Progressive release of long-stored carbon from tropical peatland disturbances.

Koarashi, Jun; Itoh, Masayuki; Atarashi-Andoh, Mariko; Saito-Kokubu, Yoko; Matsueda, Makoto; Kusin, Kitso; Jaya, Adi; Dohong, Salampak et al. · Nat Commun · 2026

basic_science · Level V

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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<sup>-2</sup> from peatlands in Central Kalimantan, Indonesia, using radiocarbon dating of peat profiles and groundwater dissolved organic carbon. Drainage contributed 5-11 kg C m<sup>-2</sup>, primarily from centuries- to millennium-old, previously waterlogged peat. Fires released 23-32 kg C m<sup>-2</sup> 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.