Amazon droughts cutting forest CO2 ABSORPTION, FINDS NASA
WASHINGTON DC: A single season of drought in the Amazon rainforest can reduce its capacity to absorb carbon dioxide for years after the rains return, a NASA study has found.
The study, published in the journal Nature, is the first to quantify the long-term legacy of drought in Amazon, the largest tropical forest on Earth.
Researchers from NASA'S Jet Propulsion Laboratory (JPL) in the US, and other institutions used satellite data to map tree damage and mortality caused by a severe drought in 2005. In years of normal weather, the undisturbed forest can be a natural carbon "sink," absorbing more carbon dioxide from the atmosphere than it puts back into it.
However, starting with the drought year of 2005 and running through 2008 - the last year of available data - the Amazon basin lost an average of 270 million metric tonnes per year of carbon, with no sign of regaining its function as a carbon sink. At about 2.3 million square miles, the Amazon is the largest tropical forest on Earth.
Scientists estimate that it absorbs as much as one-tenth of human fossil fuel emissions during photosynthesis.
"The ecosystem has become so vulnerable to these warming and episodic drought events that it can switch from sink to source depending on the severity and the extent," said Sassan Saatchi of JPL, who led the study.