Earth’s melting permafrost threatens to unleash a dangerous climate feedback loop

By Joe Romm, overview of new research was published in the journal Nature Climate Change. April 2016

As Steve Hanley says:  Joe Romm, one of the hardest working climate change reporters, has come across a scary new study just published in Nature. It finds that higher average temperatures are contributing to permafrost melting in the Arctic and sub-Arctic regions faster than previously thought. Permafrost contains twice as much carbon as the atmosphere does today. If all of it melted, it would be equivalent to taking all the oil in the Alberta tar sands and burning it at once.

Permafrost melting in Arctic
In this so-called “drunken forest,” in Alaska, the trees tilt because the permafrost is melting. CREDIT: NSIDC.

Permafrost, or tundra, is soil that stays below freezing for at least two years. Normally, plants capture carbon dioxide from the air during photosynthesis. Then they slowly release that carbon dioxide back into the atmosphere after they die. The Arctic acts like a very large carbon freezer, which keeps the decomposition rate very low. That is changing, according to the report. Romm writes in Think Progress, “We are leaving the freezer door wide open. The tundra is being transformed from a long term carbon locker to a short-term carbon unlocker.”

The study finds that for every 1° C global temperatures rise, a quarter of the world’s permafrost will melt, releasing massive amounts of carbon dioxide and methane into the atmosphere. Those gases, in turn, will contribute to more warming which will lead inevitably to more permafrost melting and more gas emissions as part of a disastrous feedback loop. It estimates that the gases trapped in the permafrost today could raise global temperatures 1.5º C all by themselves.

That’s why Donald Trump’s efforts to undermine the Paris climate change agreements are so dangerous, says Romm. In fact, they may put the permafrost  — and hence the ability of the earth to support human habitation — beyond the point of no return. If we can limit total warming to the 1.5° C target identified in the Paris deal, that would save 800,000 square miles of permafrost compared to 2° C of warming. But if the Trump administration succeeds in thwarting Paris, fully one half of the permafrost may melt with cataclysmic consequences.

The study concludes with this observation: “Huge permafrost thaw can be limited by ambitious climate targets.” And that means huge permafrost thaw and significantly higher global temperatures will most likely result if those targets are undermined. Ambitious climate targets in the age of Trump? The United States wants no part of that.

Source:

Joe Romm, Think Progress

Global warming will defrost much more permafrost than we thought, a new study finds. Every 1°C (1.8°F) of additional warming would thaw one-quarter of the earth’s frozen tundra area — releasing staggering amounts of heat-trapping greenhouse gases (GHGs).  Those GHGs would in turn warm the planet more, melting more permafrost, releasing more GHGs, and so on. This is perhaps the most dangerous amplifying carbon-cycle feedback humanity faces — considering permafrost contains twice as much carbon as the atmosphere does today.

More than 40 percent of the world’s permafrost—landscape covered in frozen soil—is at risk of thawing even if the world succeeds in limiting global warming to the international goal of 2 degrees Celsius, according to a new study.

Currently, permafrost covers about nearly 5.8 million square miles, and scientists found as much as 2.5 million square miles of that could thaw—about twice the area of Alaska, California and Texas combined—in a 2 degree Celsius scenario. Thawing would be more limited if warming can be held to 1.5 degrees Celsius, but could still affect 1.8 million square miles.

The new research was published in the journal Nature Climate Change.

Permafrost contains vast amounts of carbon in the form of plants that died since the last ice age and have remained frozen rather than decomposing. When permafrost thaws, this long-trapped carbon is released into the atmosphere, further propelling future warming. A 2015 study estimated that the thawing permafrost could release up to 92 gigatons of carbon into the atmosphere by the century’s end.

This new study did not estimate the greenhouse gas emissions that would be released from the thawing, or how those emissions could then spur greater rates of permafrost loss in a vicious cycle.

Instead, the international team of scientists focused on how warming air temperatures would affect the extent of permafrost.

They said their calculations suggest a much more extensive loss than previously thought.

“These results alarm me because they predict even greater permafrost loss than shown in the global models for the 2°C warming target,” Kevin Schaefer, a researcher at the National Snow and Ice Data Center, wrote in an email to InsideClimate News. “Even hitting the global 2°C warming target implies major impacts to people and infrastructure in the Arctic.” Schaefer was not involved in the study.

Roughly 35 million people live in permafrost zones. Collapsing ground under roads and buildings present serious risks to those communities.

“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,” said study author Eleanor Burke in a statement. Burke is a permafrost scientist at the Met Office; she conducted this study with colleagues at the University of Exeter, University of Leeds, Stockholm University and University of Oslo.

Global warming will defrost much more permafrost than we thought, a new study finds. Every 1°C (1.8°F) of additional warming would thaw one-quarter of the earth’s frozen tundra area — releasing staggering amounts of heat-trapping greenhouse gases (GHGs).  Those GHGs would in turn warm the planet more, melting more permafrost, releasing more GHGs, and so on. This is perhaps the most dangerous amplifying carbon-cycle feedback humanity faces — considering permafrost contains twice as much carbon as the atmosphere does today.

That’s why it’s so vital the U.S. adheres to its commitments in the 2015 Paris climate agreement — a landmark accord in which the world unanimously committed to keep ratcheting down carbon pollution to ensure total warming stays “well below 2°C [3.6°F] above pre-industrial levels.” And that’s why President Donald Trump’s efforts to undermine the deal are so dangerous, since they may put the permafrost — and hence our livable climate — across a point of no return.

If we could limit total warming to the 1.5°C target identified in the Paris deal, that would save 800,000 square miles of permafrost compared to 2°C warming. But if the Trump administration succeeds in thwarting Paris, then we may lose more than half of the permafrost.

By way of background, the permafrost, or tundra, is soil that stays below freezing (0°C or 32°F) for at least two years. Normally, plants capture CO2 from the air during photosynthesis and slowly release that carbon back into the atmosphere after they die. But the Arctic acts like a very large carbon freezer — and the decomposition rate is very low. Or, rather, it was. We are leaving the freezer door wide open. The tundra is being transformed from a long-term carbon locker to a short-term carbon unlocker.

Significantly, while most of the carbon in a defrosting permafrost would probably be released as CO2, some would be released as methane, which which traps 86 times as much heat as CO2 over a 20-year period.

Yet one study found that the feedback from just the CO2 released by the thawing permafrost alone could add 1.5°F to total global warming by 2100, if we don’t sharply curtail carbon pollution as soon as possible. Worse, none of the models for the recent Fifth Assessment of the climate by the world’s top scientists incorporate loss of the permafrost in their warming assessments.

The bottom line of this new study was well summed up in the headline of its news release: “Huge permafrost thaw can be limited by ambitious climate targets.” And that means huge permafrost thaw can be caused by undermining those targets.



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