Showing posts with label PIOMAS. Show all posts
Showing posts with label PIOMAS. Show all posts

Friday, May 9, 2014

Outlook for sea ice remains bleak

In April 2014, Arctic sea ice reached its annual maximum volume. It was the second lowest on record, according to calculations by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center. The ice volume in March 2014 also was the second lowest on record, as discussed in an earlier post. The fall in volume over the years is illustrated in the graph below, by Wipneus.
Another way of depicting the continuing fall in sea ice volume is the Arctic Death Spiral below, by Andy Lee Robinson.

The graph below, from the Danish Metereological Institute, shows mean temperatures that have been much higher than they used to be at higher latitudes. Mean 2 m temperatures for the region north of the 80th northern parallel as a function of the day of year are shown (red line), against the 1958 - 2002 mean (green line).

High levels of methane over the Arctic will have contributed to these high temperatures. Furthermore, the Jet Stream is changing as the difference in temperature between the Arctic and the equator decreases, causing more extreme weather events such as heatwaves and storms that could speed up the demise of snow and ice cover in the Arctic.

The graph below, by the Japan Aerospace Exploration Agency, shows that Arctic sea ice extent was 12,469,546 km² on May 8, 2014.

In addition, an El Niño event could cause even more ferocious heatwaves and storms to hit the Arctic. The image below, from IRI at Columbia University, shows that the chance of an El Niño event developing in the course of 2014 is close to 80%.

The outlook for the sea ice remains bleak and the possibility that a total collapse could occur in September calls for comprehensive and effective action, as discussed at the climate plan blog.

Tuesday, April 8, 2014

March 2014 Arctic Sea Ice Volume 2nd lowest on Record

The March 2014 Arctic sea ice volume, as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center, was the 2nd lowest on record at 21.818 km³. Only March 2011 had a lower volume, at 21.421 km³, as illustrated by the graph below, by Wipneus.
Another way of depicting the continued fall of the sea ice volume is the Arctic Death Spiral below, by Andy Lee Robinson.

This puts the sea ice in a very weak position. This month, the sea ice will reach its highest volume, which may well be the lowest volume on record for April. The Naval Reserach Laboratory 30-day animation below shows recent sea ice thickness.

The lowest sea ice volume for 2014 is expected to be reached in September, and - given the shape the ice is in now - will likely be one of the lowest minima on record. In fact, there is a chance that there will be no ice left whatsoever later this year. As illustrated by the image below, again by Wipneus, an exponential curve based on annual minima from 1979 points at zero ice volume end 2016, with the lower limit of the 95% confidence interval pointing at zero ice end of 2014.
Absence of sea ice will mean that a lot of more heat will be absorbed by the Arctic Ocean.

As describes, sea ice reflects 50% to 70% of the incoming energy, but thick sea ice covered with snow reflects as much as 90% of the incoming solar radiation. After the snow begins to melt, and because shallow melt ponds have an albedo of approximately 0.2 to 0.4, the surface albedo drops to about 0.75. As melt ponds grow and deepen, the surface albedo can drop to 0.15. The ocean reflects only 6% of the incoming solar radiation and absorbs the rest. Furthermore, all the heat that during the melt went into transforming ice into water will - in the absence of ice - be absorbed by the ocean as well.

Such feedbacks are causing warming to accelerate in the Arctic Ocean, much of which is very shallow and thus vulnerable to warming. The Gulf Stream can be expected to keep carrying warmer water into the Arctic Ocean. Extreme weather events such as heatwaves and cyclones could make the situation a lot worse.

Warming of the Arctic Ocean threatens to destabilize huge amounts of methane held in sediments at the seafloor, in the form of free gas and hydrates. The danger is that release of methane from the seafloor of the Arctic Ocean will warm up the Arctic even further, triggering even more methane releases, as well as heatwaves, wildfires and further feedbacks, in a spiral of runaway warming that will lead to starvation, destruction and extintion at massive scale across the globe.

In conclusion, the situation is dire and calls for comprehensive and effective action, as discussed at the climate plan blog.

Thursday, June 13, 2013

Arctic sea ice thickness falls by 2m in 21 days in some areas

For years, warnings have been raised about the dramatic decline of Arctic sea ice. Various posts at this blog have also analyzed the exponential nature of the decline in summer sea ice volume and the many feedbacks that fuel this decline. And for years, the conclusion has been that - without action - the sea ice looks set to disappear altogether within years.

Yet, many are still ignoring this warning, often with remarks such as "some of the ice is 5 meters thick; it would take decades for all that ice to melt!" Thick ice does indeed pile up along the northern coast of Greenland and Ellesmere Island, due to the way the ice drifts. This has lead some to argue that an S-shaped curve (sigmoid or gompertz trendline) was more appropriate, with the decline in sea ice volume slowing down as it approaches zero.

However, this argument doesn't seem make much sense, since such a S-shaped trendline would only apply to a relatively small area with very thick sea ice. Exponential curves would still remain the best fit to predict the decline of the sea ice in the Arctic Ocean at large.

Moreover, is it really more appropriate to say that summer sea ice looks set to virtually disappear within years, with just a tiny sliver of ice remaining north of Greenland and Ellesmere Island, instead of saying that the sea ice looks set to disappear altogether within years? How persistent will such a sliver really be?

One of the feedbacks of sea ice decline is that, as the decline progresses, cyclones can be expected to hit the remaining sea ice ever harder. How much damage can such cyclones and further feedbacks do? A previous post describes thin spots developing in the sea ice under the influence of a cyclone. The image below shows areas at the center of the Arctic Ocean (large circle) where thickness of the sea ice fell from 2 meters to 1 meters over a period of 21 days. Furthermore, the image below also shows that, over this period, 5m-thick ice was reduced to 3-meters thickness (top small circle), while 2m-thick ice was reduced to zero (bottom small circle).

2m falls in thickness in 21 days - click on image to enlarge
In conclusion, without action the Arctic sea ice looks set to continue to decline exponentially, while strong feedbacks such as cyclones developing when there is more open water, look set to add to the decline and cause the Arctic sea ice to disappear completely within years. For an overview of lines of action, see this post at the methane hydrates blog.

Wednesday, April 24, 2013

Arctic Sea Ice Animation

Arctic Sea Ice Minimum Volume

Above a tilted screenshot from the animation below, by Andy Lee Robinson, of Arctic Sea Ice minimum volumes reached every September since 1979, based on data from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, Zhang and Rothrock, 2003) at the University of Washington.

Andy also composed and performed the piano music, "Ice Dreams", accompanying the video.

video from

Dorsi Diaz
By Dorsi Diaz

They say a picture can be worth a thousand words. If so, then this video of the Arctic Sea ice loss between 1979 and 2012 must be worth a million. As the recently released video begins to go viral, more people are waking up to the reality of climate change.

Produced by Andy Lee Robinson, this beautiful short clip with its haunting music is revealing the reality of climate change in a brutal and honest way - perhaps even better than any journalist ever could.

In an interview with Robinson, I was amazed at how he had managed to put together this vital information in such a compelling video, and sought to find out more.

To the climate deniers horror, Andy has done this video with no sort of compensation - dashing away climate deniers theories that all climate activists "are on the payroll." With hundreds of painstaking hours put into the development of his video, Andy says he was motivated by "experimenting with ideas and what ifs" and sought to "bring to life something that only existed in my mind to communicate an important message that is being ignored."

To create the video, he used a text editor, numbers and only his imagination to weave together the horrifying decline of Arctic sea ice that has occurred in just 13 short years.

Andy says one of the reasons for creating the video was, "to contribute something to humanity and be recognized for it, applying the skills I have learnt with my free time and not to live in vain" and also, "to prove that anyone can achieve anything they want to given enough determination and dedication."

With over 100 hours invested just into the writing of the program for the video, Andy also said it took 28 hours for 7 servers to render the final video, then about a half hour to write, record, edit and merge the music. The piano composition in the video, "Ice Dreams", was also composed by Andy, who also specializes in digital audio sampling and signal processing.

Robinson, a linux system administrator and consultant, has a passion to bring awareness about climate change to the masses and is adamant about what may happen if civilization does not address this growing threat: "We are in a period of mass extinction and heading for decimation of the quality of life for most lifeforms on the planet, including ourselves who are also subject to the laws of nature of boom and bust as resources are exploited and depleted."

Robinson also believes, with many others, that climate change and ocean acidification are, "planetary emergencies in progress."

Robinson doesn't mince any words either when asked why he created the video: "To be heard loudly and truthfully because mainstream media is still tiptoeing around the herd of elephants in the room because of the fear of change and the pressure of special interests committed to ensuring it stays that way, ignoring the fact that it cannot."

Until recently, climate deniers had dominated much of the political landscape and held a tight reign on the mainstream media. Now that climate change seems to be spiraling out of control with billions of dollars in weather related disasters, people are waking up to a preview of what it's like to live in a climate altered world.

Robinson's research for the video uses records of Arctic sea ice loss from PIOMAS through the Polar Ice Center, a group of dedicated investigators that conducts interdisciplinary research on the oceanography, climatology, meteorology, biology and ecology of the ice-covered regions on Earth and elsewhere in the solar system.

Through the perfect dance of loss and hauntingly beautiful music merged with pending disaster, Robinson has brought home a message in this video that we all need to heed: "Survival is not compulsory, nor a God given right. It requires effort, investment and cooperation."

Are we listening yet?

Dorsi Diaz is a freelance writer and art educator living in the San Francisco Bay Area. Dorsi's passion is to help adults and children unlock their creativity and imagination and to also spread the word about the effects of world-wide climate change - follow Dorsi Diaz on Twitter

Below, the Arctic Death Spiral, another visualization of the PIOMAS data by Andy Lee Robinson. 

Andy's Arctic Death Spiral - update incl May 2013 - latest version at

Below, Andy's Arctic Death Spiral video, with the sea ice volume data controlling spectral harmonics.

Added below is a video of another Arctic Death Spiral, accompanied by Chopin's 'Funeral March'. This work is not by Andy, it's from by R. Eric Collins.

Friday, January 25, 2013

Arctic sea ice volume decline animation

Screenshot showing the exponential decline of minimum Arctic sea ice volume at the bottom end of the annual graphs
To see a 3-D animation of the decline of Arctic sea ice volume over the years, click on the play button below.

This excellent animation was produced by Andy Lee Robinson using PIOMAS data.

The image below was part of last year's post Polar jet stream appears hugely deformed. The image highlights that Arctic sea ice minimum volume in 2012 was only 19.3% what it was in 1979. The background image, prepared by Wipneus, shows an exponential trend projecting a 2013 minimum of only 2000 cubic km of sea ice, with a margin of error that allows Arctic sea ice to disappear altogether this year, i.e. in less than six  months time. 


- Polar jet stream appears hugely deformed

Saturday, January 12, 2013

Arctic sea ice volume 2012

Above images show Arctic sea ice volume data up to and including the year 2012. On the right, monthly data - click on the image to view data in more detail. On the left, annual minimum data with trendline added.

Details of minimum data (as on the image on the left) - Big changes in Arctic within years
Further albedo changes in the Arctic - Albedo changes in the Arctic
Discussion of some of the implications - Getting the picture
Policies to change the climate back - President Obama, here's a climate plan!

Tuesday, October 16, 2012

Albedo change in the Arctic threatens to cause runaway global warming

Mark Flanner et al. calculated in 2011 that snow and ice on the Northern Hemisphere had a combined cooling effect of 3.3 Watts per square meter (of which 2 W/sm relates to the snow cover on land and 1.3 W/sm to the sea ice).

This cooling effect is deminishing rapidly, as temperatures rise and snow and ice cover declines. Snow and ice on the Northern Hemisphere had already declined substantially over the years and was reflecting 0.45 watts less energy per square meter in 2011 than it did in 1979 (Flanner, 2011).

As discussed in Albedo change in the Arctic, Professor Peter Wadhams calculates that the loss of the Arctic sea ice cooling effect alone can be compared to the net global warming caused by people's emissions (1.66 W/sm, IPCC, 2007b).

The exponential trends added by Wipneus to PIOMAS Arctic sea ice volume data show that the Arctic Ocean looks set to be ice-free from 2015 onwards for the period from August through to October, while July and November look set to follow from 2017, respectively 2018 onwards with June following closely thereafter. In other words, we could soon face an Arctic Ocean that is ice-free for half the year.

Snow cover on land takes up an even larger area than sea ice. The chart below illustrates the decline of snow cover on land in the Northern Hemisphere (without Greenland) for the month June.

What trends could fit these data? On the image below, I've added trendlines and I encourage others to come up with better ones.

Clearly, a lot of snow and ice looks set to disappear over the next few years. Note that what happens in winter doesn't matter as much, as little sunlight reaches the Arctic in winter. What matters most is how much sunlight is reflected when insolation in the Arctic is high. Insolation during the months June and July is higher in the Arctic than anywhere else on Earth, as shown on the image below, by Pidwirny (2006).

While Greenland remains extensively covered with snow and ice, the reflectivity of its cover shows rapid decline, as illustrated by the image below. The July data since 2000, from the meltfactor blog with projection in red added by Sam Carana, suggest a exponential fall in reflectivity that looks set to go into freefall next year.
From: Greenland is melting at incredible rate


A drop of as little as 1% in Earth’s albedo corresponds with a warming roughly equal to the effect of doubling the amount of carbon dioxide in the atmosphere, which would cause Earth to retain an additional 3.4 watts of energy for every square meter of surface area (NASA, 2005; Flanner et al., 2011).

Combined, the snow line retreat, loss of sea ice and decline of Greenland's reflectivity constitute a huge loss of summer cooling in the Arctic.

As a result, summer temperatures in the Arctic look set to rise rapidly over the next few years, threatening to unleash massive amounts of methane from sediments below shallow waters of the Arctic Ocean, spiraling Earth into runaway global warming.

If you are also concerned about this development, please share the image below at Facebook, with a link to this post.

- Albedo - Wikipedia

- Albedo change in the Arctic

- Flanner et al. (2011), Radiative forcing and albedo feedback from the Northern Hemisphere cryosphere between 1979 and 2008.

- Flanner et al. (2011), Presentation October 27, 2011, WCRP Open Science Conference

- Greenland is melting at incredible rate

- NASA, 2005 (at

Pidwirny, M. (2006). "Earth-Sun Relationships and Insolation". Fundamentals of Physical Geography, 2nd Edition

- PIOMAS monthly average sea ice volume, with exponential trends added

- Snow Climate Lab, Rutgers University

Wednesday, October 10, 2012

Saving the Arctic Ice (#1)

By Nathan Currier

Greenpeace, Greenwashing and Geoengineering

Nathan Currier, senior climate advisor for Public Policy Virginia

There was much media attention a couple of weeks ago when this year's sea ice extent minimum broke all records: it was down almost 50 percent from the 1979-2000 average. Little attention, though, accompanied a possibly even more significant figure, released a few days ago: those who run the PIOMAS sea ice volume model at the Polar Research Centershowed the 2012 sea ice volume minimum was down almost 50 percent not from decades ago -- but from 2007! That's right: the volume of arctic sea ice this September minimum was probably about half of what it was, just back in 2007. This figure should deeply trouble any reasonable human being, as it strongly suggests reaching an ice-free arctic sea ice minimum within half a decade, and, since there is little dispute that some summer sea ice will persist to the north and west of Greenland for much longer, the first "near-ice-free" point will likely arrive in just the next few years, as sea ice expert Peter Wadhams has pointed out, and the London-based policy group and think tank Ameg has maintained.

How should we respond? Greenpeace recently started a "Save the Arctic" campaign. That's great -- but you can only save the arctic by saving its ice. And, unfortunately, it is now clear that this can no longer be achieved through emissions reductions alone. It's too late for that. Greenpeace held ameeting on the polar emergency in New York City, by chance on the same day the record extent minimum was called, and while on the surface it seemed pretty ordinary, it was at heart very odd. Nobody suggested any change of approach, any specific re-strategizing, to respond to the accelerating situation. The word emergency was a common currency passing all lips, but in fact it was unclear whether people were really speaking the same language, especially as concerns that most precious thing in emergencies -- time. And there seemed to be no translator in the room, saying "this is the timescale of this, that's the timescale of that."

The meeting's two scientists, Wieslaw Maslowski (on ice) and James Hansen (general climate), themselves focusing on somewhat different time scales, were followed by the 'social/political' panel discussing what we should do: the panel discussed green energy, solar power, how we shouldn't move towards nuclear, that kind of stuff. But Jim Hansen had said in answer to a question (mine), "We are going to lose that sea ice," and also said that to save it, "You could do some quick things." As I'll discuss in my next post, Hansen meant geoengineering. Greenpeace Director Kumi Naidoo later couldn't even remember the word -- geoengineering. But if he's going to save the arctic, I'm afraid he's going to need to know it.

A big issue in whether to consider something an important 'threshold' is its reversibility, and we will discuss the reversibility of this one further in the next episode. At the meeting, since Maslowski focused on sea ice modeling failures, and Hansen on the whole climate picture, many of the potential immediate physical impacts of allowing this coming ice loss remained poorly or not at all elaborated -- although they are important for Greenpeace, and everyone else, to understand, I feel. Hansen showed a slide of three major tipping points which he said place us in a climate 'emergency,' because one can lose control around tipping points. One was methane hydrate, for example. But what Hansen didn't show were what I might dub the 'minor tipping points,' far more immediate changes stemming from this coming loss, which could make it hard to turn around, and could lead us straight to those more major ones Hansen fears, in a slippery slope.

Keep in mind that what we're talking about here is losing almost as much summer ice cover in just the next few years as we have over the last few decades, and that these are all circularly interrelated reinforcing mechanisms. Sorry, if it seems a bit mind-numbing for some readers, but here's my list:

1. Greatly increased arctic water vapor, increasing arctic warming (water vapor is a potent greenhouse gas) but also fundamentally altering arctic hydrology and hence weather patterns.

2. Immediately and fundamentally altered arctic atmospheric chemistry, causing increased arctic methane lifetime, among other basic changes.

3. Certain increase in acceleration of arctic warming, from increased solar energy entering the arctic ocean (this engenders 1.) and the release of latent heat into the atmosphere during autumn's rapid re-freezing.

4. Consequent increased potential for large arctic storms like the Great Arctic Cyclone this summer.

5. Consequent increased deep convection events (mixing to bottom) of arctic ocean, particularly important over the shallow water of the shelves, where lower layers can now often be methane-saturated.

6. Consequently an increase of seabed methane emissions -- including from seabed permafrost, shallow methane hydrate, and from thawing of either or both of these and increased gas migration pathways allowing free gas from underneath the hydrates to outgas.

(For full PowerPoint PDF, scroll down to Topic/Title Methane Release from Eastern Siberian Shelf.)

7. This increase in seabed permafrost thawing leads to a subsequent increased risk that a random seismic event could suddenly release large amounts of methane from the above combination of thawing sources, or from other thawed arctic carbon stores (see PowerPoint above).

8. Increased risk of general degradation of shallow methane hydrates leading to slope failure and consequent methane release.

9. Certain increase in chronic emissions of methane (and CO2) from thawing land permafrost, peat, etc. with the general added warming mentioned above.

10. The increased arctic methane lifetime (2.) is indistinguishable from an increase in its arctic abundance.

11. Increasing continued rate of ice (and snow) loss as the ice-free-period subsequently lengthens, from all the above, particularly significant as the insolation increases earlier in the season to around the solstice in June (discussion here, scroll down to An Ice-free Solstice).

And here are some immediate potential global impacts to chew on:

12. Recent research suggests that ice (and snow cover) loss is at least one causative factor in recentextreme weather -- drought, flood, fires, etc. -- and if so this could quickly be amplified.

13. Consequently, recent global impacts on food security could increase proportionally.

14. Economic losses from each of those (12., 13) would probably increase proportionally, and potentially could amplify into global economic recession or even depression.

15. If there's large-scale (multi gigaton-scale) methane release soon, this would of course fundamentally alter the whole path of global warming (see my Twilight posts #1,#2), with vast consequences.

16. If the ice-free period expands significantly, altered arctic tropospheric oxidation could rapidly start to impact high latitude urban areas, making cities with large populations rapidly become more difficult to live in (good discussion here at GISS, where Hansen is himself director).

No one said a word at the Greenpeace meeting, seemingly dismissing it as a major threshold at all. No one ever said, "Let's fight this." But I am suggesting that you should see skull and crossbones hanging above this threshold crossing. Like playing around high voltage wires or train tracks, allowing this threshold to be crossed will add considerable risk. And I'm suggesting that it will be crossed in just the next few years, unless we do something about it.

As I'll discuss next time, it might prove much harder to reverse than many assume within the climate world. Therefore, as Energy Secretary Steven Chu said about allowing an eventual runaway arctic permafrost carbon feedback, we must all say loudly now about this initial step onto that vast and treacherous slippery slope: "We cannot go there!" And if we don't want to go there, there's now no longer any question -- geoengineering will have to be part of the remedy.

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

Friday, September 21, 2012

Arctic sea ice gone in September 2014

NSIDC have already made a preliminary call that September 16 was the date that sea ice extent was at its minimum in the year 2012.

Volume is something else and the record low hasn't been called yet. Nonetheless, it's interesting to look at where the trend might point at, once a value for 2012 has been added into the picture. On the interactive graph below, data for September 2nd have been added.

Granted, when making projections, it's good to have sophisticated models. I don't claim to have used those, but I've got a good eye and by the looks of it, sea ice will be gone in September 2014.

I look forward to your comments.

Monday, September 17, 2012

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.

Wednesday, September 12, 2012

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]

Saturday, September 8, 2012

Two important images

As Arctic sea ice continues to decline, breaking one record after the other, one wonders what more can be said to capture the significance of what is happening. Two images spring to mind.

The image below, from The Cryosphere Today, shows that Arctic sea ice has shrunk in area by 11.41475 million square km from March 28, 2012, to September 6, 2012, a fall of about 83¼ percent in 162 days.

The image below illustrates the dramatic drop in sea ice volume over the years. The image is based on data calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) developed at the Applied Physics Laboratory/Polar Science Center at the University of Washington.

The PIOMAS data for the annual minimum values are the black dots. The trend (in red) is added by Wipneus and points at the start of the year 2015 as the moment when ice volume will first reach zero. The red point indicates the most recent value for 2012 volume, noting of course that this value may still come down further as the year progresses.

This image is further discussed in the post Getting the picture.

Monday, September 3, 2012

PIOMAS data confirm exponential trend

The Applied Physics Laboratory/Polar Science Center at the University of Washington has issued an extra release of Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) data.

Sea ice volume on August 25th, 2012, was 3500 km3, or about 500 km3 less than the prior minimum, reached on September 10th, 2011.

The image below shows that recent data for 2012 appear to match almost perfectly the expected values based on exponential trends added by Wipneus.
The image below, again based on PIOMAS data, shows trends added by Wipneus for each month of the year. The black line shows the average for the month September, pointing at zero a bit into the year 2015, while the average for August and October (the overlapping red and dark blue lines, appearing as a single purple line) point at zero before the start of the year 2016.
In conclusion, it looks like there will be no sea ice from August 2015 through to October 2015, while a further three months look set to reach zero in 2017, 2018 and 2019 (respectively July, November and June). Before the start of the year 2020, in other words, there will be zero sea ice for the six months from June through to November.

And, events may unfold even more rapidly, as discussed earlier at Getting the picture.

The image below, from the Naval Research Laboratory, shows the dramatic decline of sea ice thickness over the last 30 days.

Monday, August 13, 2012

Getting the picture

Have a look at the picture below. It shows a graph based on data calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) developed at the Applied Physics Laboratory/Polar Science Center at the University of Washington.
image from arctische pinguin - click to enlarge
The PIOMAS data for the annual minimum values are the black dots. The trend (in red) is added by Wipneus and points at 2015 as the year when ice volume will reach zero. Note that the red line points at the start of the year 2015. The minimum in September 2014 will be already be close to zero, with perhaps a few hundred cubic km remaining just north of Greenland and Canada.
image from arctische pinguin - click to enlarge
Above image, again based on PIOMAS data, shows trends added by Wipneus for each month of the year. The black line shows that the average for the month September looks set to reach zero a few months into the year 2015, while the average for October (purple line) will reach zero before the start of the year 2016. Similarly, the average for August (red line) looks set to reach zero before the start of the year 2016.

In conclusion, it looks like there will be no sea ice from August 2015 through to October 2015, while a further three months look set to reach zero in 2017, 2018 and 2019 (respectively July, November and June). Before the start of the year 2020, in other words, there will be zero sea ice for the six months from June through to November.

Actually, events may unfold even more rapidly. As the ice gets thinner, it becomes more prone to break up if there are storms. At the same time, the frequency and intensity of storms looks set to increase as temperatures rise and as there will be more open water in the Arctic Ocean.

Above photo features Peter Wadhams, professor of Ocean Physics, and Head of the Polar Ocean Physics Group in the Department of Applied Mathematics and Theoretical Physics, University of Cambridge. Professor Wadhams has been measuring the sea ice in the Arctic for the 40 years, getting underneath the ice with the assistance of submarines, collecting ice thickness data and monitoring the thinning of the ice. This enabled 1970s data and 1980s data to be compared, which showed that the ice had thinned by about 15%. Satellite measurements only started in 1979.

Thinning of the ice is only one of the problems. "The next stage will be a collapse," Professor Wadhams warns, "where the winter growth is more than offset by the summer melt. If we look at the volume of ice that is present in the summer, the trend is so rapidly downwards that this collapse might happen within three or four years."

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. 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.

Recent events in the Arctic underline this warning. A huge cyclone battered the sea ice early August 2012. The image below, from The Cryosphere Today, shows a retreat in sea ice area to 3.09958 million km2 on the 222nd day of 2012, down from 3.91533 million km2 on the 212th day of 2012, i.e. 815,750 km2 less in ten days. Or, more than one-fifth less in just ten days.

Image from  The Cryosphere Today - click to enlarge

Sunday, April 29, 2012

Supplementary evidence by Prof. Peter Wadhams

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