Thursday, March 3, 2016

Leaking pingos 'can explode under the sea in the Arctic'

Attention has focused recently on the mysterious large methane 'blow holes' that have appeared in the Siberian Arctic.

Now there is evidence of a similar process underwater in southern areas of the Kara Sea.

Large mounds - described as pingos - have been identified on the seabed off the Yamal Peninsula, and their formation is seen as due to the thawing of subsea permafrost, causing a 'high accumulation' of methane gas.

These mounds are leaking methane and their 'blowout potential' poses a significant threat according to new research by scientists.
In 1990 a well drilled by ExxonMobil in about 100 metres water depth in the North Sea blew out. This resulted in a massive release of methane that created a crater at the seafloor. In 1994 major gas emissions were still evident.

In 2005 it was verified that ongoing gas bubble emissions were coming from a crater 60 metres wide and 20 metres deep up to the sea surface.

IASI methane levels March 1-10, 2013 against. NSIDC sea ice concentration map March 12, 2013.
There are such massive methane reserves below the Arctic Ocean floor, that they represent around 100 times the amount that is required to cause a Permian style major extinction event, should the subsea Arctic methane be released in a short period of time into the atmosphere.

Vast expanses of permafrost in Siberia and Alaska has started to thaw for the first time since it formed 11,000 years ago. It is caused by the recent 3+°C rise in local temperature over the past 40 years - more than four times the long-term global average.

A global temperature rise of 1.5 °C (2.7 °F) above current levels would be enough to start the thawing of all permafrost in Siberia, according to one group of scientists.

Well-Preserved Mammoth Discovered in the Permafrost of Northern Siberia
It is one of the coldest parts of Siberia. The frozen landscape has trapped methane in the ice-packed earth. This soil has, in recent decades, begun to soften as the climate warms.
A view from the edge of a crater - about 100 feet across - that has opened in Siberian permafrost.
Siberia's blowholes are exploding in numbers: Up to 20 have now been located, raising new fears the warming permafrost is releasing its methane reserves. Expeditions to the bottom of several craters late last year appeared to support speculation that they may have been caused by pockets of defrosted methane gas erupting though the softening surface. Deep lakes of methane-infused “slurry” were found beneath.
The ripples caused by bubbling methane shows in this picture of a lake in Siberia.

Global distribution of methane averaged over 2011 by NASA/AIRS. Note the very high concentrations in the Arctic region.
Climate monitoring by the Hydrometeorological Centre of Russia indicates spring 2015 was the warmest in the 125-year history of regular meteorological observations.

As formerly frozen methane hydrate/clathrate deposits on sea and lake beds thaw, the methane migrates to the surface where it can be temporarily trapped.

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