Tropical rainforests are called the lungs of the earth, because they suck in pollution and breath out clean, healthy air. There is a darker side to this story, though -- without protection, these same forests could actually speed up global warming.
A new paper from a team of British and Brazilian researchers has some worrying news about the Amazon rainforest, the biggest single lung on the planet. It describes how last year's drought left some areas as dry as a tinderbox.
The thing is, this happened in 2005 too. Back then the drought was described as a once in a hundred year event, but then it happened again.
The new study shows how these dry spells are really bad news for the trees, and many are dying. They then stop absorbing carbon dioxide and start pumping out gases as they burn or rot away. And so we get into a kind of vicious circle.
Climate science tells us that we'll be seeing more droughts like this, more often. And if the rainforest starts breathing out more than it's absorbing, then the forests begin to contribute to the problem they help solve today.
So far, so grim, but there are reasons for hope. Deforestation in the Amazon is falling, due in part to new agreements from the big players in the leather world (like Nike and Timberland) not to buy from ranchers who are cutting down the forest to graze cows. Larger chunks of rainforest are much better at withstanding drought, and so this drop in deforestation matters.
Every nation on earth also has a stake in this. By cutting carbon pollution down instead of trees, we can help to slowly stabilize the world's climate and preserve the rainforests that are left.
Right now the world's ancient rainforests are on our side in the fight against climate change. They can mop up a huge amount of our pollution, but there is a limit. It's time for us to realize that this deal cuts two ways.