Monday, July 30, 2012

Ocean acidity rivals climate change as environmental threat

The Smithsonian puts a confusing title to this article, since acidification is a consequence of greenhouse gas emissions: .... [W]ithin the last 50 years, human industry has caused the world’s oceans to experience a sharp increase in acidity that rivals levels seen when ancient carbon cycles triggered mass extinctions, which took out more than 90 percent of the oceans’ species and more than 75 percent of terrestrial species.

Rising ocean acidity is now considered to be just as much of a formidable threat to the health of Earth’s environment as the atmospheric climate changes brought on by pumping out greenhouse gases. Scientists are now trying to understand what that means for the future survival of marine and terrestrial organisms.

In June, ScienceNOW reported that out of the 35 billion metric tons of carbon dioxide released annually through fossil fuel use, one-third of those emissions diffuse into the surface layer of the ocean. The effects those emissions will have on the biosphere is sobering, as rising ocean acidity will completely upset the balance of marine life in the world’s oceans and will subsequently affect humans and animals who benefit from the oceans’ food resources.

The damage to marine life is due in large part to the fact that higher acidity dissolves naturally-occurring calcium carbonate that many marine species–including plankton, sea urchins, shellfish and coral–use to construct their shells and external skeletons. Studies conducted off Arctic regions have shown that the combination of melting sea ice, atmospheric carbon dioxide and subsequently hotter, CO2-saturated surface waters has led to the undersaturation of calcium carbonate in ocean waters. The reduction in the amount of calcium carbonate in the ocean spells out disaster for the organisms that rely on those nutrients to build their protective shells and body structures....

Some clown fish off the coast of Spain, Esv, public domain

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