Bobby Bascomb – Agriculture is the biggest driver of peatland loss in Indonesia, Peru and the Democratic Republic of Congo, home to the largest expanses of tropical peatlands in the world, a recent study has found.
Peatlands are crucial in the fight against climate change: They cover less than 3% of the world's landmass, but sequester more carbon than any other terrestrial ecosystem. Yet, the boggy wetlands are being deforested and drained at unsustainable rates, releasing climate-warming greenhouse gases. However, scientists have lacked a clear understanding of the emissions associated with the different drivers of recent tropical peatland degradation.
In the new study, researchers analyzed satellite imagery from 2020-2021 to determine what's driving peatland conversion in Indonesia, Peru and the DRC, and to quantify the greenhouse gas emissions associated with it.
Logging emerged as a key driver of tropical peatland loss in all three countries. Mining and road development were major factors in Indonesia and Peru. However, agriculture was by far the biggest driver across all three regions, the study found.
In Indonesia, where large-scale agriculture was the leading source of emissions, agriculture overall accounted for 67% of peatland conversion. In Peru, smallholder agriculture was most responsible, for the 61% of agricultural conversion. In the DRC, smallholder agriculture alone accounted for 93% of peatland conversion and 94% of emissions, with no significant role by large-scale agriculture.
Tropical peatlands are often cleared by burning, which the study found accounted for roughly half the total greenhouse gas emissions of the conversion. "Fire emits a very high amount of greenhouse gases over a very short period of time," lead author Karimon Nesha, from Wageningen University & Research in the Netherlands, told Mongabay in a video call. That's because fire quickly releases the carbon stored in both vegetation and soil.
The study found that the initial emissions in 2020 from fires used to clear peatlands was 19-20 times higher than the emissions from decaying peat the following year. However, scientists know that peat continues to decompose for decades and can eventually release roughly the same amount of emissions as the initial period of peatland draining, clearing and burning.
Overall, researchers found the highest greenhouse gas emissions in the DRC, home to the largest tropical peatland in the world, the Cuvette Centrale. However, Shona Jenkins, a research fellow at the University of St. Andrews, Scotland, who wasn't involved in the study, questioned part of the methodology quantifying the emissions.
She said the peatland map the researchers used may overestimate peatland depth in the DRC, meaning emissions there "could be vastly overestimated."
While some uncertainty may remain around emissions estimates, Nesha said the path to reducing peatland emissions is clear: Don't use fire, which generates the most short-term emissions, and "rewet" drained peatlands; cover them with water to stop the decomposition that results in long-term emissions.