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![]() July 23, 2008 Nutrients washed out of the Amazon River are powering huge amounts of previously unexpected plant life far out to sea, thus trapping atmospheric carbon dioxide, according to a new study. Until now, the areas around the Amazon and other great rivers had been thought to be emitting CO2, so the study may affect climate scientists' calculations of how the greenhouse gas acts. The study appears in this week's Proceedings of the National Academy of Sciences. http://www.pnas.org/ "This new understanding allows us to better think about how carbon dioxide is cycled between the atmosphere and the oceans, and how this might change in the future," said lead author Ajit Subramaniam, a biological oceanographer at Columbia University's Lamont-Doherty Earth Observatory. Lamont is part of The Earth Institute. Each year the world's oceans are thought to absorb about 2 billion tons of CO2 from the atmosphere, but the amount permanently sequestered by sinkage is unclear. The new discovery may tilt the estimated balance between air and oceans by only about 2 percent, said Subramaniam. However, he said, "it alters our view about the processes that we think are going on. There may be other surprises out there." Studies of other large rivers including the Congo, Orinoco and Mekong suggest that similar processes may be taking place there. Subramaniam said that climate change, booming human populations and intensified land uses could alter the workings of the great river basins. For instance, ongoing conversion of Amazonian rainforest into farmland may increase outwash of nutrients; in some regions, future warming could greatly increase rainfall, and thus river flows. On the other hand, proposed large dam projects on rivers like the Orinoco could cut flow by as much as half. "The whole process could change," said Subramaniam. "But we can't predict how it will change, or what the outcome will be."## Contact: Kevin Krajick The Earth Institute at Columbia University 212-854-9729 kkrajick@ei.columbia.edu This text derived from: http://www.earth.columbia.edu/articles/view/2213 Recommend this Article to a Friend Back to: News |
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