The Ocean and Climate Change

Our ocean is changing. With 70 percent of the planet covered in water, the seas are important drivers of the global climate. Yet increasing greenhouse gases from human activities are altering the ocean before our eyes. NASA and its partners are on a mission to find out more.

  • The map above shows sea surface temperature anomalies on August 21, 2023, when many areas were more than 3°C (5.4°F) warmer than normal. On that date, much of the central and eastern regions of the equatorial Pacific were unusually warm, the signature of a developing El Niño. As has been the case for weeks, large patches of warm water were also present in the Northwest Pacific near Japan and the Northeast Pacific near California and Oregon. Portions of the Indian, Southern, and Arctic Oceans also showed unusual warmth.

    The ocean is warming

    Rising greenhouse gas concentrations not only warm the air, but the ocean, too. Research shows that around 90 percent of the excess heat from global warming is being absorbed by the ocean. Ocean heat has steadily risen since measurements began in 1955, breaking records in 2023. All this added heat has led to more frequent and intense marine heat waves.

    The image visualizes sea surface temperature anomalies in August 2023. Warm colors (red, orange) show where the ocean was warmer than normal. Cool colors (blues) show where temperatures were cooler. The red swath in the Eastern Pacific was due to an El Niño event. El Niño is a climate phenomenon in the tropical Pacific that results in warmer than normal sea surface temperatures leading to weather impacts across the planet.
    Credit: NASA

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  • Sea levels are rising

    Global sea levels have risen more than 4 inches (101 millimeters) since measurements began in 1992, increasing coastal flooding in some places. As ocean water warms, it expands and takes up more space. The added heat in the air and ocean is also melting ice sheets and glaciers, which adds freshwater to the ocean and further raises sea levels. The Surface Water and Ocean Topography (SWOT) mission, launched in 2022, and Sentinel 6 Michael Freilich, launched in 2020, are providing unparalleled views of sea level rise on top of decades of data from other missions.

    The video shows a 21-day average of sea surface height anomalies highlighting ocean eddies and currents as imaged by the Surface Water and Ocean Topography (SWOT) satellite. The red and orange colors indicate where the sea surface was higher than normal and the blues are where it was lower than normal.
    Credit: NASA

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The ocean is getting a little greener

Recent research found that over the past 20 years, the tropical ocean turned greener. Ocean color reflects the life that is found in it. Green colors often correspond to phytoplankton, microscopic plant-like organisms that form the center of the ocean's food web. Observations of changes in phytoplankton populations due to climate change are a key part of the Plankton, Aerosol, Cloud, and ocean Ecosystem (PACE) mission, which launched in 2024.

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A composite satellite image of southern Africa and its surrounding water is shown highlighting three different views the satellite provides. The first view on the left shows a true color view with blues and turquoise water and white clouds. The middle view has green colors swirling around the coast and pink colors further out into the water. The last view has rainbow colors with red, yellow and green along the coast and blue and purple further out into the water. The land is different shades of brown.
The PACE satellite’s Ocean Color Instrument (OCI) detects light across a hyperspectral range, which gives scientists new information to differentiate communities of phytoplankton. This first image released from OCI identified two different communities of these microscopic marine organisms in the ocean off the coast of South Africa in February 2024. The central panel of this image shows Synechococcus in pink and picoeukaryotes in green. The left panel of this image shows a natural color view of the ocean, and the right panel displays the concentration of chlorophyll-a, a photosynthetic pigment present in phytoplankton.
Credit: NASA
  • An animation showing a hurricane changing from weak to strong over the ocean. The hurricane is spinning counterclockwise with rainbow colors, and bright red and black colors swirling in the center around an empty circle. The water around the storm is gray colored.

    Ocean warming is altering hurricanes

    Hurricanes need warm water to form and strengthen. Recent research points to warmer ocean temperatures as a key factor causing more storms to rapidly intensify. One way to detect rapid intensification before it happens may be through a change in lightning around the eye of the storm. Plus, higher sea levels worsen storm surge flooding when a storm travels over a coastline.

    NOAA’s GOES-East satellite captures the rapid intensification of Hurricane Lee on Sept. 7, 2023. 
    Credit: NASA/NOAA

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  • Three images are shown side by side of the same coral reef at different times. The first shows yellow-colored branching corals. The middle shows the same corals but they are now white. The last image shows the same corals again but they are now brown and fragmented.

    Ocean acidification and heating are altering marine ecosystems

    Carbon dioxide and heat are both absorbed by the ocean as greenhouse gas levels increase. When carbon dioxide is dissolved in the ocean, the water becomes more acidic. This makes it harder for corals and some other marine life to grow shells and protect themselves. Marine heat waves are complicating the matter by making it too warm for many corals to survive. Satellites are providing important data to scientists measuring such changes in ocean environments.

    When corals are stressed from changes in their environment, they turn white, or "bleach." Sometimes the coral is able to recover, but other times the bleaching event leads to its death. This image shows the decay of a healthy coral reef to a reef between 2014 and 2015 in the National Marine Sanctuary of American Samoa.
    Credit: NOAA/ XL Catlin Seaview Survey

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  • White-colored sea ice is shown with many dark-colored cracks.

    Sea ice is thinning and shrinking

    Melting sea ice does not affect sea levels, but it does impact global temperatures. Sea ice is light-colored and reflects sunlight back into space; open water is darker and absorbs more sunlight. Warming ocean waters melt sea ice from below, and warmer air helps melt it from above. As ice cover thins and shrinks, more ocean is exposed and less sunlight is reflected, further warming the water and air. Satellites help monitor changes in sea ice which is an area of research for upcoming missions in the Earth Systems Observatory.

    A photograph of Arctic sea ice breaking up as seen during an overhead flight during NASA’s Operation IceBridge in March 2011.
    Credit: NASA

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  • El Niño can add to the heat

    El Niño occurs when the central and eastern tropical Pacific Ocean become warmer than normal. This periodic ocean warming can add to the long-term global warming that has already accumulated, making a hot year even hotter. That’s because ocean temperatures are major drivers of global temperatures, as seen in 2023.

    A visualization showing sea surface height anomalies in the Pacific Ocean in June 2023 based on satellite data. The red and orange colors show a higher-than-normal sea surface height. The blue areas were lower than normal.
    Credit: NASA

    Read More About 2023's Record Heat

  • A photograph of Earth from the International Space Station. At the top of the image, the Earth is curved has a blue line dividing it from black-colored space. At the middle and bottom of the image, the Earth has blue and turquoise-colored water around various green islands. On the sides of the image are various instruments on the space station.

    Ocean circulation may be changing

    Ocean currents are vital transporters of heat around the planet. As the Greenland and Antarctic ice sheets melt, the excess fresh water running into the ocean could disrupt the balance of temperature and salinity that drive deep ocean currents. NASA satellite missions are monitoring the ocean for changes in heat transport as glaciers continue to melt and the ocean warms.

    Clouds trace out islands in the Caribbean Sea in this photo taken by an astronaut aboard the International Space Station. 
    Credit: NASA

    Read More About Ocean Circulation