Cryosphere > Permafrost

Toward Improved Discussions of Methane & Climate

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Peter Ellis:
An article from Skeptical Science that seems to me to be pretty fair and balanced.

http://www.skepticalscience.com/news.php?n=2130

The clincher for me is the palaeoclimate argument: given that orbital forcings meant the Arctic was warmer (and quite possibly seasonally ice-free) several thousand years ago, with no runaway methane release, means the same likely applies to current warming.

Peter Ellis:
(note the extensive references to the primary literature)

SteveMDFP:

--- Quote from: Peter Ellis on August 01, 2013, 10:46:24 PM ---An article from Skeptical Science that seems to me to be pretty fair and balanced.

http://www.skepticalscience.com/news.php?n=2130

The clincher for me is the palaeoclimate argument: given that orbital forcings meant the Arctic was warmer (and quite possibly seasonally ice-free) several thousand years ago, with no runaway methane release, means the same likely applies to current warming.

--- End quote ---

No, the same doesn't likely apply to current warming.  Methane released from seabed deposits slowly get oxidized in the water column, but bubble up to the air when release is rapid.  Methane released to the air slowly gets oxidized by atmospherice hydroxyl radicals.  But those hydroxyl radicals can be depleted by large releases, allowing methane to persist in the atmosphere.

In other words, RATE of release is likely to be critical.  Past warm periods got warm slowly.  Our current warming is happening fast.  It's certainly plausible (and in my mind very likely) that rate of methane release from shallow seabeds and permafrost is likely to be determined as much by rate of warming as absolute temperature.

A gigaton of methane released over centuries is going to have much less global impact than the same gigaton released over a decade.

In terms of methane, since we're in unprecedented rate of global warming, we're in unprecedented territory about methane releases.  We have no past road map of relevance for comparison.

jonthed:
I agree with Steve, and while i recognize my opinion and insight doesn't count for much, I have been disappointed with the scientists, and now skeptical science, who seem to keep saying that the historic record doesn't show such a spike, so it's 'unlikely' there will be one.

Firstly, despite what they have said about previous analogs, I don't see them as being the same as current warming, as the rate of warming, as Steve has pointed out, makes a huge difference to the effect of any methane thawing.

I'm not seeing any previous warming like we're seeing now, including where sea levels are over the shelf, what the arctic sea ice is doing, the injection of ghg we have seen, and the rate of warming we're seeing/going to see.

Regardless of the facts about the mechanism by which the ESAS methane is supposed to thaw according to Wadhams' new disputed paper, you'll probably see this in the news today: "Climate change on pace to occur 10 times faster than any change recorded in past 65 million years, Stanford scientists say"

see here:
http://news.stanford.edu/news/2013/august/climate-change-speed-080113.html

and climate central's piece on it:
http://www.climatecentral.org/news/ecosystems-face-unprecedented-changes-in-the-next-century-16301

If you read the articles, you'll note a quote from Diffenbaugh:
“The key difference is the rate of change,” said co-author Noah Diffenbaugh, a climate scientist and Senior Fellow at the Woods Institute for the Environment at Stanford University, in an interview. “The combination of rate and magnitude over the next century is unprecedented. In the context of the geological record of the last 65 million years, this (change in the 21st century) is likely to be an order of magnitude, or two or three orders, more rapid.”

As if one order of magnitude wasn't enough already.
enough to be concerned.
enough to see there's no historic analog.

And yet people are still insisting the paleo-record means there's nothing to worry about: a large methane release is "unlikely".

I don't follow their logic at all.

The mechanism Wadhams is suggesting seems to be supported by observed data, including observed sea temperatures, perhaps it might need more years to be more certain, but it certainly shouldn't be dismissed based on not having seen anything like what he's suggesting in the paleo-record.

-

As for the mechanism:

How many years has sea ice been retreating so far and for so long over the ESAS? probably less than 20. (http://climate.nasa.gov/key_indicators#seaIce)
How many years have summer sea surface temperatures over the ESAS been above zero in summer? well it used to be mostly ice so again, probably less than 20 (http://www.esrl.noaa.gov/psd/map/images/sst/sst.month.anom.hov.io.gif)

Any previous retreat of sea ice would have been more gradual, and any thawing too.
Any previous warming of summer temps would also have been more gradual, and any thawing too.

Wadhams' mechanism does indeed appear to be a new one, only possible because of the retreating sea ice. coupled with the rate of change and rate of warming, and how critical to the impact of methane release the rate of thawing is, I can't see how the mechanism is unsound or comparable to previous warmings.

That leaves me convinced that there is definitely reason to be concerned.

johnm33:
Oh boy, you're not going to like this. From a catastrophists point of view the east siberian shelf was further from the axis of rotation prior to about 5,200 years bp and even further away before about 11,500 years bp. The axis being before that pretty much where the geomagnetic pole is. This would put the whole area further south [Including that Siberian lake that was 8degC warmer than expected] and allow the possibility that the eye witness accounts/myths/legends, carried down the generations, about the area having a permanent spring climate, contain a grain of truth. Born out to some extent by the 'springtime vegetation' [typical of a black sea meadow] stomach contents of every frozen mammoth I've ever read about. Also check out 'Arctic home in the Vedas' by Tilak. Also IIRC there's an ethnic group in the Lena valley that recall a mass migration to the south [India] in prehistory, and a return after the Mongol conquest of the sub continent, with proven genetic connections to the Punjab. As to the dates of the shifts there are many guesses, my first relates to the time suggested in the Oera Linda, also by timing of the demise of the pygmy mammoths on the new siberian islands, and the massive floods that left 3m [?] mud deposits in mesopotamia, which were pretty much coincident.
 The older date is more speculative, but a comprehensive overview of the facts on the ground can be found in 'When the earth nearly died' Allan/Delair which also has an intimidating bibliography. I have to say I don't altogether share the views of the authors but there is a vast array of facts which should be accommodated by any realistic worldview.
Back to the shelf, the area was above sea level throughout the 'ice age' and also during that whole time we could expect the growth of peat beds, and to quite some depth. I'm too ignorant about the Eemian to speculate beyond that whatever methane event happened was gradual.
 Whatever befell the mammoths froze their stomach contents so quickly that, when defrosted, it was still identifiable and 'fresh', but the same event could be expected to form a serious frozen crust on the aforementioned peat beds.  Whatever process decayed this peat to methane should not have disguised it's provenance, but if/when they take samples I hope they reinstate long deep frozen plugs to reseal the holes, otherwise I'd expect a spreading collapse of the sealing layer.
The most convincing evidence, for me, of polar shift are the ancient agricultural terraces stretching past 18,000ft above lake Titicaca, taken with the ancient seashells, and the current apparently oceanic fauna in it's companion salt lake suggest that either there has been a massive uplifting of the whole area, by 12,600ft, or it previously lay quite close to the equator, and the oceanic bulge meant it was much closer to sea level. Of course if it was near the equator that would put large tracts of amazonia below sea level, and the rest in the arid zone so would explain the sandy nature of its soil. I've never come across any evidence pointing to a more Nilotic period for the Amazon but then who'd be looking. My guess is that the best way of deciding the likelyhood of this is to determine the genetic homeland of the equatorial species of the forest [nearer the Andes and the Mato Grosso?] and to look for candidates for the movement from the likely temperate rainforests to the north.
Actually there's a massive amount more evidence that supports this possible worldview, from all around the world, and it took me 20 odd years of stumbling across it before it undermined my confidence in the regular paradigm [and another 5 before I read what Velikovsky had to say]so I'm not expecting or trying to convince anyone, but as far as a catastrophic methane release goes, if there's any truth in all this, the past is no guide to the future.
 

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