The amount of carbon dioxide released due to the destruction of the Brazilian Amazon exceeded the amount that the rainforest was able to absorb between 2010 and 2019, according to new research in the journal Nature Climate Change. Using satellite data, the study authors calculate that the region saw a net loss of 0.67 billion tonnes of carbon during the decade, suggesting that the Amazon’s ability to remove carbon from the atmosphere may be a thing of the past.
With more than 60 percent of the Amazon rainforest lying within Brazil’s borders, the country holds huge strategic importance in the fight against climate change. However, since current president Jair Bolsonaro entered office at the start of 2019, reduced environmental protections have sparked a massive increase in deforestation.
According to the data presented in the new study, 3.9 million hectares of Amazon rainforest were destroyed in 2019, representing a near-four-fold increase on each of the previous two years, which both saw around one million hectares of Brazilian Amazon wiped out by deforestation.
However, while satellite images have allowed scientists to accurately track deforestation for a number of years, actual changes in the forest’s carbon storage capacity have proved much harder to track. The study authors therefore utilized new methods of analyzing satellite data to calculate overall changes in aboveground biomass (AGB) throughout the decade.
Doing so allowed them to compare the amount of carbon dioxide absorbed as the forest grew with the amount released as it was destroyed. Overall, they found that the Brazilian Amazon emitted about 18 percent more carbon than it absorbed during the decade under consideration.
The researchers also noted that 73 percent of AGB loss could be attributed to forest degradation, with only 27 percent being due to deforestation. Degradation refers to events or practices that damage the forest without destroying it, such as selective cutting, fires, and drought.
This insight gives a more nuanced appreciation of the factors influencing the Amazon’s ability to store carbon, and could help guide conservation efforts. For instance, despite the fact that 2019 saw 30 percent more deforestation than 2015, the overall loss of AGB was in fact three times higher in 2015, as tree mortality and wildfires produced by El Niño droughts resulted in severe degradation throughout the region.
“We all know the importance of Amazon deforestation for global climate change,” explained study author Professor Peter Sitch in a statement. "Yet our study shows how emissions from associated forest degradation processes can be even larger.”
As this research illustrates, degradation-driven losses in biomass are predominantly responsible for the Brazilian Amazon’s net carbon release over the past decade. Based on this finding, Sitch insists that "degradation is a pervasive threat to future forest integrity and requires urgent research attention."