Research shows oceans are becoming more acidic

July 16, 2004

Paris, July 16 - The world's oceans are absorbing an unprecedented amount of carbon dioxide (CO2), which is increasing their acidity and possibly threatening the survival many marine species, especially calcifying organisms including corals, shellfish and phytoplankton. According to research presented recently at a symposium organized by UNESCO's Intergovernmental Oceanographic Commission and the International Council for Science's Committee on Oceanic Research (SCOR), this in turn could disrupt marine food chains and alter ocean biogeochemistry in ways that are not yet understood or predictable.

The symposium brought together scientists from the world's leading oceanographic institutions to discuss how the ocean might be affected by higher levels of atmospheric carbon dioxide, and to develop research priorities to study these future effects. They were also called upon to discuss potential environmental consequences of proposals to use the ocean to sequester excess atmospheric CO2, which is one of the most important greenhouse gases.

A report on the meeting's conclusions, now available online*, points out that the ocean is one of the Earth's largest natural reservoirs of carbon and each year absorbs approximately one third of the carbon dioxide emitted by human activities. According to research** led by Christopher Sabine of the National Oceanographic and Atmospheric Administration in the United States (NOAA, an IOC Member State Agency)* the ocean has taken up approximately 120 billion metric tons of carbon generated by human activities since 1800. The IOC reports that some 20-25 million tons of CO2 are being are being added to the oceans each day.

The absorption of carbon dioxide by the oceans is considered a beneficial process that reduces the concentration of CO2 in the atmosphere and mitigates its impact on global temperatures. However there is growing concern over the price of this service. For the symposium participants, it is now well established that by the middle of this century, the accumulating burden of CO2 entering the ocean will lead to changes in pH or acidity of the upper layers that are three times greater in magnitude and 100 times faster than those experienced between ice ages. Such dramatic changes in the CO2 system in open-ocean surface waters have not been observed for more than 20 million years of earth's history, concluded the meeting.

The initial findings of limited observation, research and modeling conducted to date and presented to the symposium indicate that in a high CO2 world:

  • the ocean would be more acidic globally, and would also be more stratifed in the high latitudes. In addition nutrient concentrations in surface waters of high-latitude regions would be lower, subsurface waters would be less oxygenated, and phytoplankton would experience increased exposure to sunlight. These changes would affect many species and change the composition of biological communities in ways that are not yet understood or predictable.
  • many calcifying organisms, including plankton and corals, and also non-calcifying organisms, would be unable to grow and reproduce effectively at higher CO2 and lower pH levels. Rising temperatures - combined with elevated CO2 and decreasing pH - pose a serious threat to coral reefs, possibly leading to the elimination of some reefs by the end of this century.

    Participants at the symposium stressed that although the impact of climate change on the ocean has been much debated, the direct impact of CO2 itself has largely been neglected. However, they concluded, changes are clearly underway and their effects may be large and may seriously destabilize marine ecosystems. Their report signals the need for more research and identifies research priorities, in a bid to increase understanding of the changes taking place and their consequences, and to allow for more informed policy decisions in this area.
    *The report is accessible on the internet at 2panel/HighOceanCO2.htm">
    ** A report on Dr. Sabine's research and findings appears in the July 15 edition of Science magazine, along with a report from fellow NOAA scientist and participant at the UNESCO meeting, Dr. Richard Feely (


    Related Phytoplankton Articles from Brightsurf:

    Phytoplankton disturbed by nanoparticles
    Products derived from nanotechnology are efficient and highly sought-after, yet their effects on the environment are still poorly understood.

    Synthesis study demonstrates phytoplankton can bloom below Arctic sea ice
    Researchers used historical scientific studies, along with contemporary observations employing autonomous floats and robotic vehicles, to demonstrate that phytoplankton blooms occur under Arctic Ocean sea ice.

    Ninety years of data shows global warming impacts on foundation of marine ecosystems
    Phytoplankton are microscopic plants that underpin ocean productivity and provide 50% of the world's oxygen via photosynthesis.

    Ocean warming and acidification effects on calcareous phytoplankton communities
    A new study led by researchers from the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) warns that the negative effects of rapid ocean warming on planktonic communities will be exacerbated by ocean acidification.

    Smaller than expected phytoplankton may mean less carbon sequestered at sea bottom
    A study that included the first-ever winter sampling of phytoplankton in the North Atlantic revealed cells smaller than what scientists expected, meaning carbon sequestration models may be too optimistic.

    Observing phytoplankton via satellite
    Thanks to a new algorithm, researchers at the AWI can now use satellite data to determine in which parts of the ocean certain types of phytoplankton are dominant.

    UCI oceanographers predict increase in phytoplankton by 2100
    A neural network-driven Earth system model has led University of California, Irvine oceanographers to a surprising conclusion: phytoplankton populations will grow in low-latitude waters by the end of the 21st century.

    Study offers solution to Ice Age ocean chemistry puzzle
    New research into the chemistry of the oceans during ice ages is helping to solve a puzzle that has engaged scientists for more than two decades.

    Kīlauea lava fuels phytoplankton bloom off Hawai'i Island
    When Kīlauea Volcano erupted in 2018, it injected millions of cubic feet of molten lava into the nutrient-poor waters off the Big Island of Hawai'i.

    Scientists who raced to study Kilauea's lava as it fueled rare phytoplankton bloom find surprise
    Results from a rapid-response oceanographic expedition in the North Pacific reveal a surprise about how lava from the Kilauea Volcano, which erupted on the island of Hawai'i during the summer of 2018, triggered a vast phytoplankton bloom.

    Read More: Phytoplankton News and Phytoplankton Current Events
  • is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to