Deep in the Amazon, a leaf falls from a tree into a river and, in a way, UCSB scientists are watching.

As this leaf and other vegetation decomposes in the Amazonian waterways it releases the most predominant greenhouse gases: carbon dioxide and methane. In the first phase of a two-phase project, UCSB researchers found last April that the amount of CO2 discharged is triple that of earlier estimates. As researchers learn more about CO2 emissions in the Amazon, they develop a more complete picture of the carbon cycle and its effect on global climate change. In contrast to earlier theories, these results show that rainforests produce roughly the same amount of CO2 they consume – a delicate balance that may be affected by human development.

NASA recently extended funding for the project with a grant of $951,697, which will allow Professor John Melack and his colleagues at UCSB’s Institute for Computational Earth System Science to continue researching into the next phase. NASA’s Earth Science Enterprise provided the grant and will pay for salaries and field studies until 2006.

“What we did was just look at how much carbon dioxide was coming out of the open water surfaces of the Amazon,” said Laura Hess, a researcher for the project. “Now what we are doing is looking at methane.”

Their study is part of an international effort joining scientists from various fields in the United States with their peers in Brazil and Japan.

The project uses a new kind of satellite radar system provided by the National Space Development Agency of Japan that penetrates the jungle canopy and maps the waterways of an area four times the size of California. The maps are cross-referenced with data collected in the South American jungle over the past twenty years.

Before the Japanese satellite data was available, it was not possible to determine the amount of carbon dioxide gas emanating from the jungle waters, Hess said.

The Amazon gives off 500 metric tons of carbon dioxide annually, about a tenth of what humans create through deforestation and the use of fossil fuels, according to the study. Rotting vegetation, releasing CO2 and methane, takes years to completely decompose as it floats down the rivers.

“If you want to know where carbon from today’s tropical forest goes, look 1,000 kilometers downstream in 20 or 30 years,” Jeffrey Richey, an oceanographer at the University of Washington and co-author of an article with Melack and Hess on the subject, said in a statement.

In the Amazon, the foremost producer of CO2 and methane is the wetlands, followed by humans and animals. A global climate change has been attributed to an increase in these gases.

Melack’s research is part of the international Large Scale Biosphere-Atmosphere Experiment in Amazonia, headed by Brazil. The immense study incorporates research in a broad range of fields, from land use to biogeochemistry. One of the project’s goals is to understand the Amazon as part of Earth’s bio-network.

“His grant proposal was one of a select few chosen for funding by NASA,” Rep. Lois Capps said in a statement, “and will help answer important scientific questions about global warming.”