Researchers have been warning about an imminent "tipping point" in the Amazon rainforest for a while now, and a new study suggests the moment has arrived for swaths of the region. The study in Nature finds that parts of the rainforest are now emitting more carbon dioxide than they absorb, per a release at Phys.org. The rainforest has long served as a buffer against environmental trouble because of its role as a "carbon sink"—its ability to absorb the greenhouse gas from the atmosphere. But the study suggests the dynamic has flipped in certain parts of the Brazilian Amazon, particularly the southeast. CNN has the numbers: Four regions emit 410 million metric tons of carbon dioxide a year, mostly because of deforestation and fires. The regions also absorb 120 million metric tons of the gas, but that leaves net emissions at 290 million metric tons.
"The overall pattern of deforestation, warmer and drier dry seasons, drought stress, fire, and carbon release in eastern Amazonia seriously threatens the Amazon carbon sink," writes Colorado State's Scott Denning in an accompanying article in Nature. Researchers figured all this out by monitoring carbon dioxide levels taken by planes in roughly 600 flights from 2010 to 2018 over the four sites studied, per the New York Times. The latter newspaper talks to an Amazon expert unaffiliated with the study who praises its thoroughness and adds that reforestation can help restore the region's status as a carbon sink. “I don’t think you’ll ever get it back to what it was, but you can certainly improve it," says Thomas Lovejoy of George Mason University. (Not helping: Illegally cleared Amazon lots were being sold on Facebook.)