Ocean Acidification from CO2 Is Happening Faster Than Thought

A lesser-known consequence of having a lot of carbon dioxide (CO2) in the air is the acidification of water. Oceans naturally absorb the greenhouse gas; in fact, they take in roughly one third of the carbon dioxide released into the atmosphere by human activities. When CO2 dissolves in water, it forms carbonic acid, the same substance found in carbonated beverages. New research now suggests that seawater might be growing acidic more quickly than climate change models have predicted.

Marine ecologist J. Timothy Wootton of the University of Chicago and his colleagues spent eight years compiling measurements of acidity, salinity, temperature and other data from Tatoosh Island off the northwestern tip of Washington State. They found that the average acidity rose more than 10 times faster than predicted by climate simulations.

Highly acidic water can wreak havoc on marine life. For instance, it can dissolve the calcium carbonate in seashells and coral reefs [see “The Dangers of Ocean Acidification,” by Scott C. Doney; Scientific American, March 2006]. In their study, published in the December 2 Proceedings of the National Academy of Sciences USA, Wootton and his team discovered that the balance of ecosystems shifted: populations of large-shelled animals such as mussels and stalked barnacles dropped, whereas smaller-shelled species and noncalcareous algae (species that lack calcium-based skeletons) became more abundant. “I see it as a harbinger of the trends we might expect to occur in the future,” says oceanographer Scott C. Doney of the Woods Hole Ocean­ographic Institution, who did not participate in this study.



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