A new study reveals that global tropical deforestation has led to a doubling of carbon loss between 2001-2019.

Tropical forests are large carbon stores, but when forests are cleared, they release these vast amounts of carbon dioxide into the atmosphere. This makes protecting forests critical in the fight against climate change.

The study, published in Nature Sustainability, is led by Southern University of Science and Technology in Shenzhen, China, and co-authored by scientists at the Wildlife Conservation Society along with more than a dozen other organizations. The results reveal that tropical forest loss between 2001 and 2019 has led to more than a doubling of carbon loss, from 3.5 billion tons of CO2 per year in 2001–2005 to 7.3 billion tons of CO2 per year in 2015–2019.

The authors paired high-resolution satellite measurements of forest loss with carbon density maps from three sources (aboveground biomass, belowground biomass, and soil) to create detailed maps of where, when, and how much carbon was impacted by forest loss during each year between 2001-2019.

Said Paul Elsen, WCS Climate Adaptation Scientist and a co-author of the study: “This new approach reveals carbon losses from tropical deforestation that were overlooked in previous assessments. This provides a more accurate accounting of carbon emissions from forest clearing.”

The authors note that most of the forest that was cleared between 2001-2019 remained cleared into 2020. Only about 30 percent of the forests that were cleared during that period began to regenerate to either forest or shrubland by 2020.

The results of the study are counter to those of previous assessments, such as the Global Carbon Budget 2021, which showed a slightly negative trend in tropical carbon loss from deforestation in recent years. The authors note that this is largely due to much more accurate accounting of carbon losses through the use of high-resolution, spatially explicit maps of carbon and forest loss, rather than simply calculating losses from government data.

The study was released on the same day as the release of the latest IPCC report, which highlighted the overwhelming vulnerability of socioeconomic and natural systems to climate change if left unabated. Late last year, nearly 150 countries convened at COP26 in Glasgow to formally commit to halting and reversing deforestation by 2030.

“The accelerating trend of forest carbon loss we observe underscores that we need to do much more to meet our international commitments on climate change,” said Elsen. “Continued forest and carbon losses of the magnitude that we’ve seen over the past five years could push limiting climate change to between 1.5-2°C out of reach, which we now know would have huge consequences for both people and nature.”