"Once a Century" Amazonian Droughts Now Happening Every 5 Years

The Amazon rain forest is often called the "lungs of the earth." Unsurprisingly, these lungs are now starting to look like those of a 5 pack-a-day Pall Mall smoker.

A severe drought last year in the Amazon rainforest outpaced a 2005 dry spell thought to be a once-in-a-century event, a new study finds.

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"If drought events continue, the era of intact Amazon forest buffering the increase in atmospheric carbon dioxide may have passed," [researchers from the United Kingdom and Brazil] wrote in a paper published yesterday in the journal Science.

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"The bigger-picture view, however, is that the Amazon has experienced two '100-year' droughts in the past five years, and there is good evidence that the forests are not adapted to drought ... and the bigger trees die first," [Scott Goetz, a senior scientist at the Woods Hole Research Center] said. "There is little doubt that continued droughts of this magnitude and frequency will change the structure of these forests and their ability to sequester carbon from the atmosphere."

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The drought in 2010 could release another 5 billion metric tons of CO2 into the atmosphere as trees killed by the drought decompose, roughly equal to the annual U.S. output of the heat-trapping gas. That dwarfs the approximately 2 billion metric tons of CO2 that entered the atmosphere as a consequence of the 2005 drought.

[Scientific American]