The Earth’s Lungs Gasp: The Effects Amazonian Drought on CO2 Emissions

Called the lungs of the planet, the Amazon rainforest absorbs some 1.5 billion metric tons of CO2, every year – except when it doesn’t.

In 2005, during a ‘once-in-a-century’ drought and again in 2010 during another still more severe drought, the Amazon stopped absorbing carbon dioxide and started to release it.

Why?

Normally the Amazon absorbs CO2 as a consequence of photosynthesis – the trees breathe in carbon and release oxygen. Yet in years when unusual weather patterns drastically reduce Amazon rainfall, the result is trees that grow more slowly (reducing their absorption of CO2), and some trees that simply die. Not only do these dead trees not absorb CO2, but as they rot they release their stored CO2 back into the atmosphere.

This is problematic. According to a February 2011 Scientific American Article:

"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," he 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."

The article goes on to say that last year’s drought may have released as much as 5-billion metric tons of CO2. Roughly the same amount of carbon as stored over the course of 3 years.

Even more disturbing is the fact that despite the return of the rains the Amazon’s greenery has not returned, suggesting that the Amazon is still absorbing less than its usual amount of CO2.

And that’s bad news not only for environmental conservation and biodiversity – but for everyone who breathes.

Photo Credit: Ivan Mlinaric