UK MET Office keeps downplaying significance of events in the Arctic

One of the most respected datasets on Arctic sea ice volume is produced by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, Zhang and Rothrock, 2003) developed at the Polar Science Center, Applied Physics Laboratory, University of Washington. The graph below shows PIOMAS data for annual minimum Arctic sea ice volume (black dots) with an exponential trend added (in red).

The Arctic Methane Emergency Group (AMEG), in a February 12, 2012, written submission to the U.K.  Environmental Audit Committee (EAC), pointed at the graph:

. . summer volume [is] less than 30% of its value 20 years ago. The trend in volume is such that if one extrapolates the observed rate forward in time, by following an exponential trend line, one obtains a September near-disappearance of the ice by 2015.

The MET Office, in a March 8, 2012, written submission:

Climate models project the Arctic will become ice-free during summer at some point this century – though likely not before 2040. . . In September 2007, sea ice extent reached an all-time low, raising the question of whether the sea ice is likely to melt more quickly than has been projected. There is, however, no evidence to support claims that this represents an exponential acceleration in the decline. Indeed, modelling evidence suggests that Arctic sea ice loss would be broadly reversible if the underlying warming were reversed.

Professor Slingo, Chief Scientist, MET Office, elaborated on this in a March 14, 2012, oral submission:

Q114 Chair: . . when the Arctic will be ice free in summer. . . Professor Slingo: . . Our own model would say between 2040 and 2060 . . Q115 Chair: You would rule out an icefree summer by as early as 2015, for example? Professor Slingo: Yes we would . . . Q117 Chair: . . In terms of the modelling that you are using, does that cover . . . volume of ice? Professor Slingo: We run quite a sophisticated sea ice model. . . and we are looking forward now to the new measurements from CryoSat-2. Q118 Chair: . . evidence that we had suggested that the volume of ice had already declined by 75%, and that further decreases may cause an immediate collapse of ice cover. Professor Slingo: I wouldn’t [give credence to that]. We don’t know what the thickness of ice is across the whole Arctic with any confidence. . . I probably would [rule it out altogether] . . . to say we have lost 75% of the volume is inconsistent with our assessments.

Professor Laxon, director of Centre for Polar Observation and Modelling, where CryoSat-2 data is being analysed, in an August 24, 2012, written submission:

. . [analysis of] CryoSat-2 and ICESat data . . suggest a decrease in ice volume over the period 2003–12 at least as large as that simulated by PIOMAS, and possibly higher.

The Met Office, in an August 31, 2012, supplementary written submission:

The changes in observed sea-ice volume only extends [sic] over a few years and cannot in isolation be interpreted as representative of a long term trend. . . . The extrapolation of short-term trends in ice volume is not a reliable way to predict when the Arctic will be seasonally ice free as negative feedbacks and changing weather patterns may slow the rate of ice loss. . . it is worth noting that climate models can show a period of recovery in ice volume following periods of large ice volume loss.

For some curious reason, some people seek to downplay the significance of the events taking place in the Arctic, as well as the risk of methane releases. Here's more on that.

AMEG added, in its above February 12, 2012 written submission:

The catastrophic risk of global warming leading to very large emissions of methane from large Arctic carbon pools, especially from subsea methane hydrate, is documented in the 2007 IPCC assessment. By collaborating with others to protect the Arctic, a climate of cooperation can be engendered to protect the whole planet for the benefit of ourselves and future generations.

Professor Lenton, in a Feb 21, 2012, oral submission:

. . the Hadley Centre [has] permafrost in the latest state-of-the-art model . . . their best estimate is we may get 0.1°C of extra warming at the end of the century from the loss of methane from the northern high latitudes.

Professor Slingo, in the above March 14, 2012, oral submission:

Q126 Dr Whitehead:. . what sort of modelling factors may be accounted for by the possibility of tipping points or feedback attached to these? For example, the argument that follows very substantially from the extent of continental shelf that there is within the Arctic Basin and, therefore, the particular relationship that warming on that relatively shallow sea has on trapped methane-for example, the emergence of methane plumes in that continental shelf, apparently in quite an anomalous way-leading possibly to the idea that there may be either tipping points there or catastrophic feedback mechanisms there, which could then have other effects on things, such as more stabilised caps like the Greenland ice cap and so on. I rapidly collated all the possible catastrophe theories, but I mean how are those factored into the modelling process? Professor Slingo: . . we are not looking at catastrophic releases of methane. . . We don’t see catastrophic change in the Arctic that would lead to catastrophic releases of methane, or very large changes in the thermohaline circulation, within the next century. Our understanding of the various feedbacks-and it is a very complex system-both through observations and modelling, suggests that we won’t see those catastrophic changes, in terms of the physical system.

Note that the above are excerpts, to make things easier to read. For the full text, click on the respective links.

Below an update of the image, produced earlier this month, with recent volume data for 2012 added. On September 2, 2012, PIOMAS recorded a volume of 3407 cubic km of ice, i.e. very close to what the exponential line projected. The volume is likely to continue to fall further before reaching its final 2012 minimum.

The image below shows Arctic sea ice extent (total area of at least 15% ice concentration) for the last 7 years, compared to the average 1972-2011, as calculated by the Polar View team at the University of Bremen, Germany.

An accounting is now due

By Nathan Currier Arctic Crisis: Far From Sight, the Top of the World's Problems

Nathan Currier, senior climate advisor for Public Policy Virginia

As this year's sea ice extent bottoms out, it's high time that more people recognize we're in a global crisis -- the Arctic crisis. I'm sorry if this sounds “alarmist”, but the Arctic, fundamental to the stability of our weather patterns, climate and agriculture, is rapidly coming apart. In the end, of course, this will just be a sub-plot to the bigger drama, the climate crisis, but by naming this the arctic crisis, I am suggesting that it needs to be treated independently, right away. It is the heart of the near-term climate issue, and its outcome could greatly alter the outcome of the larger story, which will be the saga of the century no matter what we do.

A crisis above all means this: a compression of time. In a medical crisis, for example, we expect that there will initially be the need to regain stability through some immediate means, and then other courses of treatment will be added subsequently to address the underlying problems. If the initial steps are not taken quickly enough, the whole trajectory can be different, rendering something quite manageable more dire, potentially even fatal. Because the arctic, which has received the brunt of warming, seems poised to pass a profound state shift in the very near future (in fact it's already underway), and because it offers such vital 'services' to the planet, one could say that the urgency of the larger climate crisis is for the time being mostly contained within this arctic crisis.

But before looking at what to do, or even describing what's at stake, there's another order of business to turn to. An accounting is now due. Today I want to look back at the most authoritative recent opinions suggesting that this isn't a crisis, and see how they've been holding up. In our pre-election season of fact-checking, let's call this the 'Arctic crisis debate' fact-checking 101. But since no one else has really been referring to an Arctic crisis, what we'll be looking at are some prominent statements from 2012 concerning the two great interrelated features of arctic stability: the state of its cryosphere, and the state of its carbon stocks. In particular, the sea ice and methane.

An accounting
is now due! 

When I last wrote, it was after a flurry of methane articles, including the front page New York Times article last December on the danger of increasing arctic methane emissions, followed by David Archer's curious Much Ado about Methane piece in RealClimate, the leading climate science blog. That article put strangeness into high gear by essentially discounting the value of near-term climate altogether. But Much Ado about Methane was valuable, too, in that Archer unwittingly demonstrated, with all his authority, just how far from 'Nothing' reasonably likely arctic methane releases could be. Archer provided a graph in his follow-up showing the radiative impact of a 10Gt release, only about 20% of what leading researchers of the Eastern Siberian Shelf (ESAS) think could potentially come from that region alone in the relatively near future. [Very little methane hydrate need be involved, incidentally: imagine some seismic event there, where a little shallow hydrate, a mere .05% of the hydrate there, gets released, destabilizing just .5% of the permafrost cap along with it, which gets metabolized to methane, and all this creates increased gas migration pathways for just 1% of the free gas from below -- that's 10Gt.] Radiative forcing, the measure scientists use to describe global warming, would jump globally to about 300% of its current level of increase since industrialization, and this would begin to express itself in the climate system almost right away. Much ado, indeed: that methane wouldn't be nothing.

In my last piece, I said I would quickly follow up with another one discussing what should be done to avoid such dangers, but have since remained silent. That's for a variety of reasons, one of them being a growing involvement with a group based in the UK called the Arctic Methane Emergency Group (AMEG), focused on just this question. And almost as soon as this began, RealClimate published a piece on arctic sea ice predictions, in which AMEG -- which has projected that summer sea ice could approach an ice-free minimum just a few years from now -- seemed a primary target.

Called Arctic Sea Ice Volume: PIOMAS, Prediction and the Perils of Extrapolation, it was written by a guest, Axel Schweiger (with Ron Lindsay and Cecilia Bitz), part of the team that runs the PIOMAS sea ice model at the Polar Science Center. The 'perils' it discussed were those of AMEG's use (or misuse) of their PIOMAS model, and some of us were actually flattered that our ragtag army of citizen scientists, along with a few major climate figures willing to brave academic censure for taking positions outside the status quo, like renowned sea ice expert Peter Wadhams, were receiving cannonballs lobbed from the heart of the climate establishment.

Now, it's almost a half year later, the sea ice minimum is upon us, and the ice has been doing just what AMEG predicted. As Neven Acropolis, who runs the Sea Ice Blog, wrote last week, he's particularly at a loss for words because the 2007 record has been shattered without this summer's arctic temperatures being particularly conducive to such large ice loss, which perhaps suggests something about the extraordinary underlying nature of what is taking place.

Meanwhile, AMEG had already presented its case, both in writing and orally, before a panel of the UK Parliament, on both sea ice and methane release, back at the beginning of the year. AMEG's testimony was rebutted by Julia Slingo, Chief Scientist for the UK Met Office. Now, how has this Met Office testimony held up since?

Unlike RealClimate, the Met Office chief scientist dismissed PIOMAS modeling altogether, saying that she expected better data, fitting their Hadley Center climate models, to come in soon. That data hasn't come. Far from it. Instead, just last month, the media was filled with news pieces about how the European Space Agency's new CryoSat-2, a satellite designed to read ice volume, showed far greater volume losses than expected -- much in line with PIOMAS modeling, and supportive of AMEG's position. Near the opening of her testimony, Prof. Slingo said that the 2007 melting event was really an “advecting” of ice, coming from extreme weather over the arctic, and not really a melting event per se. Of course, we have just noted how that 2007 record has now been widely surpassed, without such weather (nor with losses coming primarily from advection).

And when it came to methane, and the danger of releases from the arctic seabed, the UK Met Office's chief scientist said: “I think there is a lack of clarity in thinking about how that heating at the upper level of the ocean can get down, and how rapidly it can get down into the layers of the ocean.”

The Great Arctic Cyclone of 2012 has perhaps provided her with a little more clarity. Beyond that, the Chief Scientist's statement was embarrassing: after all, even those most convinced that there is little danger of large immediate methane releases do not doubt the well established and drastic warming of the sea bottom precisely in the most methane-rich areas (see this paper), and Lena river discharge also greatly impacts the seabed in some of this same region, providing yet another mechanism for seabed warming. Prof. Slingo said: “At the moment, our estimates are that the increases in sea floor temperatures that have been observed have at the most been about one-tenth of a degree, except in one or two regions, like the West Spitsbergen Current.”

Clearly, Prof. Slingo doesn't seem to have studied the ESAS, where anomolies of 5ºC at the seabed have been recorded, where almost all of it has warmed some 20 times more than she says (and is still currently warming, ten times more than she suggests per decade), where significant areas of permafrost cap are thawing or already thawed, and where methane is starting to be released (see my own last post on all these points). Unlike the phony “Climategate” scandal, this is a true embarrassment for climate science. And if such “expert” testimony helps the arctic climate to pass through some invisible gate without our society lifting a finger to stop it, it will also turn out to have been one of the greatest tragedies of modern times.

So, how now, for the ice and methane? Schweiger's Perils of Extrapolation piece clearly stated how PIOMAS shows September sea ice volumes having dropped by a breathtaking 75% over just the last few decades (1979-2011). It might even seem simple to deduce that ice-free minima would be arriving quite soon, given this. But it is, I would agree, a vastly complex situation. Fully coupled models - those that do not, like PIOMAS, leave out the atmosphere, the weather, etc., but that try to create a realistic world that can be run into the future -- almost all suggest an eventual dampening effect on the underlying feedbacks leading to ice loss once it is mostly gone, thus leading to a long 'tail' of one or more decades in which a small amount of thinner summer ice remains, rather than an imminent disappearance, as both AMEG's Peter Wadhams and Wieslaw Maslowski, whose work Gore cited in his 2007 Nobel speech, have suggested.

That dampening, however, isn't happening. One almost feels sorry for Gavin Schmidt at RealClimate these days. After their latest sea ice update, he repeated in its comment thread how there is no reason to extrapolate PIOMAS into the future using an exponential curve (which shows a collapse just a few years from now). RealClimate wants to deal with the real underlying physical mechanisms involved, not just take some simple line that best fits the ice's past behavior and then extrapolate that line into the future. But, darn! The newest PIOMAS data have just been released last week, and, again, that exponential curve is being eerily followed by the real world's sea ice! In fact, Wieslaw Maslowski has also developed a new model recently, a fully coupled model free from 'perilous extrapolations,' which shows much the same thing as his prior research -- that a summer sea ice collapse is likely in the coming years, not decades.

As you can see, the reasons for thinking that there isn't an arctic crisis are about as firm as cotton candy. Next you'll need to learn the more solid reasons for suspecting that there is one. Then, after that, the big questions -- What real climate perils could this entail? What should we be doing about it right now? -- are what one needs to turn to next.

[First posted at the Huffington Post; posted with author's permission]

Supplementary evidence by Prof. Peter Wadhams

Supplementary written evidence 
submitted by Professor Peter Wadhams 
to the Environmental Audit Committee (EAC)

http://www.publications.parliament.uk/pa/cm201012/cmselect/cmenvaud/writev/1739/arc26.htm

I am writing in response to information provided recently by Professor Julia Slingo OBE, Chief Scientist, Meteorological Office, firstly in the report 'Possibility and Impact of Rapid Climate Change in the Arctic' to the Environmental Audit Committee and subsequently in answering questions from the Committee on Wednesday 14 March 2012. In the responses, the Meteorological Office refers to an earlier presentation to the Committee by myself, made on 21 February 2012.

The following comments are based on the uncorrected transcript of Professor Slingo’s presentation to the EAC, 14 March 2012 session, as at: 
http://www.publications.parliament.uk/pa/cm201012/cmselect/cmenvaud/uc1739-iv/uc173901.htm

1. Speed of ice loss

In response to questions from the Chair, Prof. Slingo ruled out an ice-free summer by as early as 2015. Furthermore, Prof. Slingo rejected data which shows a decline in Arctic sea ice volume of 75% and also rejected the possibility that further decreases may cause an immediate collapse of ice cover.

The data that Prof. Slingo rejected are part of PIOMAS, which is held in high regard, not only by me, but also by many experts in the field. From my position of somebody who has studied the Arctic for many years and has been actively participating in submarine measurements of the Arctic ice thickness since 1976, it seems extraordinary to me that for Prof. Slingo can effectively rule out these PIOMAS data in her consideration of the evidence for decreasing ice volume, when one considers the vast effort and diligence that has been invested over such an extended period in collecting data under the ice by both British and US scientists. Prof. Slingo offers no reason whatsoever for dismissing this extremely pertinent set of measurements and their associated interpretation, arguing that "the observational estimates are still very uncertain". This is not the case. I expand on this in an Appendix to my letter.

It has to be said that it is very poor scientific practice to reject in such a cavalier fashion any source of data that has been gathered according to accepted high scientific standards and published in numerous papers in high-profile journals such as Nature and Journal of Geophysical Research, the more so when the sole reason for this rejection appears to be perceived uncertainty. If other data are in conflict with one’s own data, then caution should be given to the validity of one’s own data, while this should immediately set in train further research and measurement in efforts to resolve possible conflicts. In this case, however, the crucial point is that there is currently no rival set of data to compare with the scale and comprehensiveness of the PIOMAS data; Prof. Slingo sets against the clear observational database only the Met. Office’s models. These models (and in fact all the models used by IPCC) have already shown themselves to be inadequate in that they failed to predict the rapid decline in sea ice area which has occurred in recent years. It is absurd in such a case to prefer the predictions of failed models to an obvious near-term extrapolation based on observed and measured trends.

Regarding the possibility of an imminent collapse of sea ice, Prof. Slingo ignores a point raised earlier by herself, i.e. that, 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.

The concluding observation I have to make on this first point is that Prof. Slingo has not provided any justification for ignoring the measurements that we have of ice volume changes and the clear trend towards imminent ice-free summers that they indicate.

2. Methane – potential emissions and escalation

My second point of contention is Prof. Slingo’s position on the possibility of imminent large releases of methane in the Arctic, which is consistent with her sanguine attitude to the rate of loss of ice cover. She states "Our estimates of those (large releases of methane) are that we are not looking at catastrophic releases of methane." Prof Slingo suggests that there was "a lack of clarity in thinking about how that heating at the upper level of the ocean can get down, and how rapidly it can get down into the deeper layers of the ocean". This appears to show a lack of understanding of the well-known process of ocean mixing. As Prof. Slingo earlier brought up herself, strong winds can cause mixing of the vertical water column, bringing heat down to the seabed, especially so in the shallow waters of the East Siberian Arctic Shelf. A recent paper shows that "data obtained in the ESAS during the drilling expedition of 2011 showed no frozen sediments at all within the 53 m long drilling core" (Dr. Natalia Shakhova et al. in: EGU General Assembly 2012;
http://meetingorganizer.copernicus.org/EGU2012/EGU2012-3877-1.pdf ).

The East Siberian Arctic Shelf (ESAS), where the intensive seabed methane emissions have been recorded, is only about 50 m deep. Throughout the world ocean, the Mixed Layer (the near-surface layer where wind-induced mixing of water occurs) is typically 100-200 m deep. It is shallower only in areas where the water is extremely calm. This used to be the case for the Arctic Ocean because of its ice cover, but it is no longer the case, because of the large-scale summer sea ice retreat which has created a wide-open Beaufort Sea where storms can create waves as high as in any other ocean, which exert their full mixing effect on the waters. It is certain that a 50 m deep open shelf sea is mixed to the bottom, so I am at a loss to understand Prof. Slingo’s remarks, unless she is thinking of the deep ocean or deeper shelves elsewhere than the East Siberian Sea.

Furthermore, Prof. Slingo states that "where there is methane coming out of the continental shelf there it is not reaching the surface either, because again the methane is oxidised during its passage through the sea water and none of those plumes made it to the surface. So there is a general consensus that only a small fraction of methane, when it is released through this gradual process of warming of the continental shelf, actually reaches the surface." This statement is also incomprehensible as far as the East Siberian Arctic Shelf is concerned. With such a shallow water depth the methane plume reaches the surface within a few seconds of release, giving little opportunity for oxidation on the way up. She may be confusing this situation with that of the much deeper waters off Svalbard where methane plumes are indeed observed to peter out before reaching the surface, due to oxidation within the water column.

To illustrate the reality of this warming of ESAS shelf water, I reproduce (fig. 1) a satellite sea surface temperature data (SST) map from September 2011, provided by Dr James Overland of Pacific Marine Environmental Laboratory (PMEL), Seattle. This shows that in summer 2011 the surface water temperature in the open part of the Beaufort and Chukchi seas reached a massive 6-7°C over most of the region and up to 9°C along the Arctic coast of Alaska. This is warmer than the temperature of the North Sea at Scarborough yesterday. This extraordinary warming is due to absorption of solar radiation by the open water. These are not the temperatures of a very thin skin as suggested by Prof. Slingo. The NOAA data apply to the uppermost 7 m of the ocean, while PMEL has backup data from Wave Gliders (automatic vehicles that run oceanographic surveys at preprogrammed depths) to show that this warming extends to at least 20 m. We can conclude from fig.1 that an extraordinary seabed warming is taking place, certainly sufficient to cause rapid melt of offshore permafrost, and this must cause serious concern with respect to the danger of a large methane outbreak.

Once the methane reaches the surface, one should note that there is very little hydroxyl in the Arctic atmosphere to break down the methane, a situation that again becomes even worse with large releases of methane.

3. The choice of pursuing geo-engineering or not.

Finally, I would like to address Prof. Slingo’s closing remarks on geo-engineering.

Both Professor Slingo and Professor Lenton repeat a point made by many critics of geo-engineering that once you start geoengineering you have to continue. On this point, I like to draw attention to evidence earlier provided to the Environmental Audit Committee by Professor Stephen Salter, as can be found at
http://www.publications.parliament.uk/pa/cm201012/cmselect/cmenvaud/writev/1739/arc22.htm

Prof. Salter responds: "I must disagree. You have to continue only until emissions have fallen sufficiently or CO2 removal methods have proved effective or there is a collective world view that abrupt global warming is a good thing after all. No action by the geo-engineering community is impeding these. Indeed everyone working in the field hopes that geoengineering will never be needed but fears that it might be needed with the greatest urgency. This is like the view of people who hope and pray that houses will not catch fire and cars will not crash but still want emergency services to be well trained and well equipped with ambulances and fires engines." Basically he is talking about the precautionary principle.

I fully agree with Prof. Salter on this point, and I also fully share with Prof. Salter the anxieties of the Arctic Methane Emergency Group. A highly proactive geo-engineering research programme aimed at mitigating global warming is more rational than expecting the worst but not taking any action to avert it.

Peter Wadhams,
Professor of Ocean Physics,
Department of Applied Mathematics and Theoretical Physics (DAMTP),
University of Cambridge
Member of Arctic Methane Emergency Group; Review Editor for Intergovernmental Panel on Climate Change 5th Assessment (chapter 1).

FIG.1. September 12-13 2011. NOAA-6 and-7 imagery of sea surface temperature in Beaufort Sea (courtesy of J. Overland). Alaska is brown land mass in bottom half. Note 6-7°C temperatures (green) in west, over East Siberian Shelf, and up to 9°C (orange) along Alaskan coast.

Appendix. The scientific database for sea ice loss.

On a previous occasion (21 February) I testified to the Committee and showed them the results of submarine measurements of ic thickness combined with satellite observations of ice retreat. When these two datasets are combined , they demonstrate beyond doubt that the volume of sea ice in the Arctic has seriously diminished over the past 40 years, by about 75% in the case of the late summer volume. If this decline is extrapolated, then without the need for models (which have demonstrably failed to predict the rapid retreat of sea ice in the last few years) it can be easily seen that the summer sea ice will disappear by about 2016 (plus or minus about 3 years). It might be useful to summarise the history of research in this subject.

In her testimony Prof Slingo placed her faith in model predictions and in future data to come from satellites on thickness (presumably Cryosat-2, which has not yet produced any usable data on ice thickness). Yet since the 1950s US and British submarines have been regularly sailing to the Arctic (I have been doing it since 1976) and accurately measuring ice thickness in transects across that ocean. Her statement that "we do not know the ice thickness in the Arctic" is false. In 1990 I published the first evidence of ice thinning in the Arctic in Nature (Wadhams, 1990). At that stage it was a 15% thinning over the Eurasian Basin. Incorporating later data my group was able to demonstrate a 43% thinning by the late 1990s (Wadhams and Davis, 2000, 2001), and this was in exact agreement with observations made by Dr Drew Rothrock of the University of Washington, who has had the main responsibility for analyzing data from US submarines (Rothrock et al., 1999, 2003; Kwok and Rothrock, 2009) and who examined all the other sectors of the Arctic Ocean. In fact in his 2003 paper Rothrock showed that in every sector of the Arctic Ocean a substantial hickness loss had occurred in the preceding 20 years. Further thinning has since been demonstrated, e.g. see my latest paper on this (Wadhams et al., 2011). Among the foremost US researchers at present active on sea ice volume decline are Dr Ron Kwok of the NASA Jet Propulsion Laboratory and Dr Axel Schweiger of University of Washington (leader of the PIOMAS project), and these have both been moved to write to Prof Slingo expressing their surprise at her remarks deriding the scientific database.

Even if we only consider a 43% loss of mean thickness (which was documented as occurring up to 1999), the accompanying loss of area (30-40%) gives a volume loss of some 75%. Summer melt measurements made in 2007 in the Beaufort Sea by Perovich et al. (2008) showed 2 m of bottom melt. If these enhanced melt rates are applied to ice which is mainly first-year and which has itself suffered thinning through global warming, then it is clear that very soon we will be facing a collapse of the ice cover through summer melt being greater than winter growth. These observations do not just come from me but also from the PIOMAS project at the University of Washington (a programme to map volume change of sea ice led by Dr Rothrock himself and Dr Schweiger), the satellite-based work of Ron Kwok, and the high-resolution modelling work of Dr Wieslaw Maslowsky at the Naval Postgraduate School, Monterey (e.g. Maslowsky et al 2011).

References

Kwok, R., and D. A. Rothrock ( 2009 ), Decline in Arctic sea ice thickness from submarine and ICESat records: 1958- 2008,Geophys. Res. Lett ., 36, L15501.

Maslowsky, W., J. Haynes, R. Osinski, W Shaw (2011). The importance of oceanic forcing on Arctic sea ice melting. European Geophysical Union congress paper XY556. See also Proceedings, State of the Arctic 2010, NSIDC.

Perovich, D.K., J.A. Richter-Menge, K.F. Jones, and B. Light (2008). Sunlight, water, ice: Extreme Arctic sea ice melt during the summer of 2007. Geophysical Research Letters 35: L11501. doi: 10.1029/2008GL034007 .

Rothrock, D.A., Y. Yu, and G.A. Maykut. (1999). Thinning of the Arctic sea-ice cover . Geophysical Research Letters 26: 3469–3472.

Rothrock, D.A., J. Zhang, and Y. Yu. (2003). The arctic ice thickness anomaly of the 1990s: A consistent view from observations and models. Journal of Geophysical Research 108: 3083. doi: 10.1029/2001JC001208 .

Shakhova, N. and I. Semiletov (2012). Methane release from the East-Siberian Arctic Shelf and its connection with permafrost and hydrate destabilization: First results and potential future development. Geophys. Res., Vol. 14, EGU2012-3877-1.

Wadhams, P. (1990). Evidence for thinning of the Arctic ice cover north of Greenland. Nature 345: 795–797.

Wadhams, P., and N.R. Davis. (2000). Further evidence of ice thinning in the Arctic Ocean. Geophysical Research Letters 27: 3973–3975.

Wadhams, P., and N.R. Davis (2001). Arctic sea-ice morphological characteristics in summer 1996. Annals of Glaciology 33: 165–170.

Wadhams, P., N Hughes and J Rodrigues (2011). Arctic sea ice thickness characteristics in winter 2004 and 2007 from submarine sonar transects. J. Geophys. Res., 116, C00E02.

Open Letter to EAC in response to Met Office

Open Letter in response to information provided by the Met Office to the Environmental Audit Committee

RE: Professor Julia Slingo OBE, Chief Scientist, Met Office, recently provided the report 'Possibility and Impact of Rapid Climate Change in the Arctic' to the Environmental Audit Committee and answered questions from the Committee on Wednesday 14 March 2012. In the responses, the Met Office referred to an earlier presentation by Prof Peter Wadhams, founding member of the Arctic Methane Emergency Group (AMEG).

The following comments are based on the uncorrected transcript, as at:
http://www.publications.parliament.uk/pa/cm201012/cmselect/cmenvaud/uc1739-iv/uc173901.htm

Prof Slingo starts out by saying that the projection of an ice-free summer in 2015, as earlier presented by Prof Peter Wadhams, is actually more credible than the modelling done by the Met Office. This remark may have been a slip of the tongue. Prof Slingo continues to rule out such a date and also rejects PIOMAS data showing an Arctic sea ice volume decline by 75% (from over 17,000 cubic kilometers before 1980 to around 4,000 cubic kilometers now). When asked to elaborate, Prof Slingo says: “We don’t know what the thickness of ice is across the whole Arctic with any confidence”, and “We know there is some thinning but it is not as dramatic as those numbers would suggest.” Prof Slingo also says that the observational estimates of sea ice volume are “still very uncertain”.

It is not good scientific practice to use uncertainty - even if it was there - as the basis for ruling something out. Moreover, Prof Wadhams’ conclusion is supported by years of direct observations of the decline of sea ice volume from submarines, taking away much uncertainty, while Prof Slingo doesn’t add any convincing evidence to the contrary.

When asked about the possibility of an immediate collapse of ice cover, Prof Slingo gives no credence to that possibility and rules it out altogether “on the basis of the extent of ice”.

Prof Slingo here ignores a point raised earlier by herself, i.e. that, apart from melting, strong winds can also influence sea ice extent, as happened in 2007 when much ice was driven across the Arctic Ocean. The fact that this occurred can only lead us to conclude that this could happen again. In fact, the thinner the sea ice gets, the more likely this is to occur. Furthermore, 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 in future, driving the smaller parts more easily out of the Arctic Ocean. Much of the sea ice loss already occurs due to sea ice moving along the edges of Greenland into the Atlantic Ocean.

In conclusion, Prof Slingo has not provided reasons to ignore the observed trend as presented by Prof Wadhams. Furthermore, Prof Slingo has not provided reasons to ignore the possibility of further feedbacks such as large releases of methane from hydrates speeding up sea ice decline.

On methane hydrates, Prof Slingo suggests that there was “a lack of clarity in thinking about how that heating at the upper level of the ocean can get down, and how rapidly it can get down into the deeper layers of the ocean”. However, as Prof Slingo earlier brought up herself, strong winds can cause mixing of the vertical water column, bringing heat down to the bottom of the seabed, especially so in the shallow waters of the East Siberian Arctic Shelf (ESAS). A recent paper shows that “data obtained in the ESAS during the drilling expedition of 2011 showed no frozen sediments at all within the 53 m long drilling core” (Dr. Natalia Shakhova et al. in: EGU General Assembly 2012).

Prof Slingo says that “where there is methane coming out of the continental shelf there it is not reaching the surface either, because again the methane is oxidised during its passage through the sea water and none of those plumes made it to the surface. So there is a general consensus that only a small fraction of methane, when it is released through this gradual process of warming of the continental shelf, actually reaches the surface.”

In fact, methane in the shallow waters of the ESAS will rise to the surface without much oxidation, while this situation can only be expected to get worse in case of large releases.

Prof Slingo ends with some comments on geo-engineering that show she appears to be rather uninformed on this issue as well.

These responses were to have provided science-based responses to AMEG's earlier presentation, as well as to elaborate on the report submitted by the Met Office; however, the Met Office's oral and written responses were inaccurate and out of date with current scientific understanding and the rapidly changing situation in the Arctic. AMEG urges the Environmental Audit Committee to consider a new meeting with AMEG so that these issues can be further discussed.

Signatories

Peter Wadhams, Professor of Ocean Physics, University of Cambridge
Member of Arctic Methane Emergency Group

John Nissen, MA (Cantab) Natural Sciences
Chair of Arctic Methane Emergency Group

Sam Carana, editor of Arctic-news.blogspot.com
Member of Arctic Methane Emergency Group

Readers are invited to comment and, if applicable, have their names added as signatories.

References

Kwok, R., and D. A. Rothrock (2009), Decline in Arctic sea ice thickness from submarine and ICESat records: 1958- 2008, Geophys. Res. Lett., 36, L15501.

Maslowsky, W., J. Haynes, R. Osinski, W Shaw (2011). The importance of oceanic forcing on Arctic sea ice melting. European Geophysical Union congress paper XY556. See also Proceedings, State of the Arctic 2010, NSIDC.

Perovich, D.K., J.A. Richter-Menge, K.F. Jones, and B. Light (2008). Sunlight, water, ice: Extreme Arctic sea ice melt during the summer of 2007. Geophysical Research Letters 35: L11501.  doi:10.1029/2008GL034007.

Rothrock, D.A., Y. Yu, and G.A. Maykut. (1999). Thinning of the Arctic sea-ice cover. Geophysical Research Letters 26: 3469–3472.

Rothrock, D.A., J. Zhang, and Y. Yu. (2003). The arctic ice thickness anomaly of the 1990s: A consistent view from observations and models. Journal of Geophysical Research 108: 3083. doi:10.1029/2001JC001208.

Wadhams, P. (1990). Evidence for thinning of the Arctic ice cover north of Greenland. Nature 345: 795–797.

Wadhams, P., and N.R. Davis. (2000). Further evidence of ice thinning in the Arctic Ocean. Geophysical Research Letters 27: 3973–3975.

Wadhams, P., and N.R. Davis (2001). Arctic sea-ice morphological characteristics in summer 1996. Annals of Glaciology 33: 165–170.

Wadhams, P., N Hughes and J Rodrigues (2011). Arctic sea ice thickness characteristics in winter 2004 and 2007 from submarine sonar transects. J. Geophys. Res., 116, C00E02.

Shakhova, N. and I. Semiletov (2012). Methane release from the East-Siberian Arctic Shelf and its connection with permafrost and hydrate destabilization: First results and potential future development. Geophys. Res., Vol. 14, EGU2012-3877-1.