Greenhouse Gas Balance of Rewetted Peatland Ecosystems

Abstract

Peatlands store approximately 600 Pg of carbon in organic soils covering just three percent of the global land surface, yet drainage for agriculture and forestry has converted many peatlands from net carbon sinks to substantial greenhouse gas sources. Rewetting drained peatlands is increasingly recognized as a climate mitigation strategy, but the trade-off between reduced CO₂ emissions and enhanced CH₄ production complicates the net greenhouse gas balance. This meta-analysis synthesizes GHG flux measurements from 64 peer-reviewed studies encompassing rewetted peatlands across boreal, temperate, and tropical climate zones. Comparison of drained and rewetted temperate fens reveals that rewetting reduces net GHG emissions by 63 percent (from 19.9 to 7.4 t CO₂e ha⁻¹ yr⁻¹), with a 69 percent reduction in CO₂ emissions partially offset by a 650 percent increase in CH₄ emissions. Among restoration approaches, active management (assisted revegetation, controlled water-table manipulation) achieves the largest net GHG reductions across all climate zones, while paludiculture (productive use of wet peatlands) provides intermediate emission reductions alongside economic returns. Tropical peatlands show the greatest absolute reduction potential (42.6 to 51.2 t CO₂e ha⁻¹ yr⁻¹) owing to their exceptionally high drained-state emissions. These findings support the inclusion of peatland rewetting in national climate mitigation portfolios and carbon market frameworks, while highlighting the need for long-term monitoring to capture temporal dynamics of post-rewetting GHG trajectories.