Global warming could destroy far more Arctic permafrost than we thought – “The current pattern of permafrost reveals the sensitivity of permafrost to global warming”Posted by Jim at Sunday, April 16, 2017
By Chelsea Harvey
10 April 2017
(The Washington Post) – Climate change could cause another 4 million square kilometers, or about 1.5 million square miles, of permafrost to disappear with every additional degree Celsius, or 1.8 degrees Fahrenheit, of warming, a new study suggests.
The estimate, which was published Monday in the journal Nature Climate Change, is about 20 percent higher than previous studies, the authors said.
The study suggests that if the Earth’s temperatures warm 2 degrees Celsius, or 3.6 degrees Fahrenheit, higher than their preindustrial levels — the maximum amount of warming nations around the world have aimed to allow under the Paris climate agreement — more than 2.5 million square miles of permafrost could disappear.
Under a more severe outcome of 6 degrees Celsius, or 10.8 degrees Fahrenheit, of warming above preindustrial levels, which could occur sometime after the turn of the century if greenhouse gas emissions continue to go on unabated, nearly all the earth’s permafrost would likely disappear.
The loss of more permafrost would release more methane, a highly potent greenhouse gas, than scientists have previously predicted. That could worsen a dangerous climate feedback loop in the Arctic, whereby increased emissions cause greater warming and greater warming causes faster thawing of permafrost, which then releases more emissions. [more]
10 April 2017 (University of Leeds) – 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 four 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 Leeds, Exeter, Sweden, Norway, and the Met Office, suggest that the huge permafrost losses could be averted if ambitious global climate targets are met.
Dr Sarah Chadburn led the research project whilst based at the School of Earth and Environment at Leeds. She 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.”
University of Leeds Media Relations Officer Anna Martinez on firstname.lastname@example.org or +44 (0)113 343 4196
ABSTRACT: Permafrost, which covers 15 million km2 of the land surface, is one of the components of the Earth system that is most sensitive to warming1, 2. Loss of permafrost would radically change high-latitude hydrology and biogeochemical cycling, and could therefore provide very significant feedbacks on climate change3, 4, 5, 6, 7, 8. The latest climate models all predict warming of high-latitude soils and thus thawing of permafrost under future climate change, but with widely varying magnitudes of permafrost thaw9, 10. Here we show that in each of the models, their present-day spatial distribution of permafrost and air temperature can be used to infer the sensitivity of permafrost to future global warming. Using the same approach for the observed permafrost distribution and air temperature, we estimate a sensitivity of permafrost area loss to global mean warming at stabilization of million km2 °C−1 (1σ confidence), which is around 20% higher than previous studies9. Our method facilitates an assessment for COP21 climate change targets11: if the climate is stabilized at 2 °C above pre-industrial levels, we estimate that the permafrost area would eventually be reduced by over 40%. Stabilizing at 1.5 °C rather than 2 °C would save approximately 2 million km2 of permafrost.