one world ocean, learn more about how we can protect the microplastics that are harming fish and how we can support the ocean cleanup..

The Southern Ocean also known as the antarctic area.

The Antarctic ocean is the smallest of our oceans and the fourth largest and is full of wildlife and mountains of ice lastly throughout the year. Although this area is so cold humans have managed to live here. One of the largest setbacks is with global warming most of the ice mountains is expected to melt by 2040. The depth of The Antarctic Ocean is 23,740′ in depth. The Southern Ocean also known as the Antarctic Area: 7.849 million mi².  How many people live in the Antarctic? No humans  live in Antarctica  permanently, but around 1,000 to 5,000  people live  through the year at the science stations in  Antarctica . The only plants and animals that can  live  in cold  live  there. The animals include penguins, seals, nematodes, tardigrades and mites.

Fun facts: Between Africa and Austral

Indian Ocean is located between Africa and Austral-Asia and the Southern Ocean. is the third largest of our oceans and covers a fifth ( 20%) of our earths surface. Until the mid 1800s the Indian Ocean was called the Eastern Oceans. The Indian Ocean is around 5.5 times the size of United States and is a warm body of water depending on the Ocean Currents of the Equator to help stabilize the temperatures. 

Atlantic Ocean ​boards North America, Africa, South America, and Europe. This Ocean is the second largest of our five oceans and home of the largest islands in the world. The Atlantic Ocean covers 1/5 of the earths surface and 29% of the waters surface area.

The  Atlantic Ocean  ranks the second for the most  dangerous ocean  waters in the world. This  ocean  water is usually affected by coastal winds, temperature of the water surface currents maps. 

6 Types of Plants That Live in the Atlantic Ocean

• Kelp. Kelp grows in cold coastal waters. …
• Seagrass. …
• Red Algae. …
• Coral and Algae. …
• Coralline Algae.

Pacific Ocean Temperatures or conditions are split:  cold  in east, and warmer in west. In Oregon the body of water is average 54 degrees. Winter has huge Oregon King Tides leaving the norther waters super rough seas. 

Fun Facts For Youth: Atolls are in the warmer conditions of the Pacific Ocean and are the Coral Sea Islands West of the Barrier Reef in Australia. Atolls are only found in the warm ocean waters, located in the southern water bodies of our ocean. 

Ocean Plastic The Pacific Ocean is also the home for the most  micro plastics  floating in our oceans. The plastic are caused by humans littering by accident or just littering. Plastic pollution makes its way to the ocean in many directions by getting into street drains, rivers, blowing in the wind, or from fishing boats. learn about how some animals help lower plastic pollution.

6 Types of Plants That Live in the Pacific Ocean

• Kelp. Kelp grows in cold coastal water bodies.
• Coral and Algae
• Coralline Algae

How do Ocean Currents affect Climate

Ocean currents move warm and cold water, to polar regions and tropical regions influencing both weather and climate and changing the regions temperatures. Learn more about Ocean Blue nonprofit working to remove plastic from our Ocean. 

Ocean currents, also known as continuous and directed movements of ocean water, play a crucial role in shaping our climate, local ecosystems, and even the seafood we enjoy.

These currents are a result of various factors, including tides, winds, and changes in the water’s density. They can be categorized into two types: surface currents and deep ocean currents, which together create a complex system with far-reaching effects on our environment. Surface currents, influenced by tides and winds, occur on the ocean’s surface and have a significant impact on weather patterns and marine travel.

Prevailing Winds – Wind Currents of The World

They can create favorable conditions for sailing or hinder maritime transportation, influencing trade routes and travel times.

These currents also have a direct influence on coastal ecosystems, affecting the distribution of nutrients and the migration patterns of marine species.

What Causes Deep Ocean Currents

Deep ocean currents, on the other hand, are driven by changes in water density, caused by variations in temperature and salinity. These currents flow in the depths of the ocean, and their slow but steady movement plays a critical role in regulating Earth’s climate.

They help distribute heat around the globe, influencing regional and global temperature patterns. Deep ocean currents also play a crucial role in the transport of nutrients and oxygen to deep-sea ecosystems, supporting a diverse array of marine life. It is important to note that ocean currents are not solely influenced by natural factors.

Coastal and sea floor features, such as underwater mountains or canyons, can alter the direction, speed, and location of these currents.

Additionally, the Coriolis effect, a result of Earth’s rotation, also contributes to the complex movement of ocean currents. In summary, ocean currents are dynamic and intricate systems that are driven by tides, winds, water density, and influenced by coastal and sea floor features.

How Does The Ocean Affect Climate and Weather on Land

Their impact extends beyond the surface of the ocean, affecting weather patterns, marine travel, and the delicate balance of marine ecosystems. Understanding these currents is crucial for comprehending the interconnectedness of our planet’s climate and ecosystems.

Why Is The Ocean Blue

Clean water is blue because water absorbs and reflects the blue sky as light bounces red light, red orange yellow, light spectrum of reflections of light as a significant to lowering sediments as for taking care of our wild rivers protective sediments runoff destroying our ocean., clean water is blue because water absorbs and reflects the blue sky as light bounces red light, red orange yellow, light spectrum of reflections of light as a significant to lowering sediments as for taking care of our wild rivers protective sediments runoff destroying our ocean. ocean blue feels beach cleanups conjointly facilitate the long wavelength of the blue color by lowering floating ocean plastics have to be compelled to facilitate keep our ocean blue by protecting clean water. because the ocean absorbs the red yellowness wavelength of light as the aspect of the white lightweight you’ll usually see a glimpse of reminder red etc once viewing the blue ocean reflections we tend to see most frequently. the blue color lower floating sediments that may lower the short wavelengths of lightweight of sunshine spectrum that permits our ocean blue wavelengths reflections of sunshine to be the blue light color. therefore removing plastic floating in our ocean helps permit blue ocean water and our water molecules of safe of blue water., ways to contribute to the ocean.

Ocean Activities for Kindergarten to 2nd Grade

Save the Whales Graphic Hoody

Save the Whale Graphic T-Shirt

Save The Ocean Shirt Microplastics Bird T-shirt (Unisex)

Eco Friendly Reusable Water Bottle

Ocean Themed Clothing Save The Ocean Birds Shirt (Unisex)

Seastar Save The Ocean T-Shirt (Unisex)

Sea the Change Microplastic Turtle Graphic T-Shirt (Unisex)

Marine Biology for Kids Science Kit — Marine Science Ocean Debris STEM Kit

Pride for the Ocean Trucker Hat

Ocean Blue Logo Trucker Hat (Adult)

STEM Activities for Preschoolers

Subscribe to our newsletter to stay up to date with upcoming program news and blogs, sign up today.

• Yes, keep me updated!

Let's save our One World Ocean

Sign up: save the ocean organization newsletter, 6699 fox centre pkwy unit 104-146, gloucester, va 23061 - [email protected] ocean blue project is a 501(c)(3) tax-exempt nonprofit..

Ocean Blue Project

Network of Partners

How the Ocean Current Affect Animals’ Life in the Sea Essay

Introduction, ocean currents and marine turtles, nekton’s (fishes), sea urchins, works cited.

An ocean current refers to a continuous water flow in the ocean following a defined path. This occurs either at the surface of the ocean or below the surface, it also may be parallel or vertical to the surface. These currents are either caused by wind or changes in density (Thermohaline currents). Ocean currents affect the climate, temperatures, and biotic systems especially the fisheries but also those plants and animals on the seashore (Gray et al. 1).

Ocean currents affect marine life in different ways some of these include; as water flows along a given path, there are many sea animals along the same path. Depending on the strength of the ocean current, sea animals along the path are flown along with the water, and the animals are moved to new regions that are sometimes thousands of kilometers away causing redistribution of marine life. During the flow, nutrients are also moved from the bottom of the sea and exposed to sunlight in the process called upwelling. This increases marine nutrients leading to the increased nutrient provision to marine life.

Ocean currents sometimes cause the movement of warmer water to colder regions or cold water to water regions. This interferes with the temperature of the water and may affect sensitive marine life in the region like it may end up freezing some marine animals to death. This paper discusses how the ocean currents affect marine animals with particular reference to turtles, sea urchins, and Nektones

Marine turtles rely entirely on ocean currents for their movements. Young marine turtles especially are moved to their pelagic nurseries by ocean currents and these serve as their habitats. The hatching of turtle eggs relies on oceanic tides and more especially on the frontal tides. This reduces the risk of exposing these eggs to predators. The fertilization of the turtle eggs also depends on ocean waves that transport the larvae to allow for fertilization to occur.

During the development of these turtles, their movement is still aided by ocean currents like in the case of searching for food they flow along with the currents to newer regions that could have food to keep them alive. The turtles are cauterized by two major directional movements where one is usually to the feeding area and the other to the nesting area; both two movements are aided by oceanic currents (Luschi, HAys, and Papi 294).

These are families of sea animals that are strong swimmers and large enough to have the strength to propel against ocean currents. Their bodies are streamlined such that they move swiftly. These include fishes, whales, and Dolphins. Ocean currents have such effects on these sea animals as they bring food to them from the shores and other places so the animals can feed on it. Besides the food, they cause the animals to move about and this allows the animals to be away from predators for their survival. During winter, ocean currents cause oceans waters to swirl around which causes a warming effect on the water and this allows the animals to survive the cold weather.

During summers, cold water from the Polar Regions is flown causing a cooling effect in the warmer regions. The currents also allow the animals to migrate or relocate to more accommodating weather conditions. Animals play in water and ocean current give the animals the whirling effect that gives the sea animals especially the large sea animals like Dolphins to whirl out and enjoy the changing weather.

Sea urchins and the starfish are greatly affected by ocean currents just like the other sea animals. Their larvae are transported over long distances to allow for fertilization to occur anywhere in the sea. These currents also aid the movement of these sea urchins. This allows them to have easy access to food, to redistribute to regions that are unoccupied and maybe unexploited. However, it should be noted that sometimes very strong oceanic currents can cause the death of sea urchins (Gray et al. 7)

Ocean currents are water movements in large volumes along a given path in the oceans, seas, or any large water bodies. These movements are usually caused by wind or the upwelling movement in the water bodies. It is important for the sea animals as it causes their movement to food-rich areas or brings feed to the animals. Food is the most essential part of the survival of any creature including those in large water bodies. Ocean currents are therefore inevitable to the survival of sea animals as they cause the flow of food nutrients within the sea.

Gray Eileen, Alexander Ann, Darling Tina, and Sharkey Nelda. “Moving water-Ocean currents and winds.” Drifters , 1998. Web.

Luschi Paolo, HAys Graeme, and Papi Florian. A review of long-distance movement by marine turtles and possible role of ocean currents . Cesenatico: Oikos, 2003.

• Chicago (A-D)
• Chicago (N-B)

IvyPanda. (2022, September 5). How the Ocean Current Affect Animals’ Life in the Sea. https://ivypanda.com/essays/how-the-ocean-current-affect-animals-life-in-the-sea/

"How the Ocean Current Affect Animals’ Life in the Sea." IvyPanda , 5 Sept. 2022, ivypanda.com/essays/how-the-ocean-current-affect-animals-life-in-the-sea/.

IvyPanda . (2022) 'How the Ocean Current Affect Animals’ Life in the Sea'. 5 September.

IvyPanda . 2022. "How the Ocean Current Affect Animals’ Life in the Sea." September 5, 2022. https://ivypanda.com/essays/how-the-ocean-current-affect-animals-life-in-the-sea/.

1. IvyPanda . "How the Ocean Current Affect Animals’ Life in the Sea." September 5, 2022. https://ivypanda.com/essays/how-the-ocean-current-affect-animals-life-in-the-sea/.

Bibliography

IvyPanda . "How the Ocean Current Affect Animals’ Life in the Sea." September 5, 2022. https://ivypanda.com/essays/how-the-ocean-current-affect-animals-life-in-the-sea/.

• Impacts of Oil Spill on Dolphins and Fishing in Gulf of Mexico
• Conserving Biodiversity: The Loggerhead Turtle
• "The Making of an Un-American" by Paul Cowan
• "The Frog Book" by Steve Jenkins and Robin Rage
• How Animals React to Their Reflection in Mirror
• Foraging and Storing Behavior of the Fox Squirrel and the Eastern Gray Squirrel
• The Feeding Behavior of the Walrus
• Applications in ABA: Reinforcement of Feeding Behavior in Rats

An essay on the winds and the currents of the ocean

Introduction. - The earth is surrounded on all sides by an exceedingly rare and elastic body, called the atmosphere, extending with a diminishing density to an unknown distance into space, but pressing upon the earth with a force equal to that of a homogenous atmosphere five and a half miles high. It is also partially surrounded by the ocean, which is of a very variable depth, and known to be, in many places, more than four miles. If the specific gravity of the atmosphere and of the ocean were everywhere the same, all the forces of gravity and of pressure which act upon any part of them, would be in exact equilibrium, and they would forever remain at rest. But as some parts of the earth are much warmer than others, and air and water expand and become rare as their temperature is increased, their specific gravities are not the same in all parts of the earth, and hence the equillibrium is destroyed, and a system of winds and currents is produced. It is proposed in this essay to inquire into the effects which are produced, both in the atmosphere and in the ocean, by this disturbance of equilibrium, and by means of a new force which has never been taken into account in any theory of winds and currents, to endeavor to account for certain phenomena in their motions, which have been a puzzle to meteorology and hydrology. As there are some uncertain data connected with the subject, such as the amount of the disturbing force, the effects of continents, friction, etc, which render a complete solution of the problem impractible, we shall aim at giving a popular explanation of observed phenomena rather than a complete solution of the problem; yet we shall give the result of some calculations, based upon known date, or at least upon very reasonable hypothesis, which will show that the causes which we have given are adequate to the effects which are attributed to them. We shall divide the subject into two parts, and treat, first, of the winds, and secondly, of the currents of the ocean.

The motions of the atmosphere. - From about the parallel of 28° on each side of the equator the winds on the ocean, where they are not influenced by any local causes, blow steadily towards the equator, having also a western motion, producing what are called the north-east and south-east trades. At the meeting of these currents near the equator there is a calm called the equatorial calm-belt, or the doldrums, where the air rises up and flows in the upper regions towards the poles, until it arrives near the 28°, where it is met by an upper current flowing from the poles. The meeting of these upper currents produces an accumulation of atmosphere from under which the air flows out in both directions on account of the increased pressure; a strong and steady current, as we have seen, towards the equator, and another not so strong and somewhat variable over the middle latitudes, towardg the poles, having at the same time an eastern motion, and producing what are called the passage-winds. As this current flows at the surface towards the poles, it gradually rises up and returns in the upper regions towards the equator, meeting the upper current from the equator near the tropics as has been stated.

Such are the general motions of the atmosphere, as laid down by Lieutenant Maury, and as represented in his diagram of the winds. [1] But there are numerous observations which have been made in very high latitudes both in the north and the south, which show that the currents flowing over the middle latitude towards the poles, do not extend to the poles, but that the atmosphere above a certain latitude, has a tendency to flow from the poles, producing another meeting of the air at the surface near the polar circles similar to the one at the equator, except that the currents are comparatively feeble and consequently the belt of meeting not so well defined, and that here also air rises up and flows each way in the upper regions towards the equator and the poles. "Sir J. Ross has shown that there is a large prevalence of north winds over the southern ones in the middle of North America as low down as latitude 70° and longitude 91°58' west, not merely in winter, but in every month in the year. The northern winds were not only more than double as frequent as the southern, but more than double as strong; and he also found southern winds largely to predominate in latitude 77° south." [2] If then there were no continents, or other local causes of disturbance, the motions of the atmosphere would be as represented in the following diagram, in which the direction of the wind is represented by the arrows, and the external part of which represents the motion of the air in the plane of the meridan. This system, however, is found to prevail on the ocean only, and is very much interfered with in other parts on account of local causes of disturbance, especially in the northern hemisphere, where the uniformity of the earth's surface is most interrupted by land.

The pressure of the atmosphere - The atmospere everywhere presses upon the surface of the earth with a force equal to the pressure of a column of mercury of nearly thirty inches in height. This pressure, however, is not the same in all parts of the earth, but varies in different latitudes as well as from an inch lower at the equator, and seems to stand the lowest about the polar circle, where a very remarkable depression has been observed in many places. "It is a singular fact," says Mrs. Somervill, (page 268) "discovered by our navigators, that the mean height of the barometer is an inch lower throughout the Antarctic ocean at Cape Horn, than it is at the Cape of Good Hope, or at Valparaiso." A similar depression has likewise been observed near the sea of Okhotsk in eastern Siberia. It also appears from the tables of the South Sea Exploring Expedition, by Captain Wilkes, that the barometer stands lowest near the polar circle, where it stands at a mean of about twentynine inches, and higher both north and south of it. After examining various authorities and all the circumstances connected with this subject, Professor Espy comes to the conclusion, that "there are three belts where the barometer stands below the mean, with almost constant rain and snow - one near the equator, one near the arctic circle, and one near the antarctic circle, and also that there are, certainly two belts in the outer borders of the trade-winds, where the barometer stands above the mean, and almost certainly two regions more - one around the north pole and the other around the south pole - where the barometer stands above the mean." It also appears for a great many observations made at different places on the Atlantic, at the level of the ocean, that the barometer stands more than half an inch lower at the arctic circle, than it does at the outer limit of the trade winds, and that there is also a considerable depression at the equator. [3]

The forces concerned in producing the motions of the atmosphere. - There are four principal forces which must be taken into account in a correct theory of the winds. The first arises from a greater specific gravity of the atmosphere in some places than others, on account of a difference of temperature and of the dew-point; for, when it becomes heated or charged with vapor in any place to a greater degree than at others, it becomes specifically lighter, and hence, the equilibrium is destroyed. There is a flowing together, then, of the heavier air on all sides, which displaces the lighter air, and causes it to rise up and flow out in a contrary direction. This is the primum mobile of the winds, and all the other forces concerned are dependent on it for their efficiency. A second force arises from the tendency which the atmosphere has, when, from any cause, it has risen above the general level, to flow to places of a lower level. These two preceding forces generally produce counter-currents. Again, when, from any cause, a particle of air has been put in motion toward the north or south, the combination of this motion with the rotatory motion of the earth produces a third force, which causes a deflection of the motion to the east when the motion is to the north, and a deflection to the west when it is toward the south. This is the same as one of the forces contained in La Place's general equations of the tides, the analytical expression of which is 2 n u r sin. l cos. l ; l being the latitude; n , the motion of the earth at the equator; u , the velocity of the particle north or south; and r , the radius of the earth. The fourth and last force arises from the combination of a relative east or west motion of the atmosphere with the rotatory motion of the earth. In consequence of the atmosphere's revolving on a common axis with that of the earth, each particle is impressed with a centrifugal force, which, being resolved into a vertical and a horizontal force, the latter causes it to assume a spheroidal form conforming to the figure of the earth. But, if the rotatory motion of any part of the atmosphere is greater than that of the surface of the earth, or, in other words, if any part of the atmosphere has a relative eastern motion with regard to the earth's surface, this force is increased, and if it has a relative western motion, it is diminished, and this difference gives rise to a disturbing force which prevents the atmosphere being in a state of equilibrium, with a figure conforming to that of the earth's surface, but causes an accumulation of the atmosphere at certain latitudes and a depression at others, and the consequent difference in the pressure of the atmosphere at these latitudes very materially influences its motions. This force is also expressed by one of the terms of La Place's equations, the analytical expression of which is 2 n v r sin. l ; v being the relative eastern or western velocity of the atmosphere.

Hadley's theory This theory, which is the commonly received theory of the trade-winds, and with which the reader is no doubt familiar, is based upon the first three forces only given above, no account being taken of the fourth. But as it may be seen from the analytical expressions of the last two forces given above, that the latter is greater than the former, and the east and west motion of the atmosphere depends upon the former, we have reason to suppose that the latter also may have a considerable effect, and that it should be taken into account in a correct theory of the winds. Accordingly we see that although Hadley's theory furnishes an explanation of the trade-winds, yet it does not account for many other remarkable phenomena in the motions of the atmosphere, but even requires motions to satisfy it entirely at variance with them. According to this theory, there should be a current on the surface of the earth from the pole to the equator in a kind of loxodromic spiral, and a similar counter-current in the upper regions from the equator towards the poles. The barometer also should stand highest at the poles where the air is coldest and most dense, and gradually fall as it is brought nearer the equator. But both of these, as we have shown, are contrary to observation. The position also of the exterior limits of the trade-winds near the parallels of 28°, the flowing of the atmosphere in the upper regions from both sides towards these parallels, and a low barometer near the polar circles, cannot be explained by this theory, and have not been satisfactorily explained by meteorologists. It is true Professor Espy says the highness of the barometer near the parallels of 28° is owing to the flowing over of the atmosphere which rises up at the equator; but this overflow of atmosphere could have no tendency to accumulate at these parallels, since it evidently would flow on gradually towards the poles to supply the draught caused by the flow towards the equator, as this theory requires. He also assigns as a cause of the low barometer about Cape Horn and the antarctic circle, the abundant rains which prevail there and the consequent disengagement of caloric, which rarefies the atmosphere there. But, if the belt of calms and rains near the equator is caused by the barometer standing lower there then at the outer limit of the trade-winds, which causes a flow of atmosphere there at the surface, and, if rains generally in any region, according to Professor Espy's own theory of clouds and rains, is caused by a low barometer there, and a consequent flowing in from all sides and a rising up of the atmosphere, then the lowness of the barometer in those regions must be the cause of the rains, and not the rain the cause of the lowness of the barometer, as will appear for other reasons.

We shall now undertake to show, that all these phenomena, and others connected with storms, which have never been accounted for by any theory, may be satisfactorily accounted for by taking into account the fourth force given above.

Why the outer limits of the trade-winds are near the parallels of 28°. - If from any cause the atmosphere receives a motion either towards or from the poles, the action of the third force above, causes a deflection of it towards the east, as it moves towards the poles, and towards the west as it moves towards the equator; and as the prime moving cause of the principal currents of the atmosphere has a tendency to cause it to flow towards and from the poles, the general result is, that towards the poles the atmosphere has a motion towards the east, but near the equator towards the west. But from the principle of the preservation of areas, the sum of the products of all the particles of the atmosphere, multiplied into their velocities and their distances from the axis of revolution, cannot be changed be the action of a central force, or by the mutual action of the particles upon each other; hence the sum of the products of each particle into its distance from the axis, and into its relative eastern velocity, must be equal to the sum of similar products, taken with regards to the particles having a relative western motion. But, as the portion of the atmosphere having a relative eastern motion, is nearer the axis than that which has a relative western motion, and as the part having a western motion, inasmuch as it is further from the axis, must be somewhat less than the part comprised between these parallels, in order to make the products equal, unless the relative velocity of the part having an easterly motion is very much greater. Hence, the dividing lines between the portions of the atmosphere having a relative east and west motion, must be within these parallels; and, as the outer limits of the trade-winds depend upon those lines, they must also fall within these parallels; and they are accordingly found to be about the parallels of 28°.

The cause of high barometer about the parallels of 28°, and the low barometer at the polar circles. - The greater pressure of the atmosphere at the parallels of 28° than at the equator and the polar circles can only be caused by an accumulation of atmosphere there. This accumulation results, necessarily, from the action of the new force which we have introduced into the theory of the winds. For, as we have seen, all the atmosphere between the parallels of 28° and the poles has, and, according to theory, must have, a general eastern motion; and this gives such a value to the analytical expression of the fourth force, enumerated above, as to cause the atmosphere to recede from the poles toward the equator. But the western motion of the atmosphere between the parallels of 28° gives that expression a negative value there; and, hence, this force causes the atmosphere to recede from the equator, also. This force then, has a tendency to cause the atmosphere in the upper regions to recede from both the poles and the equator, and to accumulate about the parallels of 28°, and, as it may seem by merely inspecting the expression of this force given above, that for the same value of v , or motion of the atmosphere east or west, this force is much greater toward the poles than it is near the equator, it causes a considerable depression of the atmosphere at the poles, and only a slight one at the equator, as represented in the diagram. The amount of this elevation and depression is not indicated entirely by the barometer, for the height of the barometer depends upon both the height of the atmosphere and its density. Therefore, as the atmosphere is much denser at the polar circles than at the parallels of 28°, on account of its being much colder, the accumulation of atmosphere at these parallels and its depression towards the poles, must be considerable to cause the barometer to stand higher at these parallels than the polar circles.

We shall now give the results of some calculations, based upon a reasonable hypothesis, which show that this new force introduced is entirely adequate to produce an accumulation of atmosphere at the parallels of 28°, and a depression of it at the poles to such an amount, that the difference in the height of the barometer at the parallels of 28°, and a depression of it at the polar circles, may correspond with observations. As friction is a very important element in calculations of the motion of the atmosphere, and its effect cannot be determined, it would be impossible to calculate the motion of the atmosphere from the forces which act upon it, if they were even accurately known. We will therefore assume certain motions of the atmosphere, which are known not to vary much from observation, upon which we will base our calculations. If we assume that the east and west motions of the atmosphere may be represented by the expression 2sin 3/2 p cos. 3/2 p v , p being the polar distance of the place, it would make these motions vanish at the poles and at the parallels of 30°, and we have reason to think, would pretty well represent the motions of the atmosphere east and west at all latitudes except near the equator, where it would make it a little too great. Upon this assumption it may be shown by calculations, the results of which only can be given here, that if v , or the maximum east or west motion of the atmosphere, were only ten miles per hour, it would cause a heaping up of the atmosphere near the parallels of 28° which would make the barometer, if the atmosphere were everywhere of the same density, stand two inches higer here than at the poles. The same hypothesis would also make the depression at the equator only one-ninth that at the poles. If we now suppose that the greater specific gravity alone of the atmosphere at the poles, is sufficient to cause the barometer to stand one inch higher there than at the equator, which would only require a difference of temperature of about 16°, it would still leave a difference in the height of the barometer between the poles and the equator about equal to the observed difference in the southern hemisphere. It would also add a little to the depression of the baromter at the equator, which would make it a little more than one-ninth of that at the poles, and consequently make it correspond with observation. We think therefore it is evident that the observed difference in the height of the barometer in difference latitudes, is owing to the joint effect of a gradual increase of specific gravity from the equator to the poles, and of a heaping up of the atmosphere near the parallels of 28°, caused by the action of this new force that we have taken into account.

Explanation of the passage-winds and calm-belts at the limits of the trade-winds. - As the pressure of the atmosphere, on account of its accumulation there, is greatest about the parallel of 28°, this pressure has a tendency to cause it to rush out from beneath both, towards the poles and the equator. If the motions of the atmosphere were as great at the surface of the earth as in the upper regions, the force which causes a heaping up of the atmosphere about the parallels of 28°, would be as great below as in the upper regions, and would prevent the flowing out of the air below towards the poles. But, on account of friction, the eastern motion of the atmosphere cannot be so great at the surface of the Earth as above, and consequently the accumulation of atmopshere mentioned above, is caused principally by the upper currents, and the pressure wich causes it to flow out below towards the poles, where the barometer, as we have seen, stands much lower, is greater than the force below which causes the accumulation of atmosphere. The lateral pressure then of the atmosphere, and its horizontal motion which has a tendency to cause it to flow at the surface of the Earth, from the poles towards the equator; and secondly, the heaping up of the atmosphere at the outer limits of the trade-winds, which causes it to rush out below, both towards the equator and the poles; thirdly the action of the force depending upon the east or west motion of the atmposphere, wich we have seen, must be greater above than at the surface of the Earth. Between the parallels of 28° and the equator, the first two forces combine against the latter, which is small near the equator, and produce a strong and steady current at the surface of the Earth towards the equator, which, being combined with the rotatory motion of the Earth, gives rise to the tradewinds. Beyond these parallels, the first and third forces are opposed to the second, but it may be seen from the analytical expression of this second force, obtained from our preceding assumption, and which cannot be given here, that this force is very great in the middle latitudes, and consequently it prevails over the two, causing a current towards the poles, which combined with the rotatory motion of the Earth, produces the southwest winds in the northern hemisphere, and northwest winds in the southern hemisphere, called passage-winds. This force has its maximum about the parallels of 48°, and above these decreases rapidly, so that at the polar circles the other two forces begin to prevail over it, and cause a current from the poles. The forces then acting upon the atmosphere at the surface of the earth, causes it to flow in opposite directions, from the parallels of 28° and the poles, and to flow together near the equator and the polar circles. Hence, there is a rising up of the atmosphere at the latter places, and a flowing thence in the upper regions to the former places, where it descends, and thus a system of current is produced as represented by the arrows in the external part of the diagram, which represents a meridional vertical section of the atmosphere. It was shown that about the parallel of 28°, the atmosphere can have no motion east or west, and it has now been shown that these are the parallels also of greatest pressure, whence the currents flow both towards the equator and the poles, consequently there must necessarily be here calm-belts, such as are well-known from observation to exist.

We think now, it is manifest, that the introduction of our new force into the theory of the winds, exactly accounts for all the principal motions of the atmosphere, and clears up the difficulties which have heretofore puzzled meteorologists.

Maury's theory of the crossing of the winds. In order to account for the motions of the winds and other phenomena, Lieutenant Maury advances the theory that there is a crossing of the winds or currents at the calm-belts of the equator and the parallels of 28°; that the currents flowing at the surface towards the equator, cross there, each becoming the upper current in the other hemisphere after it crosses the calm-belt at the equator, and then flowing towards the poles until it meets the upper current flowing toward the equator about the parallel of 28°, where there is supposed to be another crossing, each current then becoming again the surface current, and flowing in the same direction as before. [4] He also makes, by his arrangement, the rains in each temperate zone depend upon the vapor received by the winds in their passage to the equator as a trade-wind in the opposite hemisphere. We think there is no necessity for resorting to such an argument to account for the phenomena of the winds, but that they all are satisfactorily accounted for, as above, by tracing out the effects of well known forces without resorting to the mysterious agents of magnetism and electricity. Besides, there is no known principle by which two currents can interpenetrate and cross each other without mingling together, and, especially, is there none by which a current saturated with vapor can pass through a dry current and each one after afterwards retain its distinctive character of a moist or dry current, which this theory requires.

The fact that Ehrenberg has discovered South American infusoria in the blood-rains and "sea-dust" of the Cape Verde Islands and other places, does not prove the crossing of the winds; for, according to the explanation of the winds given above, there are two curents flowing into each calm-belt, and also two flowing out in opposite directions, as it were from a common reservoir, and, consequently, whatever is carried into these belts from either side down flow out again in each direction; and so infusoria in one hemisphere can easily pass to the other without a distinct crossing of the currents. And it even the moist current of the torrid zone could pass though the dry ones to the temperate zones, they could not produce rain there; for Professor Espy has conclusively shown that no descending current, however saturated with moisture, can ever produce rain. [5]

Explanation of the winds at the peak of Tenerife. - We have stated that the greatest atmospheric pressure is about the parallels of 28°, but these cannot be accurately the parallels of the greatest accumulation, for this pressure depends both upon the height of the atmosphere and its density, and, as the density increases gradually with the latitude, there must be an increase of pressure beyond the parallel of greatest accumulation, until the decrease of pressure from the one cause equals the increase from the other. But, as the calm-belts in the upper regions must be where the currents meet, and consequently where there is the greatest accumulation of atmosphere, it follows that the calm-belts are not exactly at the same parallels at the surface of the Earth as in the upper regions, but that they incline above toward the equator, as represented in the diagram. And this explains the peculiarity in the winds at the Peak of Tenerife. This peak stands near the outer limits of the trade-winds, and, as this limit moves north an south with the seasons, the northeast and southwest winds are found to prevail at the base alternatively. But at the top of the peak the southwest winds always prevail, because, when the calm-belt is furthest north, it still leaves the top of the peak north of it, where the southwest winds prevail, where the northwest trades are blowing below. When this belt occupies its most southern position, it leaves both at the top and the bottom of the peak north of it, and, consequently, the southwest wind blows both at the top and the bottom. In the fall, as the calm-belt moves south, more of the peak gradually becomes north of the calm-belt, and hence the southwest winds, which always prevail at the top, should gradually descend lower on the peak until they reach the base, which is exactly in accordance with observation.

The effect of continents - If the surface of the earth were all covered by the sea, uninterrupted by continents, the tradewinds and passage-winds, and also the calm-belts, would extend, without any interruption, entirely round the earth. But continents, and especially high mountain ranges, seem to have a very material effect in changing this regular system of winds. Thus the high table-lands and mountain ranges in Mexico and the western part of the United states, seem to turn the westward current of the trade-winds on the Caribbean sea and the Gulf of Mexico northward over the parallel of the calm-belt into the Unites States, where it arrives at the latitudes where the atmosphere has a general tendency to flow eastward, and thus a kind of aerial gulf-stream is produced. This is evident not only from observations on the general directions of the winds in the Guld of Mexico and the United States, but also from the observed routes of storms, which must be governed very much by the general movements of the part of the atmosphere in which they occur. Instead of the regular trade-winds from the northeast in the Caribbean sea, the prevailing cours of the lower current, is from a point south of east instead of north of east. [6] It is also found from observations at Barbedoes that, while the eastern winds are most prevalent, the southeast winds greatly predominate over the northeast ones. Of a great many hurricanes, also, which had their origin in the Atlantic, east of the Caribbean sea, and whose routes have been determined, by Mr. Redfield, nearly all moved in a direction north of west, until they arrived at the longitude of Florida or the Gulf of Mexico, where they curved around towards the north, and after passing the parallel of the calm-belt, towards the northeast, in the direction of Newfoundland and the northern part of the Atlantic. And this is exactly the route we would suppose the westward currents of the lower part of the atmosphere, interrupted by the high mountain ranges of Mexico, would take. But on the west coast of North America, the eastward current of the northern part of the Pacific, impinging against the range of the Rocky mountains, is turned down towards the equator, and hence the prevailing direction of the wind on the Pacific, west of Mexico, is from the northwest. The eastern coast of Africa also seems to have a similar effect upon the westward current of air in the Indian ocean; for the hurricanes which orginate in that ocean, on approaching that coast, are turned southward and finally towards the southeast into the southern ocean. The typhoons, also, of the China sea seem to be influenced in a similar manner by the eastern part of Asia. These changes of the general direction of the wind which prevail on the open ocean must be caused by the continents.

Hurricanes and storms. - Hurricanes are generally supposed to be produced by the meeting of adverse currents, which produce gyratory motions of the atmosphere at the place of meeting. That they may receive their origin and first impulse in this way, we think is very probable; but that violent hurricanes, extending over a circular area nearly one thousand miles in diameter, and continuing for ten days, and proceeding with increasing violence from the torrid zone to high northern latitudes, depends upon any primitive impuls alone, we think is very improbable. For if even any part of the atmosphere should receive such an impulse as to pruduce a most violent hurricane, friction would soon destroy all motion and bring the atmosphere to rest. Besides, no gradually accelerated motion can depend upon a primitive impulse alone, even where there is no friction. Hurricanes then, and all ordinary storms, must begin and gradually increase in violence by the action of some constantly acting force, and when this force subsides, friction brings the atmospher to a state of rest. This force may be furnished by the condensation of vapor ascending in the upward current in the middle of the hurricane, in accordance with Professor Espy's theory of storms and rains. According to this theory, all storms are produced by an ascending current of warmer atmosphere above by means of the caloric given out of the vapor which is condensed as it ascends to colder regions above. Therefore, as long as this ascending current can be supplied with air saturated with vapor this continual rarefaction must take place, and also the ascent of the air from all sides to supply its place. If, then, all the lower stratum of atmosphere over a large district were saturated with vapor, without some disturbing cause, it might remain undisturbed; but if from any cause an ascending current is produced, either by local rarefaction of air my means of heat, or by the meeting of two adverse currents, which produces a gyratory motion and consequent rarefaction in the middle on account of the pressures being taken away by the centrifugal force, as soon as the air below, saturated with vapor, ascends to the colder regions above, the vapor is condensed and the caloric given out continues to rarefy it so long as the ascending column is supplied with moist air, and consequently the surrounding colder air presses in below from all sides, and thus a hurricane of more or less violence is produced and kept up for ten or twelve days, moving with the general direction of the motion of the atmosphere where it occurs. The violence then of the hurricane, and also its duration, depends upon the quality of vapor supplied by the currents flowing in below. Hence, it is, that the tropical hurricanes which originate in the Atlantic, east of the Caribbean sea, do not abate their violence until they reach a high northern latitude where the atmosphere is cold and dry.

The cause of the gyratory motions of hurricanes. - It has been established by Redfield, Reid, Piddington, and others, that all hurricanes and ordinary storms have a gyroatory motion around a center, and that these gyrations in the northern hemisphere, ar from right to left against the hands of a watch, but in the southern hemisphere from left to right with the hands of a watch. There are some however, amongst whom is Professor Espy, who deny the gyratory character of storm entirely, and contend that there is only a rushing of the air from all sides below towards a centre, without any gyration. We think this gyratory character of storms has been too well established to admit of any doubt. No one, however, has ever given any satisfactory reason why these gyrations in the one hemisphere are always sinistrorsal and in the other dectrorsal. It is true, Mr Redfield [7] endeavors to account for the sinistrorsal gyrations of the hurricanes and storms which proceed from the Gulf of Mexico towards Newfoundland, by means of the pecularities of the aerial currents in the region of the Gulf and the adjacent coast of the Pacific. But if there are the same kind of gyrations over the whole hemisphere, it is evident that the cause which produces them must be as extended as the hemisphere itself. It has also been suggested that this tendency to a distinct kind of gyration in each hemisphere, may be owing to the magnetism of the air. [8]

We shall now undertake to show that there cannot be a rushing of air from all sides towards a center, on any part of the earth except at the equator, without producing a gyration, and that the tendency to a distinct kind of gyration in each hemisphere, is owing, neither to any pecularities of the winds or aerial currents, nor to the mysterious agent of magnetism, bu that it results, as a necessary consequence, form the action, upon the atmosphere, of the four forces which we have taken into consideration in the first part of this essay.

It has been shown that when a particle of air receives a motion toward the poles it is deflected toward the east, as in the passage-winds, but when it revieves a motion toward the south, there is a force which also turns it toward the west, as in the tradewinds. It has likewise been shown that when the air has a relative motion east, it has a tendency, on account of the greater centrifugal force, to move also towards the south, but that when it has a relative motion west, it has a tendency, on account of the diminished centrifugal force, to move also towards the north. If, then, we suppose that the air at M , N , O and P on the diagram (page 8), has a tendency, on account of rarefaction or for any other reason, to flow towards c , from what has been stated, the air at M would not move equally towards c , but would be deflected northward a little towards m . In like manner the air at N when there is any force which tends to make the surrounding air flow towards a center, the resultants of all the forces which act upon it must cause it to receive a gyratory motion, and that this motion in the northern hemisphere must be sinistrorsal, but in the southern hemisphere the contrary.

It may be observed here that these gyrations are not cucular but spiral, gradually approaching the center; for the forces which tend to produce these gyrations depend for their efficacy upon a motion from all sides towards the center. First, the force of which we have already treated tends to give the atmosphere a gyratory motion, as soon as it begins to converge towards a center; and secondly, these gyrations, however slight, being once produced, the centripetal force, which causes the air to flow towards the center, accelerates these gyrations as they approach the center, upon the principle by means of a string, are rapidly accelerated as the string becomes shorter. Hence if the first of these forces be only sufficient to produce a very slight gyration, the latter or centripetal force may cause very rapid gyrations near the center. And it is only upon this principle that the rapid motion of the air in a hurricane can be produced, and any theory which does not take this principle into account is defective. This centripetal force is caused by the superior pressure of the denser atmosphere on the borders of the hurricane or storm, and consequently prevails only in the lower part of the atmosphere. In the upper regions it has a tendency to recede from the center for two reasons; first, on account of the gyratory motion wich it has received below in appraoching the center, which it still, in some measure, retains after ascending to the regions above, where the surrounding pressure does not prevail, and consequently the centrifugal force resulting from the gyrations, causes it to recede from the center; secondly, because the ascending current causes an accumulation of atmosphere above the general level, which gives it a tendency also to flow out in all directions form the center. These motions however, are not distinctly towards and from the center, but in spirals, so that the currents below may be at right angles with the currents above; and hence it is that in our ordinary storms attended with rain, the clouds in the lower part of the atmosphere frequently move in a direction at right angles with the direction of those above.

It has been stated that the gyrations below approach the center in a spiral, but this approach must be slow towards the center; for, at a certain distance from the center, the gyrations becoms so rapid that the centrifugal force nearly equals the centripetal, produced by the external pressure of the atmosphere, and then the further appoach towards the center in a great measure ceases,and consequently the force which produces the gyrations. Hence, at a certain distance from the center the hurricane has the greatest violence, and within this circumference, friction in a great measure destroys the gyrations, so that the middle of our most violent hurrianes is a calm. The extent of this calm is a circle, varying generally from five to thirty miles in diameter.

If we examine the analytical expressions of the forces which produce these gyrations, we will see that at the equator they have no value, and hence no hurricane can have its origin exactly on the equator. Accordingly, of all the hurricanes which have originated within the tropics, none have been traced back to the equator, but always to some region from 10° to 20° from it.

The reason why the hurricanes which originate east of the Caribbean sea pass northward to the east of the United States, may be owing to the direction of the wind here and on the Caribbean sea, which generally blows north of west, as has been observed in the former part of this essay. If the general direction of the trade-winds prevailed here, they would be carried on towards the equator, as those without doubt are which originate at other places in the same latitude.

We come now ot the second part of our subject, the currents of the ocean.

The general motions of the ocean. - Inasmuch as the atmosphere and the ocean are both fluids somewhat similarly situated, except that there is a similarity of their general motions. This is known from observation to be the case, except that the continents interfere more with the motion of the ocean than with those of the atmosphere. The general motion of the ocean in the torrid zone, where it is not interrupted by continents, is toward the west with an average velocity of about ten miles in twenty-four hours. Towards the poles the motion, in general, is towards the east, which is a necessary consequence of the preservation of areas; for if one part have a western motion, another part must have an eastern one, as was shown with regard to the atmosphere. If, then, there were no continents, there would be a general flowing of all the tropical parts of the ocean westward, and of the remaining parts toward the east. But when the tropical or equatorial current impinges agains the eastern sides of the continents as in the Atlantic, a part is turned along the eastern side towards each pole. Likewise, when the eastern flow towards the poles, strikes against the western sides of a continent, it is deflected towards the equator. Hence the northern parts of both the Atlantic and Pacific, have a tendency to a vortical motion, their tropical parts moving westward, and then turning northward on the eastern sides of the continents and joining the eastern flow, and south again towards the equator on the western sides of the continents. And it is evident from observation, that the southern parts of these oceans, and also the Indian ocean, have a tendency, in some measure, to the same kind of motions, except that the continents do not extend so far south, and consequently only a part of the eastern flow is turned towards the equator, the rest flowing on and producing the general eastern motion of the waters observed in the southern ocean.

The forces which produce the motions of the ocean - The primum mobile of the motions of the ocean, as of the atmosphere, depends principally upon the difference of temperature between the equatorial and polar regions. The temperature of the ocean, on the surface at the equator, is about 80°, and it has a temperature above the mean temperature of the earth, which is 39°.5, to the depth of 7200 feet. Towards the poles it is below the freezing point, and continues below the mean temperature at the parallel of 70°, to the depth of 4500 feet.* As water expands about 0.000455 of its bulk for every degree of increasing tempeature, and sea-water contracts down to the temperature of 28°, calculations based upon these data, supposing the temperature to increase or decrease in proportion to the depth, make the specific gravity of the part at the equator, so much less than that at the poles, that it would have to rise about ten feet above the general level of the equator to be in equilibrium at the bottom of the sea, with the part at the poles. But then the equilibrium at the surface would be destroyed, and the waters would flow there towards the poles, where the superior pressure at the bottom over that of the equator, would cause a current to flow back at the bottom of the sea, towards the equator. Hence, if this cause of disturbance existed alone, ther would be a current at the bottom of the sea from the poles to the equator, moved by a force equal to the pressure of a stratum of water of about five feet, and one at the surface from the equator towards the poles, moved by an equal force. But this motion, combined with the rotatory motion of the earth, gives rise to other forces, just as in the case of the atmosphere, which greatly modify these motions, as will be shown hereafter.

The preceding are the principle forces concerned in giving motion ot the waters of the ocean. Lieutenant Maury, however, lays little stress upon these, and seems to think that the principle agencies concerned in these motions, arise from evaporation, the saltness of the ocean, galvanism, &c.* But we think it may be shown that these agencies can have no perceptible effect.

First, Lieutenant Maury supposes excessive evaporation to take place within the tropics and this vapor to be carried away and precipitated in extra-tropical regions, and infers that this would have, at least, a very sensible effect in producing the currents of the ocean. He puts the amount of evaporation of a stratum of one-half of an inch per day. Now if a stratum of water one-half of an inch in thickness is evaporated in twenty-four hours in one place and precipitated in another, it produces a difference of level of one inch between the two places, and the currents which it produces must be such as are sufficient to restore this level in the same space of time. Now we may judge how exceedingly small a current this would produce when we consider that there is a rise of about two feet in the open ocean at one place and a fall of the same amount at another every six hours, caused by the tides, and yet the flowing of the water from the one place to the other place to produce this rise at one place, and fall at the other, it is well known does not produce any sensible currents in the open sea. Again, this matter can be easily reproduced by calculation. If a stratum of water, one-half of an inch in thickness were taken up by evaporation from the torrid zone, and none of it precipitated there but all conveyed to the temperate and polar zones, it may be demonstrated upon the supposition that the ocean is four miles in depth, that the flow of water towards the equator to restore the equilibrium in the same time would not amount to a velocity of one foot per hour.

We think it may be likewise shown by calculations based upon reasonable hypothesis, if not entirely upon well-known data, that the salts of the sea also can have but little influence in producing currents. Lieutenant Maury makes a similar hypothesis in treating of the influence of the salt of the ocean, which he does in treating of the influence of evaporation, and supposes that the excess of salt left in the torrid zone by the excess of evaporation there, and the great precipitation in the temperate and polar regions produces such a difference in the specific gravity as to destroy the equilibrium of the sea, and to have a very sensible influence in producing current, and especially the Gulf-stream.

With regard to the latter, he supposes that the water of the Gulf of Mexico has a much greater specific gravity than the water in the Atlantic, on account of the great evaporation to which it has been exposed in its passage from the coast of Africa across the Atlantic ocean and through the Caribbean sea, and that, consequently, it is forced out into the Atlantic by its greater pressure. Now, suppose it takes the water a year, which is about the actual time, to pass from the coast of Africa to the Gulf of Mexico; in this time, according to the hypothesis, there is evaporated a stratum of water fifteen feet in depth, and, as the salt contained in this stratum cannot be evaporated, it remains in the part left, and increases it saltness. But sea-water contains only about three per cent of saline matter, and consequently the amount of salt contained in this stratum of fifteen feet only increases the weight of the rest to an amount equal to the weight of a stratum of water about six inches deep. Hence, it only gives the water of the Gulf a tendency to flow out into the Atlantic with a force equal to the force with which a homogenous fluid would flow out with its surface six inches above the general level of the Atlantic. This is much less than the opposing force arising from the great specific gravity of the water in the northern part of the Atlantic on account of its lower temperature, as we have shown by calculations. The same reasoning may be applied to any other part of the ocean; for, if the salt of the ocean has any influence in producing currents, it must be to produce an undercurrent from the torrid zone, where evaporation is supposed to be in excess, toward the poles, and consequently, a counter-current at the surface from the poles toward the equator. But, upon any reasonable hypothesis, the water at the surface cannot lose by evaporation in passing from the poles to the equator, a stratum of water of such a depth, that the amount of salt contained in it can increase the specific gravity at the equator as much as the lower temperature increases it toward the poles; hence, if the salt of the sea has any sensible influence, it is only in opposition to a greater influence, and, consequently, it has a tendency to diminish, rather than increase, the currents of the ocean. We think it, therefore, manifest that neither evaporation nor the salts of the sea can have much influence in producing currents, even upon Lieutenants Maury's hypothesis, that evaprotation is greatly in excess of precipitation in the torrid zone. But is this a true hypothesis? Although there is a great evaporation in the torrid zone, there is also great precipitation; for, with few exception, more rain falls at the equator than in any other part of the earth, and it is only the amount of evaporation over precipitation that should be taken into account, which we have reason to think is very small, and, if professor Espy's theory is correct, it can not be anything; for, according to this theory, no vapor can pass from the torrid to the temperate zones and produce rain, since the current bearing it there would be a descending current, and consequently could not produce it.

The ocean not level. - As it has been shown in the case of the atmosphere, that the resultant of the forces causes an accumulation about the parallels of 28°, so as the motions of the ocean are somewhat similar, and it is acted upon by the same forces, it may be shown that there must be a slight accumulation about those parallels in the ocean also. Whatever may be the causes of the motion of the ocean, we know that in the torrid zone it has a small western motion, and in the other parts a slight motion towards the east. The great equatorial current of the Atlantic moves about ten miles in twenty-four hours, but if we suppose that the average motion of the water in the torrid zone is five miles only per day, and that the mximum velocity of the water eastward in the extra-tropical regions is the same, using the same hypothesis we did with regard to the atmosphere, the forces which result from these motions must cause an accumulation of more than forty feet about the parallel of 28°, above the level of the sea at the poles, and about five feet above the level of the equator. This however, would be the amount of accumulation to produce an equilibrium of the forces at the surface, but as this accumulation would then produce greater pressure there upon the bottom than towards the poles and at the equator, it would produce, as in the case of the atmosphere, a flowing out from beneath this accumulation towards the poles and the equator, and settling down of the surface above, below the state of equilibrium, sufficient to cause a counter-current at the surface from the poles and the equator to supply the currents below. The accumulation there would be only about one-half that stated above, and there would be a flowing of water at the surface from both sides towards the parallel of 28°, and below a current in both directions from these parallels, similare to the motions in the atmosphere.

That the water of the ocean has such a motion as has been stated, appears from observations of its motions and other circumstances. Says Lieutenant Maury, "There seems to be a larger flow of polar water into the Atlantic than of waters from it, and I cannot account for the preservation of the equilibrium of this ocean by any other hypothesis than that which calls in the aid of undercurrents." It is well-known that in Baffin's bay there is a strong surface-current running south, and a strong counter-current beneath running north. Another evidence of this general tendency of the waters, is, that icebergs, in both hemispheres, are drifted from the poles towards the equator, and in the south Atlantic and Pacific oceans,there are large collections of drift and sea-weed about the parallels of 28°, so thickly matted that vessels are retarded in passing through them. [9]

These collections can only be formed by the flowing of the water at the surface from both sides to these parallels. It has been supposed that these collections are owing to the slight vortical motion of these oceans, it being supposed that any floating substances on the surface would have a tendency to collect at the vortex. This, however, would not be the case, for on account of friction at the bottom, the surface would have a greater vortical motion than the bottom, and consequently the water would be driven very slowly at the surface by the centrifugal force towards the sides, where it would cause a slight elevation and increase of pressure, which would cause the water to return towards the vortex at the bottom and not at the top; and hence floating substances at the surface could have no tendency to collect at the vortex.

We have corroborated these deductions from theory by numerous experiments made with a vessel of water with light substances on the surface. When the vessel is first receiving a vortical motion, the substances collect in the middle; for, as it is the vessel which gives motion to the water by means of the friction, the vessel, and consequently the bottom of the water, has then a greater motion than the top; and hence the reverse of what is stated above takes place; but, if the vessel is now stopped, and the water within allowed to continue its motion, the vortical motion at the bottom is retarded faster than at the top, and soon has a slower motion there, when the light substances on the surface are seen to recede from the vortex towards the sides, and if there are any light substances on the bottom they collect in the centre, all of which proves, that the water recedes from the middle at the surface, and returns to it at the bottom, and exactly agrees with the deductions from theory. These collections of sea-weed, then, cannot be caused by the vortical motions of the ocean, but must be the result of a general tendency of the surface water, to flow from both the equator and the poles towards these parallels; and, as it is prevented from collecting on these parallels near either side, on account of the slight vortical motion of the ocean, it collects only in the middle.

Explanation of the Gulf-stream - We come now to the Gulf-stream, which has been a puzzle to philosophers ever since it was discovered. Many explanations have been given, and all known forces which can have any influence, have been brought in to account for this wonderful phenomenon. The most usual explanation is, that it is the escaping of the waters which have been forced into the Caribbean sea and the Gulf of Mexico by the trade-winds, which have been supposed to raise their surface above the general level, and thus afford a head as it were for the stream. This, without doubt, has a very considerable effect, but it has not generally been deemed adequate alone to account for the phenomenon, nor does it, in connection with all other known influences, afford a satisfactory explanation. "What is the cause of the Gulf-stream." says Lieutenant Maury, "has always puzzled philosophers. Modern investigations are beginning to throw some light upon the subject, though still all is not yet clear."

We shall now endeavor to show that the additional force which we have taken into account in explaining both the winds and the currents of the ocean, and which seems to have been overlooked heretofore, will at least throw much additional light upon the subject, if not afford a complete explanation. We have shown that this force, which results form the eastward flow of the water in extra-tropical regions, and from the western motion within the tropics, has a tendency to drive the water from the poles towards the equator, and also slightly from the equator towards the poles, and to produce an accumulation of at least twenty feet on the parallel of 28° above the level at the poles, upon the supposition that the maximum of this east and west flow is only five miles per day. But if, from any cause, the force which results from this eastward flow should be cut off at any place, the water would flow northward at that place with a force equal to that which would result from a head on the parallels of 28°, at least twenty feet above the level towards the poles. Now, it may be seen from the configuration of the coast of the United States, that this force is actually cut off along that coast; for this force depends upon the eastward flow of the water there, which it cannot have, inasmuch as it must flow in both ways along the coast to fill up the vacuum which such a motion would produce. As the Gulf of Mexico, therefore, and the adjacent parts of the Atlantic, lie in the parallel of greatest accumulation, the water must flow from these parts along the coast with a force equal to that stated above. In addition to this, the momentum of the water flowing westward in the torrid zone, with a motion depending upon the prime moving course, due to a difference of specific gravity between the poles and the equator, in connection with the rotatory motion of the earth, and being independent of the effect of the trade-winds, must force the water in the Caribbean sea and the Gulf of Mexico considerably above the general level and add to the preceeding force. When we consider that the motion of the water which produces tides on our coasts, is in general imperceptible in the open ocean, and yet, on account of the sloping bottom of the ocean, which causes a smaller volume of water to receive the momentum of a larger one, it causes considerable rise of the water along the coast, we have reason to think that the general tendency of water westward in the torrid zone may keep the water in the Gulf considerably above the general level, since its water and that in the Caribbean sea, if the bottom of the ocean be sloping, must in great measure receive the momentum of the whole body of the water moving westward in the adjacent part of the Atlantic. The eastern tendency of the water in the northen part of the north Atlantic, due to the prime moving force mentioned above and independent of the winds which prevail there, causes the surface of the ocean in the latitude of Newfoundland to be somewhat depressed below the general level next to the coast, which also adds to the force of the Gulf-stream. All these forces, taken in connection withthe influence of the trade-windst, to which this phenomenon has been mainy attributed, we think, furnish a complete and satisfactory explanation of that great wonder and mystery of the ocean, the Gulf-stream.

The Greenland and other currents. - The general eastward motion of the waters of the ocean in the northern part of the Atlantic, and consequent depression next the coast of North America, also furnish an explanation of the cold current of water flowing between the Gulf-stream and the coast of the United States, called the Greenland current. On account of the rotatory motion of the earth, the water of the Gulf-stream in flowing northward, tends to the east, and for the same reason the water flowing from Greenland and Baffin's bay to supply the eastern flow, tends towards the west, and consequently flows in between the Gulf-stream and the coast of the United States.

There must be a motion of the waters somewhat similar to that of the Gulf-stream and the Greenland current, wherever the great equatorial current impinges against a continent, and the eastward flow towards the poles is cut off. Hence, on the eastern coast of South America, there is a warm Brazilian current towards Cape Horn, and on the eastern coast of Africa, the Mozambique current which at the Cape of Good Hope is called the Agulhas current. Also, on the eastern coast of Asia, there is the warm China current, flowing towards the north, similar to the Gulf-stream, and the cold Asiatic current, insinuating itself between it and the coast, like the Greenland current.

On the western side of the continents a motion somewhat the reverse of this must take place. Hence, instead of a warm stream flowing towards the north, there is a cold current flowing towards the equator. On the west of Portugal, and the northern part of Africa, there is a flow of colder water towards the equator, both to join the great equatorial current flowing across the Atlantic. On the west coast of South America, is Humboldt's current, 8° or 10° colder than the rest of the ocean in the same latitude, both tending towards the equator to there join the great western current across the Pacific, and to fill up, as it were, the vacuum which this current has a tendency to leave about the equator, on the western coast of America.

NASHVILLE, October 4, 1856.

• ↑ Physical Geography of the sea, page 70.
• ↑ Professor Espy's Third Report on Meterology, § 101.
• ↑ See Kaenitz' Meteorology. by C. Walker, page 277.
• ↑ See "Physical geography of the Sea" § 106.
• ↑ Third report on Meteorology §§ 68, 69.
• ↑ See W. C. Redfield Esq. on three several hurricanes, etc., in Silliman's Journal, second series, vol. I., page 13.
• ↑ Silliman's Journal, second series, Vol II., page 325.
• ↑ Maury's Physical Geography of the Sea § 224.
• ↑ Humbold's Cosmos, Vol. 2 page 278

This work was published before January 1, 1929, and is in the public domain worldwide because the author died at least 100 years ago.

Public domain Public domain false false

• Meteorology
• Headers applying DefaultSort key

Navigation menu

• IAS Preparation
• UPSC Preparation Strategy

Ocean Currents

What is Ocean Current? It is a horizontal movement of seawater that is produced by gravity, wind, and water density. Ocean currents play an important role in the determination of climates of coastal regions.

As an important topic of Geography (Oceanography), questions could be framed either in Prelims or Mains (GS 1) papers of the IAS Exam .

Candidates can check previous years’ Geography Questions in UPSC Prelims in the linked article.

Understand the basics of ocean currents in this article.

Ocean Water and Ocean Currents

The movement of ocean water is continuous. This movement of ocean water is broadly categorized into three types:

The streams of water that flow constantly on the ocean surface in definite directions are called ocean currents.

Ocean currents are one of the factors that affect the temperature of ocean water.

• Warm ocean currents raise the temperature in cold areas
• Cold ocean currents decrease the temperature in warmer areas.

To understand the ocean waves and related concepts, check the links below:

Relevant Facts about Ocean Currents for UPSC

• The magnitude of the ocean currents ranges from a few centimetres per second to as much as 4 metres (about 13 feet) per second.
• The intensity of the ocean currents generally decreases with increasing depth.
• The speed of ocean currents is more than that of upwelling or downwelling which are the vertical movements of ocean water.
• Warm Ocean Currents
• Cold Ocean Currents

What causes ocean currents?

Horizontal pressure-gradient forces, Coriolis forces, and frictional forces are important forces that cause and affect ocean currents. NCERT Notes on Factors Affecting Wind mention Coriolis Force that one can read in the linked article.

Rise and fall of the tide

Tides give rise to tidal currents. Near the shore, tidal currents are the strongest. The change in tidal currents is periodical in nature and can be predicted for the near future. The speed of tidal currents at some places can be around 8 knots or more.

The ocean currents at or near the ocean surface are driven by wind forces.

Thermohaline Circulation

‘Thermo’ stands for temperature and ‘Haline’ stands for salinity. The variations in temperature and salinity at different parts of the oceans create density differences which in turn affect the ocean currents.

What is a Frictional Force?

The movement of water through the oceans is slowed by friction, with surrounding fluid moving at a different velocity. A faster-moving layer of water and a slower-moving layer of water would impact each other. This causes momentum transfer between both layers producing frictional forces.

What are geostrophic currents?

When the pressure gradient force on the ocean current is balanced by the Coriolis forces, it results in the geostrophic currents.

• The direction of geostrophic flow is parallel to an isobar.
• The high pressure is to the right of the flow in the Northern Hemisphere, and the high pressure to the left is found in the Southern Hemisphere.

North and South Equatorial Currents

North Equatorial Current

• North Equatorial Current flows from east to west in the Pacific and the Atlantic Ocean.
• North Equatorial Current flows between the latitudes of 10 degrees and 20 degrees north.
• It is not connected to the equator.
• Equatorial circulation separates this current between the Pacific and Atlantic oceans.

South Equatorial Current

• It flows in the Pacific, Atlantic, and Indian oceans.
• The direction of the south equatorial current is east to west.
• The latitudes in which the current flows are between the equator and 20 degrees south.
• It flows across the equator to 5 degrees north latitudes in the Pacific and Atlantic Oceans.

What is the Equatorial Counter Current?

It is found in the following three oceans:

• Indian Ocean
• Atlantic Ocean
• Pacific Ocean

It is found between north and south equatorial currents at about 3-10 degrees north latitude.

What is Antarctic Circumpolar Current?

The ocean current that flows clockwise around the Antarctic is called the Antarctic Circumpolar Current. It is also called West Wind Drift. It is a feature of ocean circulation of the Southern Ocean.

• It does not have a well-defined axis
• It consists of a series of individual currents which are separated by frontal zones.

What is a Global Conveyor Belt?

A system of ocean currents that helps in the transportation of water around the world is called a global conveyor belt. As per National Geographic, “Along this conveyor belt, heat and nutrients are moved around the world in a leisurely 1000-year cycle.”

Distribution of Ocean Currents

The ocean currents are distributed across five oceans. The list of important ocean-wise currents is given below:

Download the  UPSC syllabus from the linked article as it will help candidates to remain on track while they prepare for any topic.

Frequently Asked Questions on Ocean Currents

Q 1. what is meant by ocean current, q 2. what are tidal currents.

For Geography preparation, check the links below:

Leave a Comment Cancel reply

Your Mobile number and Email id will not be published. Required fields are marked *

Request OTP on Voice Call

Post My Comment

IAS 2024 - Your dream can come true!

Download the ultimate guide to upsc cse preparation.

• Share Share

Register with BYJU'S & Download Free PDFs

Register with byju's & watch live videos.

• Ocean Exploration Facts

Why do we explore the ocean?

Exploration is key to increasing our understanding of the ocean, so we can more effectively manage, conserve, regulate, and use ocean resources that are vital to our economy and to all of our lives..

To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video 

We explore the ocean because it is important to ALL of us. Thanks to game-changing technological advancements, we can now look into the ocean like never before. But exploration can only be achieved through cooperation and collaboration, such as the partnership between the NOAA Ocean Exploration, Schmidt Ocean Institute, and Ocean Exploration Trust. Video courtesy of the Schmidt Ocean Institute. Download larger version (mp4, 225 MB) .

Despite the fact that the ocean covers approximately 70% of Earth’s surface and plays a critical role in supporting life on our planet, from the air we breathe and the food we eat to weather and climate patterns , our understanding of the ocean remains limited .

Ocean exploration is about making discoveries, searching for things that are unusual and unexpected. As the first step in the scientific process, the rigorous observations and documentation of biological, chemical, physical, geological, and archaeological aspects of the ocean gained from exploration set the stage for future research and decision-making.

Through ocean exploration, we collect data and information needed to address both current and emerging science and management needs. Exploration helps to ensure that ocean resources are not just managed, but managed in a sustainable way, so those resources are around for future generations to enjoy. Exploration of the U.S. Exclusive Economic Zone is important for national security, allowing us to set boundaries, protect American interests, and claim ocean resources.

Unlocking the mysteries of ocean ecosystems can reveal new sources for medical therapies and vaccines, food, energy, and more as well as inspire inventions that mimic adaptations of deep-sea animals. Information from ocean exploration can help us understand how we are affecting and being affected by changes in Earth’s environment, including changes in weather and climate. Insights from ocean exploration can help us better understand and respond to earthquakes, tsunamis, and other hazards.

The challenges met while exploring the ocean can provide the impetus for new technologies and engineering innovations that can be applied in other situations, allowing us to respond more effectively in the face of an ocean crisis, such as an oil spill. And, ocean exploration can improve ocean literacy and inspire young people to seek critical careers in science, technology, engineering, and mathematics.

As a species, humans are naturally inquisitive — curiosity, desire for knowledge, and quest for adventure motivate modern explorers even today. And if all of these examples don’t provide enough reasons to explore the ocean, well, ocean exploration is also just cool (if you need it: proof ).

NOAA Ocean Exploration is a federal organization dedicated to exploring the unknown ocean, unlocking its potential through scientific discovery, technological advancements, and data delivery. By working closely with partners across public, private, and academic sectors, we are filling gaps in our basic understanding of the marine environment. This allows us, collectively, to protect ocean health, sustainably manage our marine resources, accelerate our national economy, better understand our changing environment, and enhance appreciation of the importance of the ocean in our everyday lives.

Related Education Materials

To Boldly Go

Grade Level: 6-8 Focus: Science/Technology

Students use learning shapes to explore modern reasons for ocean exploration including: climate change, energy, human health, ocean health, research and exploration, technology and innovation, underwater cultural heritage, and ocean literacy. This lesson can be used to acquaint students with the concept of ocean exploration and build a foundation for additional lessons.

Why Do We Explore the Deep Ocean? (pdf, 722 KB)

For More Information

How much of the ocean has been explored?

Why do we explore the water column?

Ocean exploration matters.

Loading metrics

Open Access

Essays articulate a specific perspective on a topic of broad interest to scientists.

See all article types »

Living in relationship with the Ocean to transform governance in the UN Ocean Decade

Affiliation Earth Law Center, Durango, Colorado, United States of America

* E-mail: [email protected]

Affiliation School of Environment, Resources, and Sustainability, University of Waterloo, Waterloo, Ontario, Canada

• Michelle Bender, 
• Rachel Bustamante, 
• Kelsey Leonard

Published: October 17, 2022

• https://doi.org/10.1371/journal.pbio.3001828
• Reader Comments

Humanity’s relationship with the Ocean needs to be transformed to effectively address the multitude of governance crises facing the Ocean, including overfishing, climate change, pollution, and habitat destruction. Earth law, including Rights of Nature, provides a pathway to center humanity as a part of Nature and transform our relationship from one of dominion and separateness towards holism and mutual enhancement. Within the Earth law framework, an Ocean-centered approach views humanity as interconnected with the Ocean, recognizes societies’ collective duty and reciprocal responsibility to protect and conserve the Ocean, and puts aside short-term gain to respect and protect future generations of all life and the Ocean’s capacity to regenerate and sustain natural cycles. This Essay presents Ocean-centered governance as an approach to help achieve the 10 challenges for collective impact put forward as part of the UN Decade of Ocean Science for Sustainable Development and therefore living in a harmonious relationship with the Ocean.

Citation: Bender M, Bustamante R, Leonard K (2022) Living in relationship with the Ocean to transform governance in the UN Ocean Decade. PLoS Biol 20(10): e3001828. https://doi.org/10.1371/journal.pbio.3001828

Academic Editor: Emanuele Di Lorenzo, Brown University, UNITED STATES

Copyright: © 2022 Bender et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Abbreviations:: ECV, essential climate variable; EOV, essential ocean variable; IPBES, Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services; IOC, Intergovernmental Oceanographic Commission; MSY, maximum sustainable yield; SDG, Sustainable Development Goal; UNCLOS, UN Convention on the Law of the Sea

Introduction

The UN Decade of Ocean Science for Sustainable Development (2021 to 2030) aims to transform Ocean science to support sustainable development, such as via Sustainable Development Goal (SDG) 14 (Life Below Water), and to connect people to the Ocean [ 1 , 2 ]. The UN General Assembly declared the UN Ocean Decade in December 2017 after the Intergovernmental Oceanographic Commission (IOC) of UNESCO developed a proposal for the decade to champion new oceanographic scientific, technological, and research advancements to support Ocean sustainability, as outlined in SDG14 [ 3 , 4 ]. The IOC was further charged with developing an implementation plan for the decade and established 7 societal outcomes and identified 10 decadal challenges ( Table 1 ) [ 3 ].

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

https://doi.org/10.1371/journal.pbio.3001828.t001

Several global environmental principles and norms (such as sustainable and equitable use) have long been debated, ill-defined on the global scale and not yet effectively implemented [ 5 , 6 ]. Most importantly, the Ocean has historically been underrepresented within international regimes that implement these environmental principles. For example, the UN Framework Convention on Climate Change does not reference the UN Convention on the Law of the Sea (UNCLOS), and the Paris Agreement only mentions the Ocean in the preamble (therefore holding “less legal value than the Treaty”) and vaguely references the conservation of “sinks and reservoirs of greenhouse gasses” in Article 5, despite the Ocean’s vital role in regulating and dictating climate [ 7 – 10 ]. There is growing discourse calling for the development of a new Ocean ethos, of established and widely accepted norms, legal principles and collective values, for greater representation of the Ocean in international law, and recognition of the Ocean’s vital processes in regulating our climate and sustaining life beyond acting as a carbon sink [ 8 , 11 ].

In order to deliver the science needed for a “well-functioning ocean” and achieve SDG14, it is important to note that tension exists regarding the definition and guiding frameworks for “sustainability” [ 1 , 12 ]. Ensuring development meets present needs while not compromising the needs of future generations has been found to be far more difficult to achieve in practice, and the SDGs have been criticized for the way growth is measured, continued adherence to “business as usual” practices, economically focused metrics, the persistence of inequality and injustices, and the lack of a holistic view to not only achieve each goal, but also in acknowledging the relationships between goals [ 13 – 15 ]. As a result, many call for a stronger interpretation of sustainability that addresses the root causes, as well as the consequences, of environmental destruction and provides a diverse understanding of the value of Nature beyond instrumental and human-centered values [ 15 , 16 ]. As noted by Campagna and colleagues, “[c]hanging this not only requires complying with the scientific evidence of dependency of humanity on nature, but forces the conservation community to analyze its concept of nature and clarify the ethical grounds for valuing life” [ 17 ]. Maintaining the status quo of environmental law equates to the legalized destruction of Nature. International law needs to evolve to reflect the Ocean’s inherent rights to exist, flourish, and regenerate. Ocean health is human health.

In this Essay, we offer Earth law as a framework that can act as a catalyst to transform humanity’s relationship with Nature and ensure science and sustainable development expand beyond a utilitarian dimension [ 17 ]. Earth law is a philosophy of law based upon “the interdependence among humans and the environment” and guided by principles of holism, mutual enhancement, and reciprocal responsibilities, among others [ 16 , 18 ]. Earth law promotes a greater respect for all living things on Earth by recognizing that nonhumans have inherent rights and value, merely by existing [ 19 , 20 ]. This connection with Earth is restored vis-à-vis the holistic reconceptualization, adaptability, and flexibility of human ethics, institutions, and laws [ 16 , 19 ]. Rights of Nature is one legal framework within the body of Earth law. As evidenced by global comparative studies, Rights of Nature recognizes Nature as a living being with inherent rights and that society has a right to defend and protect Nature [ 16 , 18 – 22 ]. Therefore, the emerging Rights of Nature movement seeks to illustrate Nature as valued for itself (intrinsic value), no longer viewed as an object or property, but as a subject with rights [ 23 ]. As such, references to the Ocean, Ocean-centered governance, and Nature are capitalized in this Essay to be consistent with the Rights of Nature framing and recognition as a legal entity and noun. For example, Helen Dancer posits that this distinction, albeit contentious, frames “Nature as subject,” rather than as “service-provider,” as is commonly articulated in discourse of the human–Earth relationship, and has been embedded within global frameworks, particularly prevalent in Latin America (Constitution of Ecuador) and globally seen within the UN Harmony with Nature project [ 24 ]. Indeed, this assumption is not novel, but reflects histories of belief systems and worldviews; “the Ancient Greek Earth goddess, Gaia, Ancient Celtic belief systems in Europe and the cosmovisions of many Indigenous Peoples today center on respect for Mother Earth” [ 24 ]. Following the scholarship of Stefan Helmreich, we seek to invoke a higher respect for the Ocean and Nature, not as objects, but living entities. Helmreich emphasizes the need for all scientists to “renarrate,” “reorient,” and reposition our relationship to the Ocean through processes of “oceanization.” A process of justice that promotes Ocean vitality by affirming the Ocean as living and disrupting colonial webs of ecological subjugation embedded in social, political, and economic systems since the onset of the Anthropocene [ 25 , 26 ].

Earth law advances several assumptions in the conceptualization and implementation of ecocentric legal theory (or Earth-centered governance) and, therefore, the necessity to advance a new paradigm for Ocean governance. First, Earth law assumes that all of Nature (ecosystems and species, plants, microorganisms and animals, as well as biotic and abiotic components) have inherent and fundamental rights [ 17 ]. Earth law also assumes that humans exist as a part of Nature within an inextricable and complex web of relationships, and as a result, human rights are embedded within and dependent on the realization of Nature’s inherent rights [ 27 – 29 ]. Just as humans have rights based on our existence and being, so too does Nature. Second, to date, environmental law has largely contributed to, and is unable to effectively react to, the growing environmental crisis. This is predominantly the result of a colonial worldview of humanity as separate from and owners of Nature, largely anthropocentric (human-centered) environmental laws and policies, and equating Nature to a resource and property with value derived from benefit and utility to humankind [ 20 , 27 , 30 – 34 ]. Although not all worldviews and legal frameworks adopt this paradigm, within this Essay, we use the vision for the Ocean Decade: “the science we need for the ocean we want,” as an example of international community norms and values that convey that humans are the primary beneficiary of a healthy Ocean [ 1 ]. Earth-centered governance, on the other hand, represents a paradigm shift in law and in thinking about humans as a part of the Earth system, aiming to understand and respect “the interactions between living (human and nonhuman) and nonliving Earth system constituents and processes, the multiple intertwined and complex governance challenges arising from such interactions, and particularly the deepening interconnected social-ecological disruptions through a complex web of feedback loops” [ 35 ]. As a result, Earth law offers a new overarching framework, based upon a shared ethic that embeds humans within Nature, for which sustainability can be reinterpreted under, address many of the concerns with its implementation, and ensure effective realization of the UN Decade of Ocean Science societal outcomes.

We asked ourselves “how might Ocean-centered governance principles transform the types of solutions put forward to address the UN Ocean Decade Challenges?” In answering this question, this Essay explores how Earth law can reshape Ocean governance to prioritize the needs of the Ocean to address societal outcomes for Ocean well-being. The development of Earth-centered law is still in its infancy in its application for Ocean protection, but precedents exist to inform the development of how humanity may respect the inextricable relationship with the Ocean and ensure science and governance frameworks such as “sustainability” center Ocean needs properly within Ocean governance (i.e., Ocean-centered governance). In this Essay, we review each of the 10 Ocean Decade challenges of the UN Decade of Ocean Science for Sustainable Development to identify pathways for solutions to pressing Ocean crises following Ocean-centered governance principles. Across these Ocean challenges, the UN Ocean Decade developed 7 outcomes to describe the “Ocean we want” ( Table 1 ). Building upon the existing literature, we highlight case studies of Ocean-centered governance across jurisdictional scales. Some examples are unique to the legal system, culture, issues, or politics present and the way they would apply or be implemented will therefore be dependent upon myriad factors including the geographic, temporal, and jurisdictional scales.

Additionally, we acknowledge that many Indigenous Peoples do not express their relationships with other humans and the natural world in terms of “rights” and that care is needed in considering appropriate ways to engage with law due to the role that western law has played in the colonization and subjugation of Indigenous Peoples, lands, and waters. As a result, tension exists between some applications of Rights of Nature and Indigenous worldviews and customary law, which has been found to overstate the connection between Rights of Nature and the legal framework being an Indigenous philosophy, as well as findings of co-opting Indigenous ontologies into universalist hegemonies [ 36 – 38 ]. However, we adopt a more conscientious approach of Earth law and Earth-centered governance, which offers a broader interpretation of Rights of Nature in order to address such concerns. Additionally, this provides a blueprint of concrete actions that scientists, practitioners, and world leaders can adopt to promote Ocean-centered governance to advance the UN Ocean Decade outcomes worldwide.

Ocean-centered governance

In order to achieve effective implementation of the UN Ocean Decade, we must recognize the interconnection and interdependence of humankind with the Ocean. One pathway to do so is through an Ocean-centered approach, which fundamentally is based upon governance principles that prioritize and apply the ecological needs and interests of the Ocean; in other words, a process that promotes scientists and decision-makers to shift from an anthropocentric lens to an Ocean-centered lens. Though great strides have been made since the industrial era, western governance systems have largely failed to protect the complex interactions and relationships between humankind and the Ocean, consider diverse knowledge systems, and include Indigenous, local, and coastal communities and traditional knowledge and science [ 6 , 39 – 41 ]. This disenfranchisement of scientific plurality maintains “business as usual” strategies rather than promoting shifts to imaginative and novel governance approaches to address our unbalanced relationship with the Ocean. In writing this Essay, we conceptualized 5 principles for Ocean-centered governance with the aim of developing more inclusive approaches for Ocean science and sustainability ( Fig 1 and S1 Appendix ).

Interconnected relationships between Ocean-centered governance principles of justice, data sovereignty, rights, protection, and relationality rippling out from the key understanding that the Ocean is living. Transformation in Ocean governance requires action across all 5 principles. Created by Rachel Bustamante via Canva.com .

https://doi.org/10.1371/journal.pbio.3001828.g001

Building upon Earth law and Rights of Nature understandings, Ocean-centered governance recognizes the Ocean as a living entity, advancing law, policy, and institutional action that centers the needs of the Ocean in decision-making. By positioning the Ocean as a living entity with inherent rights, governance advances understandings that the Ocean has agency, is an actor worthy of representation, and that democratization of global Ocean governance must be inclusive of Ocean values and diverse “waves of knowing” or deep ancestral knowledge and connections to place that center Ocean relationality [ 42 , 43 ]. As political scientist Karin Amimoto Ingersoll underscores, Indigenous Peoples and coastal communities have rich “seascape epistemologies” built on millennia of coexisting with and learning from the Ocean [ 42 ]. This line of thinking suggests that we need radical and revolutionary transformation in how we imagine ourselves within a collective Oceanic future [ 44 , 45 ]. Ocean-centered governance therefore embraces the plurality of Oceanic knowledge, culture, and identities and enables us to ask ourselves “what is the science the Ocean needs” for a shared harmonious future. Not only recognizing the rights of the Ocean, but also its intrinsic values, may transform the human–Ocean relationship and provide the paradigm shift necessary in order to restore Ocean health [ 46 ].

Ocean-centered governance seeks to create new legal mechanisms that act as a catalyst for humanity to rethink our role as an inherent part of the Oceanic system, recognize the Ocean as “an entity that maintains its existence and functions as a whole through the interaction of its parts,” and become responsive to and understands the functioning of the Ocean and “the entire community of life it hosts” and supports [ 47 – 50 ]. Therefore, an Ocean-centered approach also places human and economic activity within the natural capacity of the Ocean and adopts an integrated, holistic, systems, and life cycle approach [ 51 ].

Importantly, an Earth-centered approach to governance is not purely defined by rights [ 52 ]. Rights equate to a statement of societal values and create a new ethic for conservation [ 53 ]. Relational- and responsibility-based values in practice leads to the reinterpretation of, or strict adherence to, key governance principles while facilitating the development of ecologically based criteria and standards. For example, Panama’s National Rights of Nature law (Ley N° 287) includes the respect for Indigenous cosmology, the prevention principle, precautionary principle, higher interest of Nature, restoration, and in dubio pro natura (when in doubt err on the side of Nature) [ 54 ]. In addition to recognizing that Nature has rights to exist, persist, and regenerate vital cycles (among others), has intrinsic values outside human utility, and that every person has the right to demand respect for Nature’s rights, the law is to be governed by the identified principles. Representation is a key principle within an Ocean-centered approach [ 55 ]. Not only does the principle ensure stakeholder representation in decision-making, but also the representation of Nature, such as through “guardians” or “trustees.” Though trusteeship is not new (e.g., applications of the Public Trust Doctrine), guardians under a Rights of Nature framework are legally required to represent the intrinsic value and interests of Nature and put aside human interests [ 55 – 57 ]. Additionally, Nature’s interests and needs inform scientific standards determining sustainability. For example, scientists convened in California in 2015 to discuss how a definition of “a healthy ocean” may comply with the Ocean’s own interests and needs, outside human benefit and utility, and lead to more adaptive and preventive management of human impacts to Ocean health [ 58 ]. Though much more work is needed to develop Ocean-centered standards, centering the Ocean’s needs in decision-making is a core component of an Ocean-centered approach and is further expanded upon in this Essay.

In the following sections, we explore how an Ocean-centered approach can produce innovative and effective solutions to each UN Ocean decadal challenge. This discussion explores specific Ocean-centered examples of policy responses or legal interventions that we recognize have been uniquely and contextually applied in practice. These cases represent and help clarify how an Ocean-centered approach is applicable to addressing each challenge and what implementation might look like in practice.

Challenge 1: Understand and beat marine pollution

Marine pollution showcases the inseparable and transboundary nature between land-based activities and Ocean health, highlighting the need to transform governance to address the relationship between democracy and sustainability, intergenerational justice, equity, and the distribution of environmental costs and benefits [ 59 – 62 ]. For example, plastic materials are cheaper to produce than renewable or biodegradable materials largely because pollution is not considered in the cost. This is due to our economic system being linear, focused on short-term gain and failing to adequately account for externalities [ 61 ].

Adopting an Ocean-centered lens to address marine pollution requires a life cycle approach to shape patterns of production and consumption and address pollution at the source (whether it be plastic production, agricultural runoff, dumping of mine tailings, etc.). Currently, the UN Environment Agency resolution “End Plastic Pollution: Towards a legally binding instrument” is entering negotiations on the global stage to address “the entire life cycle of plastics, from extraction of raw materials to legacy plastic pollution,” thereby transferring the cost of impacts on plastic to producers and signaling a market transition to circular products while incentivizing recovery and recycling [ 63 – 68 ].

Naturally, as reduction of pollutants to “near zero-input” in the Ocean necessitates collective action and coordinated governance in all respects, a holistic approach has been suggested to be most effective [ 63 ]. Thus, this represents an opportunity to frame the negotiations and development of the plastics treaty around an Ocean-centered approach, as it requires holistically assessing Ocean well-being interconnected to human activity, which can be fundamental to implementing regulations to halt marine pollution at the local, national, and international levels. Overall, an Ocean-centered approach to address pollution creates a shift in consumer values and producer practices by taking into account what the Ocean needs to be healthy. As such, cost-benefit analysis on plastic products would include externalities, impacts to human health and the health of other species and ecosystems, for present and future generations, from extraction to disposal [ 64 ].

The City of Santa Monica, California offers an example of how “public education and a local focus on shifting legal perspectives and consumer values can lead to larger cultural shifts” [ 69 ]. For example, the City passed a Sustainability Ordinance in 2013 recognizing “the rights of people, natural communities, and ecosystems to exist, regenerate, and flourish” [ 70 ]. This effort began first with a resolution, identifying a philosophical foundation and environmental ethic for human activity within the city, and the Ordinance was incorporated into the City’s Sustainability Plan. Guiding principles for the Plan include the recognition of the local communities’ linkage with the regional, national, and global community and the commitment towards sustainable rights for its residents, natural communities, and ecosystems [ 71 ]. Bans of plastic bags and nonmarine-degradable food service containers are examples of local actions taken by the city to mitigate plastic pollution. As scientist Max Liboiron highlights, anticolonial science, especially within the field of oceanography, acknowledges that plastic pollution is not merely a condition of market systems or reliance on fossil fuels but intertwined with colonialism and Indigenous land and water dispossession [ 61 ]. If the Ocean is recognized as a living entity with rights to be respected ( Fig 1 ), then regulatory instruments would reorient the standards and metrics therein to holistically include ecologically based criteria to control pollution and dismantle colonial extractivism. This could apply in cases of scientific uncertainty, where a strengthened application of precaution could prove necessary. For example, the severity of toxicant effects of plastic and their interactions with other contaminants at varying concentrations, distributions and ecosystem conditions to harming marine life is still in early stages of understanding [ 68 ]. Overall, an Ocean-centered approach invokes the responsibility of all sectors to consider human interests but ultimately respect ecological and planetary boundaries.

Challenge 2: Protect and restore ecosystems and biodiversity

Over the past 50 years, marine biodiversity has declined by 49% [ 72 – 74 ]. Predominantly, conservation interventions are reactive, taking effect once species and their ecosystems are threatened or endangered, and without addressing the primary drivers of biodiversity loss or the cumulative effects of human activity [ 24 ]. For governance practices to protect the Ocean ( Fig 1 ), they must actually bring about “changes on or in the water” [ 59 ]. Ocean-centered governance aims to incorporate anticipatory, adaptive, and flexible decision-making by reconsidering core values and recognizing the intrinsic worth of the Ocean and constitutive species, ecosystems, biodiversity, and abiotic and biotic components [ 75 ]. Recognition of the intrinsic value of biodiversity is essential in order to effectively protect and restore ecosystems and ensure development is sustainable. Fortunately, changes in this direction can now be seen at all scales. For example, the current negotiations to develop a new treaty under UNCLOS to protect biodiversity on the High Seas include the stewardship principle and the obligation to “preserve the inherent value of biodiversity of areas beyond national jurisdiction (draft text as of IGC5)” [ 76 ]. Additionally, the Convention on Biological Diversity preamble recognizes State’s to be “[c]onscious of the intrinsic value of biological diversity” [ 77 ]. This would facilitate changes in how decision makers currently decide what level of human activity is “sustainable” and what may constitute “severe or irreversible harm” in international waters, which to date, have been overexploited [ 78 ].

However, no international standard currently exists for the inclusion of intrinsic worth of biodiversity in decision-making. Local examples exist, such as in Aotearoa/New Zealand, where Māori successfully negotiated the Te Awa Tupua (Whanganui River Claims Settlement) Act of 2017 around the intrinsic values of the River or Tupua te Kawa. Those values provide that “Te Awa Tupua is a living and indivisible whole…[including] all of its physical and metaphysical elements,” “the source of spiritual and physical sustenance”, and “sustains both the life and natural resources within the Whanganui River and the health and well-being of the iwi, hapū, and other communities of the River” [ 57 ]. As a result, the Act requires that any person exercising a function under another identified law must recognize and have regard to not only the legal status of the River, but also its intrinsic values [ 57 ]. The Te Awa Tupua Act explicitly defines diverse values and relationships surrounding the River and local communities. This example highlights how governance, and therefore an Ocean-centered approach, can begin to integrate social, economic, and environmental impacts from both a monetary and nonmonetary view of the existence of biodiversity [ 75 ].

The Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES) Values Assessment illuminates that the causes of and solutions for our global environmental challenges are tightly linked to the ways in which we value our environments [ 79 ]. Importantly, the report concludes that environmental policy is “more likely to foster transformative change” when aligned with and incorporating “the diverse values of nature,” recognizing Rights of Nature can advance both justice and sustainability by addressing the diverse ways in which people relate to and value Nature [ 79 ]. In fact, the IPBES produced a methodological assessment that calls for the inclusion of worldviews, broad values (moral principles), and specific values, including intrinsic values, suggesting that local examples such as Te Awa Tupua are vital and should be incorporated into assessments and implementation of environmental policy [ 79 ].

Beyond the inclusion of the intrinsic value of Nature, the recognition of Nature’s inherent rights enables proactive and adaptive management in order to protect, defend, and restore Nature’s rights. For example, the Special Law of the Galapagos for Ecuador’s Galapagos Marine Reserve states that citizens and Nature are both guaranteed the constitutional right of living well (adhering to the 2008 Constitutional Amendment recognizing Nature as having inherent rights) [ 80 ]. In fact a guiding principle for governance is to create an equilibrium among society, the economy, and Nature. As a result, industrial fishing and harming sharks in the archipelago were entirely prohibited to protect sharks and maintain the ecosystem under “minimal human interference” [ 80 ]. With this example, we can see how policy proactively protected sharks in the Reserve, and adapted to scientific evidence on the importance of sharks as keystone species, and to the local economy via ecotourism [ 81 ]. Similarly, principles in Ecuador’s environmental code and Panama’s National Law are vital to an Ocean-centered approach, including in dubio pro natura (when in doubt favor Nature) and the prevention principle, to encourage decision-making to err on the side of Nature in any case of doubt regarding the impacts of human activity. In order to ensure ecosystems and biodiversity are protected and restored, it is critical that governments apply proactive and adaptive measures. Recognition of the Ocean’s legal agency and intrinsic value provide a mechanism to legally require such measures [ 54 , 82 ].

Challenge 3: Sustainably feed the global population

Policies to regulate fishing as well as harmful fishing subsidies highlight the “unprecedented power that humans exert over nonhuman Nature” and the inequalities in allocation, agency, and justice (including the disproportionate burden on Indigenous Peoples, developing States, big Ocean States, and local communities) [ 83 , 84 ]. Valuing fish as a resource, such as objectifying a population as a “fishery,” and using maximum sustainable yield (MSY) fails to fully grasp the needs of the system as whole, and the nonhuman species within it, as well as adequately accounting for future impacts, including climate change [ 85 ]. For example, the European Union’s Common Fisheries Policy and total allowable catch (based upon MSY) was found to be “on average 48% higher than those advised by scientists” [ 86 , 87 ]. As a result, MSY, as a metric to regulate human behavior, allows governance to focus on short-term needs rather than maintaining a healthy and thriving ecosystem for future generations of all species. Though enshrined in international governance (UNCLOS Article 61), more holistic measures continue to be explored that are inclusive of whole-ecosystem processes and dynamics along with social and economic factors, such as reframing MSY as a limit, rather than a target, or managing human activity with higher metrics of precaution, rather than total allowable catches [ 88 – 90 ].

An Ocean-centered approach is a valuable lens from which to reevaluate human relationships with fish populations ( Fig 1 ), and is arguably, a research need moving forward. As noted above, Ocean-centered governance ensures the agency or representation of nonhuman stakeholders in decision-making processes, such as through human guardians (other terms used include protectors, stewards, trustees, and custodians) and recognizes the global population as including all species, with humans as just one entity within the system, thereby constraining economic activity within ecological limits [ 55 , 91 ]. For example, ʔEsdilagh First Nation Sturgeon River Law of 2020 states “[p]eople, animals, fish, plants, the nen (“lands”), and the tu (“waters”) have rights in the decisions about their care and use that must be considered and respected” [ 92 ]. It further calls for proactive planning and management to ensure the health of the tu is maintained, the consideration of the needs of the fish, plants, and other relations before taking from or using tu and allows for the ʔEsdilagh Government to suspend or cancel an authorization where necessary to protect fish, habitat, and water flow [ 93 ]. In 2020, the Tsilhqot’in Nation similarly voiced concerns that stronger action was needed in order to mitigate extinction risk of Fraser River Chinook salmon, and even forfeited their fishing rights in order to preserve salmon for future generations [ 93 ]. Ensuring the agency and representation of marine biodiversity in decision-making processes addresses a major challenge in democratization, supports a shift in power to those communities most affected by poor governance, and ensures a fair and equitable process to feed the global population by ascribing the responsibility on humankind to ensure intergenerational equity. Therefore, Ocean-centered governance empowers adaptive and preventive action to maintain restorative human–Ocean relationships.

Challenge 4: Develop a sustainable and equitable Ocean economy

Current global frameworks promoting sustainable development inherently focus on human rights and needs and hold “anthropocentric notions of equity” (e.g., principle 1 of the Rio Declaration states “human beings are at the center of concerns for sustainable development”) [ 46 , 94 ]. In addition to recognizing the agency of the Ocean, we can propel a mutually enhancing and equitable economy by redefining law and policy concepts to embrace principles of justice for the Ocean and people [ 95 ]. Ocean justice ( Fig 1 ) supports the inherent rights of the Ocean as a living entity worthy of protection expanding notions of marine jurisdiction to be inclusive of diverse actors including the Ocean itself [ 95 ]. A rethink of sustainability is necessary going forward, and could take the form of “ecological sustainability,” defined as: “the maintenance of life support systems and the achievement of a ‘natural’ extinction rate” [ 96 ]. In practice, our existing institutions (economy, governance, laws, etc.) and policymaking tools (cost-benefit analysis, qualitative data, etc.) can shift to the recognition that the “economy is a subsystem of human society which is a subsystem of the Earth” [ 97 ]. Doing so will help to fulfill the standards of intergenerational equity, a future healthy and livable planet for future generations of humans and all life on Earth [ 98 ]. A sustainable Ocean economy is guided by and adaptive to Ocean health, respective and responsive to ecological boundaries. For example, “sumak kawsay,” “suma qamaña,” “küme Mongen,” “buen vivir,” or “good living,” originating from Andean Indigenous ontologies (such as Quechua, Aymara, and Mapuche communities, respectively), identifies well-being and development as “community-centric, ecologically balanced, and culturally sensitive” [ 99 ]. These concepts “both reflect a fundamental morality (respect for ecological integrity) and require action [to protect and restore]” Nature while sustaining human activity [ 100 ].

Importantly, more work is needed to include and amplify the agency of Indigenous and local communities, customary law, science, and other “waves of knowing” in decision-making processes, providing genuine participation in governance [ 42 ]. Fundamentally, an inclusive process will not appropriate knowledge, but will deconstruct colonial ideologies, seeking to redress historical exclusion, dispossession and disregard of Indigenous sovereign rights and Ocean-relations [ 39 , 101 , 102 ]. It is critical we not only ensure economic activity is consistent with respecting the ecological integrity of the Ocean, but also that the ecological integrity is defined outside human benefit and utility. An equitable Ocean economy must ensure Indigenous, local, and coastal communities are rights holders that are respected and included in Ocean governance.

Another concept to reimagine is the western-derived understanding of “what is healthy.” Maintaining a “healthy ocean” constitutes a main objective of laws and policies worldwide [ 58 , 103 ]. However, this standard and similar metrics to measure whether activities support health are largely based upon human benefit and utility, viewing benefits as “ecosystem services” rather than a holistic view of the benefits a healthy Ocean provides to other species, ecosystems, functions, and systems [ 104 , 105 ]. For example, Ruhl and Salzman position that ecosystems have long been valued “as a source of valuable commodities and recreational pursuits that, obviously, do not always align with the goal of maintaining ecological integrity” [ 106 ]. Linda Sheehan postulates a definition of health as “normal form and function” over a long period of time and “demonstrat[ing] sufficient organization, vigor, and resilience to allow ecosystems and species to exist, thrive, and evolve as natural systems within the context of their expected natural life spans” [ 58 ]. Ocean-centered governance recognizes Oceanic ecosystems as all intrinsically valuable and determines metrics for what constitutes a “healthy” Ocean as defined by the Ocean’s intrinsic needs, including chemical, physical, and biological needs, rather than the Ocean’s utility as a human resource or economic benefit [ 58 , 107 ]. These metrics and valuations of the Ocean are then integrated and fundamental to economic policy decisions, guiding development towards a circular and reciprocal Ocean economy.

Challenge 5: Unlock Ocean-based solutions to climate change

Climate scientists have highlighted that existing adaptation strategies to climate change often overlook systemic injustices and promote colonialism, environmental racism, and anthropocentric ideologies while international frameworks are siloed from each other and are only beginning to recognize and respect the Ocean–climate nexus [ 102 , 108 , 109 ]. In fact, the World Meteorological Organization “revealed that 4 key climate indicators broke new records in 2021: sea-level rise; ocean heat; ocean acidification; and greenhouse gas concentrations” [ 110 ]. Ocean-centered governance provides an opportunity to unlock Ocean-based solutions to climate change grounded in principles of relationality, interconnectivity, and equity, whereby the rights and needs of the Ocean are prioritized for climate action alongside other relations [ 62 , 111 ]. Globally, mitigation solutions and adaptation frameworks need to be designed to fit local contexts and the specific needs of the Ocean and coastal communities disproportionately impacted. For example, the WAMPUM Adaptation Framework is an Ocean-centric approach to sea-level rise adaptation planning, focusing on first observing ecosystem change indicators, identifying traditional ecological knowledge solutions, and then restoring wetlands, seagrass, aquatic species, and other life-giving relatives to support Ocean well-being [ 102 ].

Moreover, Ocean-centered solutions would recognize the inherent rights of blue carbon ecosystems as living entities. For example, the government of Belize recognized the Belize Barrier Reef as a living entity in 2011 [ 112 , 113 ]. In 2009, a ship ran aground causing extensive damage to the reef and the Government of Belize brought legal action against the shipowners, arguing the reef was not “property” but rather a living entity and that they were its “custodian and guardian” [ 113 ]. The government was awarded damages beyond those of liability to property requiring the shipowners to pay not only for physical damage, but also the reparation costs of the loss of habitat, protection against erosion and storm surge, and biodiversity as well as the monetary restitution for damage caused to tourism, recreational, aesthetic, and cultural value [ 113 ]. Ocean-centered governance promotes transformation towards a harmonized human–Ocean relationship by being reflexive and adaptive to the needs and acknowledging the agency of the Ocean and blue carbon ecosystems, recognizing the interconnectivity of all life among changing climatic conditions.

Challenge 6: Increase community resilience to Ocean hazards

Blue carbon ecosystems not only provide Ocean-based climate solutions, but also they provide early warning and hazard reduction services for coastal communities in the face of climate emergency [ 114 ]. Ocean-centered governance builds adaptive and preventative measures to extreme climate events. Coastal hazards are often exacerbated by human exploitation and overdevelopment of the coastline [ 115 ]. Community preparedness and resilience will require innovative advancements in law to address compounding climate change hazards across geographies and scales. As an example, there is a growing surfing movement to protect the Ocean, coastlines, and, in particular, Waves, from overdevelopment and land use degradation using innovative Ocean-centric legal mechanisms [ 116 ]. In 2016, the Chicama wave, considered to be the longest left-breaking wave in the world, was granted legal protections under Peruvian national law. The law prohibits changes to the coastline and seabed that would alter the integrity of the wave [ 117 , 118 ]. The surfing community is a critical stakeholder in promoting community resilience and Ocean conservation [ 118 – 120 ].

Similarly, in 2020 the state of Victoria, Australia recognized the Great Ocean Road as “one living and integrated natural entity” under section 1(a) of the Great Ocean Road and Environs Protection Act [ 121 ]. These measures were taken to protect the region from infrastructure sprawl and ensure environmentally sustainable development, particularly noting the urgent need to holistically mitigate current and projected climate impacts affecting the coastlines. Moreover, the Act acknowledges the “intrinsic connection” of Indigenous Peoples to the sea and affirms their responsibility as caretakers and decision-makers [ 122 ]. These approaches highlight how Ocean-centered governance can reverse perspectives of the Ocean as hazard and reframe human–Ocean relationships as interdependent. Coastal hazard managers often base decisions on the application of cost-benefit analyses that commodify ecological and cultural benefits, but exclude long-term planning and ecological needs of shorelines. For example, as these assessments cannot fully quantify the human–Ocean relationship, Revell and colleagues suggest application of a precautionary approach [ 123 ]. An Ocean-centered approach applies ecological-based criteria in risk assessment and evaluates Ocean health needs now and based upon modeled future projections when deciding whether there is scientific uncertainty of potential harm from coastal development or other human activities. Finally, an Ocean-centered approach could help ensure inclusion and representation of Indigenous, local, and coastal communities with active voices and roles in coastal decision-making and planning, amplifying stewardship practices which have been known and integral to many of their communities since time immemorial [ 41 , 124 ].

Challenge 7: Expand the Global Ocean Observing System

Existing Ocean observing systems prioritize human needs over the Ocean’s for observation, data collection, and priority setting [ 125 – 130 ]. “Restorying” Ocean observing system architecture to prioritize and embrace the science the Ocean needs is critical to address persistent ecological changes and crises. According to political scientist Jeff Corntassel (Cherokee Nation), restorying is the process by which institutions reexamine the dominance of colonial histories and erasure of Indigenous Peoples in stories of place [ 131 ]. Restorying information systems for Ocean observing is critical to democratizing data ecosystems to be inclusive of diverse peoples and “waves of knowing” [ 42 ]. This could be realized through ensuring enhanced monitoring efforts to better track biological data and best practices for Ocean conservation [ 130 , 132 ] ( Fig 1 ). Data collection processes can also build in frameworks that support Indigenous Data Sovereignty [ 133 ]. The Ira Moana Project based in Aotearoa/New Zealand has incorporated principles of Indigenous Data Sovereignty to retain Indigenous provenance information of marine genetic samples in metadata of large marine databases to protect the rights of Indigenous Peoples [ 134 , 135 ]. These policies have broad applicability for ethical applications in future environmental DNA sampling in marine environments. Future data collection standardization efforts may also provide for data governance to be entrusted to Ocean guardians charged with protecting the Ocean’s needs. Monitoring should be inclusive of legal and policy changes that recognize Ocean ecosystems as living entities and that existing and emerging marine life programs adopt preventative measures to combat monetization of Ocean data. For example, essential ocean variables (EOVs) are integral measurements to understand the connection between the Ocean and Earth’s climate system, focusing “on the physics of the ocean system, the biogeochemistry, and the biology and ecosystems” [ 136 , 137 ]. EOVs and essential climate variables (ECVs) provide critical information to assess the health of the Ocean and enable predictions of climate change impacts and associated adaptation needs [ 136 , 137 ].

If global Ocean observation systems recognize the inherent rights of the Ocean and marine life, this would engage a more integrated and interconnected approach, alleviating several known challenges of sustaining these systems in a collaborative environment [ 138 , 139 ]. Révelard and colleagues confirm that all stakeholders of the Ocean observing system “need to establish a shared vision and commit to common priorities,” addressing the current “absence of a well-established overall governance framework” [ 139 ]. The lack of sustained long-term funding associated with Ocean observing systems, and associated costs in facilitating an integrated approach is one foreseen challenge that would benefit from future research. An observing system that centers the Ocean’s well-being in data collection and analysis, establishes a collective view of the Ocean as living, and seeks to realize a harmonized human–Ocean relationship can help enhance protection of Oceanic ecosystems. A key component of recognizing the Ocean as a rightsholder, is ensuring representation and ownership of data is protected across the totality of the data ecosystem (all the data components, models, and infrastructure) and life cycle (from collection to analytics and governance). Going forward, governance of the Global Ocean Observing System could include Ocean guardians as steering committee members or as a new expert panel that can act as a voice for the Ocean and advance EOVs with the greatest potential for the protection of the Ocean’s right to exist, flourish, and naturally evolve. Enhancing Ocean observation systems [ 140 ] will also provide valuable validation metrics on the efficacy of Rights of Nature instruments in protecting Ocean and coastal habitats. Without legislative, policy, and legal drivers, observing systems will miss critical opportunities for innovation in Ocean protection [ 130 , 141 ].

Ocean data sovereignty also encompasses Indigenous data governance principles, including the CARE Principles: collective benefit, authority to control, responsibility, and ethics [ 142 ]. The CARE principles provide standards to measure operationalization of ethical systems architecture in support of the Ocean’s data needs. Moreover, these principles ensure equitable distribution of benefits from current and future data use. However, steps towards implementation must ensure data collection, use, and governance protect individual and collective rights of Indigenous Peoples, local and coastal communities, and the Ocean. Ocean observing systems must democratize to not only be more inclusive of diverse knowledge systems but also center the data needs of the Ocean for holistic health in perpetuity.

Challenge 8: Create a digital representation of the Ocean

Reliance on Mercator projections to digitally represent the Ocean has led to centering on western positionality [ 143 ]. Drawing on scholarship of legal geography, Ntona and Schröder invite us “to question how […] representational devices (e.g., maps) and information management technologies (e.g., geographic information systems) associated with [Ocean mapping] work together to “gentrify” marine spaces, constructing them in ways that reflect the hierarchy of values and the differentiated rights of access” [ 144 ]. The Ocean is not a static entity but a living and “lively space,” and digital representations must account for the fluid plurality of existence and material manifestations [ 144 ]. Ocean-centered governance recognizes the Ocean as a data actor and rightsholder.

Digital representations of the Ocean, including the development of a dynamic Ocean map, must center the Ocean uninterrupted by imagined state borders and Exclusive Economic Zones [ 145 ]. Epeli Hau’ofa advocates for society to rethink colonial logics of the sea as divisive and rather embrace that “we’re connected rather than separated by the sea” [ 146 ]. Charne Lavery further argues such projections would debunk continental centricity to focus on “oceanicity,” “indicating the degree to which a place is overall subject to the influence of the sea” [ 143 ]. Therefore, Ocean-centered governance emphasizes principles that empower oceanicity to radically transform digital representations of the Ocean so that the Ocean itself is the center of focus, rather than geopolitical borders of terrestrial occupation.

As Kira Coley highlights, Ocean mapping is critical to building resilience for the Ocean and the global community requiring commitments to accessibility and diverse stakeholders to be co-creators of mapping initiatives [ 147 ]. The Spilhaus World Ocean Map is often used as an example of an Ocean-centric map, but as the author notes “a map of the world ocean is essentially a world map” because Earth is an Ocean planet [ 145 , 148 ]. However, it has been decades since these Ocean maps were created and a new digital Ocean map is needed that fully reflects the dynamism and stories of diverse waves of knowing Ocean relationality. Connecting people to the Ocean through innovative digital representations (e.g., maps) that propel oceanicity and orient users to points of centricity of greatest importance to the Ocean can have lasting transformative impact on science, law, and policy for the Ocean Decade [ 149 ].

Challenge 9: Skills, knowledge, and technology for all

The knowledge, practices, and technology that embody and advance an Ocean-centered approach must be made accessible to all Ocean users [ 150 – 152 ]. Recent developments in literature have sought to quantify global Rights of Nature initiatives and Earth law governance reports, analyses, laws, and policy advancements, such as a mapping analysis by Kauffman and colleagues, and as expanded upon by Putzer and colleagues, whose database has over 400 logged Rights of Nature initiatives, spanning across 39 countries ( S1 Appendix ) [ 52 ]. Ocean-specific repositories of data and best practices, such as the IOC-UNESCO Ocean Best Practices system, can elevate living in harmony with Nature and crosslink to other existing repositories.

To ensure comprehensive knowledge and technology across all aspects of Ocean science, Ocean governance must also carve out space for valuing Indigenous knowledge, traditions, and management [ 41 , 146 ]. Historically, Indigenous nations and communities have been widely excluded, underrepresented, and culturally erased in international forums and Ocean policy. Intentional work is needed to ensure genuine participation and agency along with deconstructing resounding colonial legacies that dispossess Indigenous communities from Ocean spaces [ 153 ]. For example, the Marae Moana Act, a conservation act of the Cook Islands that, among other purposes, develops a marine spatial plan and designates Marine Protected Areas, includes space for Cook Islanders’ traditional knowledge “around marine custodianship including ra’ui and ra’ui mutukore” [ 154 ]. Ra’ui is a temporary ban on the extraction of a species and ra’ui mutukore is a permanent ban, both of which are determined by a tribal chief, and are utilized “to enhance food security, intrinsic value, protect and improve biodiversity, rehabilitated or restored areas and traditional customary practices” [ 155 ].

Several global frameworks have recognized the importance of ensuring Indigenous rights to self-determination, including the Convention on Biological Diversity Aichi Targets and UN Declaration on the Rights of Indigenous Peoples. However, Indigenous scholars Fischer and colleagues, conclude that implementation and enforcement of these standards is uneven [ 31 ]. Equitable decision-making requires more than involvement, but representation in conservation science, and respect of Indigenous rights and leadership. These practices are most recommended contextually “for Indigenous Peoples whose conception of rights is that it comes with coinciding responsibilities to steward or care for the environment” [ 98 ]. Bridging diverse scientific traditions including Indigenous knowledge and science can help us to better understand and sustain the interconnected relationship we have with the Ocean and lead to more effective protection of Ocean health [ 31 ]. By ensuring the best science and technology is available and used by all, and bridging diverse scientific traditions, the global community can advance innovation and adaptation, as well as address power imbalances and allocation inequalities [ 84 ].

Challenge 10: Change humanity’s relationship with the Ocean

The Ocean faces imminent danger of losing its capacity to support life, including from increased human-induced pressures such as climate change, overfishing, and land-based pollution [ 8 ]. The persisting “heavily privatised, zoned, and securitised Ocean undermines the human-Ocean relationship” and has led to a focus on rights to exploit over responsibilities to protect and preserve [ 40 , 90 ]. In order for the Ocean to continue to support life, “a new relationship between humanity and the Ocean is required” [ 8 , 39 , 40 , 51 ].

Ocean scientists and practitioners argue a biocultural framework would provide a transition to enhanced human–Ocean reciprocal relationality [ 156 ]. A biocultural approach is evident in many Indigenous and “place-based coastal communities” and emphasizes the “mutual interdependence of biological and cultural diversity into complementary, relational values of humans with one another and with nature” [ 156 ]. Situated within this biocultural perspective, the Ocean is a living being worthy of care and healing, as a whole. A “more-than-human-world” is a key concept in this perspective [ 8 , 156 ]. Across Oceania, governance principles of stewardship or guardianship are prevalent and help guide many communities to live in a harmonious relationship with the Ocean [ 8 , 31 , 40 , 145 , 157 , 158 ]. For example, in Aotearoa/New Zealand, laws and policies include kaitiakitanga, which is “the exercise of guardianship by the tangata whenua of an area in accordance with tikanga Māori in relation to natural and physical resources” and emphasizes the human responsibility to nurture and care for the environment [ 158 , 159 ]. The values of kaitiakitanga are relational and are considered a principle of law that predates common law [ 159 ]; cases in point include the Resource Management Act and the Sea Change–Tai Timu Tai Pari Hauraki Gulf Marine Spatial Plan (the Plan). The Plan has 4 fundamental pillars for governance and states that considering the Gulf “as a being in its own right will help us to rethink our reciprocal responsibilities and work toward a better balance” [ 160 ]. Additionally, the Plan recognizes the Māori and local Iwi as spiritual guardians or protectors (kaitiaki) of the lands, territories, and waters they have ancestrally possessed, having a personal and collective responsibility to maintain them. In practice, this includes setting temporary restrictions on fishing within certain areas, using the lunar calendar to guide planting and harvesting, banning recreational fishing and birding, harvesting only what is needed, and Iwi feedback and consent on regulations and permits within the Continental Shelf [ 161 , 162 ].

Kaitiakitanga was recently discussed heavily in a Supreme Court decision in New Zealand regarding whether consents should be given to undertake seabed mining. In addition to ruling that if the environment cannot be protected from harm through regulation then the activity must be prohibited, the court ruled that the decision-making committee needed to consider existing interests, which included the kaitiakitanga of iwi. The impact on spiritual and cultural values was underestimated and seabed mining was found to be inconsistent with the iwi parties’ exercise of kaitiakitanga to protect the life force of the marine environment [ 160 ].

Kaitiakitanga and other Indigenous values and understandings are important for decision makers to engage with, recognize and respect, as they can help transform humanity’s relationship with the Ocean by establishing a shared common vision and goals, and “creating principled guiding frameworks and processes to facilitate coherent systems-oriented regulations” [ 8 ]. Moreover, recognizing that humankind has a collective duty (reciprocal responsibilities) to protect and conserve the Ocean for the benefit of all life and future generations may maintain mutually beneficial and restorative human–Ocean relationships [ 55 ].

In this Essay, we explored examples of Earth law internationally, how governance principles and standards are defined and applied in practice, and how they can inform the 10 decadal challenges. Recognizing the Ocean as a living being is increasingly important for planetary well-being and global sustainability. We have presented Ocean-centered governance principles and examples to guide implementation to help transform the vision of the Ocean Decade towards supporting the science needed for the Ocean that the Ocean wants. To ensure full and effective realization of the 10 decadal challenges ( Table 1 ), and therefore the sustainable use of the Ocean, humankind must transform our relationship with the Ocean and evolve our perceptions and values guiding the challenges ( Box 1 ). Although the 10th challenge itself calls for this transformation, this challenge must be completed first and foremost and guide the implementation of the 9 other challenges. Shifting our relationship with the Ocean from one of ownership and separateness towards loving interdependence, reciprocity, and reverence can transform Ocean governance.

Box 1. Five Ocean-centric principles to transform Ocean governance

Ocean rights.

Recognizing the Ocean as a living being, stakeholder, and rightsholder and hearing the Ocean’s voice in decision-making can positively influence every challenge to Ocean health by reorienting standards for decision-making and governance principles to respect the Ocean’s rights to life, to restoration, and to flourish.

Ocean relationality

Restoring a balanced and reciprocal relationship with the Ocean leads to a greater fulfillment of human rights in tandem; grounding human activity based upon this interconnection will enhance respect of ecological/planetary boundaries and help ensure resilience for all life while respecting and amplifying, but not appropriating, Indigenous and local knowledge from communities that have long known and practiced these relations in Ocean spaces.

Ocean data sovereignty

Global observing systems can create imaginative and accessible technological infrastructure, orienting digital users to points of Ocean centricity that address fragmentation in normative, technical, temporal, spatial, and scalar interactions, as well as alleviate power inequalities.

Ocean protection

A shared and collective responsibility of all to protect and conserve the Ocean can shift the imbalances between allocation and use, and a life cycle approach can shape patterns of production and consumption to advance holistic Ocean regeneration.

Ocean justice

Recognizing the Ocean’s agency encourages democratization, supports a shift in power to those communities most affected by poor governance, and ensures a fair and equitable process to nurture the global population by ascribing the responsibility on humankind to ensure intergenerational equity.

The UN Ocean Decade scientific community is uniquely positioned to advance wise practices for living in relationship with the Ocean. Adopting an Ocean-centered governance approach is vital to inform the development of how humanity may respect the inextricable relationship with the Ocean and ensure science and governance frameworks, such as those determining “sustainability” can meet the Ocean Decade challenges. Centering the Ocean as living, with humanity as part of the Oceanic system, can produce not only the science we need for the Ocean we want, but also the science the Ocean needs and wants.

Supporting information

S1 appendix. summary of materials and methods..

File documenting materials and methods used for identifying Ocean rights laws and initiatives for Ocean-centered governance.

https://doi.org/10.1371/journal.pbio.3001828.s001

• 1. United Nations. The Ocean Decade Challenges for Collective Impact. Ocean Decade. Available from: https://www.oceandecade.org/challenges/ .
• 2. United Nations. The 2030 Agenda for Sustainable Development [Internet]. 2015. Available from: https://www.un.org/en/development/desa/population/migration/generalassembly/docs/globalcompact/A_RES_70_1_E.pdf .
• View Article
• Google Scholar
• 6. Rothwell DR, VanderZwaag DL, editors. Towards Principled Oceans Governance [Internet]. 0 ed. Routledge; 2006 [cited 2022 Aug 23]. Available from: https://www.taylorfrancis.com/books/9781134175888 .
• 9. United Nations. United Nations / Framework Convention on Climate Change (2015) Adoption of the Paris Agreement 21st Conference of the Parties, Paris. 2015.
• PubMed/NCBI
• 16. Cullinan C. Wild law: A Manifesto for Earth Justice. Green Books; 2011.
• 18. Burdon P. Exploring wild law, the philosophy of Earth Jurisprudence. Wakefield Press. 2012.
• 19. Berry T. The great work: Our way into the future. Bell Tower; 2000.
• 21. Boyd D. The Environmental Rights Revolution: A Global Study of Constitutions, Human Rights, and the Environment. University of British Columbia Press; 2012.
• 23. Stone CD. Should Trees Have Standing? Law, Morality, and the Environment. Oxford University Press; 1972.
• 30. Pinchot. The Training of a Forester. Philadelphia, PA: J.B. Lippincott Co; 1914.
• 42. Ingersoll KA. Waves of Knowing: A Seascape Epistemology [Internet]. Duke University Press; 2016 [cited 2022 Aug 23]. Available from: https://www.degruyter.com/document/doi/10.1515/9780822373803/html .
• 57. Te Awa Tupua (Whanganui River Claims Settlement) Act 2017, Public Act 2017 No 7 [Internet]. 2017. Available from: http://www.legislation.govt.nz/act/public/2017/0007/latest/whole.html .
• 61. Liboiron M. Pollution Is Colonialism [Internet]. Duke University Press; 2021 [cited 2022 Aug 23]. Available from: https://www.degruyter.com/document/doi/10.1515/9781478021445/html .
• 73. Living Planet Report 2014. Species and spaces, people and places [Internet]. 2014. Available from: http://awsassets.panda.org/downloads/lpr_living_planet_report_2014.pdf .
• 79. IPBES (2022): Methodological assessment of the diverse values and valuation of nature of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Balvanera P, Pascual U, Christie M, Baptiste B, González-Jiménez D, editors. IPBES secretariat, Bonn, Germany. XX pages. https://doi.org/10.5281/zenodo.6522522
• 80. Ecuador. Special Law for the Province of Galapagos, year III, No. 520. [Internet]. 2015. Available from: http://www.galapagos.gob.ec/wp-content/uploads/downloads/2017/01/Ley_organica_de_regimen_especial_de_la_provincia_de_galapagos_ro_2do_s_11_06_2015.pdf .
• 81. Lynham J and others “Economic Valuation of Marine- and Shark-Based Tourism in the Galápagos…” 2022 [cited Aug 2]. Available from: https://media.nationalgeographic.org/assets/file/GalapagosEconReport_Nov15.pdf .
• 85. Pacific Fishery Management Council (PFMC). Pacific Coast Salmon Fishery Management Plan for Commercial and Recreational Salmon Fisheries off the Coasts of Washington, Oregon, and California as Amended through Amendment 20. Portland, OR; p. 13. Report No.: 81.
• 87. Bender M. Ocean Rights: The Baltic Sea and World Ocean Health. In: Sustainability and the Rights of Nature in Practice. 1st ed. CRC Press; 2019. p. 20.
• 90. United Nations Treaty Series. Convention on the Law of the Sea. 1982. Art. 193 and Art. 192.
• 91. Carlsson CS. Mining from the Lens of Ecological Law: Obstacles and Opportunities for Re-formation [Internet]. Ottawa, Canada: University of Ottawa; 2019. Available from: https://www.academia.edu/39149609/Mining_from_the_Lens_of_Ecological_Law_Obstacles_and_Opportunities_for_Re_formation .
• 95. Johnson AE. What I know about the ocean: We need ocean justice. Oakland, CA: Sierra Magazine; 2020.
• 96. Dogmo Pokem, Sicco Dany (2008): Linking normative and strategic planning in a unique forest management planning framework: A theoretical proposal, Arbeitsbericht, No. 52-2009, Albert-Ludwigs-Universität Freiburg, Institut für Forstökonomie, Freiburg i. Br. Available from: https://www.ife.uni-freiburg.de/dateien/pdf-dateien/ar52 .
• 105. Fleming L, Depledge M, McDonough N, White M, Pahl S, Austen M, et al. The Oceans and Human Health. In: Oxford Research Encyclopedia of Environmental Science [Internet]. Oxford University Press; 2015 [cited 2022 Aug 23]. Available from: http://environmentalscience.oxfordre.com/view/10.1093/acrefore/9780199389414.001.0001/acrefore-9780199389414-e-12 .
• 113. In the Court of Appeal of Belize, A.D. Civil Appeal No. 19 of 2010 [Internet]. 2011. Available from: http://files.harmonywithnatureun.org/uploads/upload715.pdf .
• 129. Moore KD, Russell R. Toward a New Ethic for the Oceans. In: Ecosystem-based management for the oceans. Washington, D.C.: Island Press; 2009.
• 132. The Global Ocean Observing System (GOOS) [Internet]. 2021. Available from: https://www.goosocean.org/index.php?option=com_content&view=article&id=7&Itemid=101 .
• 135. Aporta C, Bishop B, Choi O, Wang W. Knowledge and data: an exploration of the use of inuit knowledge in decision support systems in marine management. In Governance of Arctic Shipping. Cham: Springer; 2020. p. 151–169.
• 146. Hau’ofa E. Our Sea of Islands. In: Wilson R, Dirlik A, editors. Asia/Pacific as Space of Cultural Production [Internet]. Duke University Press; 2020 [cited 2022 Aug 23]. p. 86–98. Available from: https://www.degruyter.com/document/doi/10.1515/9780822396116-008/html .
• 151. Government-University-Industry Research Roundtable, Policy and Global Affairs, National Academies of Sciences, Engineering, and Medicine. The Role of Research and Technology in the Changing Ocean Economy: Proceedings of a Workshop-in Brief [Internet]. Saunders J, editor. Washington, D.C.: National Academies Press; 2020 [cited 2022 Aug 23]. Available from: https://www.nap.edu/catalog/25810 .
• 159. The encyclopedia of New Zealand. Te Ahukaramū Charles Royal, Kaitiakitanga–guardianship and conservation. Available from: https://teara.govt.nz/en/kaitiakitanga-guardianship-and-conservation/print .

Search the United Nations

• What Is Climate Change
• Myth Busters
• Renewable Energy
• Finance & Justice
• Initiatives
• Sustainable Development Goals
• Paris Agreement
• Climate Ambition Summit 2023
• Climate Conferences
• Press Material
• Communications Tips

How is climate change impacting the world’s ocean

The ocean has long taken the brunt of the impacts of human-made global warming, says UN Climate Change . As the planet’s greatest carbon sink, the ocean absorbs excess heat and energy released from rising greenhouse gas emissions trapped in the Earth’s system. Today, the ocean has absorbed about 90 percent of the heat generated by rising emissions. 

As the excessive heat and energy warms the ocean, the change in temperature leads to unparalleled cascading effects, including ice-melting, sea-level rise, marine heatwaves, and ocean acidification. 

These changes ultimately cause a lasting impact on marine biodiversity, and the lives and livelihoods of coastal communities and beyond - including around 680 million people living in low-lying coastal areas, almost 2 billion who live in half of the world’s megacities that are coastal, nearly half of the world’s population (3.3 billion) that depends on fish for protein, and almost 60 million people who work in fisheries and the aquaculture sector worldwide. 

Here are some of the major consequences of the impacts of climate change on the ocean.

Sea-level rise

Sea-level rise has accelerated in recent decades due to increasing ice loss in the world’s polar regions. Latest data from the World Meteorological Organization shows that global mean sea-level reached a new record high in 2021, rising an average of 4.5 millimeter per year over the period 2013 to 2021. 

Together with intensifying tropical cyclones, sea-level rise has exacerbated extreme events such as deadly storm surges and coastal hazards such as flooding, erosion and landslides, which are now projected to occur at least once a year in many locations. Such events occurred once per century historically.

Moreover, the Intergovernmental Panel on Climate Change (IPCC) says that several regions, such as the western Tropical Pacific, the South-west Pacific, the North Pacific, the South-west Indian Ocean and the South Atlantic, face substantially faster sea-level rise.  

Marine heatwaves

Marine heatwaves have doubled in frequency, and have become longer-lasting, more intense and extensive. The IPCC says that human influence has been the main driver of the ocean heat increase observed since the 1970s. 

The majority of heatwaves took place between 2006 and 2015, causing widespread coral bleaching and reef degradation. In 2021, nearly 60 percent of the world’s ocean surface experienced at least one spell of marine heatwaves. The UN Environment Programme says that every one of the world’s coral reefs could bleach by the end of the century if the water continues to warm. 

Coral bleaching occurs as reefs lose their life-sustaining microscopic algae when under stress. The last global bleaching event started in 2014 and extended well into 2017 - spreading across the Pacific, Indian and Atlantic oceans.   

Loss of marine biodiversity

Rising temperatures increase the risk of irreversible loss of marine and coastal ecosystems . Today, widespread changes have been observed, including damage to coral reefs and mangroves that support ocean life, and migration of species to higher latitudes and altitudes where the water could be cooler.  Latest estimates from the UN Educational, Scientific and Cultural Organization warn that more than half of the world’s marine species may stand on the brink of extinction by 2100. At a 1.1°C  increase in temperature today, an estimated 60 percent of the world's marine ecosystems have already been degraded or are being used unsustainably. A warming of 1.5°C threatens to destroy 70 to 90 percent of coral reefs , and a 2°C increase means a nearly 100 percent loss - a point of no return.

The ocean – the world’s greatest ally against climate change

The ocean is central to reducing global greenhouse gas emissions. Here are a few reasons we need to safeguard the ocean as our best ally for climate solutions.

Peter Thomson: Moving the needle on the sustainable blue economy

Ambassador Peter Thomson of Fiji, UN Special Envoy for the Ocean, mobilizes global action to conserve and sustainably use the ocean. Read the full interview.

Climate Adaptation

Climate change is here. There are many ways to adapt to what is happening and what will happen. For more tips, check out the ActNow campaign .

Facts and figures

• What is climate change?
• Causes and effects
• Myth busters

Cutting emissions

• Explaining net zero
• High-level expert group on net zero
• Checklists for credibility of net-zero pledges
• Greenwashing
• What you can do

Clean energy

• Renewable energy – key to a safer future
• What is renewable energy
• Five ways to speed up the energy transition
• Why invest in renewable energy
• Clean energy stories
• A just transition

Adapting to climate change

• Climate adaptation
• Early warnings for all
• Youth voices

Financing climate action

• Finance and justice
• Loss and damage
• $100 billion commitment
• Why finance climate action
• Biodiversity
• Human Security

International cooperation

• What are Nationally Determined Contributions
• Acceleration Agenda
• Climate Ambition Summit
• Climate conferences (COPs)
• Youth Advisory Group
• Action initiatives
• Secretary-General’s speeches
• Press material
• Fact sheets
• Communications tips

Ocean Conveyor Belt

The ocean is in constant motion, transporting nutrients through its layers and around the globe.

Earth Science, Meteorology, Oceanography, Geography, Physical Geography

Loading ...

The  ocean  is in constant motion. You can see this for yourself when you watch  waves crash onto  shore . If you go swimming, you may even feel an ocean   current  pulling you along. Surface currents , such as the  Gulf Stream , move water across the globe like mighty rivers. Surface currents are powered by Earth’s various  wind  patterns. The ocean also has deep underwater currents . These are more  massive  but move more slowly than surface currents . Underwater currents mix the ocean ’s waters on a global scale. A process known as  thermohaline circulation , or the  ocean conveyor belt , drives these deep, underwater currents . Thermohaline Circulation Thermohaline circulation moves a massive current of water around the globe, from northern oceans to southern oceans , and back again. Currents slowly turn over water in the entire ocean , from top to bottom. It is somewhat like a giant conveyor belt, moving warm surface waters downward and forcing cold,  nutrient -rich waters upward. The term thermohaline combines the words  thermo  (heat) and  haline  (salt), both factors that influence the  density  of seawater. The ocean is constantly shifting and moving in reaction to changes in water density . To best understand ocean -water dynamics, or how water moves, there are a few simple principles to keep in mind:

• Water always flows down toward the lowest point.
• Water’s density is determined by the water’s temperature and  salinity (amount of salt).
• Cold water is denser than warm water.
• Water with high salinity is denser than water with low salinity.
• Ocean water always moves toward an  equilibrium , or balance. For example, if surface water cools and becomes denser, it will sink. The warmer water below will rise to balance out the missing surface water.

Ocean Layers The ocean can be divided into several layers. The top layer of the ocean collects the warmth and energy of sunlight, while the bottom layers collect the rich, nutrient -filled  sediment  of  decayed plant and animal matter. The top  ocean layer  is about 100 meters (330 feet) deep. Enough sunlight reaches that depth for organisms, such as  phytoplankton , to carry out  photosynthesis . Phytoplankton makes up the first part of the  marine food chain  and is essential to all ocean life. The middle, or barrier, layer is called the  thermocline . The ocean ’s temperature and density change very quickly at this layer. The barrier layer is about 200 to 1,000 meters (656 to 3,300 feet) deep. Below the barrier layer is the bottom layer, referred to as the deep ocean . It averages about three kilometers (two miles) in depth. The Conveyor Belt Scientists have long understood how nutrients move from the ocean ’s surface to its depths. As phytoplankton die, they sink and collect on the ocean floor. But if nutrients are continually sinking to the depths of the ocean , how are surface waters replenished with nutrients ? Scientists discovered that in certain regions of the ocean , the nutrient -rich deep water was  upwelling , or rising to the surface. Scientists realized that the ocean was slowly turning over from top to bottom in a continuous global loop. Like a conveyor belt, thermohaline circulation moves nutrients from one part of the ocean to another. Let’s start in the northern Atlantic Ocean and follow the conveyor belt as it moves water around the planet. In the seas near Greenland and Norway, the water is cold. Some of it freezes, leaving salt behind. The cold, salty water becomes dense and sinks to the ocean floor. This water is known as the North Atlantic Deep Water, and it is one of the  primary  driving forces of the conveyor belt. The force of the sinking, cold water pushes the existing North Atlantic Deep Water south, toward Antarctica, in a slow-moving underwater current . When it reaches Antarctica, the water flows east with the Antarctic Circum polar Current , a massive and powerful current that circles the  continent . Parts of the Antarctic Circum polar Current flow northward and move into the Indian and Pacific Oceans . As the deep, cold water travels through the oceans , it mixes with warmer water. The water eventually becomes warm enough to rise, creating a slow upwelling that brings nutrients to the surface. In the Pacific, the surface water flows through the Indonesian islands into the Indian Ocean , around southern Africa, and back into the Atlantic. The warm waters eventually travel back to the North Atlantic Deep Water, completing the global loop. It takes about 500 years for the conveyor belt to turn over the ocean ’s waters and make one complete trip around Earth. The North Atlantic Deep Water The deep water in the Greenland Sea flows along toward the lowest point on the floor of the North Atlantic. The water collects in a  basin , the same way river water flows into a lake or pond. The basin is the North Atlantic Deep Water. Other seas feed their cool ocean waters into the North Atlantic Deep Water. In the Labrador Sea, off the coast of northeastern Canada, the cold water sinks to depths of 3,000 meters (9,900 feet) at a rate of 10 centimeters (about four inches) per second. Another source of the North Atlantic Deep Water is the Mediterranean Sea. As the warm surface water of the Mediterranean  evaporates , the water grows saltier and denser. This water exits the Mediterranean through the Strait of Gibraltar, the narrow channel between Spain and Morocco that connects the sea to the Atlantic Ocean . The Mediterranean’s deep water pours into the Atlantic at a rate of two meters (about 6.5 feet) per second and helps raise the overall salinity of the Atlantic Ocean . The Antarctic Circumpolar Current When the conveyor belt reaches the southern part of the globe, it is driven back to the northern oceans by the Antarctic Circum polar Current . Western winds are very strong in the Antarctic. They help create the intensely powerful Antarctic Circum polar Current . The current moves a lot of water very quickly around the continent of Antarctica—about 140 million cubic meters (4.9 billion cubic feet) of water per second. Overturning occurs in the waters around Antarctica. Overturning happens when the extremely frigid Antarctic surface water sinks. This forces the nutrient -rich deep water to rise. Overturning moves massive amounts of water. An estimated 35 million to 45 million cubic meters (between 1.2 billion and 1.6 billion cubic feet) of water per second are continually moved from the ocean bottom to the surface. The Antarctic Circum polar Current and overturning make the waters around Antarctica an ideal  habitat  for many marine mammals. Many types of whales, for instance, migrate to the waters around Antarctica every year to feed on phytoplankton and other tiny sea creatures churned up by overturning waters. Climate Change Ocean temperature plays a key role in the conveyor belt, so a change in Earth’s  climate  might have drastic effects on the system. If one part of the conveyor belt were to break down—if cold water is not lifted to the surface in upwelling , for instance— nutrients will not be distributed to start the food chain . Organisms, such as phytoplankton , need those nutrients to thrive. Severe  climate change  slows phytoplankton from forming the first link in the marine food chain . If the first link is threatened, all life in the oceans is threatened.

Antarctic Circumpolar Current The Antarctic Circumpolar Current moves 140 million cubic meters (4.9 billion cubic feet) of water per second around Antarctica. That single current moves more water than all the rivers on the planet combined. The world's rivers move 1.3 million cubic meters (46 million cubic feet) of water per second.

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Illustrators

Educator reviewer, expert reviewer, last updated.

October 19, 2023

User Permissions

For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource.

If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media.

Text on this page is printable and can be used according to our Terms of Service .

Interactives

Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.

Related Resources