Gulf Stream destabilizing methyl hydrates

Thus Nature:

The Gulf Stream is an ocean current that modulates climate in the Northern Hemisphere by transporting warm waters from the Gulf of Mexico into the North Atlantic and Arctic oceans^{1, 2}. A changing Gulf Stream has the potential to thaw and convert hundreds of gigatonnes of frozen methane hydrate trapped below the sea floor into methane gas, increasing the risk of slope failure and methane release^{3, 4, 5, 6, 7, 8, 9}. How the Gulf Stream changes with time and what effect these changes have on methane hydrate stability is unclear. Here, using seismic data combined with thermal models, we show that recent changes in intermediate-depth ocean temperature associated with the Gulf Stream are rapidly destabilizing methane hydrate along a broad swathe of the North American margin. The area of active hydrate destabilization covers at least 10,000 square kilometres of the United States eastern margin, and occurs in a region prone to kilometre-scale slope failures. Previous hypothetical studies^{3, 5} postulated that an increase of five degrees Celsius in intermediate-depth ocean temperatures could release enough methane to explain extreme global warming events like the Palaeocene–Eocene thermal maximum (PETM) and trigger widespread ocean acidification⁷. Our analysis suggests that changes in Gulf Stream flow or temperature within the past 5,000 years or so are warming the western North Atlantic margin by up to eight degrees Celsius and are now triggering the destabilization of 2.5 gigatonnes of methane hydrate (about 0.2 per cent of that required to cause the PETM). This destabilization extends along hundreds of kilometres of the margin and may continue for centuries. It is unlikely that the western North Atlantic margin is the only area experiencing changing ocean currents^{10, 11, 12}; our estimate of 2.5 gigatonnes of destabilizing methane hydrate may therefore represent only a fraction of the methane hydrate currently destabilizing globally. The transport from ocean to atmosphere of any methane released—and thus its impact on climate—remains uncertain.

A number of outlets have picked up on this story, and it's easy to see why. This is another classic we-thought-it-would-take-thousands-of-years moment. In recent years methyl hydrate deposits in the Arctic, and especially the shallow deposits in the East Siberian Arctic Shelf, have grabbed the spotlight. Another recent study made headline when it warned of large methane deposits under Antarctica. It seemed that methane was on the move North and South, and the poles grabbed most of the popular attention. But:

Methane hydrates are over over the place. Including places in the ocean dramatically warmed by shifting ocean currents. So there's that.

Key points from the study include:

1. Methyl hydrate deposits are being destabilized by warming oceans right now.
2. We don't know how much of this carbon will make it into the atmosphere, vs contributing to the acidification of the oceans.
3. The study looked at part of the North American coastline, but this process is likely unfolding in other parts of the world as well.
4. Reports of the death of the clathrate gun hypothesis have been greatly exaggerated. This is only one of many recent studies to illustrate that carbon-cycle feedbacks have the potential to add large amounts of greenhouse gases to the atmosphere. How fast? Not overnight, but not necessarily over thousands of years, either.
5. With vulnerable carbon stores in the Arctic, the Antarctic, and on the continental shelves in between, it is becoming painfully clear that anthropogenic global warming is a game of Russian roulette played with a semiautomatic.

Bottom line: Does switching from coal to shale gas slow climate change?

Keith Kloor "asks" Will Fracking Help Or Hinder the Fight Against Climate Change? Unfortunately, it soon becomes clear that he has little interest in trying to answer that question, and instead uses it as an excuse to beat up on his favorite villains, those crazy environmentalists:

Gas emits much less carbon than coal (probably between 25% and 50% less), which is a net plus on the global warming ledger. And shale gas, in case you hadn’t heard, is entering a golden age; it is abundant and newly retrievable across the world, not just in the United States. It’s the bridge fuel to a clean energy future that liberal think tanks and university researchers were touting just a few years ago. Given the political stalemate on climate change, one energy expert gushed in a recent NYT op-ed: “Shale gas to the rescue.”



But a grassroots backlash to the relatively new technology (hydraulic fracturing) that unlocks shale gas has set in motion powerful forces opposed to this bridge getting built. Leading climate campaigners, citing concerns about industry practices and continued reliance on fossil fuels (even if less carbon intensive), are now a big part of the growing anti-fracking coalition. Mainstream environmentalists have also jumped on that bandwagon.

Thus the battle lines are drawn, with enviros and climate activists digging in their heels against a shale gas revolution that could pay big climate dividends.

Lest you think I'm quoting Kloor's conclusions following a careful analysis of the pros and cons of shale gas, the above is from the third, fourth, and fifth paragraphs of Kloor's essay. Really. So the title of the essay is really quite misleading. Kloor spends not a bit of virtual ink on whether fracking will "help or hinder the fight against climate change." Instead he blandly proclaims it "the bridge fuel to the clean energy future" and directs the remainder of his energies to the question of whether "enviros and climate activists" will help or hinder it.

It's a shame, and not just because it is rehash of an essay Kloor has written approximately five hundred times (Enviros crazy! Me sane and moderate!) dressed up as something new. It is a shame because the question itself is very interesting and important: is shale gas a good thing from the perspective of global warming, or not?

There are three major factors to examine in considering the relative impact of shale gas and coal on climate change:

1. CO2 produced per unit of energy.
2. Methane produced per unit of energy (conventionally referred to, with gas, as the methane leakage rate).
3. Aerosol cooling (coal more than gas, by far.)

Non-AGW factors will be left out of the equation for now. These include water pollution, direct harm from inhalation (asthma, COPD, lung cancer), and damage to the landscape. These are not unimportant, but they complicate an analysis that is already quite complicated. So we will stick with the effects on global warming.

Looking at the three factors above, we can see that the long-term factor (CO2) favors gas, while the short-term factors (methane and aerosols with their short half-lives in the atmosphere) favor coal. So we would expect, intuitively, that shale gas would do well in the long term, and less well in the short term. And this is exactly what the literature shows.

Source.

Looking at Hultman et al (2011) (4th abstract below) we see that methane leakage make shale gas worse than coal in the short term (20 years) about the same in the medium term (100 years) and better in the long term (500 years). Hultman et al does not consider the negative aerosol forcing associated with burning coal, so gas is relatively advantaged in these calculations.

When aerosols are included in the calculations, the break-even point for shale gas is even further in the future.

Here are a few of the recent papers examining this question:

"Methane and the greenhouse-gas footprint of natural gas from shale formations"(Robert W. Howarth, Renee Santoro and Anthony Ingraffea)

We evaluate the greenhouse gas footprint of natural gas obtained by high-volume hydraulic fracturing from shale formations, focusing on methane emissions. Natural gas is composed largely of methane, and 3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the life-time of a well. These methane emissions are at least 30% more than and perhaps more than twice as great as those from conventional gas. The higher emissions from shale gas occur at the time wells are hydraulically fractured—as methane escapes from flow-back return fluids—and during drill out following the fracturing. Methane is a powerful greenhouse gas, with a global warming potential that is far greater than that of carbon dioxide, particularly over the time horizon of the first few decades following emission. Methane contributes substantially to the greenhouse gas footprint of shale gas on shorter time scales, dominating it on a 20-year time horizon. The footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20 years. Compared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years. [Howarth et al became the focus of a debate between the authors and another group of researchers championed by Anthony Revkin. Cathles et al substituted optimistic estimates of methane leakage for Howarth's pessimistic estimates (which led to a letter, which led to a press release), and ignored the 20-year horizon, arguing that only 100 years and longer are appropriate measures of climate impact. Ignoring the 20-year time horizon is a common tactic of shale gas boosters, as we see below. Cathles goes further by ignoring the difference in aerosol forcing between present-day coal and shale gas, reasoning that we'll have to get rid of dirty coal plants someday anyway!]

"Greater focus needed on methane leakage from natural gas infrastructure"

Natural gas is seen by many as the future of American energy: a fuel that can provide energy independence and reduce greenhouse gas emissions in the process. However, there has also been confusion about the climate implications of increased use of natural gas for electric power and transportation. We propose and illustrate the use of technology warming potentials as a robust and transparent way to compare the cumulative radiative forcing created by alternative technologies fueled by natural gas and oil or coal by using the best available estimates of greenhouse gas emissions from each fuel cycle (i.e., production, transportation and use). We find that a shift to compressed natural gas vehicles from gasoline or diesel vehicles leads to greater radiative forcing of the climate for 80 or 280 yr, respectively, before beginning to produce benefits. Compressed natural gas vehicles could produce climate benefits on all time frames if the well-to-wheels CH₄ leakage were capped at a level 45–70% below current estimates. By contrast, using natural gas instead of coal for electric power plants can reduce radiative forcing immediately, and reducing CH₄ losses from the production and transportation of natural gas would produce even greater benefits. There is a need for the natural gas industry and science community to help obtain better emissions data and for increased efforts to reduce methane leakage in order to minimize the climate footprint of natural gas. 

"Modeling the Relative GHG Emissions of Conventional and Shale Gas Production"

Recent reports show growing reserves of unconventional gas are available and that there is an appetite from policy makers, industry, and others to better understand the GHG impact of exploiting reserves such as shale gas. There is little publicly available data comparing unconventional and conventional gas production. Existing studies rely on national inventories, but it is not generally possible to separate emissions from unconventional and conventional sources within these totals. Even if unconventional and conventional sites had been listed separately, it would not be possible to eliminate site-specific factors to compare gas production methods on an equal footing. To address this difficulty, the emissions of gas production have instead been modeled. In this way, parameters common to both methods of production can be held constant, while allowing those parameters which differentiate unconventional gas and conventional gas production to vary. The results are placed into the context of power generation, to give a ″well-to-wire″ (WtW) intensity. It was estimated that shale gas typically has a WtW emissions intensity about 1.8–2.4% higher than conventional gas, arising mainly from higher methane releases in well completion. Even using extreme assumptions, it was found that WtW emissions from shale gas need be no more than 15% higher than conventional gas if flaring or recovery measures are used. In all cases considered, the WtW emissions of shale gas powergen are significantly lower than those of coal.[Note, however, that this paper, brought to you by "Shell Global Solutions," ignores the 20-year horizon completely: "Some authors have considered 20-year global warming potential
factors, but use of these is not widely accepted."]

"The greenhouse impact of unconventional gas for electricity generation" Nathan Hultman, Dylan Rebois, Michael Scholten and Christopher Ramig 2011 Environ. Res. Lett.

 New techniques to extract natural gas from unconventional resources have become economically competitive over the past several years, leading to a rapid and largely unanticipated expansion in natural gas production. The US Energy Information Administration projects that unconventional gas will supply nearly half of US gas production by 2035. In addition, by significantly expanding and diversifying the gas supply internationally, the exploitation of new unconventional gas resources has the potential to reshape energy policy at national and international levels—altering geopolitics and energy security, recasting the economics of energy technology investment decisions, and shifting trends in greenhouse gas (GHG) emissions. In anticipation of this expansion, one of the perceived core advantages of unconventional gas—its relatively moderate GHG impact compared to coal—has recently come under scrutiny. In this paper, we compare the GHG footprints of conventional natural gas, unconventional natural gas (i.e. shale gas that has been produced using the process of hydraulic fracturing, or 'fracking'), and coal in a transparent and consistent way, focusing primarily on the electricity generation sector. We show that for electricity generation the GHG impacts of shale gas are 11% higher than those of conventional gas, and only 56% that of coal for standard assumptions. [But see above.]

Climatic Change, Volume 54, Numbers 1-2 (2002), 107-139, DOI: 10.1023/A:1015737505552

Substitution of Natural Gas for Coal: Climatic Effects of Utility Sector Emissions

Katharine Hayhoe, Haroon S. Kheshgi, Atul K. Jain and Donald J. Wuebbles

 Substitution of natural gas for coal is one means of reducing carbon dioxide (CO₂) emissions. However, natural gas and coal use also results in emissions of other radiatively active substances including methane (CH₄), sulfur dioxide (SO₂), a sulfate aerosolprecursor, and black carbon (BC) particles. Will switching from coal to gas reduce the net impact of fossil fuel use on global climate? Using the electric utility sector as an example, changes in emissions of CO₂, CH₄,SO₂ and BC resulting from the replacement of coal by natural gas are evaluated, and their modeled net effect on global mean-annual temperature calculated. Coal-to-gas substitution initially produces higher temperatures relative to continued coal use. This warming is due to reduced SO₂ emissionsand possible increases in CH₄ emissions, and can last from 1 to 30years, depending on the sulfur controls assumed. This is followed by a net decrease in temperature relative to continued coal use, resulting from lower emissions of CO₂ and BC. The length of this period and the extent of the warming or cooling expected from coal-to-gas substitution is found to depend on key uncertainties and characteristics of the substitutions, especially those related to: (1) SO₂ emissions and consequentsulphate aerosol forcing; and (2) the relative efficiencies of the power plantsinvolved in the switch. [Short-term: more warming with shale gas. Longer term: gas beats coal. The exact time horizons seem to be quite sensitive to the initial assumptions, but there seems to be fairly broad agreement about the overall picture, and dissenters -- like "Shell Global Solutions" -- get around these facts by simply ignoring the short-term time frame.]

Coal to gas: the influence of methane leakage
Tom M. L. Wigley

Carbon dioxide (CO2) emissions from fossil fuel combustion may be reduced by
using natural gas rather than coal to produce energy. Gas produces approximately half the amount of CO2 per unit of primary energy compared with coal. Here we consider a scenario where a fraction of coal usage is replaced by natural gas (i.e., methane, CH4) over a given time period, and where a percentage of the gas production is assumed to leak into the atmosphere. The additional CH4 from leakage adds to the radiative forcing of the climate system, offsetting the reduction in CO2 forcing that accompanies the transition from coal to gas. We also consider the effects of: methane leakage from coal mining; changes in radiative forcing due to changes in the emissions of sulfur dioxide and carbonaceous aerosols; and differences in the efficiency of electricity production between coal- and gas-fired power generation. On balance, these factors more than offset the reduction in warming due to reduced CO2 emissions. When gas replaces coal there is additional warming out to 2,050 with an assumed leakage rate of 0%, and out to 2,140 if the leakage rate is as high as 10%.
. . .
In our analyses, the temperature differences between the baseline and coal-to-gas
scenarios are small (less than 0.1°C) out to at least 2100. The most important result,
however, in accord with the above authors, is that, unless leakage rates for new
methane can be kept below 2%, substituting gas for coal is not an effective means for reducing the magnitude of future climate change. This is contrary to claims such as that by Ridley (2011) who states (p. 5), with regard to the exploitation of shale gas, that it will “accelerate the decarbonisation of the world economy”. The key point here is that it is not decarbonisation per se that is the goal, but the attendant reduction of climate
change. Indeed, the shorter-term effects are in the opposite direction. Given the small
climate differences between the baseline and the coal-to-gas scenarios, decisions regarding further exploitation of gas reserves should be based on resource availability (both gas and water), the economics of extraction, and environmental impacts unrelated
to climate change.

----------------------------

So after this whirlwind tour of shale gas research, what do we know? There is no consensus about whether or not substituting shale gas for coal will slow global warming this century. This is not going to be one of those issues where all the science is lined up on one side, and all the partisan kooks are lined up on the other. The exact effect of switching from coal to shale gas depends upon a number of factors that are difficult to pin down, including:

1. The size of the aerosol forcing. After many decades of trying to pin it down, we still do not know exactly how much cooling the SO2 and other coal-burning byproducts are causing. Obviously the effects of switching from coal to gas depend on how much coal-burning byproducts temporarily cool the planet.

2. The amount of methane leakage. This is a function of not just how well we measure methane leakage, but whether we aggressively regulate methane leakage to hold it to an absolute minimum.

3. The discount rate. Not really a physical constant, but more of a philosophical question: how important is relative cooling 300 years from now compared to worsening global warming over the next twenty years (or fifty years, or hundred years)?

4. The half-life of methane in the atmosphere. As far as I know, no one has discussed this relative to the shale gas question, but the oxidization of methane to CO2 by free radicals is subject to saturation, which is the science-y way of saying that the more methane you put in the atmosphere, the longer each molecule stays in the atmosphere:

The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art” atmospheric chemistry transport model to show that large emissions of CH 4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH 4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH 4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO 2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming.

So depending on how widely shale gas is adopted, and on whether other sources of methane such as permafrost melting or methyl hydrates come into play, methane leaks from shale gas could have double or even quadruple the impact on the climate presently assumed.

Given these uncertainties, what can we say with at least moderate confidence?

1. Shale gas is probably worse than coal on the 20 year horizon. Apart from all the other evidence, the determination of shale gas boosters to avoid talking about the 20 year horizon suggests that this is the case.

2. There is a time horizon out there at which shale gas becomes better from a warming perspective than coal. It's just not clear yet whether it is at 25, 100, or 300 years . . . i.e., whether it is soon enough to do us any real good.

3. Shale gas is significantly worse than every other sort of energy except coal and oil. In the absence of a carbon price, cheap shale gas will tend to displace all energy sources, not just coal. Thus a realistic analysis of a Tea Partyesque policy of letting frackers "do their thing" with minimal regulation would compare shale gas to a basket of power sources that would be displaced, including hydro, geothermal, solar, wind, and nuclear, as well as discouraging investments in efficiency or decisions to conserve. Shale gas is unlikely to look good on this basis.

So, can shale gas be a "bridge fuel"? In my opinion, not in the way shale gas is happening right now. To have any hope of a real net benefit in terms of global warming this century, we need draconian limits on methane leakage and a carbon price (including both CO2 and methane) to ensure that shale gas replaces coal, not low-carbon energy sources or improvements in efficiency. The narrative of "the free market slashed CO2 emissions while the enviros weren't looking HAHAHA" has no basis in fact. The blind squirrel of the free market may stumble into an instance of profit-driven accidental mitigation once in a while (like the Russians controlling methane leakage from pipelines after the fall of the Soviet Union), but this ain't it. Similarly the idea that shale gas is an unambiguous "win" in mitigation terms, so much so that those questioning it are self-evidently trolls lurking under "the bridge to the clean energy future" is also not supported by the research.

Sea level rise to 2500. Source.

How we do shale gas is going to determine whether there is a window where there might be some net benefit. Both proponents and opponents of mitigation have tended to stress the 100-year time frame, for different reasons. If you accept that framing, even optimal shale gas substitution is probably going to show, at best, moderate benefits. If you are looking 500 years into the future, shale gas instead of coal is the best thing since sliced bread, but then, if you're looking 500 years into the future,  you can hardly help but realize that stopping all fossil fuel use as soon as possible should be our overarching priority.

The Antarctic carbon feedback: a worst case scenario

It's the single study to end all single studies:

The researchers estimate that 50 per cent of the West Antarctic Ice Sheet (1 million km2) and 25 per cent of the East Antarctic Ice Sheet (2.5 million km2) overlies preglacial sedimentary basins, containing about 21,000 billion tonnes of organic carbon.

If this carbon proves to be vulnerable in the way we now think the northern permafrost carbon is vulnerable, it will mean we could soon be literally incapable of stabilizing the climate without geoengineering.

The reason is very simple.  Based on the experience of the Eocene (above), at between 3 and 4 degrees above preindustrial, the Antarctica ice pack can be expected to melt completely (of the course question of exactly what temperature will lead to the deglaciation of Antarctica is a complex scientific question, while the above is an eyeballed guesstimate; see below). If these researchers are right, that will gradually release 21,000 gigatons of carbon.

So let's get down to brass tacks. The carbon is divided between the larger East Antarctic Ice Sheet and the more vulnerable West Antarctic Ice Sheet:

The researchers estimate that 50 per cent of the West Antarctic Ice Sheet (1 million km2) and 25 per cent of the East Antarctic Ice Sheet (2.5 million km2) overlies preglacial sedimentary basins, containing about 21,000 billion tonnes of organic carbon.

Experts place the chances of for the beginning of a total collapse of the WAIS in the next 200 years at upwards of 5%. Estimates of how long such a collapse would take to reach completion range from 300 to 1600 years. The temperature that would trigger that collapse is thought to be somewhere between +1C and +5C compared to 1990 temperatures (2).

Suppose that happened, and, since that's a fairly pessimistic assumption, let's throw in a couple of optimistic assumptions: the EAIS contributes nothing significant, and the northern permafrost and methyl hydrates contribute nothing.

The proportion of the trapped carbon under the WAIS is 4/9 of the total of 21,000 gigatons (about 9,300 gigatons) (1). If the WAIS melts, what proportion of that carbon will enter the atmosphere? Some will obviously remain locked a carbon sink that will develop as the continent warms. Suppose only 60% or so, 6,000 gigatons, ends up in the atmosphere.

A couple hundred billion tons of that will be methane; ignore it. The trapped methane has figured prominently in the news accounts about this research, but compared to the staggering amount of carbon under the ice, most of which would enter the atmosphere as carbon dioxide and the rest of which would be oxidized to carbon dioxide after a brief stint as methane, the news that we have a southern methane time bomb to go with the Arctic one is merely a footnote.

Suppose significant outgassing of the carbon under the WAIS starts in about a hundred years and takes two hundred years to run to completion. Six thousand gigatons over two hundred years is 30 gigatons of carbon per year (on average). By way of comparison, total fossil fuel emissions are running at about 7 gigatons per year:

Source

Thirty gigatons a year is about what the human race is expected to produce at the end of the century is the world economy grows rapidly despite our making no effort to rein in our emissions:

Source

The effect of 6,000 gigatons of carbon entering the atmosphere would be an extinction-level event. One part per million of atmospheric CO2 is equivalent to 2.13 gigatons of carbon. Assuming a 50% airborne fraction (which is incredibly optimistic) 6,000 tons of carbon entering the atmosphere would raise the CO2 concentration by about 1,400ppm. In a worst case in which the carbon sinks finally give up the ghost, the rise is 2,800ppm. Supposing we were at that point at 800ppm and +4C, that would quickly take us to +8C with the EAIS adding its share soon after.

You would be looking at centuries of further warming independent of human emissions -- leading to an increasingly inhospitable climate even if economic collapse reduced the anthropogenic contribution significantly.

There is a large distance between the publication of this one study and a solid scientific case for an Antarctic carbon bomb. The steps along that road are, roughly:

1. Are the authors correct about the scale of the buried carbon?
2. Are the authors right about the distribution of that carbon, specifically about a heavy concentration of it under the most vulnerable part of the ice sheet?
3. Will that ice sheet decay significantly over the next few centuries?
4. If the ice sheet decades, what proportion of the buried carbon will make its way into the atmosphere?
------------------------------------
1. "Potential methane reservoirs beneath Antarctica"  J. L. Wadham, S. Arndt, S. Tulaczyk, M. Stibal,  M. Tranter, J. Telling, G. P. Lis, E. Lawson, A. Ridgwell, A. Dubnick, M. J. Sharp, A. M. Anesio & C. E. H. Butler.  Nature 488, 633–637 (30 August 2012) -- abstract.
2. "The Future of the West Antarctic Ice Sheet: Observed and Predicted Changes, Tipping Points, and Policy Considerations" -- full text.
 ------------------------------------
UPDATE: Round up from around the interwebs.

 "Potential New Methane Risk in Antarctica" -- SustainableBusiness.com News

"Antarctica’s Hidden Carbon Stores Pose Warming Risk in Study" -- Bloomberg

“There’s a potentially large pool of methane hydrate in part of the Earth where we haven’t previously considered it,” Wadham said in a telephone interview. “Depending on where that hydrate is, and how much there is, if the ice thins in those regions, some of that hydrate could come out with a possible feedback on climate.”

"Large methane reservoirs suggested beneath Antarctic ice sheet" -- phys.org

 "Antarctic Methane: A New Factor in the Climate Equation" -- Climate Central

Wadham and her co-authors took soil samples from the margins of glaciers in both Antarctica and Greenland. “We spent a couple of years chain-sawing out sediments frozen into the bottom of the ice,” she said, adding with a connoisseur’s judgment, “They were very nicely preserved.”

They hauled the samples back to the lab and allowed them to thaw under carefully controlled, oxygen-deprived conditions where oxygen-hating, methane-belching bacteria known as methanogens could do their work — assuming they were there. And sure enough, the soil began producing methane.

The same thing should presumably be happening underneath Antarctica’s ice, where heat percolating from the depths of the Earth have prevented sediments from ever having frozen.

The Anna Karenina scenario

Every happy family is alike; every unhappy family is unhappy in its own way.

Leo Tolstoy, Anna Karenina

Apropos of the Anna Karenina Principle, how many things would have to go right for climate change to be merely an expensive annoyance (or one human problem among many), rather than a planetary disaster?

First, we need continued rapid economic growth. Even in the best case, dealing with the impacts of global warming -- drought, sea level rise, heat waves, extreme weather events -- between now and 2100 or 2200 will require resources we don't have today. Without continual economic growth, even most optimistic global scenarios offer certain disaster.

Stern Review

 Five percent of 2100's projected GDP is over 40% of our GDP today -- an impossible burden that would lead to global impoverishment.

The assumption of continued economic growth is a reasonable one, as the world's economy has been on an upward trend for many years:

Nevertheless, continued rapid economic growth is not inevitable, and should be ranked as one of the requirements in realizing the Anna Karenina scenario. Wars, a global depression, unrelated natural disasters, and climate change itself could all compromise this pillar of futurists everywhere.

It is necessary but not sufficient that climate sensitivity prove to be on the low end of estimates. With a climate sensitivity of 3C, and a BAU pathway of 1000ppm CO2 equivalent (1), we can expect +4-6C of warming, which would wipe out most forms of life on earth.

Extract from p. 42 of Technical Summary of IPCC WGIII Fourth assessment Report (2007)

Reasonable people trying to strike a middle course between "alarmism" and "skepticism" will often say that climate change may not be a big deal, but we should protect ourselves from the possibility that climate sensitivity is high. This is well-intended, but a wrongheaded oversimplification. The reality is that while five degrees and onward is a planetary catastrophe under almost any set of assumptions you chose does not mean that 2-3 degrees is an expensive but manageable problem. A high total temperature rise is game over; a low total temperature rise still requires many other things to go right (2).

Sea level rise is presently estimated at between 0.5m to 2.0m between now and 2100. It needs to be closer to 0.5m to avoid the loss of huge numbers of human settlements to the sea. We must hope that the Greenland ice sheet and the WAIS respond very slowly to warming and are largely incapable of responding on a decadal scale. Of course other ice sheets, such as the less-popular sibling of the West Antarctic ice sheet, the East Antarctic ice sheet, must not have any nasty surprises in store.

Agriculture will have to prove highly resistant to climate shocks. Varying the type of crops and making efficient irrigation broadly available while avoiding massive losses to pests, diseases, and extreme precipitation.

We cannot afford to lose the Amazon (as is expected) or the boreal forests: the Anna Karenina scenario requires they resist warming and there is no massive die-off that would turn the terrestrial biosphere into a net source of carbon. That would insure catastrophic long-term warming.

No Arctic warming tipping points.

Healthcare technology and delivery systems will have to advance faster than the spread of tropical diseases north and south. Efficient building designs and/or air conditioning will need to be available to rich and poor alike to avoid millions of deaths from the direct thermal effects alone.

Permafrost melting will need to release its stored carbon slowly, and overwhelmingly as carbon dioxide and only a small amount as methane. Methyl hydrates need to stay put, or leak out only very slowly.

Political systems will have to prove highly resilient and adaptive. They will have to respond to the escalating climate harms with aggressive long-term adaptation, and not make things worse with panic responses like hoarding, protectionism, or conflicts over migration, borders, or resources. As the Economist cogently put it:

I feel fairly comfortable arguing that a modern economy can handle the stresses of climate change reasonably well; economies are built to handle big change. I feel very nervous about the ability of various political systems to survive temperatures unprecedented in human history. Many political systems rely explicitly on stability to survive, and even those capable of handling climate impacts may struggle to handle the knock-on effects of climate impacts on their more vulnerable neighbours. And as political systems are disrupted, it will become more difficult to sustain growth.

This is a partial list. There are impacts I haven't covered; there are certain to be impacts no one has yet guessed at.

The nasty aftertaste of a clear-eyed look at the possibilities is this: even if everything goes right -- if humanity holds the winning climate lottery ticket and none of the terrible things come to pass, or happen only in a blunted and delayed form, and only (in large part) after we are all healthier and wealthier and wiser than we are today: even so, in the best of all possible worlds, global warming will be an expensive destructive mess than will drag on for thousands of years, making the impoverishment of the natural world and disruption of the benign Holocene climate our civilization's permanent legacy.

Most economic analyses assume all these good things happen and neglect, not out of malice but due to the limitations of their science, most of the horrible disasters climate scientists think are possible -- in some cases likely. Even so, the benefits of slowing climate change outstrip the costs in virtually every economic analysis out there.

One of my least favorite lukewarmer fallacies is the concept of "no regrets" policies -- that we should push ahead with policies that can be sold to the right wing as energy independence or job creation or whatever appeals to those in denial of the science. This is an asinine idea. Climate change is real. You don't get to smart policy by agreeing to disagree on critical scientific facts pertaining to the future of human civilization. Here's the truth; aggressive emissions cuts are the true no-regrets strategy. Uncertainty in climate change lies between bad and worse. The benefits range from saving trillions of dollars and millions of lives, on the low side, to averting planetary catastrophe.

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1) Meaning a forcing caused by human activities similar to change the level of CO2 to 1000ppm, comprised mostly of CO2 but also with contributions from methane, NO, CFCs, and land use changes.

2) The best analysis of the economic implications of a "fat tail" probability of climate catastrophe is "On modeling and interpreting the economics of catastrophic climate change" (2009) by Martin L. Weitzman, the undisputed expert in this area (400+ citations for that paper alone in less than three years). He wisely make the limitations of climate sensitivity highly explicit:

There are so many sources of uncertainty in climate change that a person almost does not know where or how to begin cataloging them. For specificity, I focus on the uncertainty of so-called "equilibrium climate sensitivity." This is a relatively well-defined and relatively well-studied example of known unknowns, even if the uncertainties themselves are uncertain. However, it should be clearly understood that under the rubric of "equilibrium climate sensitivity" am trying to aggregate together an entire suite of uncertainties, including some non-negligible unknown unknowns. So climate sensitivity is to be understood here as a prototype example or a metaphor, which is being used to illustrate much more generic issues in the economics of highly uncertain climate change.

Five things I learned in 2011

1. Trees matter. A lot. They sequester more carbon than we thought; they generate cooling aerosols in their own right. We could do a lot to slow the advance of global warming if we decide to stop reducing forests in extent and start intensive reforestation.

2. The howls of outrage from deniers in the blogosphere in response to an argument vary in direct proportion to how effective that argument is with the broader public. There is a scientific consensus, and in many respects, the science is settled. The global is warming, and humans are the cause. Many deniers or "skeptics" get their funding from fossil fuel companies, exaggerate their qualifications, and misrepresent their results. This is simple stuff to those of us that live and breath this stuff, and deniers try to discourage us from making this arguments with howls of rage and jeering contempt. But they are not the people we need to convince, and the people we do need to convince -- the broader disengaged public -- these are powerful messages that should be underscored. Deniers know they are powerful, which is why they try and silence them.

3. Methane and CO2 release from the North (permafrost and methyl hydrates) could be apocalyptic in its effects. But the significance of this is undercut by the fact that the BAU pathway will almost certainly be apocalyptic in its effects. A lot of carbon is going to come out of those frozen deposits, but having studied it a fair bit this year, this quote from Raymond T. Pierrehumbert most closely reflects my own layperson's view:

But the clathrate release problem is in a rather different category from the runaway greenhouse issue. It has to be seen as just one of the many fast or slow carbon catastrophes possibly awaiting us, in a system we are just groping to understand. The models of destabilization are largely based on variants of diffusive heat transport, but the state of understanding of slope avalanches and other more exotic release mechanisms is rather poor — and even if it turns out that rapid methane degassing isn’t in the cards, you still do have to worry about those several trillion metric tons of near-surface carbon and how secure they are. It’s like worrying about the state of security of Soviet nuclear warheads, but where you have no idea what kind of terrorists there might be out there and what their capabilities are — and on what time scales they operate.

Or to put it another way: what would be the state of the climate today if this carbon didn't exist? Call that scenario one:

On a BAU pathway, we face mass extinctions, tremendous human suffering, and unpredictable feedbacks that could greatly accelerate climate change, including ice loss, glacier melt, forest fires, changes in ocean currents, and other known and unknown shifts in the climate and the biosphere.

With intensive mitigation, many of the same problems await us, but will hopefully develop more slowly, over several centuries, blunting the impact somewhat and giving us an opportunity to reverse some of the effects. We still have to worry about unpredictable feedbacks that could greatly accelerate climate change, including ice loss, glacier melt, forest fires, changes in ocean currents, and other known and unknown shifts in the climate and the biosphere, but forcing the system less intensely will, logically, reduce the risk.

Now add the carbon back in:

On a BAU pathway, we face mass extinctions, tremendous human suffering, and unpredictable feedbacks that could greatly accelerate climate change, including ice loss, glacier melt, forest fires, changes in ocean currents, release of methane and CO2 from permafrost and methyl hydrates, and other known and unknown shifts in the climate and the biosphere.


With intensive mitigation, many of the same problems await us, but will hopefully develop more slowly, over several centuries, blunting the impact somewhat and giving us an opportunity to reverse some of the effects. We still have to worry about unpredictable feedbacks that could greatly accelerate climate change, including ice loss, glacier melt, forest fires, changes in ocean currents, release of methane and CO2 from permafrost and methyl hydrates, and other known and unknown shifts in the climate and the biosphere, but forcing the system less intensely will, logically, reduce the risk.

In isolation, the potential for destabilization of this buried carbon would be a looming global catastrophe. But as it is, it becomes one aspect of a global catastrophe already in progress. That's how I see it, anyway.

4. Climate deniers represent a hard fringe of the American right; climate deniers in the blogosphere are an even smaller and more radicalized sub-group. Their views are not only more extreme than the large minority of the public that doubts the science of climate change, or the majority that is not ready to pay a significant price to combat climate change: they are fundamentally different in their outlook. You can see this in the opinion polls; you can see it in the comments and posts they make, in which a extreme anarcho-libertarianism features prominently. This ideology is totally unknown and would be bizarre to most American conservatives; to climate deniers it is practically conventional wisdom. Note also the amazing prevalence of what can only be described as the mentally ill, suffering from delusions that demonstrate grandiosity, paranoia, loose associations, and flight of ideas.

We can win the undecided middle to our side; there is evidence that this is already happening. We do it not by trying to win over or placate deniers, nor by trying to bait them. We win by telling the truth in a clear, simple, understandable way, by being less crazy and more normal, with the caveat that part of being normal is reacting strongly to people who attack hysterically and dishonestly.

5. Even as the overall picture continues to be grim, I found some of the research I came across this year comforting. This is turn reassures me that my filters, such as they are, are not the industrial-strength blast shields one often notes in one's opponents, but can easily overlook in oneself.

Although I remain very concerned about agriculture, I was happy to see that models that incorporated varying the type of crops and where they are sowed found a less severe impact from warming. Some crops will benefit from a CO2 fertilization effect.

Since warming over the last couple of decades has run at about 0.14-0.17C/decade, versus slightly more, 0.18-0.21C, as we would expect from the bulk of the models, the cheerful possibility exists that short-term climate sensitivity is a little lower than we thought, 2-3C instead of 3C-4C (possibly because the aerosol forcing is on the high side). So while the consequences of climate change, like glacier melt, continue to mostly run ahead of the models, it is hopeful that temperatures are running slightly behind. Of course, even a warming of 0.05C/decade or 0.10C/decade would be incredibly fast in geological terms and very dangerous. To see the danger we need only look at the response of the climate and the natural world. Still, better to be warming a little slower than we expected than a little faster.

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What did you learn in 2011?

Revkin vs Revkin: the final battle

Andrew Revkin has completed his methane trilogy. The final installment, "More Views on Climate Risk and Arctic Methane," like part two "Leaders of Arctic Methane Project Clarify Climate Concerns" could be taken as a debunking of his original post on the subject ("Methane Time Bomb in Arctic Seas – Apocalypse Not"). But I prefer to think of it as journalism (very good journalism, when all is said and done) in real time.

 Revkin begins his journey with the piece in the Independent, which he (correctly) recognizes as overhyped. He thinks he already knows this is rubbish, based upon his reporting in 2010:

This all builds on what I was told in 2010, when I last visited the question of methane releases from Arctic seas. . . .  I urge you to read, and pass around, the 2010 post — “The Heat Over Bubbling Arctic Methane.”

He talks to a couple of scientists, and gets a couple of quotes bolstering his view that nothing can have changed:

To review, the authors confirm “drastic bottom layer heating over the coastal zone” that they attribute to warming of the Arctic atmosphere, but conclude that “recent climate change cannot produce an immediate response in sub-sea permafrost.” That’s the understatement of the year considering their conclusion that even under sustained heating, the brunt of the sub-sea methane won’t be affected in this millennium.

We of course do not need the brunt of it, but only, say 2% of it, to radically transform the world(1). No matter. Onward to the "publish" button!

Yet, he cannot have been without the nagging feeling that he forgot something. Something kind of important. Something like talking to the scientists being debunked. But they were on vacation! (2)

So, to his credit, he does a follow-up to that post when Natalia Shakhova and Igor Semiletov check in. And Revkin is no Michael Bay; his sequels are all better than the original. In part two, we find that these researchers were not panicky about methane plumes, as the Independent made them sound, be had real and legitimate concerns about the accuracy of the models Revkin spent his first post praising:

Yes, modeling is important. However, we know that modeling results cannot prove or disprove real observations because modeling always assumes significant simplification and should be validated with observational data, not vice versa. Much of our work includes this field validation. Last spring, we extracted a 53-meter long core sample from the East Siberian Arctic Shelf, to validate our conclusions about the current state of subsea permafrost. We found that the temperatures of the sediments were from 1.2 to 0.6 degrees below zero, Celsius, yet they were completely thawed. The model in the Dmitrenko paper [link] assumed a thaw point of zero degrees. Our observations show that the cornerstone assumption taken in their modeling was wrong.

The obvious thing to do after this bombshell was to talk to even more scientists, which Revkin has now done. While none of them look like retreating to a compound in the Rockies just yet, no one appears quite as sanguine as the December 14 Revkin of "Apocalypse Not":

Raymond T. Pierrehumbert: But the clathrate release problem is in a rather different category from the runaway greenhouse issue. It has to be seen as just one of the many fast or slow carbon catastrophes possibly awaiting us, in a system we are just groping to understand. The models of destabilization are largely based on variants of diffusive heat transport, but the state of understanding of slope avalanches and other more exotic release mechanisms is rather poor — and even if it turns out that rapid methane degassing isn’t in the cards, you still do have to worry about those several trillion metric tons of near-surface carbon and how secure they are. It’s like worrying about the state of security of Soviet nuclear warheads, but where you have no idea what kind of terrorists there might be out there and what their capabilities are — and on what time scales they operate.

Edward Brook: One problem with this discussion is that there is no definition of “time bomb” so people get confused. It seems quite likely that continued global warming will increase the emissions of methane from permafrost deposits and marine hydrates. Some of that will get in to the atmosphere, though … some will also be consumed in the water column and in soils. This “chronic” source may increase over time, and affect climate, but for the reasons you discussed it is likely to be slow, and not a catastrophic risk. [So we can't say there's nothing to worry about for a millennium?] Of course it is still important. 

He goes on to quote a few other scientists to the effect that yes, methyl hydrates may contribute to climate change as a feedback, but no, massive near-instantaneous releases don't seem very likely. Which is comforting, of course, but only up to a point. Besides the fact that they could be wrong (and we know that climate science is not at its best when predicting when stuff is gonna melt) even if they are spot on, how gradual are we talking? Suppose a linear release over a thousands years -- 0.1% per year. That's 1.7 Gt of methane -- roughly half the amount of methane in the atmosphere today. Even if half of it were oxidized in the water column, you would still double the amount of methane in the atmosphere in four years and increase it by a factor of ten in fairly short order. Sweet dreams.

I can't judge Andrew Revkin harshly in this. It's impossible for me to dislike the man (how could I -- he left a comment on my blog!) The worst thing you can say about him is, he's a blogger. He's quick off the draw. Sometimes he'll print first and collect more facts afterwards. He has hobbyhorses and is the more likely to launch into debate to defend positions he's staked out before. But he will keep eleborating, keep talking to people, and correct his original views where they were excessive or misinformed (though you still need to change the date of publication (Oct 19, not Dec 6) in your original post, Andy!) What can I say to that, without being a hypocrite? Let he who has never done a quick edit after reading comments, cast the first stone.


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1) 2% of 1700Gt = 34Gt, increasing the existing methane burden in the atmosphere by a factor of tem, with a change in forcing of about +4W/m^2. Given that such a release over a short time period would overwhelm the supply of reactive species to break it down, despite methane's normally short life in the atmosphere, you'd probably be looking at a good 30 years of that before it even began to wane.

2) If I had ever made that excuse to an editor of mine, they would have fried me in extra virgin olive oil and served me with a light white sauce. Especially if I included nothing in the piece to the effect that "I tried to contact these people, but I couldn't reach them."

Semiletov and Shakhova report

The methane researchers who disturbed our rest and inspired immediate, pre-communication debunking by Andrew Revkin, Semiletov and Shakhova, now explain their concerns to him based on the recent findings:

We would first note that we have never stated that the reason for the currently observed methane emissions were due to recent climate change. In fact, we explained in detail the mechanism of subsea permafrost destabilization as a result of inundation with seawater thousands of years ago. We have been working in this scientific field and this region for a decade. We understand its complexity more than anyone.  And like most scientists in our field, we have to deal with slowly improving understanding of ongoing processes that often incorporates different points of views expressed by different groups of researchers.

Yes, modeling is important. However, we know that modeling results cannot prove or disprove real observations because modeling always assumes significant simplification and should be validated with observational data, not vice versa. Much of our work includes this field validation. Last spring, we extracted a 53-meter long core sample from the East Siberian Arctic Shelf, to validate our conclusions about the current state of subsea permafrost. We found that the temperatures of the sediments were from 1.2 to 0.6 degrees below zero, Celsius, yet they were completely thawed. The model in the Dmitrenko paper [link] assumed a thaw point of zero degrees. Our observations show that the cornerstone assumption taken in their modeling was wrong. The rate at which the subsea permafrost is currently degrading largely depends on what state it was in when recent climate change appeared. It makes sense that modeling on an incorrect assumption about thaw point could create inaccurate results.

Observations are at the core of our work now. It is no surprise to us that others monitoring global methane have not found a signal from the Siberian Arctic or increase in global emissions. [This refers to the work of Ed Dlugokencky and others; see his comments in my Dot Earth post.] The number of stations monitoring atmospheric methane concentrations worldwide is very few. In the Arctic there are only three such stations — Barrow, Alert, Zeppelin — and all are far away from the Siberian Arctic. We are doing our multi-year observations, including year-round monitoring, in proximity to the source. In addition to measuring the amount of methane emitted from the area, we are trying to find out whether there is anything specific about those emissions that could distinguish them from other sources. It is incorrect to say that anyone is able to trace that signal yet.

All models must be validated by observations. New data obtained in our 2011 cruise and other unpublished data give us a clue to reevaluate if the scale of methane releases from the East Siberian Arctic Shelf seabed is assessed correctly (papers are now in preparation). This is how science works: step by step, from hypothesis based on limited data and logic to expanded observations in order to gain more facts that could equally prove or disprove the hypothesis. We would urge people to consider this process, not jump to conclusions and be open to the idea that new observations may significantly change what we understand about our world.

So what is the news here? The different thaw point result will need to be replicated. How far down the melt goes should be directly measured in as many locations as possible. Meanwhile, it should be trivial to do model runs at different thaw points and see what effect that might have.

Alaska methane levels spike

Let's hope the data at the far right (which is preliminary and unconfirmed) represents a measurement artifact and not the postscript to Ed Dlugokencky recent reassurances:

[B]ased on what we see in the atmosphere, there is no evidence of substantial increases in methane emissions from the Arctic in the past 20 years.

This came up at Neven's, whereupon it was pointed out that CO2 is spiking too:

Which could indicate the sensors are off. On the other hand, we would expect a significant fraction of any undersea methane release to be oxidized to CO2, and melting permafrost also releases both gases . . . so I don't know that the presence of a similar anomalous spike in the CO2 measurements really helps us decide if the methane spike is real. Only time will tell, I suppose . . . updates as I find them.

UPDATE:

Cold Bay shows a spike for CO2:

But nothing out of the ordinary for methane:

While NOAA's interactive map is incredibly helpful, what one would not give for a few Siberian sites.

Making sense of methane

I'm traveling today, but here are a few review articles about methane which are free online:

"Atmospheric Methane: Trends and Impacts"

"As discussed earlier, increasing water vapor from methane could be leading to an increased amount of polar stratospheric clouds. Ramanathan (1988) notes that both water and ice clouds, when formed at cold lower stratospheric temperatures, are extremely efficient in enhancing the atmospheric greenhouse effect. He also notes that there is a distinct possibility that large increases in future methane may lead to a surface warming that increases nonlinearly with the methane concentration."

"Archer: Destabilization of Methane Hydrates: A Risk Analysis"

"Methane is less concentrated than CO2, and its absorption bands less saturated, so a single molecule of additional methane has a larger impact on the radiation balance than a molecule of CO2, by about a factor of 24 [Wuebbles and Hayhoe, 2002]. The radiative impact of CH4 follows the concentration to roughly the 1/3 power, while the CO2 impact follows the log of the concentration. To get an idea of the scale, we note that a doubling of methane from present-day concentration would be equivalent to 60 ppm increase in CO2 from present-day, and 10 times present methane would be equivalent to about a doubling of CO2." 

"Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions"

"The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes."

. . . so make sense of it your own damn self! Kidding. Here are a some things I gleaned:

* The East Siberian Arctic Shelf is uniquely vulnerable, and this vulnerable formation has its own vulnerable sub-sections. So a leak, while serious, would not necessarily imply a planetary disaster.

* Doubling methane would increase forcing by about 0.4 - 0.6 W/m^2 (that is a harder number to find then you might think.) The calculation is complicated, because the effect of methane on water vapor, ozone, and reactive O2 species effects both the warming caused by the methane and the lifespan of the methane in the atmosphere.

* The impact of an event similar to the Storegga landslide I found helpfully described as "similar in magnitude and duration but opposite in sign to a large volcanic eruption." The largest known "mud volcanoes" have similar potential.


Overall, this is a complex but not unapproachable subject. Worriers like me will find plenty to worry about, but there are also good reasons why oceanic methane release is not the thing keeping methane scientists up at night. And the science and research is really cool.

Justin Gillis on methyl hydrates

Justin Gillis' dead eyes will burn into you until he gets to the truth.

Man, I should buy a lottery ticket.

While we were working our way through the very excited British accounts of the methyl hydrate threat, and the very phlegmatic (but not entirely convincing) response of Andy Revkin, Justin Gillis came out with a fantastic article on permafrost that is already getting rave reviews. And I thought "I wish Justin Gillis would take on this methane thing."

And in less than a day, Justin Gillis took on the methane thing: "Arctic Methane: Is Catastrophe Imminent?" And Gills' sources, like Revkin's are not overly impressed with the threat of massive methane release:

While examples can already be found of warmer ocean currents that are apparently destabilizing such deposits—for example, at this site off Spitsbergen, an island in the Svalbard archipelago in the Arctic—the scientists explained that a pervasive ocean warming sufficient to destabilize a lot of methane hydrates would almost certainly take thousands of years.
And even if that happened, many scientists say that the methane released would largely be consumed in the sea (by bacteria that specialize in eating methane) and would not reach the atmosphere. That is what seems to be happening off Svalbard.
“I think it’s just dead wrong to talk about ‘Arctic Armageddon,’ ” said William S. Reeburgh, an emeritus scientist at the University of California, Irvine, who spent decades studying such matters and says the likely consumption of methane within the ocean should not be underestimated. “Most of this methane is never going to see the atmosphere.”
Nobody regards the case as closed, and more research is necessary, but most of the methane deposits lining the margins of continents would seem to be fairly low on the list of scientific concerns about global warming.

 But the Arctic is, perhaps, something of an exception:

The methane hydrate deposits in the Arctic Ocean may represent a somewhat greater hazard because the Arctic is warming so rapidly. Considerable attention was devoted to a paper published last year that found methane bubbling out across large areas of ocean above the East Siberian Shelf, which has some of the Arctic’s largest methane hydrate deposits.
But that paper did not prove that the methane release was new, much less that it was increasing. Subsequent work by others has in fact suggested that these particular deposits have probably been unstable and slowly breaking down since the end of the last ice age, some 10,000 years ago.
Moreover, the zone from which the methane is escaping appears to represent only a fraction of the total methane beneath the Arctic Ocean. Most methane hydrate is far enough below the sea floor that sediments serve as an insulating layer, limiting how fast heat can spread downward. Again, the most careful calculations seem to put any significant methane release at hundreds or even thousands of years in the future.
As I hope to describe in more detail later this week, methane measurements in the atmosphere are consistent with the picture I just outlined. They do not support the idea that any big new releases of methane are occurring in the Arctic yet, at least not on a sufficient scale to have an overall impact on the planet’s methane burden. So if a methane “time bomb” actually exists in the ocean, as some news stories would have you believe, it seems fairly clear that it hasn’t gone off yet.
Still, there’s no question that some scientists are worried about this issue — less by what we know than what we don’t. Carolyn Ruppel, a geophysicist with the United States Geological Survey, is leading some of the efforts to get better information and especially to map areas off northern Alaska that may contain deposits of methane hydrate. “We need a baseline” against which future changes can be judged, she said.

None of these reassurances are entirely satisfying as regards the recent observations, but until we have some clear numbers on those observations and preferably confirmation from another team at the Shelf, or detect a change in the atmospheric burden of methane, it's hard to judge how, if at all, the new observations are going to change how we see the situation under the East Siberian Arctic Shelf.

We await developments (I do feel somewhat better). Meanwhile, a couple of good sources:


Neven's post and thread are superb, as usual.
The Columbia Journalism Review went over the major articles in this mini-methane-stampede.