University of Leeds: Tropical carbon loss has doubled due to forest clearance

Researchers using multiple high-resolution satellite observations have found that carbon loss has more than doubled since 2001 due to forest clearance across the tropics.

The findings are critical because they suggest that existing strategies to reduce forest loss are unsuccessful, and highlighting the importance of monitoring deforestation trends following new pledges made at COP26 in Glasgow.

The study published in Nature Sustainability involved researchers from around the globe, and used high-resolution satellite observations to investigate the trajectory and drivers of forest carbon loss in the 21st century.

The observations found doubling of tropical forest carbon loss worldwide from one billion tonnes of carbon per year in 2001–2005 to two billion tonnes of carbon in 2015–2019. This increase in carbon loss from forest conversion is higher than in previous estimates, which show no trend or a slight decline in land-use emissions in the early 21st century.

This report shows a stark and worrying divergence between international commitments – which is to halve or stop deforestation – and reality, which is an acceleration of deforestation

Professor Dominick Spracklen, School of Earth and Environment
The lead author on this study is PhD candidate Yu Feng from the Southern University of Science and Technology (SUSTech) and the University of Hong Kong.

He said: “The doubling in the loss of forest carbon, including biomass and soil organic carbon, is primarily driven by agricultural expansion.

“This acceleration in forest carbon loss differs from current estimates of land-use change emissions in the assessments of the global carbon budget that shows a flat or decreasing trend.”

Co-author Professor Dominick Spracklen, from the School of Earth and Environment at Leeds, said: “This report shows a stark and worrying divergence between international commitments – which is to halve or stop deforestation – and reality, which is an acceleration of deforestation.

“Our paper highlights the need to rethink and refocus efforts to reduce deforestation.”

Tropical forests are the largest terrestrial component of the global carbon cycle. Therefore, loss of forests could be devastating because both the stored carbon stocks in biomass and soil, as well as the function of sequestering atmospheric carbon, will be lost.

The conversion of forests to agricultural lands also induces other environmental consequences, like biodiversity extinction and land degradation. Most (82%) of the forest carbon loss is triggered by large-scale commodity or small-scale agriculture activities, such as shifting cultivation, particularly in Africa and Southeast Asia.

The study found the largest increases in the rate of forest carbon loss occurred in the Democratic Republic of Congo, Indonesia and Brazil. Increasing rates of forest loss in the Congo are particularly worrying, as this region had relatively low rates of deforestation until recently.

Co-author, Professor Zhenzhong Zeng from SUSTech, said: “Our study observed that around 70% of former forest lands that had been converted into agricultural spaces in 2001–2019 remained so in 2020, confirming a dominant role of agriculture in long-term pan-tropical carbon reductions on formerly forested landscapes.”

Professor Joseph Holden, from the University’s School of Geography, said: “Changing this tropical deforestation path requires serious political and private sector commitments and, importantly, both global and local actions to accompany those commitments.

“Worryingly, our results show that carbon loss from tropical deforestation has actually accelerated over the last 10 years.”

Co-author and chair Professor of SUSTech, Chunmiao Zheng, said: “The 2014 New York Declaration on Forests promised to halve tropical deforestation by 2020.

“However, our results demonstrate a failure to the commitment and highlight the colossal challenge posed by the 2021 Glasgow Leaders’ Declaration on Forests and Land Use, which pledges to halt forest loss by 2030.”

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