Unprecedented burning in tropical peatlands during the 20th century compared to the previous two millennia: Tropical peatland burning through time

Tropical peatland wildfire incidence has risen in recent decades, driven by drainage for land use and intensified by severe droughts with global climate change. These disturbances have altered vegetation structure, disrupted ecosystem functioning, and led to significant carbon emissions, particularly in Southeast Asia. However, the long-term history and characteristics of wildfires in tropical peatlands remain largely unknown. Here, we compiled fifty-eight macro-charcoal records from peatlands across the tropics, ranging from lowland forested to montane peatlands, to assess millennia-scale changes and controlling factors of tropical peatland burning. We divided the datasets into four main sub-regions: Neotropical, Afrotropical, Indomalayan, and Australasian ecoregions to explore regional variability. Tropical peatlands had higher burning levels between 0 and 850 CE, followed by a relatively low and stable period until a marked increase during the 20th century. The general trend in tropical peatland burning follows changes in global temperature, and climate variables that control the length and severity of drought events have a notable influence on peat burning before 1900 CE. During the last century (1900-2000 CE), regional variability was observed, with declining fire trends in the Neotropical and Afrotropical regions and upward trends in the Indomalayan and Australasian regions. This difference is likely to be attributed to human activities and human intervention is also seen in palm swamps and hardwood swamps under similar climatic settings. With the increase in anthropogenic pressures on peatlands and greater climate variability, future wildfires in peatlands are likely to become more frequent and widespread across all tropical ecoregions. Conservation and sustainable land-use practices are needed to mitigate and control peatland burning and protect these carbon-rich sinks.