The giant forest had previously been a carbon sink, a place that absorbs more carbon than it releases, but is now thought to be contributing towards the climate crisis, scientists confirmed.
Deforestation and “rapid local warming” in parts of the forest have had a major impact on its role as a “carbon sink”.
Professor Luciana Gatti and her colleagues have collected air samples from four regions of the Amazon, about twice a month over the span of nine years, to measure the tropical forest’s atmosphere.
The scientists, from Brazil’s National Institute for Space Research (INPE), analysed data to determine how carbon dioxide (CO2) and carbon monoxide (CO) are concentrated in different parts of the Amazon.
The INPE scientists’ data reveals western Amazonia is still a carbon sink, albeit a weak one, due to its almost constantly wet climate and relatively little decay compared to other areas.
Eastern Amazonia’s ability to absorb carbon has been degraded, or even reversed, due to deforestation and its increasingly warm and dry climate.
The south-eastern part of the forest, which makes up 20 per cent of the Amazon, has even reversed its ability to absorb carbon by becoming a carbon source, the findings suggest.
The research is newly published, but the researchers spoke to the BBC last year about the implications a reversal of carbon absorption would have on climate change.
Prof Gatti said: “Each year is worse. We observed that this area in the south-east is an important source of carbon. And it doesn’t matter whether it is a wet year or a dry year. 2017-18 was a wet year, but it didn’t make any difference.”
In Brazil, deforestation has surged since right-wing President Jair Bolsonaro took office in 2019, reaching a 12-year high last year and causing an international outcry.
Bolsonaro has called for mining and agriculture in protected areas of the Amazon and has weakened environmental enforcement agencies, which environmentalists and scientists say has directly resulted in the rising destruction.
Additional reporting by the Reuters news agency.