For years, climate scientists have sounded the alarm about the growing likelihood that the Amazon rainforest, now one of the world’s largest carbon absorbers, can actually become a source of carbon inside only 15 years old. New research shows that for some other types of nearby rainforests this is already happening.
This is largely due to the deliberate burning of forests. In South America, the mining, livestock, and soybean industries frequently set trees on fire to make way for their operations, turning forests into open pastures.
This means that forests contain less foliage to suck in greenhouse gases from the atmosphere. To make matters worse, when a tree catches fire, it releases all the carbon it hijacked during its lifetime, which means forests become a source of global warming emissions. And in the midst of the climate crisis, this problem is even more serious, as in the middle of warmer, drier conditions, forests do not produce enough moisture to quickly extinguish the flames, which means more areas are burned with less effort.
A new study, published Friday in Science Advances, aimed to see how the carbon intake of South American forests has changed in recent years. To do so, the authors analyzed monitoring data for greenhouse gases from 1987 to 2020 on 32 deciduous, semi-deciduous and perennial forests, each of which has been deforested, in the lush state of Minas Gerais in the southeastern Brazil. In total, the area they examined spread over 33 hectares.
By connecting these data to statistical models, the authors found that, on average, these forests now absorb 2.6% less carbon a year than they did 33 years ago. At the same time, the carbon production of forests from fires increased by 3.4% per year, which means that they generally lose the ability to absorb gas. These changes were enough to push forests along the edge of carbon sinks into carbon sources. The authors fear that their findings could be extrapolated to the tropical forests of the region in general.
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The data show that the change occurred in 2013. That year, on average, the forests examined released 0.14 US tons per 2.5 acres (0.13 metric tons of carbon per hectare), or the equivalent production of drive 323 miles in a diesel car.
The authors’ findings are particularly troubling because separate search recently found that the importance of carbon sequestration in tropical forests is almost as important as that in the Amazon rainforest.
Scientists point out that not everything is lost. We should remove the pressure from these forests by curbing our greenhouse gas emissions and therefore curbing the climate crisis. Brazil should also restore the carbon sinking capabilities of these forests, protecting forests by stopping intentional burning.
“The key path is conservation,” Vinícius Maia, a researcher at the Federal University of Lavras in Brazil, wrote in an email.
The authors say particular efforts should be made to preserve deciduous forests, which are the driest and warmest the researchers examined and saw how carbon emissions increased even more. But really, these protections have to be extended to all the foliage in the area.