A revolutionary new approach to measuring changes in forest carbon density has helped scientists determine that the tropics now emit more carbon than they capture, countering their role as a net carbon “sink.”*

“These findings provide the world with a wakeup call on forests,” said scientist Alessandro Baccini, the report’s lead author….Forests are the only carbon capture and storage ‘technology’ we have in our grasp that is safe, proven, inexpensive, immediately available at scale, and capable of providing beneficial ripple effects—from regulating rainfall patterns to providing livelihoods to indigenous communities.”

Using 12 years (2003-2014) of satellite imagery, laser remote sensing technology and field measurements, Baccini and his team were able to capture losses in forest carbon from wholesale deforestation as well as from more difficult-to-measure fine-scale degradation and disturbance …from smallholder farmers removing individual trees for fuel wood. These losses can be relatively small in any one place, but added up across large areas they become considerable.

[T] he researchers discovered that tropics represent a net source of carbon to the atmosphere — about 425 teragrams of carbon annually – which is more than the annual emissions from all cars and trucks in the United States.

Excerpts from New approach to measuring forest carbon density shows tropics now emit more carbon than they capture, Woods Hole Research Institute Press Release, Sept. 28, 2017

*Tropical forests are a net carbon source based on aboveground measurements of gain and loss by A. Baccini et al., Science, Sept. 28, 2017