Permafrost now melting in Alaskan Arctic hasn't melted in >30,000 years

[stellarfun]

http://www.nytimes.c...orries.html?hpw

University of Alaska Fairbanks dated the carbon within the escaping methane as being between 30,000-43,000 years old.

Related article in Nature, published December 1, 2011, which includes projections for the amount of carbon released through 2040 and 2100. (Their projections do not factor in release of nethane hydrates from Arctic sea floor.)

http://www.lter.uaf....Abbott_2011.pdf

In any event,unless the MWP melted away an uppermost layer of permafrost, the carbon-dating would indicate that the Arctic in this area hasn't been this warm in tens of thousands of years.

[donsutherland1]

Thanks for sharing this informative piece and the article. This is a troubling development and the carbon dating speaks for itself.

[dabize]

The increased rate of tundra fires is particularly troubling - it suggests that there are multiple nested positive feedback loops being activated

drying - fires, more drying

thermokarst formation, shallow lake formation - more thawing, more thermokarsts

Is it possible that the methane releases are helping to fuel the tundra fires?

[TerryM]

Intriguing that none of the skeptic/denyer crowd even want to touch this. Perhaps the Koch brothers haven't added it to the playbook yet.

I've been watching as ice shelves thousands of years old melted away, and as arctic passages closed for millenia opened - but this is definitive proof that the changes we are experiencing are beyond anything civilized man has witnessed.

[turtlehurricane]

Yup, the climate changes. Why it's changing or how important any particular change is isn't well understood though, so one must be careful not to make jumps of logic from one piece of data (or alot of data for that matter).

[stellarfun]

Is it possible that the methane releases are helping to fuel the tundra fires?

Probably not at this time. As the permafrost melts, microorganisms convert most of the stored methane into CO2, CO2 is a fire suppressant, so it would tend to inhibit any inflammatory effect of methane that was being released.

There is much more research needed examining the sensitivity to warming temperatures of these methane stores in the Arctic, both submerged and in the permafrost. I don't believe anyone knows, for example, the depth of any permafrost thawing during the MWP,. It may be that 'younger' methane stores melted away during the MWP, and the earth's climate has only now reached a point of melting 'older' stores, or maybe there was little melting of any methane stores during the MWP.

Carbon dated from >30,000 years ago was stored and frozen before the Last Glacial Maximum, so it may be that all/nearly all the Arctic methane stores were formed before the LGM, and the earth's climate is only now getting warm enough to begin releasing them.

What is known is what the Arctic looked like during the Pliocene Warm Period of 3-5 million years ago, and I believe that the oldest permafrost dates to the Pliocene cooling of about 2.5 million years ago. (CO2 levels during the Pliocene Warm Period are estimated to be about 400 PPM.)

[The_Global_Warmer]

It's been a very dramatic pattern change from decade to decade.

No sure why you posted these maps. I assuming it is to direct attention away from AGW onto the "pattern".

But either way, you probably should have checked the 80s, 70s, 60s..... And so on.

It surely has not been very dramatic from decade to decade

[TerryM]

It's been a very dramatic pattern change from decade to decade.

This is a very dramatic change from the subject under discussion.

To get back OT:

What are your thoughts about the discovery that ice now melting has been in place for <30,000 yrs?

Does this put to rest all arguments that this has happened before as recently as the Middle Ages?

Does this put to rest all arguments that this has happened before as recently as the Viking Age?

Does this put to rest all arguments that this has happened before as recently as the Holocene Maximum?

[The_Global_Warmer]

So why did you post the height anomalies pointing to rapid change. But leaving out data showing it is not what you presented?

Why did you post in this thread in the first ?

[TerryM]

The most recent study finds that it's the lowest in the last 1450 years.

http://www.nature.co...ature10581.html

But is believed to have been lower 6-8 thousand years ago.

http://www.theglobea...article2246787/

Actually that's a study from 12/10 - and what it proves is that ice was present in areas now bereft of the same for the last 1400 years.

They held out the possibility that there may have been a period 6-8 kyr earlier when more ice might have melted back even further.

More recent data out of Alaska shows that, at least in that area, the ice now melting has been in place for at least 30kyr.

[TerryM]

Calling Friv - the most data oriented poster on the site a troll?

Surly you jest.