Arctic News: Peter Wadhams

Showing posts with label Peter Wadhams. Show all posts

Monday, January 19, 2015

Temperature Rise

Record High Temperatures in 2014

The year 2014 was the warmest year across global land and ocean surfaces since records began in 1880, writes NOAA, adding the graph below. This graph illustrates that temperatures have risen even when focusing on a relatively short recent period with a linear trendline starting in 1998, which was an El Niño year, whereas 2014 wasn't.

Source: NOAA Global Analysis - Annual 2014

Most Appropriate Trendline

While the purple 1998-2014 trendline serves the useful purpose of dispelling the myth that warming had halted recently, it isn't the most appropriate trendline, since extending this trendline backward to 1880 would leave too many data too remote from the trendline, as is further illustrated by the animated image below.

What about the blue linear trendline that is based on data for all the years from 1880 to 2014? By that same logic, the appropriateness of this trendline must also be questioned. Temperatures in recent years have been well above this trendline. A polynomial trendline seems a much better fit, as illustrated by the image below.

Above image also extends the trendline forward, showing that 2 degrees Celsius warming looks set to be exceeded in 2038, based on the same data.

And while this is a frightening scenario, the picture may well be much too optimistic, because the heat is felt most in the Arctic Ocean, the very location where some of the most terrifying feedbacks are accelerating local warming, as further explained below.

Feedbacks in the Arctic

As NOAA writes, much of the record warmth for the globe can be attributed to record warmth in the global oceans, which reached the highest temperature among all years in the 1880–2014 record.

As above image shows, ocean heat reached a record high in 2014. In other words, it was ocean heat that pushed the combined ocean and land temperature to a record high. Anomalies were especially high in the Arctic Ocean, as illustrated by the image below.

Waters close to Svalbard reached temperatures as high as 63.5°F (17.5°C) on September 1, 2014 (green circle). Note that the image below shows sea surface temperatures only. At greater depths (say about 300 m), the Gulf Stream is pushing even warmer water through the Greenland Sea than temperatures at the sea surface.

Since the passage west of Svalbard is rather shallow, a lot of this very warm water comes to the surface at that spot, resulting in an anomaly of 11.9°C. The high sea surface temperatures west of Svalbard thus show that the Gulf Stream can carry very warm water (warmer than 17°C) at greater depths and is pushing this underneath the sea ice north of Svalbard.

Planetary energy imbalance (0.6 W/m2) equals the amount of energy in exploding 400,000 Hiroshima atomic bombs per day, 365 days/year (J. Hansen, 16 Jan. 2015).

Planetary imbalance now is 0.6 W/m². This has made the rise in ocean heat (up to 2000 m deep) more than double over the past decade. Data from 2005 through to 2014 contain a polynomial trendline that points at a similar rise by 2017, followed by an even steeper rise.

What could cause such non-linear rise?

The answer is feedbacks. Arctic snow and ice loss alone may well cause over 2 W/m² warming, warns Prof. Peter Wadhams. Another such feedback is methane erupting from the ocean floor, as methane hydrates get destabilized due to higher temperatures.

As illustrated by the graph below, most of this excess heat is absorbed by oceans and ice. Some of the heat is consumed by the process of melting ice into water, and 93.4% of this excess heat ends up warming up the oceans.

Graph by Sceptical Science based on study by by Nuccitelli et al.

As the Gulf Stream keeps carrying ever warmer water into the Arctic Ocean, methane gets released in large quantities, as illustrated in the images below showing high methane levels over the East Siberian Arctic Shelf (red oval left) and over Baffin Bay (red oval right) with concentrations as high as 2619 ppb.

click on image to enlarge

The images below show methane levels on Jan 25 (top), and Jan 26, 2015 (bottom).

The threat is that huge amounts of methane will erupt from the seafloor of the Arctic Ocean over the coming decades, as illustrated by the image below.

For more on this image, see this post and this page.

Demise of the Arctic sea ice and snow cover is another terrifying feedback. The image below features a NASA/Goddard Space Flight Center Scientific Visualization Studio screenshot showing decline of multi-year Arctic sea ice area over the years.

Below is a video by Nick Breeze who interviews Professor Peter Wadhams on multi-year Arctic sea ice.

An exponential trendline based on sea ice volume observations shows that sea ice looks set to disappear in 2019, while disappearance in 2015 is within the margins of a 5% confidence interval, reflecting natural variability. In other words, extreme weather events could cause Arctic sea ice to collapse as early as 2015, with the resulting albedo changes further contributing to the acceleration of warming in the Arctic and causing further methane eruptions from the seafloor of the Arctic Ocean.

click on image to enlarge

As the Arctic continues to warm, the temperature difference between the equator and the Arctic declines, resulting in changes to the jet streams and polar vortex.

One such change is a slowing down of the speed at which the jet streams and polar vortex circumnavigate the globe, as discussed in a recent post.

The image on the right shows that the jet streams on the Northern Hemisphere reached speeds as high as 410 km/h (255 miles per hour) on January 9, 2015. Also note the jet stream crossing the Arctic Ocean, rather than staying between 50 and 60 degrees latitude, where the polar jet streams used to be.

The image below shows winds on January 11, 2015, at several altitudes, i.e. at 10 hPa | ~26,500 m (16.5 mile), high in stratosphere, polar vortex (left, at 250 hPa | ~10,500 m (6.5 mile), jet stream (center), and at 700 hPa | ~3,500 m (2.2 mile), high in planetary boundary layer.

click on image to enlarge

As a result, extreme weather events such as heatwaves and storms can be expected to occur with greater frequency and intensity, as also discussed in a recent post. Heatwaves can heat up the water in the North Atlantic, as it flows into the Arctic Ocean, driven by the Gulf Stream, while heatwaves can also warm up the water in rivers that end up in the Arctic Ocean. Heatwaves can also hit the sea ice in the Arctic Ocean directly, causing rapid sea ice melting, while storms can make the ice break up and be driven out of the Arctic ocean,

Demise of the sea ice and snow cover in the Arctic results in further acceleration of warming, not only due to less sunlight getting reflected back into space, but also due to loss of the buffer that currently absorbs huge amounts of heat as it melts in summer. With the demise of this latent heat buffer, more sunlight will instead go into heating up the water of the Arctic Ocean. For more on the latter, see the page on latent heat.

Above image illustrates some of the self-reinforcing feedback loops that have been highlighted in this and earlier posts. Further feedbacks are pictured in the image below.

from the Feedbacks page

Runaway Global Warming

Above feedbacks are already pushing the temperature rise in the Arctic through the 2°C guardrail.

Based on existing temperature data, global warming on land looks set to exceed 2°C (3.6°CF) warming by the year 2034, but methane eruptions from the seafloor of the Arctic Ocean could push up global temperature rise even faster, in a runaway global warming scenario.

click to enlarge image

This raises the specter of human extinction. With no action taken, there appears to be a 55% risk that humans will be extinct by the year 2045, while taking little action will only postpone near-term human extinction by a few years. Only with rapid implementation of comprehensive and effective action may we be able to avoid this fate.

Comprehensive and Effective Action

In conclusion, the situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan blog at climateplan.blogspot.com and as illustrated by the image below.

Tuesday, January 6, 2015

Edge of Extinction

Guy McPherson

Guy McPherson is convinced that humunity will go extinct soon. Guy estimates that it will happen in 5 to 20 years time.

In the video below, Guy discusses a chain of events causing several degrees warming within a few years time, including failure of the electric grid and subsequent fall in aerosols from fossil fuel burning that now mask warming, and failure to maintain nuclear power plants cooling, causing them to melt down.

These events will cause rapid warming that will accelerate loss of the snow and sea ice in the Arctic and cause massive methane releases from the seafloor of the Arctic Ocean, both adding even further warming.

Such massive warming will result in widespread crop failure and loss of habitat for humans over a timespan of up to 20 years, while events could all unfold in just 5 years time.

In the video below, Guy discusses that we are on the edge of extinction, episode 1.

Feedbacks

Professor Peter Wadhams on albedo changes in the Arctic

Conclusion from a paper presented at the 2008 EGU conference, on background
of a frame from a video interview by Nick Breeze with Natalia Shakhova.

In the video below, episode 2, Guy describes how large releases of methane from the seafloor of the Arctic Ocean alone could end civilization, as they will cause crop failure on the Northern Hemisphere and subsequent collapse of civilization. This will in turn cause failure of the electric grid, etc., as described above. So, whatever event comes first, it will trigger the other events, resulting in several degrees Celsius warming within years and loss of habitat for humans.

The image below highlights some of the complexities associated with the necessary cuts in emissions, including the impact of aerosols that mask the full wrath of global warming by half. In 2007, the IPCC described aerosols as a negative (cooling) force equal to between -0.5 and -2.5 W m-2. In 2009, Murphy et al suggested an aerosol forcing about -1.5 W m-2, reducing the net climate forcing of the past century by about half. In 2011, Hansen et al, based mainly on analysis of Earth's energy imbalance, derived an aerosol forcing -1.6 ± 0.3 W m-2. [source] As David Spratt points out, this equates to a cooling of about 1.2°C. In other words, abrupt ending of aerosols emissions would result in a temperature rise of about 1.2°C in a matter of weeks.

In the video below, Guy McPherson further discusses the impact of aerosols.

Below, 'Edge of Extinction', episode 3, published on 15 January, 2015, featuring Guy McPherson in a fine moment of comedy! Excerpt from his presentation at Butte College, November 20, 2014, Chico, California.

Below, 'Edge of Extinction', episode 4, published on 21 January, 2015, in which Guy comments on the State of the Union address of January 20, 2015.

Below, 'Edge of Extinction', episode 5, published on 27 Jan 2015, featuring an excerpt from Guy McPherson's interview on Global Research December 12, 2014 on the stages of grief.

Follow Guy McPherson's European Trip March/April 2015.

Wednesday, August 13, 2014

Horrific Methane Eruptions in East Siberian Sea

A catastrophe of unimaginable propertions is unfolding in the Arctic Ocean. Huge quantities of methane are erupting from the seafloor of the East Siberian Sea and entering the atmosphere over the Arctic Ocean.

As the top image above shows, peak levels as high as 2363 ppb were recorded at an altitude of 19,820 ft (6041 m) on the morning of August 12, 2014. The middle image shows that huge quantities of methane continued to be present over the East Siberian Sea that afternoon, while the bottom image shows that methane levels as high as 2441 ppb were recorded a few days earlier, further indicating that the methane did indeed originate from the seafloor of the East Siberian Sea.

On August 12, 2014, peak methane levels at higher altitudes were even higher than the readings mentioned on above image. Levels as high as 2367 ppb were reached at an altitude of 36,850 ft (11,232 m). Such high levels have become possible as the huge quantities of methane that were released from the seafloor of the Arctic Ocean over the period from October 2013 to March 2014, have meanwhile descended to lower latitudes where they show up at higher altitudes.

Methane eruptions from the Arctic Ocean's seafloor helped push up mean global methane levels to readings as high as 1832 ppb on August 12, 2014.

Ironically, the methane started to erupt just as an international team of scientists from Sweden, Russia and the U.S. (SWERUS-C3), visiting the Arctic Ocean to measure methane, had ended their research.

Örjan Gustafsson describes part of their work: “Using the mid-water sonar, we mapped out an area of several kilometers where bubbles were filling the water column from depths of 200 to 500 m. During the preceding 48 h we have performed station work in two areas on the shallow shelf with depths of 60-70m where we discovered over 100 new methane seep sites.”

Örjan Gustafsson adds that “a tongue of relatively warm Atlantic water, with a core at depths of 200–600 m may have warmed up some in recent years. As this Atlantic water, the last remnants of the Gulf Stream, propagates eastward along the upper slope of the East Siberian margin, our SWERUS-C3 program is hypothesizing that this heating may lead to destabilization of upper portion of the slope methane hydrates.”

Schematics of key components of the Arctic climate-cryosphere-carbon system that are addressed by the SWE-C3 Program. a,b) Sonar images of gas plumes in the water column caused by sea floor venting of methane (a: slope west of Svalbard, Westbrook et al., 2009; b: ESAO, Shakhova et al., 2010, Science). c) Coastal erosion of organic-rich Yedoma permafrost, Muostoh Island, SE Laptev Sea. d) multibeam image showing pockmarks from gas venting off the East Siberian shelf. e) distribution of Yedoma permafrost in NE Siberia. f) Atmospheric venting of CH₄, CO₂. (SWERUS-C3)

Örjan Gustafsson further adds that SWERUS-C3 researchers have on earlier expeditions documented extensive venting of methane from the subsea system to the atmosphere over the East Siberian Arctic Shelf.

In 2010, team members Natalia Shakhova and Igor Semiletov estimated the accumulated methane potential for the Eastern Siberian Arctic Shelf alone to be as follows:
- organic carbon in permafrost of about 500 Gt;
- about 1000 Gt in hydrate deposits; and
- about 700 Gt in free gas beneath the gas hydrate stability zone.

Back in 2008, Shakhova et al. wrote a paper warning that “we consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time.”

Last year, a team of researchers including Professor Peter Wadhams calculated that such a 50 Gt release would cause global damage with a price-tag of $60 trillion.

As Prof Wadhams explains in the video below: “We really have no choice except to seriously consider the use of geoengineering.”

Sea surface temperatures as high as 18.8°C are now recorded at locations where warm water from the Pacific Ocean is threatening to invade the Arctic Ocean.

At the same time, huge amounts of very warm water are carried into the Arctic Ocean by the Gulf Stream through the North Atlantic. The image below illustrates how the Gulf Stream brings very warm water to the edge of the sea ice.

Waters close to Svalbard reached temperatures as high as 62°F (16.4°C) on July 29, 2014 (green circle). Note that the image below shows sea surface temperatures only. At greater depths (say about 300 m), the Gulf Stream is pushing even warmer water through the Greenland Sea than temperatures at the sea surface.

Since the passage west of Svalbard is rather shallow, a lot of this very warm water comes to the surface at that spot, resulting in an anomaly of 11.1°C. The high sea surface temperatures west of Svalbard thus show that the Gulf Stream can carry very warm water (warmer than 16°C) at greater depths and is pushing this underneath the sea ice north of Svalbard. Similarly, warm water from greater depth comes to the surface where the Gulf Stream pushes it against the west coast of Novaya Zemlya.

[ click on image to enlarge ]

As Malcolm Light writes in an earlier post: The West Spitzbergen Current dives under the Arctic ice pack west of Svalbard, continuing as the Yermak Branch (YB on map) into the Nansen Basin, while the Norwegian Current runs along the southern continental shelf of the Arctic Ocean, its hottest core zone at 300 metres depth destabilizing the methane hydrates en route to where the Eurasian Basin meets the Laptev Sea, a region of extreme methane hydrate destabilization and methane emissions.

The images below give an impression of the amount of heat transported into the Arctic Ocean.

The image below gives an idea how methane eruptions from the seafloor of the Arctic Ocean could unfold over the coming decades. For more on this image, see this post and this page.

As said, the situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan blog at climateplan.blogspot.com and as illustrated by the image below.

Thursday, August 15, 2013

Arctic Sea Ice in Free Fall

Arctic Sea Ice has declined dramatically recently. The recent image below, by the Danish Meteorological Institute, shows the decline in extent over the past few days, with extent calculated by including all areas with ice concentration higher than 30%.

As the above image shows, sea ice extent (30%+ concentration) is now lower than any other year, except 2007 and 2012. Moreover, the sharp decline looks set to continue.

Ice volume and concentration have dropped dramatically, partly as a result of the cyclone that hit the Arctic Ocean a few days ago. The eye of the cyclone is still visible almost exactly above the North Pole on the Naval Research Laboratory image below on the right, where sea ice concentration appears to form a circle.

The sea ice looks set for an all-time record low; all this thin ice looks set to disappear over the next few weeks.

The graph below, also by the Danish Meteorological Institute, calculates sea ice extent by including all areas with 15% or more ice concentration.

The above graph also shows a steep recent descent, although not as pronounced as in the graph at the top that includes spots with 30% or more ice concentration. The graph at the top better illustrates recent drops in ice concentration from, say, 40% to 20%, which can occur quite abruptly due to the impact of a cyclone.

The Danish Meteorological Institute has meanwhile produced a more recent version of the graph based on spots with 30% or more ice concentration (added below).

The above graph shows an August 15 extent that appears to be back in line with the earlier trend. At first glance, it may appear as if the sea ice has largely recovered from the impact of three cyclones that have hit the Arctic Ocean over the past two months.

However, these cyclones are likely to have contributed to the appearance and persistence of thin spots in the ice close to the North Pole. This phenomenon was earlier described in posts such as Thin Spots developing in Arctic Sea Ice.

The conclusion remains the same as the one drawn then in that post, i.e. that for years, observation-based projections have been warning about Arctic sea ice collapse within years, with dire consequences for the Arctic and for the world at large.

Cyclones can speed up this collapse. On this point, it's good to remember what Prof. Peter Wadhams said in 2012:

". . apart from melting, strong winds can also influence sea ice extent, as happened in 2007 when much ice was driven across the Arctic Ocean by southerly winds (not northerly, as she stated). The fact that this occurred can only lead us to conclude that this could happen again. Natural variability offers no reason to rule out such a collapse, since natural variability works both ways, it could bring about such a collapse either earlier or later than models indicate.

In fact, the thinner the sea ice gets, the more likely an early collapse is to occur. It is accepted science that global warming will increase the intensity of extreme weather events, so more heavy winds and more intense storms can be expected to increasingly break up the remaining ice, both mechanically and by enhancing ocean heat transfer to the under-ice surface."

Hopefully, more people will realize the urgency of the situation and realize the need for a comprehensive and effective plan of action as described here.

Friday, August 9, 2013

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.

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

Wednesday, July 24, 2013

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.