The natural forests in the Amazon removes more carbon dioxide from the atmosphere than it emits, reducing global warming, according to a recent study.

Researchers from NASA's Jet Propulsion Laboratory in Pasadena, Calif., resolved a long-standing debate about a key component of the overall carbon balance of the Amazon basin by when they determined that living trees in the undisturbed forest draw more carbon dioxide from the air than the forest's dead trees emit, according to a press release.

"The Amazon's carbon balance is a matter of life and death: living trees take carbon dioxide out of the air as they grow, and dead trees put the greenhouse gas back into the air as they decompose," researchers wrote in a statement. 

For the seven-year study, investigators measured tree deaths caused by natural processes throughout the Amazon forest, even in remote areas where no data have been collected at ground level.

They found that each year, dead Amazonian trees emit an estimated 1.9 billion tons of carbon to the atmosphere. To compare this with Amazon carbon absorption, the researchers used censuses of forest growth and different modeling scenarios that accounted for uncertainties. In every scenario, carbon absorption by living trees outweighed emissions from the dead ones, indicating that the prevailing effect in natural forests of the Amazon is absorption.

This study looked only at natural processes in Amazonia, not at the results of human activities such as logging and deforestation, which vary widely and rapidly with changing political and social conditions.

"We found that large natural disturbances - the sort not captured by plots - have only a tiny effect on carbon cycling throughout the Amazon," Sassan Saatchi, a co-author of the study, said in a statement. 

The findings were recently published in Nature Communications.