Researchers in the Amazon, attending the United Nations Conference on Climate Change in Bali, say a vicious cycle of climate change and deforestation could destroy the world's largest tropical rain forest more quickly than expected. Trish Anderton explains, in a background report.
Researcher Dan Nepstad calls it a "perfect storm" of deforestation: as fire and ranching destroy the Amazon forest in Brazil, the remaining trees release less moisture, producing a dryer climate that kills more trees. It adds up to a vicious cycle of destruction.
Tapajos River near Amazonia National Park in northern state of Para, Brazil, 29 Apr 2006
A World Bank-funded study released early this year predicted the Amazon could become a grassy savannah by the end of the century.
Nepstad produced a report for the World Wildlife Fund or WWF that was released at the Bali climate change conference. He says substantial destruction could come much sooner than that.
"If we add these processes up, we see that by 2030 - not by the end of the century but in the next two and a half decades - given current trends, 55 percent of the forests of the Amazon will have been cleared or impoverished through some combination of logging, drought and fire," said Nepstad.
Living trees absorb carbon, and many scientists believe the release of carbon into the atmosphere is warming the planet and fueling global climate change.
Nepstad says a widespread death of trees in the Amazon of the scale he is predicting would release up to 26 billion tons of carbon, or as much as the whole planet produces in about two and a half years.
Antonio Nobre of Brazil's National Institute for Research in the Amazon says signs of a destructive climate cycle are already detectable.
"What we are seeing already in southern Brazil, which is in the wake of the river of water vapor coming from the Amazon, is already a drying up. We have analyzed just ten years but you see clearly a tendency of drying," said Nobre.
Christiane Ehringhaus, who studies the Amazon for the Center for International Forestry Research, says she would not be surprised if the Amazon's future is bleaker than previously expected. She says the cycle of drying may have contributed to, and been intensified by, widespread forest fires in 2005.
"You saw fires in areas of the Amazon that hadn't been detected even as flammable in previous models. So you saw forest fires that are undetectable from space that do tremendous damage and dry up the forest for subsequent fires," said Ehringhaus.
The WWF report says much of the destruction results from burning of the forest to clear land, which is then used to meet the global demand for soybeans, beef and biofuel. It says one way to help preserve the forest is to strengthen existing government land-use policies and programs.
Nepstad praises recent efforts by Brazil to create conservation areas.
"We see enormous successes the Brazilian government has made in creating protected areas in the pathway of the expanding agro-industrial frontier - 23 million hectares of new areas protected in the two-year period beginning in early 2004," he said.
Even so, the report says the prediction of substantial damage by 2030 is conservative. It urges a reforesting of cleared areas and promotion of reduced-impact logging and sustainable agriculture, to slow or reverse damage to the rain forest.
Eduardo Bandeira de Mello of the Brazilian Development Bank says his bank is trying to fund such efforts.
"We can finance the states of the Amazon region in order to have institutional strengthening to be more proactive in fighting against deforestation, and we can finance alternative projects in the deforestation belt," said de Mello.
Besides absorbing heat from sunlight and converting it into cooling water vapor, the Amazon provides as much as one-fifth of the earth's river water. It is one of the world's most biologically diverse regions.