Global Warming

Global Warming Forecast for Amazon Rain Forest: Dry and Dying

The Amazon rain forest's dry season lasts three weeks longer than it did 30 years ago, and the likely culprit is global warming, a new study finds.

Rain falls year-round in the Amazon, but most of the annual deluge drops during the wet season. (The rainy season's timing varies with latitude.) Scientists think that a longer dry season will stress trees, raising the risk of wildfires and forest dieback. The forest's annual fire season became longer as the dry season lengthened.

"The length of the dry season in the southern Amazon is the most important climate condition controlling the rain forest," Rong Fu, a climate scientist at The University of Texas at Austin's Jackson School of Geosciences, said in a statement. "If the dry season is too long, the rain forest will not survive."

With the dry season already spanning an extra week each decade since 1979, the future effects will be more severe.

During the 2005 and 2010 droughts, satellites detected decreased vegetation greenness over the southern Amazon rain forest (orange and red regions).

"The dry season over the southern Amazon is already marginal for maintaining rain forest," Fu said. "At some point, if it becomes too long, the rain forest will reach a tipping point."