Quantifying Arctic Methane

The paper 'Ebullition and storm-induced methane release from the East Siberian Arctic Shelf', was published in the journal Nature Geoscience on November 24, 2013.

The paper is dedicated “to the memory of the crew of Russian vessel RV Alexei Kulakovsky”, the 11 people who died when their tugboat perished in efforts to assist the scientists who were measuring methane from a fishing boat.

The research team used methods including drilling into the seabed of the Laptev Sea and sonar to analyse methane releases in the water, seeking to quantify the significant amounts of methane that are bubbling up from the sea bed in the East Siberian Arctic Shelf (ESAS, rectangle on image below), the area with shallow seas north of Siberia covering some 810,800 square miles (2.1 million square kilometers). By comparison, the United States (land and water) covers an area of nearly 10 million square kilometers.

“We have proven that the current state of subsea permafrost is incomparably closer to the thaw point than terrestrial permafrost, and that modern warming does contribute to warming the subsea permafrost,” says Natalia Shakhova, adding that an increase in storminess in the Arctic would further speed up the release of methane.

The scientists estimate, on the basis of the sonar data, that “bubbles escaping the partially thawed permafrost inject 100–630 mg methane square meters daily into the overlying water column”, and suggest that “bubbles and storms facilitate the flux of this methane to the overlying ocean and atmosphere, respectively”.

Some 17 teragrams (Tg or Mt) of methane escapes annually from the ESAS, said Natalia Shakova, lead study author and a biogeochemist at the University of Alaska, Fairbanks. This is an upgrade from the earlier estimate of 8 Tg of annual outgassing from the ESAS (Shakhova et al. 2010).

While including a reference to this earlier paper (Shakhova et al. 2010), the IPCC did give much lower estimates for emissions from all hydrates globally and from permafrost (excl. lakes and wetlands), i.e. 6 and 1 Tg per year, respectively.

And by comparison, IPCC estimates for all global methane emissions from manmade and natural sources go from 526 Tg per year to 852 Tg per year, of which 514 to 785 Tg per year is broken down (mostly by hydroxyl).

Sadly, as discussed in an earlier post, the IPCC has decided NOT to warn people about the danger that methane from hydrates will lead to abrupt climate change within decades. Yet, when entering the data by Shakhova et al. in a spreadsheet, a linear trendline (green line on image below) shows methane release in the ESAS reaching 20 Tg by 2013 and 26 Tg by 2015.

An exponential trendline (red/blue line) shows methane release in the ESAS reaching 22 Tg by 2013 and 36 Tg by 2015. Extending that same exponential trendline further into the future shows methane release in the ESAS reaching 2 Gt by the year 2031 and 50 Gt by the year 2043.

Note that accumulated totals over the years will be much higher than the annual release. While the IPCC gives methane a perturbation lifetime of 12.4 years, this methane will persist in the Arctic for much longer because its release is concentrated in the Arctic where hydroxyl levels are also very low.

Globally, IPCC/NOAA figures suggest that abundance of methane in the atmosphere currently (2013) is 1814 parts per billion (ppb), rising with 5 or 6 ppb annually, and that this rise is caused by a difference of 8 Tg between the methane emitted (548 Tg, top-down estimate) and broken down annually (540 Tg, top-down estimate). It is also worth noting that the IPCC has increased methane's global warming potential to 86 over 20 years with climate-carbon feedbacks, while there are reasons to assume that methane's impact, especially short-term and in case of large abrupt releases in the Arctic, is even stronger. Furthermore, the IPCC now gives methane a Radiative Forcing (RF) of 0.97 W/m^-2 (up from 48 W/m^-2 in 2007 and relative to 1750), as illustrated by the image below.

According to the IPCC, methane levels in 1750 and 2011 were 722 ppb and 1803 ppb, respectively. The total global methane burden is estimated to be about 5 Gt, i.e. 5 petagrams (Pg) or 5,000 Tg. A back-of-envelope calculation sugests that the methane burden in 1750 was 5 Gt x (722 : 1803) = 2 Gt. Furthermore, methane's 0.97 W/m^-2 RF is 42% of the total RF 2.29 W/m^-2. Therefore, the 3 Gt of methane that has been added to the atmosphere since 1750 is responsible for almost half of all the global warming since that time.

For now, the IPCC's estimated annual increase in global methane levels may seem small, but this figure appears to be based on low-altitude data collected over the past few decades. The total methane burden may already be rising much more rapidly, also because methane is rising in the atmosphere, increasing the burden especially at higher altitudes, as evidenced by the increasing occurence of noctilucent clouds. In other words, the 8 Tg estimate may reflect older data related to changes in lower-altitude measurements only, but the total methane burden may well be rising much more rapidly due to increases at higher altitudes. Further analysis comparing satellite data at different altitudes over the years could verify this.

An earlier post estimated that as much as 2.1 Mt (or 2.1 Tg) of methane could have been released abruptly end 2011. If you compare the animation of that earlier post with the recent animation, then current abrupt releases from the sea floor of the Arctic Ocean appear to be even higher.

As said, methane releases from the Arctic Ocean may for now seem small and may not yet make global temperatures rise much, but nonetheless the methane cloud hanging over the Arctic is contributing to warming locally. Combined with the increased likelyhood of extreme weather and rapid loss of ice and snow cover in the Arctic, this could make water temperatures in the Arctic Ocean rise even further, causing further destabilization of methane hydrates. Furthermore, the mechanical force of methane release from hydrates (rapidly expanding 160 times in volume) itself can also contribute to hydrate destabilization. Seismic activity could also lead to destabilization. Indeed, there are many factors that could contribute to exponential rise of methane release from the Arctic Ocean, as discussed in the post on methane hydrates, which calls for comprehensive and effective action, such as discussed at the Climate Plan blog.


References

Ebullition and storm-induced methane release from the East Siberian Arctic Shelf, by Natalia Shakhova, Igor Semiletov, Ira Leifer, Valentin Sergienko, Anatoly Salyuk, Denis Kosmach, Denis Chernykh, Chris Stubbs, Dmitry Nicolsky, Vladimir Tumskoy & Örjan Gustafsson (2013)
http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2007.html

Arctic storms speed up release of methane plumes, by Fred Pearce
http://www.newscientist.com/article/dn24639-arctic-storms-speed-up-release-of-methane-plumes.html

Twice as Much Methane Escaping Arctic Seafloor, by Becky Oskin
http://www.livescience.com/41476-more-arctic-seafloor-methane-found.html

Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic shelf, by Natalia Shakhova, Igor Semiletov, Anatoly Salyuk, Vladimir Yusupov, Denis Kosmach, and Örjan Gustafsson, in: Science, 327, 1246-1250 (2010).
http://www.sciencemag.org/content/327/5970/1246.abstract

On carbon transport and fate in the East Siberian Arctic land–shelf–atmosphere system, by Semiletov et al. (2012)
http://iopscience.iop.org/1748-9326/7/1/015201

Intergovernmental Panel on Climate Change (IPCC), AR5 Working Group 1
http://www.climatechange2013.org/

Post by Sam Carana.

Epic Methane Releases from East Siberian Arctic Shelf

By Harold Hensel

[ click to enlarge ]

This is epic! Keep watching the Laptev and East Siberian Sea. This is a very dangerous place for methane to come up. Huge amounts of methane hydrates are stored below. They have been frozen there safely for over 10,000 years.

We are witnessing the thawing and large release of methane from this area for the first time in over 10,000 years. The fear is that at a critical point there may be a catastrophic sudden burst of methane from this area. This would more than likely trigger runaway global warming.

We could be watching the beginnings of this. If the red on the 1750 ppb and the yellow on the 1950 ppb setting on the methanetracker.org keeps spreading and intensifies, we are watching it happen. I hope this is an anomaly and these areas return to little or no activity.


Harold Hensel is at Facebook as facebook.com/mhhensel

Toward Genuinely Improved Discussions of Methane & Climate

The post 'Toward Improved Discussions of Methane & Climate' recently appeared at SkepticalScience, in response to the recent publication in Nature of 'Vast Costs of Arctic Change', by Gail Whiteman, Chris Hope, and Peter Wadhams.

Below are Paul Beckwith's comments that were recently submitted at that post. The text by SkepticalScience is in italics. Paul's comments are in red.

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SkepticalScience: “Here at Skeptical Science, there is an ongoing effort to combat disinformation from those who maintain that climate change is a non-issue or non-reality. From time to time, however, individuals or groups overhype the impacts of climate change beyond the realm of plausibility. Some of this is well-intentioned but misguided. For those who advocate climate literacy or for scientists who engage with the public, it is necessary to call out this stuff in the same manner as one would call out a scientist who doesn’t think that the modern CO2 rise is due to human activities.

Many overblown scenarios or catastrophes seem to involve methane in the Arctic in some way. There are even groups out there declaring a planet-wide emergency because of catastrophic, runaway feedbacks, involving the interplay between high latitude methane sources and sea ice.”

Paul Beckwith: The above two paragraphs set the tone of this discourse. AMEG (Arctic Methane Emergency Group) is unjustly framed in this introduction as a fringe group using such terms as “overhype”, “beyond realm of plausibility”, “overblown scenarios or catastrophes”, “planet-wide emergency”. This is the complete opposite of the truth. AMEG was founded based on a meeting in October, 2011 in the U.K. and I joined in December, 2011. We are a group of concerned professionals with a varied background including climate scientists, engineers, doctors, moviemakers, economists, journalists.

We have studied the Arctic, methane, sea ice, and climate change as a group since that time, and individually for much longer. We base our work and analysis on observations, not on models.

The facts on the ground and ocean in the Arctic region speak for themselves. The PIOMAS work, which has been substantiated independently by CryoSat satellite data, show that the sea ice volume is trending downwards exponentially and if that trend continued would reach zero around 2015 or 2016. Trending down even faster is the May and June Arctic snow cover, as measured clearly by Rutgers data. Methane levels in the Arctic have increased significantly over the last several years. In fact, the mainstream scientific viewpoint was that the seafloor over the ESAS (Eastern Siberia Arctic Shelf) was impermeable to methane outgassing. Then Shakhova, Yurganov, and other Russian scientists measured outgassing plumes tens of meters in diameter one year expanding to kilometers in diameter the very next year. Flask measurements in Barrow, Alaska and Svalbaard indicated local levels of >2100 ppb and AIRS satellite measurements over the last decade have shown greatly increase levels of methane in the last few years. This is all observation, and not modeled by anybody. In fact, higher methane emissions have been reported along the Arctic coastlines, presumably from enhanced wave action due to larger wave action from the increased ice-free ocean.

Also, higher emissions have been measured elsewhere from continental shelves, for example off the east coast of North America from warm Gulf Stream water that has shifted eastward over the shelves, warming ocean temperatures several degrees.

Thus, the “radical” or “fringe” or “out-there” view is not from AMEG, quite the opposite. Based on the precautionary principle, it is imperative that so called “mainstream” science examine this data without preconceptions that it takes centuries or millennia for methane to outgas. It is unfathomable to AMEG and many others that main-stream science are behaving like “methane denialists” when the observations are clearly undermining such out-of-hand rejection, based on inaccurate models that are clearly missing feedbacks. In fact the situation is so ridiculous that the IPCC is not even considering methane as a strong feedback in their next report.

People on the street are now recognizing that the weather extremes are moving off the charts in terms of frequency, severity, and spatial extent (mostly for extensive long duration droughts, and also torrential rains causing floods). They are starting to recognize that the collapse in Arctic albedo from declining snow cover and sea ice loss is greatly amplifying the warming in the Arctic. This obviously lowers the temperature gradient between the equator and North Pole which via simple physical laws slows the jet streams making them wavier and stickier. This changing global circulation, combined with 4% higher water vapor in the atmosphere is causing these weather extremes.

Things are happening that have never been observed before in human history. Like the rate of decline of sea ice and snow cover, the extensive cracking of sea ice this March-2013, the “hole” forming near the north pole from relatively weak cyclones, the massive, long duration cyclone at the beginning of August-2012, and the list goes on and on. AMEG being extreme? Hardly, more like science compartmentalization and specialization being myopic to the collection of system changes that are screaming out that the climate system has entered a period of abrupt change that has not been seen before in human history, but has happened many times in the paleorecords. In fact, rates of change now are at least 10x higher than any seen in the geologic record.

SkepticalScience: About a week ago, a Nature article by Gail Whiteman, Chris Hope, and Peter Wadhams came out analyzing the "Vast Costs of Arctic Change." The Whiteman article is an honest and thoughtful commentary about the economic impacts of a changing Arctic climate. I will not comment on their economic modeling here, but rather on a key scenario assumption that they use which calls for vast increases in Arctic-sourced methane to the atmosphere. In this case, they have in mind a very rapid pulse of 50 Gigatons of methane emanating from the East Siberian Shelf (see image, including Laptev and East Siberian sea). Note: 1 GtCH4= 1 Gigaton of methane = 1 billion tons of methane. Whiteman et al. essentially assume that this "extra methane" will be put in the atmosphere on timescales of years or a couple decades. This article has been widely publicized because it calls for an average of 60 trillion dollars on top of all other climate change costs. Since this was discussed in a prediction context rather than as a thought experiment, it demands analysis of evidence.

In this article, I will argue that there is no compelling evidence for any looming methane spike. Other scientists have spoken out against this scenario as well, and I will encompass some of their arguments into this piece. In summary, the reason a huge feedback is unlikely is because of the long timescale required for global warming to reach some of the largest methane hydrate reservoirs (defined later) (Paul Beckwith: no methane was expected from ESAS since seafloor was thought to be impermeable, until it was measured to rapidly outgas from one year to the next), and because no evidence exists for such an extreme methane concentration sensitivity to climate in the past record (Paul Beckwith: methane pulses released over several years or a few decades is not detectable in ice cores since bubble closure below firn takes about 50 years or more).Permafrost feedbacks are of concern, but there is no basis for assuming a dramatic "tipping point" in the atmospheric methane concentration (Paul Beckwith: no basis for this statement since observations show large increase in methane).

The Methane Tour

Methane (CH4) is a greenhouse gas. It absorbs thermal energy that the Earth is trying to shed into outer space, and can thus warm the surface of the planet. Its concentration in the modern atmosphere is a little bit shy of 2 parts per million by volume (ppm), compared to roughly 0.72 ppm in 1750 or 0.38 ppm in typical glacial conditions. Like CO2, methane has not risen to modern day concentrations during the entirety of the now ~800,000 year long ice core record.

So what about Whiteman's scenario?

For perspective on how big 50 GtCH4 is, I've used data from David Archer's online methane model to see how atmospheric methane concentrations would change in response to such a big carbon injection. You can do this as a back-of-envelope calculation by noting that 1 ppm is about 2.8 GtCH4 if it all stays as methane and isn't removed, but this model lets you see the decay timescale too. For methane, the decay back to original concentrations occurs within decades, whereas for CO2 it takes millennia (CH4 is rapidly oxidized by the hydroxyl radical in the atmosphere). Therefore, CO2 dominates the long-term climate change picture but the methane spike can induce very large transitory effects. (Paul Beckwith: keep in mind that the methane lifetime varies greatly depending on the availability of the hydroxyl radical. On average it is 12 years, however in dry regions like the Arctic with little water vapor it is longer, while at moist equatorial regions it is shorter).

I've run two scenarios in which the 50 GtCH4 injection takes 1 year and 10 years to complete (red and blue lines, respectively). The model starts with pre-industrial CH4 concentrations in years -10 through zero. The modern concentration of methane is shown as a horizontal orange line.



Everything having to do methane in the ice core record resides below the orange line in Figure 1 (at least within the resolution of the cores). So we're potentially talking about a very big change, which the Whiteman article contends is likely to be emitted fairly soon and should have implications for Arctic policy. (Paul Beckwith: This graph clearly demonstrates that if glacial ice bubble closure takes 50 years, then the pulse will not be captured. Also, the molecular weight of CH4 is 16 compared to 30 or so for air (mostly N2) so the methane does not stay around the surface for long).

For many, the primary concern about “big” abrupt changes in atmospheric CH4 stems from the large quantity of CH4 stored as methane hydrate or in permafrost in the Arctic region. These terms are defined below. It should be noted that globally, wetlands are the largest single methane source to the modern atmosphere. Most of that contribution is from the tropics and not from high latitudes (even if the Arctic was to start pumping harder). The Denman et al., 2007 carbon cycle chapter in the last IPCC report is a useful reference. (Paul Beckwith: methane from wetlands in tropics has short lifetime due to extremely large quantities of water and thus hydroxyl ions in that region, as opposed to methane from the Arctic in much drier conditions)

Nonetheless, the Arctic is a region that is quite dynamic and is changing rapidly. The high latitudes are currently a CO2 sink (Paul Beckwith: this cannot be correct, since CO2 concentrations are higher in the Arctic than the global values measured at Mauna Loa, for example) and CH4 source in the modern atmosphere, and it’s not implausible that the effectiveness of the sink could diminish (or reverse) or that the methane source could enhance in the future, since we expect a transition to a warmer, wetter climate with an extended thawing season. This makes the carbon budget in the Arctic a “hot” place for research.

In these discussions, it is important to clarify what sort of methane source we're talking about.

Methane hydrate is a solid substance that forms at low temperatures / high pressures in the presence of sufficient methane. It is an ice-like substance of frozen carbon, occurring in deep permafrost soils, marine continental margins, and also in deeper ocean bottom sediments. It's also very concentrated (a cubic foot of methane hydrate contains well over 100 times the same volume of methane gas).

On the decade-to-century timescale, the liberation of methane from the marine hydrate reservoir (or the deep hydrates on land) should be well insulated from anthropogenic climate change. Deep ocean responses by methane are a very slow response (many centuries to millennia, Archer et al., 2009). Methane released in deep water also needs to evacuate the water column and get to the atmosphere in order to have a climate impact, although much of it should get eaten up by micro-organisms before it gets the chance. These issues are discussed in a review paper by O’Connor et al., 2010. (Paul Beckwith: Methane response in deep ocean is not always slow, thus this section is very misleading. Underwater landslides from slope instability or earthquakes are know to have resulting in large methane pulses many times in the paleorecords. For example, Storegga off Norway or off New Zealand, there are extensive pockmarks on the ocean floor indicating abrupt episodic events. The mainstream view that methane outgassing from deep water regions does not enter the atmosphere. If release is slow that is correct, however rapid outbursts overwhelm the micro-organisms and result in large amounts of methane entering the atmosphere. Even slower releases from deep water off Svalbard have been observed recently to enter the atmosphere; another unexpected development).

There’s also carbon in near-surface permafrost, which is the more vulnerable carbon pool during this century. Permafrost is frozen soil (perennial sub-0°C ground), and can also encompass the sub-sea permafrost on the shelves of the Arctic Ocean. This includes the eastern Siberian shelf, a very shallow shelf region (only ~10-20 m deep, and very broad, extending a distance of 400– 800 km from the shoreline). This is a bit of a special case. These subsea deposits formed during glacial times, when sea levels were lower and the modern-day seafloor was instead exposed to the cold atmosphere. The ground then became submerged as sea levels rose (going into the warmer Holocene). The rising seas have been warming the deposits for thousands of years. Because of their exposure during the Last Glacial Maximum, the shelves may be almost entirely underlain by permafrost from the coastline all the way down to a water depth of tens or even a hundred meters (e.g., Rachold et al., 2007 and this USGS page).

There's actually no good evidence of shallow hydrate on the Siberian shelves, even though there are substantial quantities of subsea permafrost. Hydrate may exist deeper down however, more than 50 meters below the seafloor. The stability of these hydrates is sustained by the existence of permafrost, and it's not quite clear to what extent hydrate can also be stored within the permafrost layer. (Paul Beckwith: Permafrost people have an over-reliance on uniform slab models which examine time taken for heat to propogate through the slabs to melt the deep permafrost. They severely underestimate the fracturing and nonuniform nature of the permafrost, presence of taliks, etc. All that is needed is one weak spot or fracture region and heat can transfer downward much faster and further than the models suggest. Similar slab models are used to estimate glacial ice melting and they have clearly been incorrect and completely underestimate the rates of melting from dynamic effects and Moulin pathways, for example.)

The estimates of the amount of methane in these various Arctic reservoirs are very uncertain. Ballpark numbers are a couple thousand gigatons of carbon (GtC) stored in hydrates in global marine sediments (e.g., Archer et al., 2009) of which a couple hundred gigatons of carbon are in the Arctic Ocean basin, and between 1000-2000 GtC in permafrost soil carbon stocks (e.g., Tarnocai et al., 2009) after you include the deeper deposits. For comparison, there is a bit over 800 GtC in the atmosphere, of which about 5 Gt is in the form of methane, and estimated ~5000 GtC in the remaining fossil fuel reserve. These numbers seem big compared to the atmosphere, but for methane direct comparison isn't too relevant unless you put it in rapidly, since it has such a short lifetime in the atmosphere. Large amounts of CO2, in contrast, last much longer.

A couple years ago, Shakhova et al. (2010a) reported extensive methane venting in the eastern Siberian shelf and suggested that the subsea permafrost could become unstable in a future warmer Arctic. Shakhova et al (2010b) cite ~1400 Gt in the East Siberian Arctic Shelf, which comprises ~25% of the Arctic continental shelf and most of the subsea permafrost. Shakhova et al (2010c) ran through a few different pathways in which they argued for 50 GtCH4 release to the atmosphere either in a 1-5 year belch or over a 50-yr smooth emission growth, which they suggest, “significantly increases the probability of a climate catastrophe.” This assessment was the foundation for the concern in the recent Whiteman Nature article, linked at the top.

The physical mechanism outlined by some of these authors is related to the rapid reduction in Arctic summer sea ice observed over the last few decades, which allows for greater amounts of solar radiation to penetrate the waters around the Arctic shelf. Warming water propagates down in the well-mixed layers tens of meters to the seabed, and might melt frozen sediments underneath. Because the shelf in this region is shallow (compared to other regions), one doesn't need to wait a long time for the seafloor to feel the atmosphere-surface forcing, and methane leakage might have an easier escape path to the atmosphere. Allegedly, this has been leading to an acceleration of methane flux.

Responses from Scientists

As a response to the first paper from Shakhova on enhanced methane fluxes, Petrenko et al (2010) criticized the authors for misunderstanding several of their references and primarily for the logical implications of their conclusions. For example,

“A newly discovered CH4 source is not necessarily a changing source, much less a source that is changing in response to Arctic warming. Shakhova et al. do acknowledge these distinctions, but in these times of enhanced scrutiny of climate change science, it is important to communicate all evidence to the scientific community and the public clearly and accurately”

(Paul Beckwith: Examination of the methane concentrations in the atmosphere in the Arctic region from AIRS satellite data over a decade or so shows an obvious large increase in the amount of methane, and has been corroborated with flask measurements at locations across the Arctic, namely Barrow, Alaska and Svalbard. How is this not a changing source?)

Another paper, Dmitrenko et al (2011) reinforced this statement and came to the conclusion that there is currently no evidence that Arctic shelf hydrate emissions have increased due to global warming. This is also discussed in the review article by O'Connor et al (2010, linked above). (Paul Beckwith: Again, does one trust a direct observation or a conclusion from a paper? Obviously the direct observation.)

The work done by the Dmitrenko paper shows that although the changing Arctic atmosphere has led to warmer temperatures throughout the water column (over the eastern Siberian shelf coastal zone), it takes a very long time for the permafrost feedback at the bed to respond to this signal. They noted that the deepening of the permafrost table should only have been on the order of 1 meter over the last several decades, which does not permit a rapid destabilization of methane hydrate.  (Paul Beckwith: Deepening of the permafrost table of 1 meter over several decades is based on a slab model and let to the erroneous mainstream view that the seafloor over the ESAS was impermeable to methane release. Measurements show otherwise.)

It is important to emphasize that simple point source emission estimates are not often suitable for determining changed sources and sinks over the last few decades, and thus don't tell you how that translates into atmospheric concentration. This should be kept in mind when seeing dramatic videos of methane venting from a shelf or exploding lake, which might not actually have much to do with global warming. (Paul Beckwith: This is a very alarming view, and would fit in fine on any of numerous climate denial websites. Rapid methane emissions in the Arctic are what they are. Call a spade a spade.)

In 2008, there was a comprehensive report on Abrupt Climate Change from the U.S. Climate Change Science Program, which is a bit dated but nonetheless makes a statement reflecting most of current scientific thinking. Quoting Ch. 5 Brook et al (2008):

"Destabilization of hydrates in permafrost by global warming is unlikely over the next few centuries (Harvey and Huang, 1995). No mechanisms have been proposed for the abrupt release of significant quantities of methane from terrestrial hydrates (Archer, 2007). Slow and perhaps sustained release from permafrost regions may occur over decades to centuries from mining extraction of methane from terrestrial hydrates in the Arctic (Boswell, 2007), over decades to centuries from continued erosion of coastal permafrost in Eurasia (Shakova [sic] et al., 2005), and over centuries to millennia from the propagation of any warming 100 to 1,000 meters down into permafrost hydrates (Harvey and Huang, 1995)" (Paul Beckwith: Again, slab model thinking. Episodic events like landslides negate these claims, as does fractures and other weakspots in the slabs which allow pathways for huge heatflow. A good analogy is polyanas in sea ice that allow for enormous heat flow between the ocean and the atmosphere in a sea ice field.)

Paleo-Analogs

One of the primary reasons we don't think there's as much methane sensitivity to warming as has been proposed by Shakhova, and argued for in the Whiteman Nature article, is because there's no evidence for it in the paleoclimate record.  This has been a point made by Gavin Schmidt on Twitter (a compilation of his many tweets on the topic here) but the objections to the Nature assumptions have been further echoed in recent days by other scientists working on the Arctic methane issue (e.g., here, here).

One can argue from a process-based and observations-based approach that we don't understand everything about Arctic methane feedback dynamics, which is fair. Nonetheless, the methane changes on the scale being argued by Whiteman et al. should have been seen in the early Holocene (when Summer Northern Hemispheric solar radiation was about 40 W/m2 higher than today at 60 degrees North, 7000-9000 years ago). (Paul Beckwith: Earth tilt was larger, so Winter Northern Hemispheric solar radiation was about 40 W/m2 lower than today at 60 degrees North. Thus, the ice formed much more quickly and much thicker in the winter back then. Also, at night much more heat was radiated out to space in the lower GHG world then as compared to our 400 ppm levels today). Even larger anomalies occurred during the Last Interglacial period between 130,000 to 120,000 years ago, though with complicated regional evolution (Bakker et al., 2013). 

Both of these times were marked by warmer Arctic regions in summer without a methane spike. It's also known pretty well (see here) that summertime Arctic sea ice was probably reduced in extent or seasonally free compared to the modern during the early Holocene, offering a suitable test case for the hypothesis of rapid, looming methane release. (Paul Beckwith: Incorrect, the summertime Arctic is not believed to be seasonally ice free during these periods. The last time this happened was likely 2 or 3 million years ago.)

It should be noted that Peter Wadhams did offer a response recently to the criticisms of the Whitehead Nature piece (Wadham is a co-author) but did not address why this idea has not been borne out paleoclimatically.

Yesterday, an objection to the paleoclimate comparison cropped up in the Guardian suggesting that the early Holocene or Last Interglacial analogs are not suitable pieces of evidence against rapid methane release. They aren't perfect analogs, but the argument does not seem compelling. (Paul Beckwith: Colder winters in the early Holocene and Last Interglacial and much colder nights (in summers and winters then) meant much thicker and extensive ice formation in winters, and slower melting at night, respectively. Compelling arguments.) The Northeast Siberian shelf regions have been exposed many times to the atmosphere during the Pleistocene when sea levels were lower (and not covered by an ice sheet since at least the Late Saalian, before 130,000 years ago, e.g., here). As mentioned before, when areas such as the Laptev shelf and adjacent lowlands were exposed, ice-rich permafrost sediments were deposited. The deposits become degraded after they are submerged (when sea levels increase again), resulting in local flooding and seabed temperature changes an order of magnitude greater than what is currently happening. Moreover, the permafrost responses have a lag time and are still responding to early Holocene forcing (some overviews in e.g., Romanovskii and Hubberten, 2001; Romanovskii et al., 2004; Nicolsky et al., 2012). A book chapter by Overduin et al., 2007 overviews the history of this region since the Last Glacial Maximum. These texts also suggest that large amounts of submarine permafrost may have existed going back at least 400,000 years. It therefore does not seem likely that the seafloor deposits will be exposed to anything in the coming decades that they haven't seen before. (Paul Beckwith: What is unique now is the extremely high concentration levels of CO2 (400ppm) and CH4 (>1900ppb). These high concentrations trap the heat in the troposphere 24/7. Thus, at night heat loss is limited by the GHG blanket. At all previous times the GHG blanket was much weaker, with CO2 ranging from 180 to 280 ppm and CH4 ranging from 350 to 700 ppb, or so. This makes an enormous difference.)

What about other times in the past? Fairly fast methane changes did occur during the abrupt climate change events embedded within the last deglaciation (e.g., Younger Dryas), just before the Holocene when the climate was still fluctuating around a state colder than today. These CH4 changes were slower than the abrupt climate changes themselves, and have been largely attributed to tropical and boreal wetland responses rather than high latitude hydrate anomalies. Marine hydrate destabilization as a major driver of glacial-interglacial CH4 variations has also been ruled out through the inter-hemispheric gradient in methane and hydrogen isotopes (e.g., Sowers, 2006) (Paul Beckwith: Episodic events like landslides, as mentioned before, cannot be discounted. In fact geological events like landslides occur at much higher frequencies when there is a rapid temperature transition, as covered extensively in Bill McGuire’s new textbook. Also, the text on “The Clathrate Gun hypothesis” cannot be completely discounted.)

To be fair, we don't have good atmospheric methane estimates during warmer climates that prevailed beyond the ice core record, going back tens of millions of years. Methane is brought up a lot in the context of the Paleocene-Eocene Thermal Maximum (PETM, 55 million years ago). During this time, proxy records show global warming at the PETM (similar to what modern models would give for a quadrupling of CO2), extending to the deep ocean and lasting for thousands of years. In addition, there were substantial amounts of carbon released. It may very well be that isotopically light carbon came from a release of some 3,000 GtC of land-based organic carbon, rather than a destabilization of methane hydrates, although this is a topic of debate and ongoing research (see e.g., Zeebe et al., 2009; Dickens et al., 2011).

It's also important to emphasize that any destabilization of oceanic methane hydrates at the PETM, or any other time period, would imply that the carbon release is a feedback to some ocean warming that occurred first- perhaps on the order of 1000 years beforehand. Furthermore, once methane was in the atmosphere, it would oxidize to CO2 on timescales significantly shorter than the PETM itself (decades.) Unfortunately, there is no bullet-proof answer right now for what caused the PETM, but rather several hypotheses that are consistent with proxy interpretation. However, methane cannot be the only story.

The Role of Methane in Climate (Change)

To be clear, CH4 is important as we go forward, and is already a key climate forcing agent behind CO2 (coming in at ~0.5 W/m2 radiative forcing since pre-industrial times). Additionally, methane is quite reactive in the atmosphere, and the effect of other things like tropospheric ozone, aerosols, or stratospheric water vapor are partly slaved to whatever is happening to methane (Shindell et al., 2009). This means methane emitted has a bigger collective impact on climate than if you just do the radiative forcing calculation by comparing methane concentration changes to what it was in 1750. (Paul Beckwith: It is important to point out an enormous misconception in public and scientific reports on methane regarding the Global Warming Potential (GWP). A number in the low 20s is almost always reported (22x, 25x…) and is based on a 100 year timescale. On a 20 year timescale, methane GWP is around 70x, and on a 1 or 2 year timescale the GWP is >150x. Clearly, in terms of methane in the Arctic sourced from marine or terrestrial permafrost the number of significance to sea ice and localized warming is 150x.)

Permafrost thawing is also going to be important in the coming century (this is a good paper), and the uncertainties pretty much go one way on this. There's not much wiggle room to argue that permafrost will reduce CH4/CO2 concentrations in the future. This is also likely to be a sustained release rather than one big catastrophic event. For example, permafrost was not included in Lenton (2008) as a "tipping point" for precisely the reason that there's no evidence for any "switch" of rapid behavior change. (Paul Beckwith: Exclusion of methane as a “tipping element” in this paper by the “experts” in 2008 was based on rates of change based on slab models, which recent observations of emissions has clearly invalidated). Much of the carbon is also likely to be in the form of CO2 to the atmosphere, and even implausible thought experiments of catastrophic methane release (see David Archer's post at RealClimate) give you comparable results in the short-term as to what CO2 is going to do for a long time.

Conclusion

The observed methane venting from the East Siberian shelf sea-floor to the atmosphere is probably not a new component of the Arctic methane budget. Furthermore, warming of the Arctic waters and sea ice decline will likely impact subsea permafrost on longer timescales, rather than the short term. (Paul Beckwith: Is this author so sure of this as to be willing to stake the stability/instability of the entire global circulation system on this?)

Methane feedbacks in the Arctic are going to be important for future climate change, just like the direct emissions from humans. This includes substantial regions of shallow permafrost in the Arctic, which is already going appreciable change. Much larger changes involving hydrate may be important longer-term. Nonetheless, these feedbacks need to be kept in context and should be thought of as one of the many other carbon cycle feedbacks, and dynamic responses, that supplement the increasing anthropogenic CO2 burden to the atmosphere. There is no evidence that methane will run out of control and initiate any sudden, catastrophic effects. (Paul Beckwith: There is no evidence that methane will not run out of control, in light of large increases of concentrations in recent years).  There's certainly no runaway greenhouse. Instead, chronic methane releases will supplement the primary role of CO2. Eventually some of this methane oxidizes into CO2, so if the injection is large enough, it can add extra CO2 forcing onto the very long term evolution of global climate, over hundreds to thousands of years.


Errata Update SkepticalScience: Gavin Schmidt let me know that in the first version of this post, I used gigatons of carbon instead of gigatons of methane. I mistakingly read the Shakhova paper as an injection of carbon. Since the molecular weight of carbon is 12 g/mol, and CH4 is 16 g/mol, then 1 GtC=1.33 GtCH4. The figure in the post has been revised accordingly and doesn't impact the argument here.


Related

- Arctic Methane Release: "Economic Time Bomb"
http://arctic-news.blogspot.com/2013/07/arctic-methane-release-economic-time-bomb.html

- Methane Hydrates
http://methane-hydrates.blogspot.com/2013/04/methane-hydrates.html

- Arctic Methane FAQ
http://arcticmethane.blogspot.com/p/faq.html


- Listen to Paul Beckwith speak on Gorilla-radio.com
http://www.gorilla-radio.com/audio/Gorilla_Radio_2012-2013-08-13-24647.mp3

CO2? Let Me Introduce You To My Little Friend: CH4 [Methane]!

by Nick Breeze

In the UK, if a person smells any gas in a building or outside, they are told to call an emergency number straight away so that an engineer can come and fix the leak and remove the danger. In the Arctic, atmospheric plumes of gas have been detected that are over 150kms across and likely to have disastrous consequences for our civilisation. We simply cannot ignore this problem; it underpins the fabric of all our lives. We must respond.

Last year I attended the EGU conference in Vienna to meet with Dr. Igor Semiletov and Dr. Natalia Shakhova and was extremely grateful to them for giving me time to discuss the issue of changing conditions in the Arctic. Increased temperatures from human caused greenhouse gas emissions are increasing the risk of methane release from thawing subsea permafrost. These two scientists make annual trips to the East Siberian Arctic Shelf (ESAS), in order to gain a better understanding of what is known to be the largest hydrocarbon store in the world. The methane is trapped in the frozen clathrate deposits that has been frozen for millions of years. In this stable condition we tend to consider the methane less of a risk, however, during the course of the last decade, things have started to change.

It is important to realise that methane (CH4) is approximately 20 x more powerful greenhouse gas than carbon dioxide (CO2) over a 100yr timescale. Afterwhich it breaks down into CO2. Obviously with current atmospheric increases in emissions and the effects of warming already being felt, we do not have a 100yrs. In a shorter timescale of 20yrs, methane is estimated to be 100 x more potent as CO2 as a greenhouse gas. Baring in mind that there is currently 5 gigatonnes of methane in the atmosphere and that the East Siberian Arctic Shelf (ESAS) is estimated to have between 100’s and 1000’s of gigatonnes trapped in the permafrost, if there is any destabilisation, supply of methane could rapidly move the world to a much hotter and dangerous state for humans and many other forms of life.

As a species humans add 35 billion tonnes of carbon dioxide to the atmosphere each year in the form of emissions. Over the course of the last 200 years this has caused a global temperature rise of about 0.8 C. Although this seems tiny, we are only just starting to understand how sensitive the Earth is to changes in temperature. Add to this that the Arctic has been warming at around 8 times the speed of the mid latitudes and it’s not hard to see why the Arctic Sea Ice has gone into an accelerated melt.

NASA Image of Melting Arctic Sea Ice

It may seem obvious that if we heat the planet up then we will melt the ice. When joining the dots on the severity of what climate change really means, it is important to grasp “feedbacks”. These are the Earth’s response to changes within the climate system. A general rule of thumb is that “positive feedbacks” generally are bad for us and “negative feedbacks” are not. In the case of the Arctic, it is important to understand that there are multiple feedbacks [watch this comprehensive analysis by David Wasdell, Apollo-Gaia Director for more information] that come into play when the temperature changes. The Arctic sea ice is one that has caught the world’s attention because we are entering a phase where we no longer have a northern polar ice-cap. This is, in turn, setting off other positive feedbacks, one of these being the heating of the Arctic ocean as it absorbs sunlight and starts to thaw the subsea permafrost in the shallow seas of the ESAS. This is effectively removing the seal on a vast store of potent methane greenhouse gases that could take us from a steady increase in temperature to the awful sounding “runaway” global heating.

During the interview with Dr Shakhova, I was chilled when she showed me 2 charts, one with small insignificant plumes of methane from over ten years ago, contrasted with a chart from 2011 where the plumes of escaping gas from the permafrost were over a kilometre wide. Dr Shakhova also stated that in recent years all the conditions were changing making the risk of a game changing release of methane from the ESAS much more likely. Dr Shakhova even pointed out that it was likely “in decades”. Dr Semiletov went further to say “anytime!”.

Below are a few video clips from the interview in April 2012. I am very much looking forward to seeing the new work by Dr’s Semiletov and Shakhova et al that will be released shortly, giving us a far greater understanding, and up to date view, of the state of this all important region in the Arctic.

In the meantime, the methane issue has been the focus of NASA’s ‘Carbon in Arctic Reservoirs Vulnerability Experiment’ (CARVE) who have detected 150 kilometre plumes of atmospheric methane. This raises a few questions that are critical to our future civilisation:

1. If the Arctic Sea Ice and permafrost are degrading at 0.8C, are the IPPCC agreed “targets” of 2C really safe? 
2. Have we underestimated Earth’s sensitivity to temperature altogether and sailed blindly over into the wild waters of runaway climate catastrophe?
3. How much longer can we continue to release carbon emissions into the atmosphere before we lose the gift of choice in the matter and the climate shifts to a hotter state increasing sea-levels significantly, and not favouring large-scale agriculture?

For a longtime the methane issue has remained outside the larger conversation of impacts of global warming, except by reference to far off future risks. There are a handful of scientists such as Professor Peter Wadhams, Head of the Polar Institute at Cambridge University, who, based on submarine observations of the Arctic sea ice’s collapse in volume, has been pointing out that a methane feedback may not be as far away as we think. Professor Wadhams has made these points in the face of angry cries of “Alarmist” from UK politicians with financial interests in the hydrocarbon industry.

The work of scientists including the Russians, Wadhams and NASA’s CARVE team now means we can no longer ignore the risk of methane as part of the Earth’s complex system of feedbacks to temperature change. It also is very likely that at 2C the world will not be the beautifully hospitable place that it has been for humans for so long. It is very likely that we are close to that “tipping point” of no return where global heating goes into a runaway phase and we lose our only life support system. I sincerely hope this isn’t the case but we have to acknowledge the risk if we are to react appropriately.

In order to answer the third question posited above, we have to comprehend the enormity of the task of transitioning away from fossil fuels (coal, oil and gas). To say it cannot be done is to kiss the world, as we know it, goodbye. It can be done but it will take the will of all of us together, starting with citizens around the world, to politicians and those in the hydrocarbon business themselves. Whilst in Vienna in 2012, I also interviewed Dr James Hansen, one of the most outspoken climate scientists alive today and former Head of The Goddard Institute for Space Studies in New York. You can watch a video clip at http://vimeo.com/71179724 on what Hansen proposes as a way to curb emissions and start turning the tide on our collective response to global heating.

So how do we respond? It is clear that we need to make changes at a societal level. Never forget that each and everyone of us is a part of society and, as such, we have influence. The action we need to take is tied in with our attitude to the problems we face. The hydrocarbon industries lobby our governments and institutions to make sure their needs are not ignored. This is for one reason alone: profit. Societal reliance on this form of energy is no longer necessary. We should be transitioning away from hydrocarbon fuels. We can’t because these powerful companies are tucked tight inside the framework of our civilisation. There is no doubt that as such, we are entering a phase of willful self-destruction. The only thing that can stop it is us. A good example of this institutional integration is the Royal Geographic Society where Shell’s logos feature prominently and they even have their own page on the society’s web site aligning themselves with our respected institutions, paying lip service to our future concerns. This is disgusting. We should treat hydrocarbon companies as we did the tobacco industries once it was proven how harmful tobacco is to our health. These companies project the use of oil and gas way into the middle of the century. Don’t believe it. On this course, we will end up clinging to an inhospitable planet, barely recognisable as it is today. Take action.


The first and most effective thing you can do is contact your local elected representative and tell them straight. I sent the following email to my own Member of Parliament, Mary McCleod MP and waiting patiently for a reply. It is critical to remember that they have our future in their hands but we have their vote. Let’s use it!

Dear ____,

As a citizen concerned with the unnecessary proven damage being done to our environment, I am writing with the following conditions that will have to be met if you are to have my vote at the next election:

1. Remove all links to hydrocarbon companies that currently exist within public institutions
2. Ban hydrocarbon company advertising
3. Introduce a fair tax on carbon that will level the playing field for renewable energy sources and force the hydrocarbon industries to clean up their act
4. Implement a framework for a transition to renewable energy immediately

As you represent me on a local and national level I will be listening with interest to all representations you make to government on my behalf. I am also keen to hear your response and will be sharing it with friends and family.

Thank you for your time.

Yours sincerely,



____________________________

A note on climate fixes such as ‘Climate Engineering’ (aka geoengineering): I have not mentioned proposed climate engineering proposals in this post as we are currently working on an in depth look at several projects that are already in progress. Climate engineering raises many scientific, political and ethical issues and to many people the idea that man can engineer Earth’s climate is a crazy and hubristic fantasy. No matter what we think, it is important that we are all cognisant of the arguments being put forward. We will be interviewing leading commentators and authorities, not just from the climate and engineering backgrounds but also from ethical and philosophical disciplines to help form a view of this controversial subject. The worst case scenario is that we ignore the subject altogether and the decision to engineer climate falls into the hands of a foreign international power willing to gamble the fate of billions, or, a wealthy individual who can afford to take an equal gamble and become what Clive Hamilton has titled his recent book, an ‘Earthmaster’. Groups such as the Arctic Methane Emergency Group have been calling for climate engineering to be deployed immediately to cool the Arctic and prevent the runaway heating that climate scientists most fear. The argument for both sides is compelling and the more we shy away from zero carbon emissions the more climate engineering solutions start to look like a relatively cheap alternative. It is time for us all to be part of this critical discussion.

This post was originally posted at: 
http://envisionation.co.uk/index.php/blogs/72-co2-let-me-introduce-you-to-my-little-friend-ch4-methane

Arctic Methane Release: "Economic Time Bomb"

On March 19, 2013, a number of experts came together for an Ecorys.com workshop, as part of a

Peter Wadhams Sc.D., Prof. of Ocean
Physics and head of the Polar Ocean
Physics group, Cambridge University.

study examining the impact of a 50-Gt release of methane from the melting permafrost at the East Siberian Arctic Shelf (ESAS) over different time periods, ranging from one to five decades.

Back in 2008, a study by Natalia Shakhova et al. considered release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time.

In order to estimate the cost of such a release, this new study used a more recent version of the model used in the renowned Stern Report. Findings of the study are published in the journal Nature. The conclusion is that such a release from the ESAS alone comes - in the absence of mitigating action - with a price tag of $60 trillion. By comparison, the size of the world economy in 2012 was about $70 trillion.

Such a methane pulse will "bring forward 15–35 years the average date at which the global mean temperature rise exceeds 2°C above pre-industrial levels", says the paper.

"The economic consequences will be distributed around the globe, but the modelling shows that about 80% of them will occur in the poorer economies of Africa, Asia and South America. The extra methane magnifies flooding of low-lying areas, extreme heat stress, droughts and storms."

"The total cost of Arctic change will be much higher," says the paper. To find out the actual cost, more feedbacks should be incorporated in the model, such as linking the extent of Arctic ice to increases in Arctic mean temperature. The full impacts of a warming Arctic include, for example, ocean acidification and altered ocean and atmospheric circulation. "Midlatitude economies such as those in Europe and the United States could be threatened, for example, by a suggested link between sea-ice retreat and the strength and position of the jet stream, bringing extreme winter and spring weather. Unusual positioning of the jet stream over the Atlantic is thought to have caused this year’s protracted cold spell in Europe."

Experts attending the workshop include: 

Peter Wadhams, Head of the Polar Ocean Physics Group at Univeristy of Cambridge.

Chris Hope,  reader in policy modelling at Judge Business School, University of Cambridge, and creator of the PAGE-models used for the Stern-report 

Carl Koopmans, Professor of Infrastructure and Economics, VU University, Amsterdam 

Henri de Groot, professor in Regional Economic Dynamics, VU University, Amsterdam 

Marcel Canoy, Professor at the School of Economics and Management, University of Tilburg

Gail Whiteman, Professor of sustainability, management and climate change at the Department of Business-Society Management, Erasmus University, Rotterdam 

Comments & Responses

Meanwhile [July 27, ed.], the piece in Nature has received wide news coverage, including a critique by Jason Samenow in the Washington Post. Peter Wadhams responds to some of the comments as follows:

Peter Wadhams: The 25 July post by Jason Samenow on the global economic impacts of methane emissions in the East Siberian Sea portrays the findings of our research as misleading, a statement with which I strongly disagree. Our work is based on a prediction of the magnitude and timing of methane emissions from the thawing of Arctic offshore permafrost by a scientist who has done extensive field work on this part of the ocean bed and is a globally recognized expert. We calculated the financial implications of these emissions for the world economy over a century and also considered the effect of the emissions on increasing overall global warming, obtaining a 0.6C figure by 2040. We rightly consider these to be substantial figures, which deserve wide circulation among climate scientists, and Nature and its referees agreed with us.

In our analysis we showed that the overall cost of a given volume of methane release is relatively insensitive to the rate of release or, within limits, its timing, BUT that the cost is roughly proportional to the overall volume of release. Thus, even if you worked with a different projection by a lesser qualified scientist than Shakhova, and revised down the figure and scale of the 60 trillion dollars accordingly, I suspect the cost will still be substantial – and that is one clear finding: The planetary cost of Arctic warming far outstrips any possible benefits to shipping or natural resource exploration.

In support of its skepticism about methane emissions the article quoted authors who wrote before the enormous retreat of summer Arctic sea ice and its oceanographic effects became so evident. 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.

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.

The 2008 US Climate Change Science Program report needs to be seen in this context. Equally, 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 Semiletov/Shakhova field experiments and the mechanism described above. Carolyn Rupple’s review of 2011 equally does not reflect awareness of this new mechanism.

Therefore I robustly defend our research and commentary, and hope that rather than dismiss the substantial risk such a methane release poses, the response might be to support more intensive research on this problem.

This is what Nathan Currier said in a comment at the Washington Post:

Nathan Currier: Earlier this year, a small piece of rock exploded over Russia, breaking some windows and causing minor injuries, yet shortly thereafter, a congressional panel was convened here in Washington, DC on the risks of significant asteroid impacts, and the panel, after being told they were about 1/20,000 for the year, was also told by the experts that billions will need to be spent to prevent a “possible catastrophe”. John Holdren, President Obama’s chief science advisor, commented, "The odds of a near-Earth object strike causing massive casualties and destruction of infrastructure are very small, but the potential consequences of such an event are so large it makes sense to takes the risk seriously." Holdren was right: in assessing a risk, it is a product of the probability and the magnitude that counts in the end. 

Nothing we do alters the risk of asteroid impacts, but our activities are profoundly altering the risks of unleashing powerful arctic carbon feedbacks. Like night and day with warming, where we don’t tend to notice that nighttime temperatures are increasing more rapidly than daytime ones, the scientific community’s assessments of risks tend to focus on those things which, by being more continuous, can have the daylight of quantitative analysis shone upon them more easily. But there is no question that the risks in the arctic that are rising most rapidly are the “nighttime” ones of abrupt changes. That is because there is already a 100% chance of increases in chronic emissions. Somewhat like larger and larger rocks hitting the earth, the risks of larger and larger methane pulses are certainly progressively smaller, but the important point here is that if we were to say conjecturally that in 1970 the risks of a 50Gt release might have been like the “city-killer” asteroid at 1/20,000, these risks now might have decreased by an order of magnitude. It is still not likely to happen now, with, let us speculate, a 1/2,000 risk, but because of the magnitude, as Holdren says, you should take this very seriously. Far more seriously, I might add, than a meteor striking the earth. Meanwhile, the leaked draft of the IPCC AR5 suggests that all arctic carbon feedbacks will be largely ignored in the report, even those that are more or less certain.

I would add that articles like this, characterizing the Nature commentary as “mischief” and “hype,” contribute to climate illiteracy in their own way, full of mischief without coming from a denialist perspective. There are too many errors here to elaborate them all. First, it makes a complete red herring of methane hydrate, quoting Ruppel on hydrate stability, etc. Let it be noted: 50Gt of methane is only about 2% of estimated Eastern Siberian Shelf (ESS) total carbon, and would only be 7% of the free gas reservoir that lies under the hydrate layer. There are many possible gas migration pathways for methane excursions, from pingo-like structures, fissures, the taliks appearing more and more throughout the permafrost layer, slope failure, sediment or mudslides around the Lena delta, an endogenous seismic event along the Gakkel ridge, etc. Thus, hydrate is really not even needed for a methane catastrophe scenario at the ESS. None of the quotes, moreover, about hydrate distinguish between the exceptional situation at the ESS of very shallow waters and the hydrates elsewhere around the world, which are indeed mostly quite secure.

Despite this, Hansen considers methane hydrate one of the three main coming tipping points in the climate system. The article quotes David Archer, a clear outlier on this issue, in that he doesn’t even believe the PETM warming (55 million years ago) was caused by methane hydrate release, which is the dominant paleoclimate theory, based on isotopic evidence. Meanwhile, it also quotes a paper claiming that there is no evidence for any major hydrate release at all over the last 100,000 years, clearly not something that Archer would agree with, as he himself has written an authoritative paper on the methane hydrate release of the Storrega landslide event (~8000 years ago).

At the group 1250 (1250now.org), we are focusing now on precisely the opposite, the subtler changes in surface-produced methane that are likely with further loss of sea ice, but it is shocking to see a response like this one to an issue of obvious importance.

To close, no one doubts that a 50Gt release of methane is “unlikely” right now if you consider 1/2,000, let’s say, unlikely. But as the thermal signal of anthropogenic warming propagates into the sediment below such shallow waters as at the ESS, and given that the ocean currents are not the same now as they have been during the paleoclimatic past, such that paleoclimate cannot ultimately be used to constrain and quantify the actual risk, it is clear that the risks, unlike those of asteroids, are growing.

But that was clearly NOT the point of the Nature commentary. The point of the commentary was to note that the impact would be very, very big. So, to go back to Holdren, it should be taken very seriously.

Also noteworthy is what Nathan Currier said in response to comments by Gavin Schmidt, quoted in the New York Times:

Gavin Schmidt: Threshold releases even 1/10 as large as postulated would be clear in ice cores. There is nothing there. In more recent past, there have been a number of times when 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 significantly warmer.

Nathan Currier: I find Gavin Schmidt’s points here very thin. Let’s review them:

First, clearly no one is suggesting that during the 800,000 year period covered by ice cores there has been any such release. Further, David Archer, quoted in Revkin’s piece and a leading authority on such issues, has specifically discussed the possibility in a peer-reviewed paper (Archer, 2007) of fern diffusion allowing a Gt-scale release to escape detection in ice cores.

The problem with this argument, made repeatedly when this same issue erupted over a year ago, is that it is looking weaker than it did just a year ago: for example, we are learning that certain key ocean currents were significantly different during the Eemian than they are today – see http://phys.org/news/2012-06-climate-cold-arctic-eemian.html. And what counts in this argument is what the sea bottom conditions are, of course, not just the surface conditions. Schmidt is right that at times it was much warmer than today in the arctic, possibly 8C warmer, as we have seen from the Lake E work, but he forgets himself, and points to the early Holocene, although the area in question was a frozen piece of land at that time, not an underwater shelf, so that is purely irrelevant, as it took almost 4,000 years before the area in question became inundated.

But risks are growing significantly in the arctic by the year, and a 5Gt release, which would double the atmospheric burden, would result from less than 1% - about .7% - of estimated ESAS free gas below the hydrate layer being released, without any hydrate needing to be involved, which some kind of endogenous seismic event could conceivably set off, perhaps a sediment pile mud slide around the Lena mouth, for example. The point of the paper, lost in all of this, was just to say, this would cost us about $6 trillion.

The worst moment of Schmidt’s points, one which really merits censure, is to refer to all the research being done in the area (he clearly means Shakhova and Semiletov here) as “one off surveys.” Note that he isn’t even asking for better research to be done there, either. I personally find that quite unfortunate, even a bit embarrassing for someone who has built up a sterling reputation.

He (Schmidt) is certainly right that there is no recent example of CH4 being higher than the pre-industrial baseline, and that includes the “super-interglacials” from Lake E bores, but it is incredibly unwise to jump to the claim from that that we are not near dramatic releases without offering any evidence at all.

It is far better to go by the best peer-reviewed research about contemporary conditions on the ground than to speculate about the few generalities we can draw from the sketch of climates past we have put together for the last few million years, as valuable as that sketch is. There was at no time during that period anything like the 400ppm of CO2 in the atmosphere now, nor the many other GHGs levels we have boosted, nor the things that have no natural analogue like the CFCs, nor is there any analogue for the rate of change we have experienced, and so the sea level’s relationship to the atmospheric conditions has no analogue either, and we are also learning at the same time just how sensitive and variable key arctic ocean currents might be in this region.

All that said, Schmidt acknowledges that “potential for Arctic CH4 to have threshold behavior is real,” and I should also acknowledge that I agree that the 50Gt scenario is not likely at this time.

Let's also add a quote from an earlier post:

Sam Carana: Analysis of sediment cores collected in 2009 from under ice-covered Lake El'gygytgyn in the northeast Russian Arctic suggest that, last time the level of carbon dioxide in the atmosphere was about as high as it is today (roughly 3.5 to 2 million years ago), regional precipitation was three times higher and summer temperatures were about 15 to 16°C (59 to 61°F), or about 8°C (14.4°F) warmer than today.

As temperatures rose back in history, it is likely that a lot of methane will have vented from hydrates in the Arctic, yet without causing runaway warming. Why not? The rise in temperature then is likely to have taken place slowly over many years. While on occasion this may have caused large abrupt releases of methane, the additional methane from such releases could each time be broken down within decades, also because global methane levels in the atmosphere were much lower than today.

In conclusion, the situation today is much more threatening, particularly in the East Siberian Arctic Shelf (ESAS), as further described in other posts at the methane hydrates blog.

Also note the comments by Veli Albert Kallio, in an earlier post:

Albert Kallio: The problem with ice cores is that if there is too sudden methane surge, then the climate warms very rapidly. This then results the glacier surfaces melting away and the ice core begins to loose regressively surface data if there is too much methane in the air.

Because of this, there has been previous occurrences of high methane, and these were instrumental to bring the ice ages ice sheets to end (Euan Nisbet's Royal Society paper). The key to this is to look at some key anomalies and devise the right experiments to test the hypothesis for methane eruptions as the period to ice ages.

Thus, the current methane melting and 1800 ppm rise is nothing new except that there are no huge Pleistocene glaciers to cool the Arctic Ocean if methane goes to overdrive this time. In fact methane may have been many times higher than that but all surface ice kept melting away and staying regressive until cold water and ice from destabilised ice sheets stopped the supply of methane (it decays fast if supply is cut and temperatures fall back rapidly when seas rose).

The Laurentide Ice Sheet alone was equivalent of 25 Greenland Ice Sheets and the Weischelian and other sheets on top of that. So, the glaciers do not act the same way as fireman to extinguish methane. Runaway global warming is now possibility if the Arctic loses its methane holding capability due to warming.

Let's conclude the debate on the following note:

Sam Carana: Uncertainty does NOT constitute a valid argument to dismiss warnings about large abrupt methane releases in the Arctic. Instead, uncertainty calls for further research and for comprehensive and effective action, especially since so much is at stake and the dangers are getting larger each time the necessary action is delayed. 

References

- Vast costs of Arctic change, in Nature, vol 499, pp 401-403, July 25, 2013
by Gail Whiteman, Chris Hope and Peter Wadhams
http://www.nature.com/nature/journal/v499/n7459/full/499401a.html
http://www.nature.com/nature/journal/v499/n7459/pdf/499401a.pdf

- Ecorys studies economic valuation of climatic change impacts in the Arctic region
http://www.ecorys.com/news/ecorys-studies-economic-valuation-climatic-change-impacts-arctic-region

- Arctic time-bomb warning
in: Cambridge News, by Jennie Baker
http://www.cambridge-news.co.uk/Education/Universities/Arctic-time-bomb-warning-20130724123026.htm

- Anomalies of methane in the atmosphere over the East Siberian shelf: Is there any sign of methane leakage from shallow shelf hydrates?
N. Shakhova, I. Semiletov, A. Salyuk, D. Kosmach
http://www.cosis.net/abstracts/EGU2008/01526/EGU2008-A-01526.pdf

- Arctic methane release is an 'economic time bomb' - study
by Nafeez Ahmed

http://www.guardian.co.uk/environment/earth-insight/2013/jul/24/arctic-melt-methane-economy-time-bomb

- Ice-free Arctic in two years heralds methane catastrophe – scientist

by Nafeez Ahmed
http://www.guardian.co.uk/environment/earth-insight/2013/jul/24/arctic-ice-free-methane-economy-catastrophe

Related posts

- How much will temperatures rise?
http://arctic-news.blogspot.com/2013/04/how-much-will-temperatures-rise.html

- Runaway Global Warming
http://arctic-news.blogspot.com/2012/07/runaway-global-warming.html

The worst-case and - unfortunately - looking almost certain to happen scenario

Aaron Franklin

By Aaron Franklin

I have asked for the world leading climate and arctic scientists I have been working with at AMEG, and Arctic-News to review this, and if they don't agree with any part or the end conclusion to please inform me immediately.

As yet no-one has come forward, with any criticisms whatsoever, only agreement that this is what we are very likely facing.

If we don't act very fast and the Arctic sea ice goes...

Up till now the sea ice, and the pool of low salinity meltwater left on the surface of the arctic ocean from it melting has blocked the warm Gulf stream from getting any further than the strip of coast with a shallow continental shelf seabed, around the north of Europe and western Russia as far as the islands and peninsulars that jut north from the west Siberian coast.

High salinity, warm gulfstream water of tropical origin does not mix freely with cold low density low salinity meltwater. It mixes and sinks in a sheet current at the boundary between these two bodies of water.

This has not caused any big problems so far as it has been happening along a fairly short boundary above shallow continental shelf and the downwards mixed flow is slowed by flowing over the the shelf before it sinks into the deep polar basin.

However... the meltpool on top of the Arctic ocean has been getting smaller every year and if we let the gulf stream get any further than it has to date then it will most likely continue all the way along the east Siberian coast, combine with the warm bering strait inflow, encircle the whole polar basin. Or at least most of it, if there is still enough multi-year sea-ice damming up against the west coast of the north Canadian archipelago to stop it getting to the extreme Canadian side of the arctic ocean.

There probably isn't enough multiyear seaice left to do this anyway and it won't make any differency to the overall outcome anyway, which is....

Encouraged by the anti-clockwise, low level Arctic atmospheric wind vortex (the low pressure system that is usually in place over the nth pole) the gulf-stream loop will accelerate, forming a mixing vortex (whirlpool), first sucking down any remaining surface meltwater pool to deep polar ocean, along a long circular front above the deep polar basin.

As this is happening the Gulf stream and Bering strait warm water inputs will accelerate dragging ever warmer water in, and the entire Arctic ocean near surface region will flood with warm high salinity water at up to 12C or even higher.

This will eliminate any chance of the arctic ocean refreezing in winter. And:

The average 12C temperatures of the upper layer of the polar ocean will be sending a big thermal pulse down through the East Siberian Arctic Shelf and other shallow submarine permafrosts in the arctic. This pulse propagating fast through liquid water in cracks and methane eruption vents. The hydrate layers containing over 1000 billion tons C of methane at the bottoms of these permafrosts will be destabilising, bottom up, when that thermal pulse pins them between itself and rising geothermal heat.

The ESAS and other Arctic shelf Methane Hydrate reefs will be fizzing like an alka-seltzer in a glass of warm water, and the wind-turbulated open water will mean lots of that methane getting into the atmosphere and spiking global warming.

As the sun has set for the north polar winter at this point, the northern Alaskan, Siberian, and Canadian tundras will cool rapidly as usual. But this time the warm surface of the polar ocean will be releasing water vapour and this warm low density air/water vapour mixture will rise, accelerating the polar low into a very deep arctic storm system, very likely far stronger than any we've ever seen.

This will erupt warm water vapour bearing air high into the troposphere, and stratosphere above the pole and this will suck in the cold air from over Alaskan, Siberian, and Canadian tundras, drawing in air from further south and causing heavy winter rainfall rather than light snowfall. (usually in winter polar highs are dominant and descending cold dry air from these flows out over the Alaskan, Siberian, and Canadian tundras).

The tundra permafrosts will now be drenched in large volume rainfalls. The warm lakes and bogs all over them will be drilling through the permafrost, and lots of the around 1700 billion tons C of organic carbon locked up in the land permafrost will be flooding into the Arctic Ocean from Siberia, Alaska and North Canada. And getting sucked down the polar plughole. Lots will be getting released into the air as methane and carbon dioxide, and spiking global warming.

The donut-shaped circulation pattern sitting like a crown over the Arctic circle will start drawing down stratospheric air from further south.

Sometime soon, very probably in the nest northern summer monsoon season...

-At this point the extra methane, ozone, water vapour, and the loss of sea ice reflecting sunlight back into space will together be producing about 3x present day global warming effect.

and...

The jetstreams that are formed by warm moist air rising from the equator, dumping that moisture as heavy tropical rain in the tropics usually descend in the subtropical desert belts that circle the globe. They like cogs intermeshing will connect with the polar donut, drawing the summer monsoon north over the subtropical desert belts and building rapidly to tropical rainfall levels over the worlds deserts.

The dry descending air from the equatorial and north polar origin tropospheric flows and jetstreams will turn the temporate zones of the northern hemisphere into deserts in one year.

The ex tundra boglands will start to dry out. Its been learnt that when you thaw and soak permafrost peats, waking up the frozen bacteria. Then drain them....

-Significant quantities of Nitrous Oxide (N2O) start being emitted. Another "super-greenhouse" gas, with its own special radiative absorption band.

-With even more water vapour, more methane, more N2O, more ozone being produced by the methane, less SO2 forming clouds because methane destroys it....

Global warming will start to spike very high.

What happens maybe very quickly now is that an equatorial origin jetstream will either detach from its mode of descending at the new temporate zone deserts and form a new anticyclone most probably over greenland, or the anticyclone from that jetstream will migrate north from the subpolar tundras over North Canada.

Either way this special anticyclone with a very big future, will winch its way around the polar low in the new easterly "tradewinds belt" where the tundras and boreal forests are now. It will probably end up over the Beaufort sea, north of Alaska and recruiting more stratospheric jetstreams of Equatorial origin, quickly grow in strength. It will start a new clockwise ocean surface vortex in the Beaufort sea region, and if any iceflows and cold meltwater are still trapped against the west coast of the Canadian Archipelago.....

They will get sucked into this new clockwise vortex and it will love feeding on them and growing just like in the first anticlockwise vortex described above.

The new polar super anticyclone will out compete the previous polar super cyclone by one by one recruiting all the equatorial and tropical origin jetstreams, and become a, for any relevance to us, permanent, extremely powerful anticyclone over the whole polar ocean.

The new clockwise polar ocean vortex will be accelerated by the clockwise anticyclonic low atmospheric vortex. There will likely be lots of Glacier calved icebergs from Greenland, stuck against the west coast of the Canadian Archipelago. It will love gobbling, melting, and feeding on those.

It will steal the deep subduction from, and outcompete and swallow the previous anticlockwise polar ocean vortex.

Powering up this vast whirlpool, will suck in ever increasing flows of Atlantic and Pacific water, flooding the Arctic ocean with more and more tropical water. It will shovel more and more warm surface water like a wedge into a new intermediate temperature, high salinity layer, building between the tidal mixed zone and the surface mixed layer .

This intermediate layer is said to be the mechanism that produces anoxic oceans in past super-greenhouse/ anoxic ocean events. And this will happen fast because....

The tundra permafrosts will be seasonal deserts, but much warmer now. In summer they will be drenched by tropical temperature and volume rainfalls, hammered by cold fronts, supercell storms and tornados spitting off the high lattitude Megacyclones. The warm lakes and bogs all over them will be drilling through the permafrost, and more of the around 1700 billion tons C of organic carbon currently locked up in the land permafrost will be flooding into the arctic ocean from Siberia, Alaska and Nth Canada. And getting sucked down the polar plughole. More methane and CO2 will be making it into the atmosphere

In winter the ex tundras will dry out. Releasing yet more N2O and CO2.

Global Warming will spike through the roof.

And...

The by now over 20 degrees Celsius temperatures of the upper layer of the polar ocean will be sending a massive thermal pulse down through the East Siberian Arctic Shelf (ESAS) and other shallow submarine permafrosts in the arctic. This pulse propagating fast through liquid water in cracks and methane eruption vents. The hydrate layers containing over 1000 billion tons C of methane at the bottoms of these permafrosts will destabilise fast, bottom up, when that thermal pulse hits them. Quite possible the pressure building up under these shelves, most particularly the ESAS will shatter them and release most of the hydrate methane, free methane, and undecomposed organic carbon, they are holding very fast indeed. Best estimate around 2750 billion tons C total in shallow submarine arctic permafrosts.

Kinda like a warm well shook champagne bottle when you pop the cork.

Lots of this methane will hit the atmosphere.

With even more water vapour, more methane, more N2O, more ozone being produced by the methane, less SO2 forming clouds because methane destroys it....

Ballpark Chart for near filling of all relevant Radiative Absorption bands

We'll have a greenhouse effect like the earth has not seen before in its 4.5 billion years of existence.

What REALLY concerns me looking at this chart is how much it would take going from this point to the Tipping Point for the Venus syndrome.

The situation in this chart would lead to a lot more stratospheric water vapour feedback. That could start to run away until the equatorial oceans boil, and there's no stopping things from there.

Lots of methane will get sucked down the Arctic plughole into the new anoxic intermediate ocean layer.

Archer 2007 states that 1000 billion tons C of methane (and/or other dissolved organic carbon) is sufficient to remove all oxygen from the worlds oceans. That won't take long.

• The polar ocean vortex might eventually stop. The momentum in ocean circulation, both deep and in surface gyres, combined with wind driven surface currents won't let this happen fast.
•  In maybe 300-1000yrs a second even larger methane release will occur, as the heat from the surface reaches the deep sea bed. The deep sea Methane hydrates are estimated as between 5000 and 78 000 billion tons C of methane. That will not be nice at all, but there may be nothing left but bacteria well before then anyhow.
•  The tropical/subtropical origin MegaCyclones to polar Mega AntiCyclone jetstreams with low atmosphere return system will most probably stick around for at least 100 000 years. 
• The previous anoxic supergreenhouse/anoxic ocean events did have stalled ocean circulation, and the only way that they could have had 27C polar ocean temps like they did is by the Equatorial-Polar jetstream circulation mode described above. 
• The most serious previously, the end-permian had no polar basin, oceanic/ atmosphere circulation, turbine pump "beartrap" for the planetary eco-geosphere to put its foot in. Neither did the PETM and Elmo supergreenhouse/anoxic ocean events, the most serious of the last 100+ million years, the polar basin was landlocked for those. 
• Never before could the earth have had as much polar permafrost methane and carbon as it does now. 

I hope this explains to everyone the urgency and seriousness of the current situation, and why we need to act with overwhelming force to stop the arctic sea-ice going this year.

If we don't act fast now all this could very well unfold unstoppably in the next year or two. Can't see it taking much longer than 10 or 20 at the most.