As much as a fifth of the amazon rainforest emits more carbon dioxide than it absorbs, according to a decade-long study of greenhouse gases. One of the main reasons is deforestation, and scientists fear that at current rates the amazon will lose its title as the “lung of the earth” faster than expected.
Every two weeks for the past decade, a team of scientists led by luciana gatti, a researcher at Brazil’s national institute for space research (INPE), has been measuring greenhouse gases in different parts of the amazon by flying vehicles fitted with sensors.
What the team found was surprising. While much of the rainforest still retains the ability to absorb large amounts of carbon dioxide — especially in wetter years — some parts of the forest, especially much of the forest that has been cut down, seem to have lost that ability.
“Every year it gets worse,” says Mr Gatti. “We have observed that the southeast is an important source of carbon dioxide. Whether it’s a wet year or a dry year. 2017-2018 was a rainy year, but no different.”
When trees die and release carbon dioxide into the atmosphere, forests become a source of carbon dioxide, rather than storing or depositing it.
Carlos nobray, co-author of gatti’s study, said the observation was “very worrying” because “it could signal the beginning of a major turning point”. Nobray believes the new findings suggest that over the next 30 years, more than half of the amazon could be converted from rainforest to savanna.
For decades, scientists have warned of an “amazon tipping point.” At this point, forests lose their ability to self-renew and start releasing more carbon dioxide than they absorb.
Scientists differ on when the tipping point will occur. Simon lewis, professor of global change science at university college London, explained: “some people believe that a tipping point will not occur until the end of the century when temperatures rise by three degrees Celsius. And others think that if the deforestation rate goes up by more than 20 percent it will reach a tipping point, which could happen in the next 10 or 20 years.”