Will droughts turn the Amazon into a giant source of carbon pollution?

Amazon Rainforest
April 27, 2016

As climate change increases temperatures and alters rainfall patterns across South America, scientists are concerned that the Amazon rainforest will shift from a carbon sponge to a carbon source.

New research published today in the journal Global Change Biology highlights this disturbing question.

NOAA Earth System Research Laboratory (ESRL) scientist John Miller, working with an international team, investigated by analyzing air samples taken by aircraft over four sites in the Amazon Basin in 2010–2012. The study found strong evidence that the 2010 drought caused much of the Amazon to significantly reduce carbon uptake for up to two years.

Drought threat Drought threat The Amazon Rainforest is a storehouse for carbon dioxide. As climate changes, the lush tropical ecosystems of the Amazon Basin may face droughts that cause the release of more carbon dioxide into the atmosphere than the forests can absorb. (NOAA) Roughly 10 billion metric tons of carbon are emitted each year by industrial activity, with about half taken up by the oceans and forest ecosystems like the Amazon, according to data collected by ESRL’s Global Monitoring Division. What scientists don’t know is how a changing climate will affect the Amazon. The new study expands on earlier work conducted by Miller and lead author Caroline Alden, currently with the University of Colorado. Their research, begun when they were both at CU's Cooperative Institute for Research in Environmental Sciences, examined atmospheric CO2 levels across the Amazon Basin. Studies of small Amazon forest plots have found a similar response to heat and drought.

If climate change causes tropical forests to stop absorbing carbon and instead give off large amounts of CO2 through decay or combustion2 it would accelerate global climate change.

“We need to know if climate change will dampen or eliminate rainforest carbon uptake,” said Miller. “Understanding how present-day climate extremes affect the rainforest will help us more accurately project future climate change.”

More Information

Video interview with NOAA's John Miller and the CIRES web story.

Media contact: Theo Stein, public affairs for NOAA's Earth System Research Laboratory, at 303-497-6288 or theo.stein@noaa.gov