Brazil’s Amazon rainforest has released more carbon than it stored over the past decade – degradation being a bigger cause than deforestation – according to new research.
More than 60% of the Amazon rainforest is in Brazil, and the new study used satellite monitoring to measure carbon storage from 2010 to 2019.
The study found that degradation (parts of the forest damaged but not destroyed) accounted for three times as much carbon loss as deforestation.
The research team – comprising INRAE, the University of Oklahoma and the University of Exeter – said large areas of rainforest had been degraded or destroyed due to human activity and change climate, resulting in carbon loss.
The results, published in Nature Climate Change, also show a significant increase in deforestation in 2019 – 3.9 million hectares compared to around 1 million per year in 2017 and 2018 – probably due to weakened environmental protection in Brazil.
Professor Stephen Sitch of the Global Systems Institute in Exeter said: “The Brazilian Amazon as a whole has lost some of its biomass and has therefore released carbon.
“We all know the importance of deforestation in the Amazon for global climate change.
“Yet our study shows how emissions from associated forest degradation processes can be even greater.
“Degradation is a pervasive threat to the future integrity of forests and requires urgent research attention.”
Degradation is linked to deforestation, especially in weakened parts of a forest near deforested areas, but it is also caused by tree felling and forest fires.
Climatic events, such as droughts, further increase tree mortality.
Such degradation can be difficult to follow, but the research team used the L-VOD satellite vegetation index developed by scientists from INRAE, CEA and CNRS.
Using this index and a new deforestation tracking technique developed by the University of Oklahoma, the study assessed changes in forest carbon stocks.
A change of government in Brazil in 2019 resulted in a sharp decline in the country’s environmental protection.
The 3.9 million hectares of deforestation that year is 30% more than in 2015, when extreme droughts in El Niño led to increased tree mortality and forest fires. However, the study shows that carbon losses in 2015 were greater than in 2019.
This demonstrates the dramatic impact that degradation can have on overall biomass and carbon storage in the rainforest.
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