Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw

TLDR

Northern peatlands have sequestered vast carbon and nitrogen over millennia, cooling the climate, but disturbances and limited mapping leave their vulnerability to warming uncertain. The study compiles over 7,000 field observations to produce a data‑driven map of northern peatlands and their carbon and nitrogen stocks. The authors model permafrost thaw impacts using the maps, predicting that warming will shift northern peatlands’ greenhouse‑gas balance. Currently peatlands act as climate coolers, but anthropogenic warming could turn them into net greenhouse‑gas sources.

Abstract

Significance Over many millennia, northern peatlands have accumulated large amounts of carbon and nitrogen, thus cooling the global climate. Over shorter timescales, peatland disturbances can trigger losses of peat and release of greenhouses gases. Despite their importance to the global climate, peatlands remain poorly mapped, and the vulnerability of permafrost peatlands to warming is uncertain. This study compiles over 7,000 field observations to present a data-driven map of northern peatlands and their carbon and nitrogen stocks. We use these maps to model the impact of permafrost thaw on peatlands and find that warming will likely shift the greenhouse gas balance of northern peatlands. At present, peatlands cool the climate, but anthropogenic warming can shift them into a net source of warming.