The acid wave is rolling in - Ka Leo O Hawaii: NEWS

The acid wave is rolling in

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Posted: Wednesday, February 15, 2012 5:00 am

The ocean is slowly becoming more acidic as it absorbs carbon dioxide emissions from human activity. Although this slows global warming, it has negative impacts on marine life.

Two scientists, Tobias Friedrich, a postdoctoral fellow, and Axel Timmermann, a professor in the Department of Oceanography at the University of Hawai‘i at Mānoa International Pacific Research Center, are working together to study ways to slow down the process of ocean acidification. Using a computer model, the two attempt to estimate the amount of calcium carbonate in ocean water, which represents the level of acidity.

"In the last ~200 years, humans have released ~500 billion tons of carbon to the atmosphere through fossil fuel burning, cement production and changes in land use. About 30 percent has been taken up by the ocean, which has led to a slower global warming compared to what we would have seen if all of this greenhouse gas had stayed in the atmosphere. However, CO2 reacts with seawater and forms carbonic acid, which leads to an increased acidity and to other changes in the chemical properties of seawater," said Friedrich.

The rising levels of CO2 in the atmosphere and oceans have a negative impact on many different types of biological marine life, such as coral reefs and mollusks. Friedrich explained that ocean acidification "reduces calcification rates of many coral species, as well as of mollusks, and pteropods (a sea snail)." Calcification is important for sea creatures that depend on shells and skeletons.

With coral dying due to bleaching and other diseases, reduced calcification rates make it hard for the populations to return to normal. Because coral reefs house so much of the ecosystem, large numbers of fish species are impacted.

Plankton, which forms the basis of many marine food chains, is another species being affected by this rapid change.

Friedrich added that ocean acidification is linked with humans. "From 11,000 years ago to about 200 years ago, atmospheric CO2 levels have been fairly stable. Thus, ocean acidification did not occur during that time," he said. "It is a man-made problem."

Atmospheric carbon dioxide concentration for the past 800,000 years:

between ~180 parts per million and ~280 parts per million


392 parts per million


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