Acid Oceans

Thursday, July 6, 2006

YOU'D THINK that the threat to the Earth's climate posed by greenhouse gas emissions would be enough to get policymakers to take seriously the need to reduce human use of fossil fuels. Rising sea levels, reduced polar ice and dramatic regional climate shifts represent serious dangers to the way of life of large swaths of the world's population. Now a new report by a group of federal scientists and university researchers highlights a different threat posed by carbon emissions, one with its own set of potentially devastating ecological consequences: the increasing acidity of the oceans.

Ocean water absorbs a huge amount of the carbon emitted by human energy use -- so much that it has long been seen as a kind of buffer mitigating global climate change, which is triggered by the presence of that carbon in the atmosphere. But it turns out that oceanic absorption of carbon is not an unqualified good. All that carbon seems to be making the waters more acidic, a trend researchers believe will continue as concentrations increase. This chemical change, in turn, inhibits the ability of animals that produce external shells-- particularly corals and certain planktons -- to grow them efficiently. As these animals are some of the basic life forms of ocean ecosystems, substantially reducing their productivity could have enormous impact on life in the seas, from devastating already-stressed coral reefs to interrupting the food chain for large fish and whales.

There's a tendency in discussing carbon emissions for policymakers to be paralyzed by the enormity of the problem. The hypothesized consequences to climate and the oceans are vast -- literally earth-changing -- and the cause is so inherent to the way industrialized societies live that the problem seems unsolvable. When combined with the inevitable scientific uncertainty associated with modeling the future of terribly complex systems, this leads some people to active denial and many others to resist responsible steps to begin getting carbon under control. Admittedly, these steps, even if taken aggressively, will not be sufficient to decrease atmospheric carbon but can only, for now, slow its rate of increase. But the paralysis has to end. While there still exist big questions surrounding climate change and carbon emissions, the best evidence all points in a single direction: that failing to reduce dependence on fossil fuels will have terrible consequences, and failing to start now will make the disruption later all the more painful.

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