July 27, 2005 5:46 PM PDT
More greenhouse gas found in rain forests
Most of the carbon dioxide being "exhaled" or released by wetlands and rivers has spent around five years sequestered in trees, according to a new study performed by researchers from the University of Washington, Rice University and the Stroud Water Research Center.
The tropical forests in the 2.4 million square miles of the Amazon river basin gulp in carbon dioxide during photosynthesis. Scientists have long believed that most of the carbon dioxide ingested by the forest stays there until the trees decompose decades later. Carbon found in water samples have been shown to be 40 to 1,000 years old, according to Emilio Mayorga of the University of Washington.
Because carbon dioxide is a greenhouse gas that can trap solar energy, many scientists postulated that the rain forests could help curb the impact of global warming caused by industrialization. Policy makers in turn could view saving forests as a form of carbon-credit trading.
Mayorga, Carrie Masiello of Rice and Anthony Aufdenkampe of Stroud, however, decided to also measure atmospheric carbon in the region. They found that an enormous amount of carbon dioxide, exhaled by river organisms, is being released after only a few years.
"Previous studies failed to detect the rapid recycling of forest carbon because they never dated the invisible greenhouse gas as it is literally exhaled by the river organisms," Aufdenkampe said in a statement. "They (previous observers) assumed that the return of this forest carbon to the atmosphere must be a slow process that offered at least temporary respite from greenhouse effects."
A full report will be released in the July 28 issue of Nature.
Although scientists and policy makers differ over how much human activity they believe contributes to global warming, the growing consensus is that the atmosphere is definitely getting hotter.
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