A paper published last week in Nature reviewed a growing body of evidence that suggests that a profound loss of forest cover in the Amazaon would have worrying consequences for the rest of the planet.
In “The Amazon basin in transition“, Davidson et al. describe how the impacts of agricultural expansion and climate events such as El Niño can conspire to destroy even more forest through drought- and fire-induced deforestation. When trees die or burn, they release carbon into the atmosphere. If more trees are destroyed than grow to replace them, more carbon is released than is absorbed; the Amazon sink becomes a source. According to the article, the Amazon rainforst currently sequesters roughly 100 billion tons of carbon, an amount equivalent to the carbon release from a decade’s worth of fossil fuel use.
Currently forest cover has been reduced to about 80% of its original area; the article suggests that if forest cover approaches 40%, a critical transition from forest to savanna may occur, given feedbacks between tree cover and precipition (see our summary in Science). If this occurs, we might witness what happens with the lost of “the lungs of the planet“.