Intact and managed peatland soils as a source and sink of GHGs from 1850 to 2100

Abstract

Land-use change disturbs the function of peatland as a natural carbon sink and triggers high GHG emissions1. Nevertheless, historical trends and future trajectories of GHG budgets from soil do not explicitly include peatlands2,3. Here, we provide an estimate of the past and future role of global peatlands as either a source or sink of GHGs based on scenario timelines of land conversion. Between 1850 and 2015, temperate and boreal regions lost 26.7 million ha, and tropical regions 24.7 million ha, of natural peatland. By 2100, peatland conversion in tropical regions might increase to 36.3 million ha. Cumulative emissions from drained sites reached 80 ± 20 PgCO2e in 2015 and will add up to 249 ± 38 Pg by 2100. At the same time, the number of intact sites accumulating peat will decline. In 1960 the global peatland biome turned from a net sink into a net source of soil-derived GHGs. Annual back-conversion of most of the drained area would render peatlands GHG neutral, whereas emissions from peatland may comprise 12–41% of the GHG emission budget for keeping global warming below +1.5 to +2 °C without rehabilitation. Natural peatlands accumulate carbon but land-use change and drainage leads to emission of GHGs from peatlands. Loss of natural peatland area globally has shifted the peatland biome from a sink to a source of carbon, but restoration of drained peatlands could make them carbon neutral.