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Overview of Ocean Acidification

Climate change impacts nearly every aspect of the marine environment and life in the seas, primarily, but not exclusively, through rising temperatures. In addition to the impacts of climate change on the ocean, the added CO2 in the atmosphere is having an additional impact on the ocean and life within it, that of ocean acidification.

Overview of Ocean Acidification

Atmospheric CO2 dissolves into sea water and forms carbonic acid (and reducing pH). The level of Hydrogen ions in sea water (a measure of acidity) has increased 30% in recent years. This can reduce shell formation in some marine animals, notably corals and some plankton, with potential knock on effects up the food chain. Early life stages may be particularly vulnerable. With current rates of acidification, by 2050, the oceans will be more acidic than at any time in the past 20 million years, possibly longer. Ocean Acidification has significant implications for fish communities and therefore fisheries. Polar oceans are anticipated to be affected first, with conditions becoming corrosive for shelled marine animals this century.

The Marine Climate Impacts Partnership (MCCIP) on Ocean Acidification

MCCIP provides detailed information on ocean acidification and its implications for marine ecosystems. The 2009 MCCIP report finds that “In the last 200 years, ocean acidity has increased by 30% and at a rate much faster than anytime in the last 65 million years. This has serious implications for marine ecosystems and climate regulation.” This new research extends the period of elevated pH concentrations reported previously from 20 million years to 65 million years. Importantly for climate mitigation, the 2009 MCCIP report finds that “Increasing ocean acidification has the potential to harm marine ecosystems and alter the oceans’ ability to take up excess CO2 from the atmosphere leading to a direct impact on future climate change.” 


Update, 27 June 2022:

Information on ocean acidification from the MCCIP can be found here and its 2020 report "Air–sea CO2 exchange and ocean acidification in UK seas and adjacent waters" can be found here. The 2022 UNESCO report "Multiple Ocean Stressors: A Scientific Summary for Policy Makers", which covers ocean acidification, can be downloaded here

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10 Mar 2011