Arctic Methane Claims Questioned

Arctic Methane Claims Questioned

www.livescience.com

One line of evidence Schmidt cites comes from ice core records, which include two warm Arctic periods that occurred 8,000 and 125,000 years ago, he said. There is strong evidence that summer sea ice was reduced during these periods, and so the methane-release mechanism (reduced sea ice causes sea floor warming and hydrate melting) could have happened then, too. But there's no methane pulse in ice cores from either warm period, Schmidt said. "It might be a small thing that we can't detect, but if it was large enough to have a big climate impact, we would see it," Schmidt told LiveScience.

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The article makes the claim that the vast majority of the methane in the Arctic is locked up in the DEEP permafrost on the sea floor and what we are seeing as methane release now is just from the sediment layer, not the permafrost layer. Additionally, there are more microbial organisms that are producing some of the methane we are detecting.

I can't imagine the permafrost layers of the Arctic being heated by warming surface temps up to a degree that does a massive release of methane. During the last two historical warming cycles 8,000 and 125,000 years ago, show no "Methane Pulse" that is detectable in ice core samples.

I just think that there has been exaggeration on the part of some scientists on methane release in the Arctic. One of the proponents of it has claimed "unprecedented" rises in methane release......what about during those warming periods 8,000 and 125,000 years ago?? He uses words "never before possible" and "unprecedented" when plainly there has been other warming periods in the relatively near geological past.

www.livescience.com
(visit the link for the full news article)

Good find

There is so much BS being pumped into the minds of the gullible concerning "climate change".

A few days ago we saw a picture of a puddle at the north pole presented as "Alarming". Yet it failed to mention that those puddles form every year and are completely normal.

We are shown pictures of ice breaking up as evidence, but again this has always happened every year and is completely normal.

Now we have the Methane scare, and again we find there is good evidence that this is yet more BS.

How do we wake up the Gullible?

reply to post by pavil


What you say is true pavil.
They have their conclusion, they simply need a theory that fits.

And the article goes on to give the counter argument by one of the co-authors of the article being critiqued.

Today (July 26), Peter Wadhams, a co-author of the Nature commentary, defended the work against critics in an essay posted online.

"The mechanism which is causing the observed mass of rising methane plumes in the East Siberian Sea is itself unprecedented, and the scientists who dismissed the idea of extensive methane release in earlier research were simply not aware of the new mechanism that is causing it," wrote Wadhams, an oceanographer at the University of Cambridge in the United Kingdom.

"But once the ice disappears, as it has done, the temperature of the water can rise significantly, and the heat content reaching the seabed can melt the frozen sediments at a rate that was never before possible," Wadhams added. "David Archer's 2010 comment that 'so far no one has seen or proposed a mechanism to make that (a catastrophic methane release) happen' was not informed by the ... mechanism described above. Carolyn Ruppel's review of 2011 equally does not reflect awareness of this new mechanism," Wadhams wrote.

OP Source (emphasis mine)

Here's a link to the original article. It is a commentary on the economic costs were such an event to happen, the article doesn't claim that this will happen within 10 years, but what the impact would be if it did. And the reality is that we don't know that it is more likely to happen over a greater amount of time, but that can easily be circumvented and happen much faster if other feedback processes begin to happen. Should we warm faster than the 2C scenario we will likely see a faster release of the arctic methane.

Ultimately though the critiqued article is mainly trying to illustrate a point, that that whether this release happens slowly or rapidly it will come with a 60T price tag. Context matters.

reply to post by Kali74


Yes that is the question. Methane seems to have about a 10 year shelf life in the atmosphere. The alarmist side seems to say it will be a massive release while the other scientists say it will be a lengthened release. I just hate when scientists use hyperbole in their statements like "unprecedented", "never seen before" ect, when plainly, there has been similar situations in the past, where man-made global warming wasn't even around.

Originally posted by pavil
reply to post by Kali74

 

Yes that is the question. Methane seems to have about a 10 year shelf life in the atmosphere. The alarmist side seems to say it will be a massive release while the other scientists say it will be a lengthened release. I just hate when scientists use hyperbole in their statements like "unprecedented", "never seen before" ect, when plainly, there has been similar situations in the past, where man-made global warming wasn't even around.

These other scientists are also climate scientists who agree with the consensus that human activity is causing global warming, just to be clear. It isn't hyperbole to state that something is unprecedented, especially since it's accurate. Obviously the permafrost has thawed before... but it has never happened this way because the last time it did, humans weren't around.

That said, I tend to agree that the methane release will be slower than 10 years.

reply to post by Kali74

It isn't hyperbole to state that something is unprecedented, especially since it's accurate. Obviously the permafrost has thawed before... but it has never happened this way because the last time it did, humans weren't around.

Yes, the permafrost has thawed before and even with no humans around, at much faster rates. The 'newly discovered' mechanism, that is also described in the response to the critique, assumes record ice-melt and sea ice-free summers over the Siberian shelf as early as 2015. Another catastrophic prediction, and not supported by science.

Peter Wadhams response

What is happening is that the summer sea ice now retreats so far, and for so long each summer, that there is a substantial ice-free season over the Siberian shelf, sufficient for solar irradiance to warm the surface water by a significant amount – up to 7C according to satellite data. That warming extends the 50 m or so to the seabed because we are dealing with only a polar surface water layer here (over the shelves the Arctic Ocean structure is one-layer rather than three layers) and the surface warming is mixed down by wave-induced mixing because the extensive open water permits large fetches.

So long as some ice persisted on the shelf, the water mass was held to about 0C in summer because any further heat content in the water column was used for melting the ice underside. But once the ice disappears, as it has done, the temperature of the water can rise significantly, and the heat content reaching the seabed can melt the frozen sediments at a rate that was never before possible.

Gavin Schmidt

In the more recent past, there have been a number of times when the Arctic (not necessarily globe) has been significantly warmer than today. Most recently, Early Holocene, which had significantly less summer sea ice than even 2012. Earlier, Eemian 125kyrs ago was sig. warmer. At neither of these times is there any evidence for CH4 emissions or concentrations in excess of base pre-industrial conditions.

Real Climate (can't get anymore mainstream than this)

But when will the Arctic be ice free then? The answer will have to come from fully coupled climate models. Only they can account for the non-linear behavior of the trajectory of the sea ice evolution and put longer term changes in the context of expected natural variability.

The sea ice simulations in the CMIP5 models are currently being analyzed. This analysis will reveal new insights about model biases, their causes, and about the role of natural variability in long-term change.It is possible that this analysis will change the predicted timing of the “ice free summers” but large uncertainties will likely remain.

Until then, we believe, we need to let science run its course and let previous model-based predictions of somewhere between “2040 and 2100″ stand”

Contrary to the claim that earlier studies "do not reflect awareness of this new mechanism", these scenarios are explicitly considered, but simply found not plausible and would still not lead to sudden extreme methane bursts.

Nature

A rudimentary estimate of the depth to which sediments are affected by an instantaneous, sustained temperature change DT in the overlying air or ocean waters can be made using the diffusive length scale 1 = √kt , which describes the depth (m) that 0.5 DT will propagate in elapsed time t (s). k denotes thermal diffusivity, which ranges from ~0.6 to 1x10-6 m2/s for unconsolidated sediments.

Over 10, 100, and 1000 yr, the calculation yields maximum of 18 m, 56 m, and 178 m, respectively, regardless of the magnitude of DT.

In real situations, DT is usually small and may have short- (e.g., seasonal) or long-term fluctuations that swamp the signal associated with climate warming trends. Even over 1000 yr, only gas hydrates close to the seafloor and initially within a few degrees of the thermodynamic stability boundary might experience dissociation in response to reasonable rates of warming. As discussed below, less than 5% of the gas hydrate inventory may meet these criteria.

Catastrophic, widespread dissociation of methane gas hydrates will not be triggered by continued climate warming at contemporary rates (0.2ºC per decade; IPCC 2007) over timescales of a few hundred years. Most of Earth's gas hydrates occur at low saturations and in sediments at such great depths below the seafloor or onshore permafrost that they will barely be affected by warming over even 1 kyr.