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Huge permafrost thaw can be limited by ambitious climate targets

University of Leeds

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IMAGE: This is a drone image -- thawing permafrost peat plateaus in northern Norway. view more

Credit: Sebastian Westermann

Global warming will thaw about 20% more permafrost than previously thought, scientists have warned -- potentially releasing significant amounts of greenhouse gases into the Earth's atmosphere.

A new international research study, including climate change experts from the University of Leeds, University of Exeter and the Met Office, reveals that permafrost is more sensitive to the effects of global warming than previously thought.

The study, published today in Nature Climate Change, suggests that nearly 4 million square kilometres of frozen soil -- an area larger than India -- could be lost for every additional degree of global warming experienced.

Permafrost is frozen soil that has been at a temperature of below 0ºC for at least two years. Large quantities of carbon are stored in organic matter trapped in the icy permafrost soils. When permafrost thaws the organic matter starts to decompose, releasing greenhouse gases such as carbon dioxide and methane which increase global temperatures.

It is estimated that there is more carbon contained in the frozen permafrost than is currently in the atmosphere.

Thawing permafrost has potentially damaging consequences, not just for greenhouse gas emissions, but also the stability of buildings located in high-latitude cities.

Roughly 35 million people live in the permafrost zone, with three cities built on continuous permafrost along with many smaller communities. A widespread thaw could cause the ground to become unstable, putting roads and buildings at risk of collapse.

Recent studies have shown that the Arctic is warming at around twice the rate as the rest of the world, with permafrost already starting to thaw across large areas.

The researchers, from Sweden and Norway as well as the UK, suggest that the huge permafrost losses could be averted if ambitious global climate targets are met.

Lead-author Dr Sarah Chadburn of the University of Leeds said: "A lower stabilisation target of 1.5ºC would save approximately two million square kilometres of permafrost.

Achieving the ambitious Paris Agreement climate targets could limit permafrost loss. For the first time we have calculated how much could be saved."

In the study, researchers used a novel combination of global climate models and observed data to deliver a robust estimate of the global loss of permafrost under climate change.

The team looked at the way that permafrost changes across the landscape, and how this is related to the air temperature. They then considered possible increases in air temperature in the future, and converted these to a permafrost distribution map using their observation-based relationship. This allowed them to calculate the amount of permafrost that would be lost under proposed climate stabilisation targets.

As co-author Professor Peter Cox of the University of Exeter explained: "We found that the current pattern of permafrost reveals the sensitivity of permafrost to global warming."

The study suggests that permafrost is more susceptible to global warming that previously thought, as stabilising the climate at 2ºC above pre-industrial levels would lead to thawing of more than 40% of today's permafrost areas.

Co-author Dr Eleanor Burke, from the Met Office Hadley Centre, said: "The advantage of our approach is that permafrost loss can be estimated for any policy-relevant global warming scenario.

"The ability to more accurately assess permafrost loss can hopefully feed into a greater understanding of the impact of global warming and potentially inform global warming policy."

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Further information

Images available for download: https://goo.gl/lfZ9wu
Image caption: Drone images - thawing permafrost peat plateaus in Northern Norway
Image credit: Sebastian Westermann

For any additional information please contact University of Leeds Media Relations Officer Anna Martinez on a.martinez@leeds.ac.uk or +44 (0)113 343 4196.

The full paper, ' An observation-based constraint on permafrost loss as a function of global warming ' is published in Nature Climate Change 10 April 2017 (DOI: 10.1038/nclimate3262)

University of Leeds

The University of Leeds is one of the largest higher education institutions in the UK, with more than 31,000 students from 147 different countries, and a member of the Russell Group research-intensive universities.

We are a top 10 university for research and impact power in the UK, according to the 2014 Research Excellence Framework, and positioned as one of the top 100 best universities in the world in the 2015 QS World University Rankings. We are The Times and The Sunday Times University of the Year 2017. http://www.leeds.ac.uk

University of Exeter

The University of Exeter is a Russell Group university that combines world-class research with very high levels of student satisfaction. Exeter has over 21,000 students and is in the top one per cent of universities worldwide. Exeter is also ranked 9th in The Times and The Sunday Times Good University Guide 2017 and 11th in the Guardian University Guide 2017. In the 2014 Research Excellence Framework (REF), the University ranked 16th nationally, with 98% of its research rated as being of international quality. Exeter was named The Times and The Sunday Times Sports University of the Year 2015-16, in recognition of excellence in performance, education and research. Exeter was The Sunday Times University of the Year 2012-13.

The University launched its flagship Living Systems Institute in 2016, a world-class, interdisciplinary research community that will revolutionise the diagnosis and treatment of diseases. This follows recent investments of more than £350 million worth of new facilities across its campuses in recent years; including landmark new student services centres -- the Forum in Exeter and The Exchange on the Penryn Campus in Cornwall, together with world-class new facilities for Biosciences, the Business School and the Environment and Sustainability Institute. http://www.exeter.ac.uk

Met Office

The Met Office is the UK's National Meteorological Service, providing 24x7 world-renowned scientific excellence in weather, climate and environmental forecasts and severe weather warnings for the protection of life and property. The Met Office Hadley Centre for Climate Science and Services provides world-class guidance on the science of climate change and is the primary focus in the UK for climate science. Its work is, in part, jointly funded by BEIS (Department for Business, Energy and Industrial Strategy) and DEFRA (Department for Environment, Food and Rural Affairs). http://www.metoffice.gov.uk

Other contributors included Stockholm University and the University of Oslo

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