Peatland restoration is anticipated to provide climate change mitigation over all time-scales: a UK case-study

Abstract Peatlands provide one of the largest terrestrial carbon stocks in the UK, but a large proportion of peatlands have been drained for peat extraction, agriculture and other uses, turning them into a major source of greenhouse gas (GHG) emissions. Restoration can ultimately return peatlands into carbon sinks. However, rewetting - the primary step in peatland restoration - can reduce CO 2 emissions while increasing CH 4 release. This may result in little overall climate benefit, or even increased warming for several years post peatland restoration, as CH 4 is a short-lived but strong GHG, and may overpower the benefits resulting from the reduction in CO 2 . Most studies are based on comparing total CO 2 -equivalent emissions pre- and post-restoration using the 100-year Global Warming Potential (GWP100), which can fail to reveal the full dynamics. We evaluated emissions and resultant climate impacts from peatland restoration using area data from The Wildlife Trusts, a federation of UK-based conservation charities. Emissions were assessed under multiple pulse emission metrics (GWP100, GWP20, GTP100) to indicate impacts over a range of time-horizons, and GWP* to reveal impacts over time. Restoration so far is modelled as providing large emission reductions under all metrics, even considering uncertainties. Increased CH 4 is unlikely to cause extra warming even in the extremely near-term (<20 years), and if peatlands are maintained in their rewetted states, they can contribute to net-cooling in the long term. There is less certainty over the climate benefits of further restoration, from rewetted to ‘near-natural’ states, especially in the shorter term, but we argue that any risks are low, while this continued restoration will provide further ecological benefits and support biodiversity. Our study lends further support for peatland restoration in the UK and other regions with similar habitats, and provides insight into the climate roles of peatlands more broadly.