Hong Kong scientists reveal massive tropical carbon loss
The team used high-resolution satellite datasets to analyse the gross forest carbon loss associated with forest removal in the tropics (between 23.5° N and 23.5 S but excluding northern Australia) during the 21st century. They found a two-fold increase in gross tropical forest carbon loss worldwide from an average of 0.97 gigatons of carbon per year in 2001–2005 to 1.99 per year in 2015–2019 due to rapid forest loss.
Given the key role of the tropics in the carbon cycle, the study poses serious implications. “The findings are critical because they suggest that existing strategies to reduce forest loss are questionable. This failure underscores the importance of monitoring deforestation trends especially following the pledges made at the UN climate summit in Glasgow in November 2021 to halt and reverse deforestation,” said Professor Ji Chen from the University of Hong Kong’s Department of Civil Engineering.
Tropical forests are the largest terrestrial component of the global carbon cycle, storing about 250 gigatons of biomass carbon in its woody vegetation and absorbing about 70 gigatons of atmospheric carbon per year through photosynthesis. The rapid and steady loss of forests could be devastating because it leads to the loss of stored carbon in biomass and soil. Deforestation also obstructs carbon sequestration or the process of capturing and retaining carbon dioxide.
“The doubling and acceleration in the loss of forest carbon, including biomass and soil organic carbon, is primarily driven by agricultural expansion which differs from current estimates of land-use change emissions in the assessments of the global carbon budget that shows a flat or decreasing trend. In addition to carbon, conversion of forests to agricultural lands also induces other environmental consequences, like biodiversity extinction and land degradation,” said Yu Feng, a postgraduate student who worked on the study.
The study was published in Nature Sustainability.