Rapid sea-ice loss may increase the rate of Arctic land warming by 3.5 times – affecting permafrost

Recently a mysterious Siberian crater has been discovered, which subsequently […]

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Climate State

Date Posted:

July 25, 2014

Recently a mysterious Siberian crater has been discovered, which subsequently raised questions about the circumstances surrounding the crater formation.  Theories include Pingo formation and connections to the thawing of permafrost (ClimateState reported).

Robert Scribbler, summed it up: One theory on the feature is that it might be a pingo — a melting of a permafrost water pocket left over by an ancient lake that was long ago buried by sediment. But a pingo would typically form in a manner similar to a sinkhole and would probably not have apparent ejected material piled around its mouth.

Another theory, advanced by Russian Arctic scientists, is that a pocket of gas beneath the permafrost spontaneously destabilized — either through chemical or physical processes. The destabilized gas then is thought to have violently blown away the surface layer “like the popping of a cork in a champagne bottle.”

Yesterday (July 22, 2014), The Moscow Times reported a second hole and Robert asked if these craters represent signs of the compost bomb. Though, model simulations by NCAR from 2008 “Permafrost threatened by rapid retreat of arctic sea ice”, connected permafrost thawing to Arctic sea ice decline.

Lead author David Lawrence of NCAR explained:

“Our study suggests that, if sea-ice continues to contract rapidly over the next several years, Arctic land warming and permafrost thaw are likely to accelerate.”

Accelerated Arctic warming. Simulations by global climate models show that when sea ice is in rapid decline, the rate of predicted Arctic warming over land can more than triple. The image at left shows simulated autumn temperature trends during periods of rapid sea-ice loss, which can last for 5 to 10 years. The accelerated warming signal (ranging from red to dark red) reaches nearly 1,000 miles inland. In contrast, the image at right shows the comparatively milder but still substantial warming rates associated with rising amounts of greenhouse gas in the atmosphere and moderate sea-ice retreat that is expected during the 21st century. Most other parts of the globe (in white) still experience warming, but at a lower rate of less than 1 degree Fahrenheit (0.5 Celsius) per decade.  Image by Steve Deyo / UCAR
Accelerated Arctic warming. Simulations by global climate models show that when sea ice is in rapid decline, the rate of predicted Arctic warming over land can more than triple. The image at left shows simulated autumn temperature trends during periods of rapid sea-ice loss, which can last for 5 to 10 years. The accelerated warming signal (ranging from red to dark red) reaches nearly 1,000 miles inland. In contrast, the image at right shows the comparatively milder but still substantial warming rates associated with rising amounts of greenhouse gas in the atmosphere and moderate sea-ice retreat that is expected during the 21st century. Most other parts of the globe (in white) still experience warming, but at a lower rate of less than 1 degree Fahrenheit (0.5 Celsius) per decade. Image by Steve Deyo / UCAR

NCAR’s press release explained:

The team found that during episodes of rapid sea-ice loss, the rate of Arctic land warming is 3.5 times greater than the average 21st century warming rates predicted in global climate models. While this warming is largest over the ocean, the simulations suggest that it can penetrate as far as 900 miles inland. The simulations also indicate that the warming acceleration during such events is especially pronounced in autumn. The decade during which a rapid sea-ice loss event occurs could see autumn temperatures warm by as much as 9 degrees F (5 degrees C) along the Arctic coasts of Russia, Alaska, and Canada.

Lawrence and his colleagues then used the model to study the influence of accelerated warming on permafrost and found that in areas where permafrost is already at risk, such as central Alaska, a period of abrupt sea-ice loss could lead to rapid soil thaw. This situation, when summer thaw extends more deeply than the next winter’s freeze, can lead to a talik, which is a layer of permanently unfrozen soil sandwiched between the seasonally frozen layer above and the perennially frozen layer below. A talik allows heat to build more quickly in the soil, hastening the long-term thaw of permafrost.

Recent warming has degraded large sections of permafrost, with pockets of soil collapsing as the ice within it melts. The results include buckled highways, destabilized houses, and “drunken forests” of trees that lean at wild angles.

“An important unresolved question is how the delicate balance of life in the Arctic will respond to such a rapid warming,” Lawrence says. “Will we see, for example, accelerated coastal erosion, or increased methane emissions, or faster shrub encroachment into tundra regions if sea ice continues to retreat rapidly?”

It appears that craters may be added to the list of visible signs of permafrost degradation.

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