Peatland permafrost closer to tipping point than assumed | Polarjournal

The circumpolar permafrost belt in the Arctic also contains extensive peatlands, where particularly large amounts of carbon are stored. Photo: Anna Konopczak via www.awi.de

Permafrost soils cover nearly a quarter of the land area of the Northern Hemisphere, most of it in the Arctic. This includes frozen peatlands, which store twice as much carbon as the entire European forests. An international team of researchers now warns in a new study published in the journal Nature Climate Change that peatland permafrost in Europe and western Siberia could reach a climate tipping point much sooner than previously thought.

It is now widely known that thawing permafrost releases huge amounts of carbon into the atmosphere as carbon dioxide and methane, which are produced when microorganisms decompose organic material, further accelerating climate change. But not all permafrost is the same. Peatlands, which are very rich in organic material, store much more carbon than mineral permafrost, up to 39 billion tons. And these areas are particularly vulnerable to rapid climate change in the 21st century.

As described by Dr Paul Morris, Associate Professor of Biogeosciences at the University of Leeds and co-author of the study, the vast peat carbon reservoirs have been protected by frost for thousands of years. However, in warmer conditions, all of the stored carbon can be lost very quickly. And these frozen peatlands have not been adequately accounted for in Earth system models, according to the study, which was led by the University of Leeds.


Permafrost regions in the northern hemisphere. Map: Global Terrestrial Network for Permafrost GTN-P via www.awi.de

For the study, the research team used the latest generation of climate models to analyze future climate conditions in peatlands and the likely impacts on permafrost peatlands. Their simulations showed that even the strongest, worldwide efforts to limit global warming by drastically reducing carbon emissions will not be enough to maintain a climate — cold and dry — in northern Europe by 2040 that is necessary for frozen peatlands.

However, in northern parts of western Siberia, whose peatlands contain 13.9 billion tons of carbon, favorable climate conditions for permafrost peatlands could be maintained if appropriately strong emission reductions are implemented.

“We examined a range of future emission trajectories. This included strong climate-change mitigation scenario, which would see large-scale efforts to curb emissions across sectors, to no-mitigations scenarios and worse-case scenarios,” says Richard Fewster, a PhD student at the University of Leeds’ School of Geography and lead author of the study. “Our modelling shows that these fragile ecosystems are on a precipice and even moderate mitigation leads to the widespread loss of suitable climates for peat permafrost by the end of the century.”

Taking strong socioeconomic measures to reduce emissions and mitigate climate change would limit the rate and extent of permafrost thaw. Photo: Paolo Verzone via www.awi.de

Despite the bleak assessment, Fewster stresses that this is no reason to give up. Implementing strong mitigation measures could still limit and even partially reverse the rate and extent to which suitable climate zones are lost.

Peatland permafrost responds differently to changing climates than mineral-soil permafrost due to the insulating properties of organic soils, but peatlands remain poorly represented in Earth system models,” says Dr Ruza Ivanovic, an associate professor of climatology at the University of Leeds and co-author of the study. “It is vitally important these ecosystems are understood and accounted for when considering the impact of climate change on the planet.”

Julia Hager, PolarJournal

Link to study: Fewster, R.E., Morris, P.J., Ivanovic, R.F. et al. Imminent loss of climate space for permafrost peatlands in Europe and Western Siberia. Nat. Clim. Chang., 2022 DOI: 10.1038/s41558-022-01296-7

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