What is the main idea of the news item? [originaltext] Researcher Dan Nepstad

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.
    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 for Nature or WWF that was released at the Bali climate change conference. He says substantial destruction could come much sooner than that.
    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.
    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.