Progressive release of long-stored carbon from tropical peatland disturbances

Abstract Tropical peatlands are globally important, millennia-old carbon sinks, yet unprecedented human-driven degradation is triggering alarming carbon emissions. Comprehensive quantification of carbon dynamics across the disturbance sequence—from peat swamp forests to drained and fire-impacted peatlands—remains a critical knowledge gap. Here we show that over 18 years (1996–2014), drainage and subsequent peat fires released approximately 30–41 kg C m −2 from peatlands in Central Kalimantan, Indonesia, using radiocarbon dating of peat profiles and groundwater dissolved organic carbon. Drainage contributed 5–11 kg C m −2 , primarily from centuries- to millennium-old, previously waterlogged peat. Fires released 23–32 kg C m −2 from peat accumulated over the past 3,000 years, initiating progressive oxidative decomposition of older peat. Extrapolation to Indonesia’s disturbed peatlands suggests a release of 0.81–3.70 Gt C between 1996 and 2014, with ongoing decomposition releasing an additional 0.03–0.08 Gt C annually, accelerating the impact on the global carbon balance.