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Being about halfway between last September and next September, I'm taking a look at how the game is going. The game is Match the September Arctic Sea Ice Volumes (in 1000's of km^3). The players are various types of curves. The scores are rounded standard deviations of the volume data from the curves. The lower the score the better. The players try to adapt to new data as it becomes available. Scores can go up or down over time.

Each player has its own score, but the players are on two teams of 4 players each: the Steepers and the Shallowers. The Steepers are projecting a progressively steeper decline into the future. The Shallowers have a progressively steeper decline at first, but then switch at some point (specific to each player) to a progressively shallower (less steep) decline.


Below are the players by team, along with their current scores.The estimated year of switch (a whole number year would correspond to September of that year) from going steeper to going shallower is also given for the members of the Shallowers, but if and when this switch has been made can be better determined in the post-game analysis (after September volumes are consistently 0).

Steepers and their Scores

Exponential _ 1.0089
Quadratic ___ 1.0040
Cubic _______ 0.9968
Hyperbolic ___ 0.9880

Shallowers, their Scores, and Estimated Time of Switch

HyperbolicTangent ___ 0.9841 __ 2009.31
HyperbolaDerivative _ 0.9783 __ 2007.87
ArcTangent _________ 0.9731 __ 2007.97
SidewaysRational ____ 0.9708 __ 2007.09

Recalling that lower scores are better, it looks like the Shallowers are ahead for now, but this could change. The Shallowers are betting that the rate of decline has already slowed.

There was another team, the Higher Degree Polynomials. They had better scores (in fact a sufficiently high degree polynomial had a score of 0, which is the best possible), but they were expelled for cheating. There is a rule against being too wobbly or having a turn that is too sharp, and members of this team broke that rule. Members of this team extrapolate poorly anyways, which is frowned upon.

Another player, Linear, didn't make a team during latest tryouts because of poor performance. Linear wasn't consistent with the theme of any of the teams anyways.


Exponential has a horizontal asymptote to the left. Exponential and Cubic are insisting that the slope should become steeper at an accelerating rate, especially Exponential. This could be detrimental to Exponential. It's in the nature of Quadratic to project that the slope should become steeper at a constant rate, and this game is no exception. Hyperbolic is the most Shallowers-like of the Steepers. Hyperbolic is counting on the slope becoming steeper at a diminishing rate, so that the slope approaches but never reaches a constant steepness. Hyperbolic has a horizontal asymptote to the left and an oblique asymptote to the right.

Each of the Shallowers' members has two horizontal asymptotes: an upper one to the left, and a lower one to the right. Each of these asymptotes can be at any position (so the lower asymptote can be at a negative volume). SidewaysRational is based on the curve (x / (x^2 - 1)), -1 < x < 1, rotated clockwise by a quarter turn. HyperbolaDerivative is based on the curve (x / SquareRoot(x^2 + 1)). ArcTangent and HyperbolicTangent are based on the curves that their respective names suggest. From the curves that these four are based on, both shifting and uniform stretching / compaction in the directions of each axis are allowed.


The players were polled with respect to their best guesses for the September 2014 volume (their guesses are shown below). None of the players seemed confident in their guess. "Our job is to try to look for the trend, not to predict the September volumes of individual years", remarked one of the players.

Steepers' Guesses for September 2014 Volume in 1000's of km^3

Exponential _ 2.520
Quadratic ___ 3.166
Cubic _______ 2.788
Hyperbolic ___ 3.087

Shallowers' Guesses for September 2014 Volume in 1000's of km^3

HyperbolicTangent __ 3.371
HyperbolaDerivative _ 3.492
ArcTangent _________ 3.586
SidewaysRational ____ 3.622

Note that each of these guesses is below the record low of 3.787 from September 2012, and well below the 5.479 from September 2013.

If the September 2014 volume (in 1000's of km^3) is between about 2.50 and about 10.15 then the order of the players from best (lowest) score to worst (highest) score will remain the same as the current order from best score to worst score, which is {SidewaysRational (Shallowers), ArcTangent (Shallowers), HyperbolaDerivative (Shallowers), HyperbolicTangent (Shallowers), Hyperbolic (Steepers), Cubic (Steepers), Quadratic (Steepers), and Exponential (Steepers)}.


Each of the current top five players believes that the beginning of when September arctic sea ice volumes are more likely than not to be virtually 0 (no arctic sea ice except for icebergs, ice shelves next to land, etc) will probably be after 2018. If this is the case then it is too early to predict, based on the game so far, whether it would be a year later than 2018 or decades later than 2018.


Quod erad demonstrandum...
it's always easy to say afterwards. I humbly submit I was very surprised last August. But this PIOMAS report is right what was to be expected.
Wellcome next melt season. The 'field of opportunity' lies wide open again for more exciting and depressing sea ice lurking!

Chris Reynolds


Having a foot in both the steeper and shallower camps - can't make up my mind. That was a very enjoyable read.

It's worth noting that, as of 28 Feb data, the volume suggests a flattening in recent years.
This is also seen in April, the month of peak volume.

So is this the start of an inflection in volume loss leading to less aggressive losses?

The problem is that over that period the Central Arctic has continued to lose volume.

And as I argue in the blog post I've just posted, this recent 'failure to thicken' is due to a Pacific North American pattern, not due to ice dynamics.

So whilst a change of trend due to increased ice production over winter seems seductive - when PIOMAS is used for forecasts it shows just such a behaviour. The volume at the end of February tells us nothing about such a shift - it was weather. And the Central Arctic, the driver of most of the volume decline, was still losing volume up to 2013.


'It was weather...' yes it was Chris. just like last summer. As both undulations cancel each other out, climate remains right on track...
Still, it tells nothing for the next minimum. Maybe an initiating El Nino season might protect the ice by cloudiness next summer.
But keep an eye on Siberia. The cold is retreating fast, might see rapid snow cover loss over there in spring.


I used only September volumes (from 1979 to 2013).


Here's annual PIOMAS volume growth from Jan 1 through February 28th over the past ten years, with percentage change from the previous year:

2005: 4.851k km3 ( -7.5%)
2006: 5.267k km3 ( +8.6%)
2007: 5.327k km3 ( +1.1%)
2008: 6.107k km3 (+14.6%)
2009: 5.770k km3 ( -5.5%)
2010: 5.872k km3 ( +1.8%)
2011: 5.706k km3 ( -2.8%)
2012: 5.536k km3 ( -3.0%)
2013: 6.884k km3 (+24.3%)
2014: 4.952k km3 (-28.1%)
AVRG: 5.627k km3 ( +0.4%)

Weather or other, that wild increase from 2012 to 2013 is surpassed only by that even wilder decrease from 2013 to this year...

Steve Bloom

Thanks, Jim. I would note that those large percentage swings become more possible as the sea ice continues its overall decline.


@Steve. Certainly true. But I suppose the point I was making was one that's already been made by Neven: last year's rebound has been by now nearly completely negated...

Andy Lee Robinson

Looks like the recovery is over, and back on trend.


It is always weather Chris, but thinner sea ice makes the weather behave differently. Less sea ice is destructive to the size of the winter bulge. But alas even simple weather is not reported accurately, hence the planetary wide confusion about what the Climate is doing, I scoff at the greatest minds not digging a little on this daily subject readily disseminated rarely right. I wonder how humanity made it so far? But that is because the modern techno world is about 100 years old.

Chris Reynolds


It's not quite always weather. The trend of volume loss isn't due to 'weather', nor is the post 2010 spring volume loss, and the increased annual range of extent/area post 2007. Ice dynamics are driving those.

But you're right that the pack does seem to be more sensitive to 'weather' now - and in a sense ice dynamics are driving that. With less overall volume (thickness) weather impacts on volume (thickness) are having a proportionately greater effect. And across the globe the effect of AGW does seem to be emerging as an observable modifying effect on weather.

Andy, Jim,

A cautionary note, whilst I think that "on the balance of probabilities there must be a substantially reduced rate of thickening during February within the Arctic Ocean, without gridded data it's impossible to be firm about this, and to what degree it has happened. So I think it opens up the possibility of being back on trend in the sense of summer volume loss, it's not possible to be absolutely sure.


Is it just me, or is this winter's not-freezing (or melting, or cracking) ignoring the peripheral seas (that will melt anyway) and going straight towards the central arctic via Fram and Bering?


Ambivalent, I can assure you it's not just you, 'cause there's me as well. The meaning of what we see is another matter.

Shared Humanity

"It's not quite always weather. The trend of volume loss isn't due to 'weather', nor is the post 2010 spring volume loss, and the increased annual range of extent/area post 2007. Ice dynamics are driving those."

The range between extent and area min/max has been increasing since the 1990's, more noticeably since the 2000's.


I believe this trend will continue as we approach a seasonally ice free Arctic. As we finally arrive at a seasonally ice free Artic, this range between min/max will stabilize and, I believe, hold steady for some time, perhaps decades. Ranges will then begin to shrink as winter max's inevitably begin to be beaten down by a warming world.

Cold Arctic winters, although warmer than the past, will continue to result in a rapid freeze, rapid seasonal growth in extent and area to a seasonal max. Denialists will continue to (foolishly, stupidly, duplicitously) claim this is evidence of a rebound. As long as this range measure indicates an increase in the min/max range, this is not the case.

About a year ago, I suggested this range measure for extent and area min/max should be tracked and, half in jest, suggested we call it BICOT for Bifurcated Intra-annual Cryosphere Oscillation Trend. Bifurcated suggesting a partial disconnect between min/max for extent and area as minimums continue to plummet while max's, also decreasing, fall more slowly, and Intra-annual to indicate this is a measurement that tracks min/max within a single melt/freeze.

I worked for some time to come up with a title because I also wanted it to stand for the impact that cold winters would continue to have on extent and area formation during the freeze. Thus, BICOT also stands for "Baby, It's Cold Out There".

I truly believe that, after we arrive at a seasonally ice free Arctic, it will be many decades before we reach a year round ice free Arctic, perhaps centuries. The shrinking of this range measure will track the progress towards that state.

Chris Reynolds


Try graphing the annual range - say summer losses - and you'll find there was a jump after 2007. It can be appreciated by looking at CT Area.
Look at the span between minima and maxima post 2007 compared to pre 2007.

A useful variant of this is simply Max Area minus Summer losses - when that hits zero the Artic Ocean is sea ice free at the end of the melt season. When it goes below 1M km^2 for CT Area - that's what I'm going to be calling 'virtually ice free' - i.e. as near as damn it open water.


I think SH was not arguing that an ice-free September wouldn't come soon, but that an ice-free March would rather take decades than years.

Shared Humanity

What I am actually saying is that SIE and SIA minimum will continue to drop until we reach a seasonal ice free state in the fall (2030 at the latest) but that cold winters will continue to prevent SIA and SIE maximums from dropping at the same rate. Because of this, the spread between minimum and maximum for a given year will continue to grow. Once we reach a seasonal ice free state the spread between min and max will remain relatively stable for a period of decades because winters will still be cold enough to cause surface freeze even if this freeze is very thin ice. BICOT or "Baby it's cold out there." I think it will be several decades before we see a significant trend down in SIE and SIA maximums which will eventually result in a year round ice free arctic. I do not expect this to happen this century.

Chris Reynolds

Ambivalent, SH,

Thanks for clarifying. I don't know how the winter peak area will respond to a transition to a seasonally sea ice free state. But there might be severe reductions in winter extent/area once the transition to a seasonally ice free state occurs. So I'd not rule out the ice edge remaining within the Arctic Ocean, and possibly less than the summer minimum for the 1980s by later this century.

Andre Koelewijn

Wouldn't the following scenario be plausible:
- hardly ice in the Arctic in September
- a serious hurricane causes a lot of mixing of water over depth, resulting in a relatively warm and salty mixture in the top 50m
- hardly ice formation in October, less than usual in November
- as a result, less ice in March next year
- no ice anymore in September
- and when again a storm occurs, this spiral goes down rather fast and in a decade or two it's all done, except for some ice in the Hudson Bay in January-April.

Chris Reynolds


What I'm thinking is that once we have a viratually sea ice free period in September the following year may see a slight recovery. But as the situation becomes regular we'll see an extension of the length of (and extent of) open water earlier into the season. The closer this gets to late June the greater the amount of sun energy absorbed by the Arctic Ocean, and the warmer it gets.

The warmer Arctic Ocean then releases more heat and water vapour in autumn. This a) delays re-freeze due to the time taken for enough heat to vent to allow freezing, and b) causes the formation of low cloud which acts like a lid keeping heat in - and incidentally leads to storms due to temperature differential with the cooling land (which has less heat capacity so can cool faster). Both of these processes delay refreeze to such a degree that the winter maximum thickness is reduced. The resultant thinner ice leads to greater heat flux through the winter ice - which further reduces thickening as the temperature differential from ocean to air through the ice is reduced.

So we're in a vicous cycle which reduces the thickness of ice starting the melt season, leading to earlier larger stretches of open water, and later re-freeze.

I'm not saying your scenario is wrong (if we change 'hurricane' to 'strong storm'), I just don't think strong storms are a necessary part of the equation.


Climate average on the DMI graph shows temps of approx -30C for approx 5 months North of 80N...


Even in ths warm winter, the peak reading is around -15C. That's still sea-ice-forming cold.

We are well, well short of a perennially ice free Arctic. If SSTs get that much hotter, you should be more worried about the Caribbean coming to a brisk simmer.

Kevin McKinney

I wouldn't be too sure about a long lag between ice-free minima and perenially ice-free AO. It may take a while, or (via some of the mechanisms Chris was mentioning) it may not. There is some support for the latter possibility in at least one modeling study, though I can't go fishing for the citation just now.

My gut feeling: you can't assume that Arctic atmospheric temps will have more 'inertia' than the ocean itself...

John Christensen

Thank you Neven for another great PIOMAS update!

Allthough we still have approx. a month and a half before reaching max. volume, we are already seeing the outline of how 2014 is considerably different from 2013, even with near identical volume by end of February.


- By end of Feb. 2013 82.4% of ice volume was gained since minimum, while by end of Feb. 2014, only 74.2% was new ice (both numbers disregarding MYI loss through Fram and other straits since minimum, so actual percentage are higher for both years).

- Feb. 2013 saw volume increase of 3055 km3 compard to just 1847 km3 in Feb. 2014, so lots of young ice late in the freezing season last year, and we saw last year in April that max. volume was reached sligthly earlier than in 2012 and that initial volume decline was stronger in 2013 than in 2012, probably due to lots of young ice at lower latitude melting out quickly.

- It would be great to see regional breakdown of recent volume development, so I will look out for updates from Chris on this. HYCOM model views seem to indicate a varied distribution by this time compared to last year:
- Barents, Okhotsk, Bering: Less volume than last year
- Arctic Ocean: Similar or less volume than last year??
- Greenland, Baffin: Similar volume
- Beaufort, Chuckchi, ESS, Laptev, Kara, Hudson, St. Lawrence: More volume than last year

If HYCOM is reasonably reliable on thickness, I am quite concerned, since it would seem necessary for the Arctic Ocean to have less volume than last year - which was created in the SSW/cracking event - in order for the total volume to match the volume of last year..

However, this begs a question to Chris: Is the total area for PIOMAS exactly the same as for CT, or could there be deviations in marginal regions, such as e.g. St. Lawrence or the limit of Okhotsk?

Secondly, it also highligths the importance of having the right conditions for ice volume growth in place (cracking and compaction, combined with considerable cold), since it seems the -20 - -25C and calm weather in many areas this winter simply did not provide for significant ice growth.

To other comments regarding early snow melt on surrounding continents, I will repeat what I mentioned last spring that I see this as beneficial to the ice cover, since this will move the high pressure areas away from the Arctic seas towards the main continental areas of North America and Russia/Siberia, and possibly create similar type low pressure/cyclone formation over Arctic seas, which clearly preserve the ice well, at least from late spring to some time early August.

Jim Hunt

We'll have to wait a few weeks to discover what PIOMAS has to say on the matter, but yesterday both NSIDC daily extent and CT area were sitting at record lows for the day of the year:


Certain sections of the denialosphere were none too happy about the news. They've been calling my alter ego all sorts of names, some of which I couldn't possibly repeat in a family forum such as this!


As an amateur who predicted the area (or was it extent) to fall to 2 million last year, I thought I would get my predictions out of the way early, before the blog gets busy with the more professional and able forecasters:

8 days with less than 1.5 million.

This is based on the same line of thought (I refuse to call it 'reasoning') as last year: once the ice levels decrease past a certain point, the melt will continue past what have been the up until now normal influences.

Colorado Bob

New Study Yanks Away Glimmer of Hope on Climate Change.

According to NASA climate scientist Drew Shindell, the lead author of Sunday’s paper, the September IPCC study assumed aerosols were distributed uniformly over the Earth’s surface rather than concentrated over Northern cities. That assumption biased the IPCC’s results, says Shindell, causing them to conclude that the observed warming so far implied the possibility of low sensitivity.

Instead, says Shindell, when you account for the actual behavior of aerosols and other atmospheric pollutants such as ground-level ozone, the resulting conclusions about the Earth’s climate sensitivity are significantly more pessimistic than those in the IPCC’s study.

John Christensen

Wanted to share also this interesting article from Sept. 2013 on relationship between NAO index and Northern Hemisphere mean temperature:


The article concludes that the NAO influences NH mean temps (not discussing in detail hos this is possible) with a 16 year lag between change in NAO and impact on NH temps.
Given NAO negative trend since the late 90's it is argued that we can expect NH temp increase to pause or even see NH temp decreases in the next couple of decades.

If this holds, it could both be argued that part of recent NH warming was caused by positive NAO back in the early 80's to mid-90's, and we will see 'masking' of global warming in the next couple of decades for the NH due to NAO going counter to CO2 and rising temps.

It will be interesting if any of this will reflect in Arctic sea ice volume development, or if we have reached a point where extraordinary protective weather events are required, as we saw last year, to preserve the ice.

Shared Humanity

My gut feeling: you can't assume that Arctic atmospheric temps will have more 'inertia' than the ocean itself...

And my gut feeling is, given the mass of the ocean relative to the atmosphere and its ability to store vast amounts of heat, the oceans have far more inertia. When the Arctic loses sunlight in the winter, the atmosphere loses heat rapidly, the ocean more reluctantly. This will certainly slow the freeze at the beginning of the freeze season as the ocean transfers heat to the atmosphere but freeze will happen.


Hi John,

There is a discussion of that paper over on the ASIF, here...


R. Gates

Sorry to interrupt the wonderful flow of conversation here, but this is a big deal. New research just coming out says that we have a lot more to worry about related to methane than just melting Clathrates. It seems certain living microbes that are thawing out in the permafrost actually produce methane in great abundance:


The potential methane time bomb just got bigger...

Chris Reynolds

John Christensen,

There will be an update to the regional breakdowns when the data is published. Dr Zhang isn't funded to produce the data, so it's out of his own time and I won't be asking for it. At least I'd love to see conditions at the end of April. For now I think a reasonable 'balance of probabilities' argument can be made that the lack of thickening is within the Arctic Ocean, not just in the Pacific and Atlantic.

The areas for the Cryosphere Today regions translated onto the PIOMAS grid are as follows (km^2).

Okhotsk 1142765
Bering 2084061
Beaufort 555049.4
Chukchi 606162.5
ESS 910374.3
Laptev 627973.3
Kara 766104.8
Barents 1567109
Greenland 2928642
Central 4294571
CAA 767629.6
Baffin 2383195
Hudson 1154502

But I think that's not quite answering your question.

I can easily calculate the area of ice covered grid cells in the PIOMAS domain by using 'area.h' files in tandem with the area of each grid cell. Area.h is only available for full years - 1978 to 2013. However as you suspect the result will not track standard area metrics. Here's the PIOMAS domain:

Notice that as well as southerly ice in Okhostk not being covered the domain does not include the Gulf Of St Lawrence at all. As we already have direct measurement from satellite of area & extent I've not considered it worthwhile to calculate a seperate PIOMAS area/extent series.


With regards snow loss and surface warming. I have a differing opinion.

Siberian snow loss creates a region warming which appears as a local warming together with warming over the Arctic and creates high pressure over a region of siberia.

This high pressure over Siberia seems to create the same sort of anomalous ridging of the atmosphere as is seen over Greenland post 2007.
More detail here:

I view the Siberian ridging as a preconditioning that sets up the Greenland anomalous summer ridging. The Greenland ridge then spreads high pressure across much of the Arctic Basin, in response a low pressure tendency happens through the summer over the Siberian coast - this pattern is known as the Arctic Dipole.
It's effect on temperatures aloft can be seen in the following graphic:

That graphic is from this post:
Where I express doubts as to the role of the AD in post 2007 increase in annual range (summer melts). However as Wang 2008 shows record melts (in red) are associtaed with +ve AD for winter and summer:
Results outside the central box are considered significant.

Hope this makes sense - I'm a bit rushed right now.

John Christensen

Hi Chris,

Thank you very much for the extensive feedback - will need to review more closely in the morning.

Regarding the continental warming and Arctic highs or lows; how does your Siberian high ridge and Greenland ridge correspond with the repeated Arctic lows/cyclones we experienced throughout most of last summer?

Others had argued then that these Arctic cyclones (See Neven's entry on that) were caused by temperature difference between Arctic ice-cover and surrounding warm continents..

Al Rodger

We have high temperature anomalies in high latitudes.

The Arctic Ocean UAH Lower Troposhpere temperature anomay for February is the highest on record, following the January that is now 4th highest. (Graph - usually 2 clicks to "download your attachment".)
Less well illustrated (here) is the NOAA SSTs for the start of the year. The actual numbers give, both the Arctic & for the high Arctic, February breaking record temperatures following a January in (now) second/third place.

Jim Hunt

@Al - See also the discussion(s) on the Arctic Sea Ice Forum - http://forum.arctic-sea-ice.net/index.php/topic,92.msg21267.html#msg21267


Changes in Arctic melt season and implications for sea ice loss

The Arctic-wide melt season has lengthened at a rate of 5 days decade−1 from 1979 to 2013, dominated by later autumn freezeup within the Kara, Laptev, East Siberian, Chukchi, and Beaufort seas between 6 and 11 days decade−1. While melt onset trends are generally smaller, the timing of melt onset has a large influence on the total amount of solar energy absorbed during summer. The additional heat stored in the upper ocean of approximately 752 MJ m−2 during the last decade increases sea surface temperatures by 0.5 to 1.5 °C and largely explains the observed delays in autumn freezeup within the Arctic Ocean's adjacent seas. Cumulative anomalies in total absorbed solar radiation from May through September for the most recent pentad locally exceed 300–400 MJ m−2 in the Beaufort, Chukchi, and East Siberian seas. This extra solar energy is equivalent to melting 0.97 to 1.3 m of ice during the summer.




I view the Siberian ridging as a preconditioning that sets up the Greenland anomalous summer ridging
I'm not sure where you're getting this view from. Your Dosbat links clearly show that in May, 500mb Eastern Siberian height is weakly correlated with 500mb height in Greenland, with what correlation there is actually running the other way, with slightly stronger Greenland ridging when Eastern Siberian ridging is weak. Both Siberian and Greenland ridging has been strong since 2005, but the year-to-year correlation over this time period is pretty much non-existent, including last year which had high Siberian ridging and and low heights over Greenland.

The summer Greenland ridging pattern is mostly just a modern version of a negative NAO. With warmer Atlantic temperatures and less Arctic sea ice, the convection surrounding Greenland in a -NAO state has shifted to be closer and more evenly distributed.

The classic Arctic Dipole is high Greenland ridging with low 500mb heights over Siberia. Clearly ridging in both areas as in 2012 leads to low season-low ice coverage. Last year with ridging only over Siberia saw large amounts of warm, moist Atlantic air sucked into the Arctic, where it ended up resulting in increased cloud cover and low melting.

Greenland blocking reduces ice in the refuge areas north of Greenland and the Canadian high Arctic. It clearly has a much larger effect on the summer total Arctic sea ice area minimum than Siberian blocking.

It's still early to predict Eastern Siberian blocking with much accuracy. Snow depth maps show way below normal snow cover in Europe, which since it's upwind and it's only March I would think would tend to indicate above normal Siberian blocking, despite the deeper than normal snow in the Dosbat "snow box". Probably things will be clearer in a few months.

The flip side of a -NAO state is convection in the northern Atlantic (see the rainfall at the bottom of the page). Warm water temperatures in the far northern Atlantic including record low sea ice in the Greenland Sea and Barents Sea would seem to indicate a -NAO state and strong Greenland blocking this year, but there's still a lot of room for random atmospheric noise to have an effect. I wouldn't have predicted a strong summer +NAO last year.

Kevin McKinney

Boa, thanks for that Stroeve et al. link. You get folks trying to argue away the increased absorption, so it's handy to have a reference.


I see that MODIS is now showing the ice edge North of Svarlsbard, and (just) the Lincoln Sea end of the Nares Strait...


Chris Reynolds


As I note in one of the posts I referenced, the use of a grid box produces an artificial effect where while in some years there is still ridgng over Siberia it does not fall within the grid box used. You will note that when the general rise in northern hemisphere GPH is subtracted from the GPH over Siberia (May) and Greenland (JJA) both of those regions show a step jump in GPH after 2007, not 2005.

The negative Arctic dipole (using Overland's convention) with low over the Siberian coast and high over the pack and Greenland draws air in off the Pacific, as with Atlantic air this is also humid. 2013 was almost the exact opposite of the pattern for 2007 to 2012. Given the tendency of the preceding years and the coincidence of 2007 ushering in more rapid open water formation in spring off Siberia this may not be a mere coincidence.

Bluthgen et al "Atmospheric response to the extreme Arctic sea ice conditions in 2007" find that in 2007 the initial low pressure over the Siberian sector of the Arctic is then contributed to by the strong retreat of sea-ice that the AD event of that year initiates, a positive feedback. Has this happened in the years 2007 to 2012? Is the summer pattern due to this process? If so it's not just the AO.

But before looking at that, first sea ice in 2013: The anomalies (1980 to 1999 baseline) of monthly rate of loss in both CT Area and NSIDC Extent show that, apart from July 2013, losses were above average in 2013.

And PIOMAS volume shows that 2013 was in a set with the other post 2010 years, again anomalies from a 1980 to 1999 baseline are used for this plot:
Note that the post 2010 years show below average loss of volume in July due to lower area/extent of ice than in the baseline period (thanks Nightvid).

The cool signature of 2013 is not just due to the atmosphere, the survival of ice over this year added to cooler temperatures by keeping surface albedo high.

Summer 2012 (JJA) was marked by a trough over the siberian seas, with the Arctic Ocean high moved closer to Greenland. Here's the SLP.

Saying that the post 2007 pattern is just a 'modern' version of the NAO doesn't explain anything IMO. Using the JJA average SLP for 2007 to 2012 as a reference pattern, here are the correlations of all summer SLP fields with that pattern since 1979.

The UK low pressure forced by the Greenland high has lead to the UK experiencing four of the wettest top ten years in the period 2007 to 2013. The probability of this being by chance is 0.14%. Studying North West European precipitation, Screen finds the following:
'Obeserved' is the difference between wet years and dry years, 'simulated' is the modelled difference in the atmosphere between 2009 and 1979 ice states prescribed in a model. In other words, the reduction of sea ice leads to atmospheric conditions similar to those historically involved in creating wet weather over western Europe.

Using UK Rainfall data post 1948, to facilitate use of NCEP/NCAR, I've taken the years with greater than 20% of average summer rainfall. Here is the early period since 1948 with a cluster of anomalously wet years (negative AO).

Here are the remaining years prior to 2007.

Now here is the pattern for the wettest years after 2007.

There is more going on than 'just' the AO here. Just as Zhang found the emergence of the Arctic Dipole (Arctic Rapid Change Pattern) involved a shift in centre of action of the AO up to 2006. Post 2007 the centre of action of the AO has moved to Greenland from the Arctic. This makes it a very different pattern from the conventional AO.

Jai Mitchell

This winter's arctic temperatures are running close to 8Kelvin above the running average. http://ocean.dmi.dk/arctic/meant80n.uk.php If we started with an ice-free arctic ocean state then to produce a sea ice cover that could potentially melt by March 1st we would need (estimation) 20K of average winter warming higher than today.

2014 is an outlier year but it is certainly an indication of the trends to come. We already know that arctic amplification is increasing in intensity (from 2.1 to 2.5 times globally average in the last 2 decades). We also know that AA is higher during the winter months. So, if the winter AA is 3 times the global average then we would need a warming of 7K to produce an ice free March, at current AA rates.

As the fall ice extent declines it will also increase the amount of latent heat (in the form of increased relative humidity) in the arctic winter) as increased arctic ocean enthalpy releases heat into the arctic.

This will raise arctic amplification to 3.5-4 times the globally averaged temperature.

When this happens, it is possible (even odds?) that the variable collapse of the polar cell into the mid-latitude cell (evidenced by large volumes of mid-latitude moisture pushing into the arctic) will result from the ice free September (occurring sometime between 2020 and no later than 2030.)

This would then increase the arctic winter temperatures in a non-linear response and produce arctic amplifications of 4-5 times the global average.

under this scenario then the arctic winter ice-free, effective (AWIFE) globally averaged temperature is 4-5C above today's values.

This is certainly within the RCP 8.5 scenario by 2100 and if carbon cycle feedbacks are included could be a reality as early as 2065.

This is, of course, in absence of a 50 Gigatonne release of methane from the ESAS in 2045 as modeled by wadhams.

Colorado Bob

Save the Keeling Curve!

By Dr. Jeff Masters

Published: 2:13 PM GMT on March 11, 2014.

Climate change's most iconic research project is in danger--a victim of budget cuts in an era of increased government belt-tightening. The Keeling Curve is a measurement of the concentration of carbon dioxide in the atmosphere made atop Hawaii’s Mauna Loa, begun in 1958 by Dr. Charles Keeling. It is the longest-running such measurement in the world. The curve was instrumental in showing how human emissions of carbon dioxide were steadily accumulating in Earth's atmosphere, and raised awareness that human-caused climate change was an ever-increasing threat to the stability of our climate. After Keeling's death in 2005, the measurements were continued by his son, Ralph F. Keeling. Support from NSF, NOAA and NASA is being diminished or withdrawn, and Keeling has turned to crowd-funding to help raise funds to continue these important measurements. I hope you can join me in making a donation.

Colorado Bob

Off topic -
The South Asia Network on Dams, Rivers and People (SANDRP) on Tuesday described it as "unprecedented."

Hailstorms by the end of February 2014, initially thought of as a one-off phenomenon, continued to batter places like Solapur for nearly two weeks now. Rabi crops like wheat, harbhara, cotton, jowar, summer onion are lost, horticultural crops like papaya, sweet lime, grapes are battered and orchards which took years to grow are ridden to the ground. For many farmers the tragedy is unbearable as majority of crops were about to be harvested. Turmeric was drying in the sun, grapes were waiting to be graded, wheat was harvested and lying in the fields.

This is way outside of what the monsoon used to do . And is like the 250 year old rainfall record in Britain, and record snows in North America.

Jai Mitchell

Colorado Bob,

the estimate of crop damages is Rs 5,000 crore which is equal to 580 million U.S. dollars.

I simply cannot imagine what 580 million dollars is able to buy in india!

reference: http://indianexpress.com/article/india/maharashtra/maharashtra-hailstorm-hits-crop-worth-rs-5000-cr/

Jim Hunt

There is still some debate about whether sea ice area/extent has now passed the maximum for 2014. Volume will take a while longer. Join in the fun over on the forum:

The 2014 Melting Season

Al Rodger

Let's tempt fate.

Nobody brave enough to call the 2013/4 winter maximum? March 12th? A lot of Arctic heat for the time of year? SIA now 200k below the value two weeks back?
Myself, I have a feeling it's there.

Jim Hunt

Al - As and when the TypePad patent pending spam filter releases my prior comment from limbo, you will note I have already (foolishly?!) called the maximum.

Al Rodger

Foolish, Jim? Surely not! "Brave" if you are wrong. And if you are proved correct, the exact opposite of "foolish," whatever that is.

Andy Lee Robinson

Possible, but too soon to call.
This time in 2012 it took a flying leap before taking its dive.

Jim Hunt

Al - Thanks for your kind words.

Andy - It will be worth it even if I end up being labelled merely "Brave". As a fortunate side effect it provides my alter ego with the enormous pleasure of simultaneously taking the piss out of both Steven Goddard and David Rose!


Laden Greg

Here's my thumb-suck prediction of sea ice extent (not volume) minimum for September 2014:


John Christensen

The ice has been compacting on the side of Barents/Kara and even into the AO the past few days with possibly some melting even in Okhotsk, but with reduced winds and change of direction to have southern flow in Bering, I would anticipate max in area and extent to come in the next 7 days (at least on Arctic ROOS), but would also think it would be possible still to top the recent max on CT with the right conditions in place..

Colorado Bob

How wind helps Antarctic sea ice grow, even as the Arctic melts

Dr Sharon Stammerjohn, a professor of ocean sciences from the University of Colorado, said the changes in sea ice were having a significant impact on marine life.

“For the southern ocean there is a huge seasonal change between the summer minimum and the winter maximum and the ecosystem has evolved to deal with that amazing phenomenal change,” she said.

“It’s the rate of change that is quite alarming in these regions, with particular regard to the ecosystems. We are seeing fundamental change in these marine ecosystems.”

Professor Simmonds said he hoped that policy makers would use this research to understand the impacts that current levels of greenhouse gases are having on the southern ocean.

“The planet is at present in uncharted waters with respect to carbon dioxide [and other greenhouse gas levels]. We are doing extraordinary things to the climate system, and the consequences will be felt downstream,” he said.

“The ocean is intimately involved with all of this, it has an extremely long memory.”


Chris Reynolds


Wipnues has used source NSIDC gridded concentration to calculate that the next few days will see CT Area increase above the maximum set on 23/2/14.

Greg Laden,

People do use the average monthly extent/area/volume! It has the advantage of evening out weather variations.

Detrending the data and regressing shows little relationship between NSIDC Extent, Cyrosphere Today Area or PIOMAS volume (either whole domain or within Arctic Ocean), and the state at minimum. What sets the minimum variation around the trend is weather, and as 2013 showed this variation can be substantial.

Steve Bloom

The EGU 2014 program is up. Lots to see, although not much detail since it's just abstracts.


Off topic:

MLO CO2 daily reading above 401 ppm on March 12 - two months earlier than last year.

METOP IASI CH4 above 1800 ppb on March 12 - two weeks earlier than last year.

See: http://a4rglobalmethanetracking.blogspot.com/

Steve Bloom

Thanks, A4R. In two or three years, 400 ppm will be in the rear view mirror.

Steve Bloom

Did a quick look through the abs, and there's plenty of interest to folks here, especially more from Coumou, Pethoukhov and Rahmstorf re resonant blocking, plus several focused on the Barents sea ice.

Hmm, anybody going to be in Austria next month?

Jim Hunt

Steve - Note that there's a big sea ice conference taking place in Hobart as we speak. More on the forum:

International Glaciological Society 2014 Sea Ice Symposium

Hans Gunnstaddar

Apocalypse4real, you probably already know this but for anyone else, the bottom graph on that link has colored areas indicating various CO2 levels. The one's in yellow are 410ppm!

Hans Gunnstaddar

Change that to above 410ppm, all located in the far north.

Chris Reynolds

Thanks Steve,

Here are some of the ones that caught my eye:

Record of methane emissions from the Arctic during the last Deglaciation.
"...The longest of these ‘methane emission events’ (MEE) coincides with the start of the warm Bølling-Allerød Interstadial (GI-1
in the Greenland ice core record). The lack of correlation between the values of 13C and 18O, however, appears to preclude warming of bottom waters as the principal control on methane release. Rather, it seems likely that methane release is related to changes in gas migration pathways, or other geological processes still under debate..."

Analysis of variability in atmospheric methane in the Arctic
"...Globally, atmospheric CH4 concentrations have increased since direct measurements began in the early 1980s but then stabilized between 1999 and 2006. However, since 2007, the atmospheric CH4 growth rate has become positive again.

...recent studies, suggest that this change is the result of a rise in wetland emissions of CH4 in the tropics and subtropics, driven by climate variation such as ENSO, combined with a rise in fossil fuel emissions...

...We found that the observed variability
could also not be explained by changes in atmospheric transport. Measurements of the methane isotope (13CH4) at Zeppelin, together with atmospheric transport analyses, point to an important influence of high latitude wetland emissions at this site, especially from Northern Eurasia."

Arctic winter sea ice collapse in MPI-ESM – ice-albedo vs. cloud radiative feedback

"...A systematic analysis of the CMIP5 database reveals that most abrupt changes in earth system models are related to sea ice cover. In particular, two earth system models show a collapse of Arctic winter sea ice cover after 2100 when forced with increasing CO2 concentrations in the extended RCP8.5 scenario....

The warming effect of clouds is strongest in the winter months, when sea ice disappears only gradually. In contrast, the collapse of the remaining sea ice occurs when there is only substantial ice left between March and May. In these months, the short-wave effect of the clouds dominates the cloud radiative forcing...

...[the model used] coincides with conceptual models which demonstrate the importance of the time lag between ice cover and insolation for the existence of a tipping point."

Observed increase of convective clouds in the Atlantic Arctic during the last century

"...We found that total and low cloud fractions have their maximums during the early 20th century warming (1930-1950) and are increasing in the recent decades. These tendencies are noted for all seasons. Clouds tend to warm surface air in all seasons except summer when they have a cooling effect. Thus, the revealed cloudiness changes are consistent with a seasonal asymmetry of the early 20th century warming....

...The tendency towards more frequent convective cloud types signals certain a decrease of the atmospheric static stability (an increase of the lapse rate), which is in good agreement with physical understanding of the amplified surface-layer warming of the Arctic. The differences in the cloud type changes during the early warming period and the present one presumably contain a fingerprint of the anthropogenic warming signal."

A coupled model system to examine ocean-atmosphere-sea ice and ice sheet processes in the Arctic: HIRHAM5 – HYCOM – CICE

"We introduce a high resolution fully coupled regional model system that describes ocean, atmosphere and sea ice
processes in the Arctic Ocean and North Atlantic. The system has been developed using three existing models, the high resolution regional climate model HIRHAM5, the regional ocean model HYCOM and the CICE model that describes sea ice dynamics. These models have been interactively coupled..."

Multiyear ice decline in the Arctic Ocean: the role of density stratification in leads

"...We introduce the term “stratification effect” (SE) to characterise this internal factors action. SE emerges as a result of fresh melt water entrapping within a thin (1-3 m) surface layer of lead by extremely strong density gradient below. SE provides additional heating of the fresh water layer (FWL) during summer ice and snow melt...

...The heat, accumulated in the lead is able to increase efficiency of bottom and lateral ice melting."
(Nightvid - if you're reading this - this is why I used volume not area/extent as you thought I should have, because of lateral melt within the pack. Not this specific process just lateral melt in general)

Towards an Ice-Free Arctic Ocean in Summertime

"Dividing the Arctic Ocean in two parts, the so-called Atlantic versus the Pacific sector, two distinct modes of variability appear for characterizing the Arctic sea-ice extent from 70N up to 80N in both sectors...

...During recent years
like 2007, sea-ice extent with sea-ice concentration above 15% retreated from 4 millions km2 to about 1 million km2 in the Arctic Pacific sector between 70 and 80N except for 2012 when most of sea-ice melted away in this region. That explained most of the differences between the two extreme years 2007 and 2012. In the Atlantic sector, Arctic sea-ice retreated from 2 millions km2 to nearly 0 during recent years including 2007 and 2012...

How long would it take to melt away the 1/4 or 1/3 of Arctic sea-ice left in summer? A root mean square extrapolation based on the last 10 years summer sea-ice minimum extent would lead to an ice-free Arctic Ocean by 2035."

Just search 'Arctic', there's a lot about the Antarctic and Ice Sheets as well.

Al Rodger

A 'heads-up' for out host.
The JAXA links on the ASI Graphs page have passed their sell-by date.
The JAXA Extent data is now at
The JAXA Extent graph is now at


Thanks, Al. I thought I had changed that already.

Chris Reynolds

PIOMAS gridded data is out for February.

Blink comparison of Feb 2013 and Feb 2014.

Interannual differences using CT regions.

February volumes by Region, note that Central Arctic is on the right hand side scale which is 1/4 the scale of the other regions.

Chris Reynolds

Forgot to add...

Volume distribution as a function of grid cell thickness for all Arctic for selected recent years.

Steve Bloom

Don't think I didn't notice you dodging my question, Neven. :)


A4R, I noticed a typo in your blog, please correct:

"global mean methane topping 398 ppm on March 11 2014 12-24 hrs UTC at 945 mb"

Should obviously be global CO2.


The biggest question of this coming melt season has been answered. Close to the Arctic Ocean Gyre Anticyclone activity is returning. Contrary to last year's multiple "ground hog day's" forever observing persistent surface to air adiabatic profiles. More compaction should guaranty a greater melt than last year, despite the "record cold " winter in the Central to East part of North America, I guess Europeans are jealous not having much of a winter. :)


Don't think I didn't notice you dodging my question, Neven. :)

Yes, I somehow hoped you wouldn't notice. ;-)

Did a quick look through the abs, and there's plenty of interest to folks here, especially more from Coumou, Pethoukhov and Rahmstorf re resonant blocking, plus several focused on the Barents sea ice.

Hmm, anybody going to be in Austria next month?

I will be in Austria next month, because I live there. :-)

Although I live just 100 miles from Vienna, it will be real difficult to go to the EGU this year, because of work and house building (couldn't go last year either). But the house will be finished by next year, and I will try to go then.

Jim Hunt

Steve - If Neven is otherwise engaged I could always endeavour to blag a press pass!

Jim Hunt

Hubert - There's a debate currently raging over on the forum about the shortcomings of the CT area data:


Steve Bloom

Really, Jim? The EGU 2014 site doesn't specifically mention bloggers, but it sounds possible, especially if some posts here were part of the plan.

Steve Bloom

I notice that "The changing Arctic" is one of 12 planned press conference topics.

Hubert Bułgajewski

Between March 16-18, begins to melt. I think so.


Hubert, Gratulujemy miejscu około lodu morskiego..... The 2014 maxima will be bi-polar in nature, with a cold ice zone and a warm ice majority area. I think the cold zone will grow further until May, and the warm zone has already started to shrink.


Study coauthor Shfaqat A. Khan of the Technical University of Denmark told Mashable he was surprised to find such significant ice loss in northeast Greenland, considering how cold and dry that region is. Previous studies of sea level rise had not included the prospect of melting there, he said.

“Nature is changing faster than expected and seems to respond much stronger than expected to small fluctuations,” he said. “This also means that predictions of future sea level rise need to be revised.”

More worrisome, Khan and his coauthors said, is that these glaciers help hold back a nearly 370-mile long ice stream that extends deep into Greenland’s interior. This ice stream accounts for about 16% of the total ice sheet, and if it destabilizes, it could have severe consequences for low-lying coastal cities worldwide.


While the northwest and southeast section of Greenland have dramatically lost ice, researchers believed the northeast section was holding its ground. From 1978-2003, that was true, but ice loss has accelerated rapidly since mid-2003...

By 2012, the snout of the Zachariae glacier had receded more than 12.4 miles from its 2003 position. In comparison, the Jakobshavn glacier, located in southeast Greenland and long considered one of the fastest-changing glaciers on the island, has retreated 21.7 miles over the past 150 years.


Hans Gunnstaddar

Slightly off topic from Arctic ice volume, instead about ice loss in the neighborhood.


Greenland's ice loss nearly tripled in a decade

Scientists have known Greenland's ice sheet has been thinning for decades, but for the first time, they've found that's even occurring in its northeast region that had been stable for 25 years. Since 2003, the northeast's ice loss has nearly tripled.

"We're seeing an acceleration of ice loss," says study co-author Michael Bevis, professor of earth sciences at Ohio State University. "Now, there's more ice leaving than snow arriving." He says the rapid change in the northeast region "surprised everyone."


I know I only have High School, but why should have they been surprised? Ice sheets in Antarctica collapsing. ice in the Arctic disappearing, glaciers all over the world disappearing and on and on. I would have been shocked if it was not the case. Is it another case of them being taught something in classrooms and having a difficult time understanding what is going on out in the real world? I do understand that they are highly educated individuals with a good reputation, but to my way of thinking they should be going out on the field with the expectation that the ice is disappearing and if does not seem to look like it is, then the followup should be, What is the ice hiding from us that we can not see? Only if the answer comes back nothing on that then say it is stable.
The only question I believe is valid on all ice around the world is How long is it going to hang around?

Steve Bloom

A tripled rate of loss over nine years? Hmm.

The abstract of Hansen and Sato (2011), "Paleoclimate Implications for Human-Made Climate Change":

Milankovic climate oscillations help define climate sensitivity and assess potential human-made climate effects. We conclude that Earth in the warmest interglacial periods was less than 1°C warmer than in the Holocene and that goals of limiting human-made warming to 2°C and CO2 to 450 ppm are prescriptions for disaster. Polar warmth in prior interglacials and the Pliocene does not imply that a significant cushion remains between today's climate and dangerous warming, rather that Earth today is poised to experience strong amplifying polar feedbacks in response to moderate additional warming. Deglaciation, disintegration of ice sheets, is nonlinear, spurred by amplifying feedbacks. If warming reaches a level that forces deglaciation, the rate of sea level rise will depend on the doubling time for ice sheet mass loss. Gravity satellite data, although too brief to be conclusive, are consistent with a doubling time of 10 years or less, implying the possibility of multi-meter sea level rise this century. The emerging shift to accelerating ice sheet mass loss supports our conclusion that Earth's temperature has returned to at least the Holocene maximum. Rapid reduction of fossil fuel emissions is required for humanity to succeed in preserving a planet resembling the one on which civilization developed.

Emphases added. Full text at link.

Shared Humanity

Whenever I read something where scientists express surprise about the rapid growth in anything, (in this case its Greenland ice loss) I can't help but wonder why they don't get the power of exponential. All indications are that we are living in a warming world that is a growth system. CO2 increases display this behavior. Arctic warming displays this behavior. Arctic Sea ice loss displays this behavior. Why should we expect Greenland ice sheet loss to behave differently?

It is this last link, provided by Steve Bloom, which restores my confidence in climate scientists. At the heart of its conclusions lies the simple concept of exponential growth.

"Gravity satellite data, although too brief to be conclusive, are consistent with a doubling time of 10 years or less, implying the possibility of multi-meter sea level rise this century."

While it may be too early to conclude that the time frame for doubling is 10 years, I have no doubt that there is a specific time frame in which doubling occurs. Given we have 90 years left in the century, the implications for ice mass loss is frightening. Let's be optimistic and say that doubling takes 20 years. Heck, let's say 30 years. If 30 years, the rate of ice mass loss at the end of the century will be 8 times the current rate.

Shared Humanity

Let's assume the doubling rate of 10 years is confirmed by additional observations.


"Already, the melting of the Greenland ice sheet is one of the largest contributors to global sea level rise, accounting for about .02 inches of the 3.3 inches per year global average sea level rise."

By 2020, the contribution will be .04 inches. By 2030, it will be .08. By 2040, it will be .16. By 2050, it will be .32. By 2060, it will be .64. By 2070, it will be 1.32 inches per year! By the end of the century, Greenland ice mass loss will be contributing 10.5 inches of sea level rise annually!

Good luck with that!

Rick Aster

“[A]bout .02 inches of the 3.3 inches per year global average sea level rise” appears to be an error at Mashable. Based on other sources, I believe .02 inches of 3.3 millimeters per year is what is intended.


This all precludes that ice melts much like an ice cube. I believe historically there is much more evidence that large glaciers create catastrophic events. Meaning there is a gradual melt, but there are hidden events going on that will then allow massive lose. Then back to gradual melt. Look at the ice sheets of Antarctica or the lose of the super glaciers of NA after the last ice age.


Rick: Good catch on the Mashable article. I alerted Andrew Freedman, and he's just posted a correction:

"Already, the melting of the Greenland ice sheet is one of the largest contributors to global sea level rise, accounting for about .02 inches of the .13 inches per year global average sea level rise (local rates of sea level rise vary significantly)."


Since this thread has migrated over to Greenland ice loss I thought I would add to the pessimism.
Assume for a moment we have a lake on the surface of the ice at 0C and 1000 meters above sea level. A crack opens under the lake and the water drains away. The question is how much heat does this falling water transfer to subsurface ice as it falls to sea level. If the water lost no heat to surrounding ice then the temperature increase of the water would be about 2.4C. In other words potential energy is converted into kinetic energy then into heat. I am assuming the temperature of the water when it has fallen 1000meters is still 0C so all of the heat has been transferred to the surrounding ice potentially causing even more melt if the ice is at 0C.

The conversion of Mechanical Energy to Heat:


This extra heat inside the ice has great potential to cut channels, and weaken underlying ice. I have seen discussion here about the channels and water stored under the ice. The canyons on the surface are also cut into the ice in a similar fashion as the water looses elevation as it runs along the bottom of the canyons.

Colorado Bob

Robert Scribbler has a very good post up on the news from Greenland , and as he points out, it's an archipelago after the ice melts.


Colorado Bob

“The rate of climate change now may be as fast as any extended warming period over the past 65 million years, and it is projected to accelerate in the coming decades,”

American Association for the Advancement of Science

Colorado Bob

Back to Greenland -
Given how complex the plumbing under the ice sheet is , there’s a real possibility that fresh water could be injected directly into the oceans. at depths we’ve never thought about .


Ice sheet mass loss rate is documented in the IPCC AR5 paper “Summary for Policy Makers” under Section B Observed Changes/B3 Cyrosphere and is reproduced in part below;

• The average rate of ice loss from the Greenland ice sheet has very likely substantially increased from 34 Gt per yr over the period 1992–2001 to 215 Gt per yr over the period 2002–2011.
• The average rate of ice loss from the Antarctic ice sheet has likely increased from 30 Gt per yr over the period 1992–2001 to 147 Gt per yr over the period 2002–2011.

In summary the average ice sheet mass loss globally has risen exponentially from 64 Gt per year in the 1990s decade to 362 Gt per year in the 2000s decade and calculates as a doubling time of about 5 years.

Measurements from Earth-orbiting satellites including GRACE and the European Space Agency CryoSat-2, also show acceleration of ice mass loss. Using NASA data taken from their graph at http://climate.nasa.gov/key_indicators also shows a doubling time of just over 5 years for Antarctica and Greenland combined.

Using ice melt data Jim Hansen, former Director of NASA’s Goddard Institute of Space Studies, has calculated a 1 metre sea level rise (SLR) by 2045 for a 5 year ice melt doubling period, 2055 for a 7 year doubling period and 2067 for a 10 year doubling period. See

These predictions are much earlier than the IPCC AR5 BAU ‘extreme’ SLR prediction of 0.98m by 2100.

For coastal planning policy makers it would be wise to continually monitor land ice melt acceleration rates as this will give more certainty to sea level rise predictions.

Allen W. McDonnell

All of these long term future models use the current three atmospheric cell model to predict weather and climate. However if an ice free Arctic Ocean flips us over into the one cell atmospheric system that existed 5 Million ybp like we had the last time CO2 levels were this high the changes would be profound and very rapid. I believer that long before we reach 2100, and possibly before we even reach 2020, we will pass the tipping point where the Arctic ocean is ice free for at least the summer. When that happens the intense warming caused by the extreme decrease in albedo reflectivity will flip us into a one cell northern hemisphere weather system. The cascading effect of that will be above freezing temperatures around Greenland 24/7/365. Just how long can the GIS last in 2C temperatures for a long period of time? Right now there are only two or three weeks when it is even possible for the entire GIS to see air temps above freezing and it is melting at an accelerating rate, multiply that to 50 or 52 weeks a year and the GIS will collapse extremely rapidly compared to all the model projections.

See http://www.fields.utoronto.ca/programs/scientific/10-11/biomathstat/Langford_W.pdf

Shared Humanity


I've read this presentation before. It was linked over on the ASIF. If the difference in temperature drives this bifurcated switch to a single cell, it would seem that a move towards an ice free Arctic in the winter would be needed to reach the point where it rapidly switches.

You may want to visit ASIF to be part of a fairly in depth discussion of the 3 cell versus 1 cell climate.

Steve Bloom

I hadn't been aware there was a current conversation on that topic, SH, and it's not readily apparent (although threads of that sort can be hard to find there). Pointer please.

Al Rodger

One point I disagree with Jim Hansen is his 5 metre SLR by 2100. I would argue that the only way such a rise is possible is from ice caps shedding icebergs. There is simply not going to be enough energy available at the ice caps themselves to melt enough ice. Thus I would argue that anybody presenting such an argument needs to point to that source of icebergs.
I also do not see any sign of the "doubling" which would be required for a 5 metre rise by 2100. The Greenland ice loss is perhaps less ambiguous than the Antarctic loss. The Greenland loss is accelerating (usually 2 clicks to 'download your attachment') but I don't see in this data any sign of an increase in this acceleration. Thus I see no "doubling".


I saw tripling/quadrupling over the last decade, judging by your link above.

Al Rodger

You can indeed say that over the last 8½ years the 12-month rolling average has increased from 150Gt/y to 400 Gt/y. That would be equivalent to 3.2x in a decade. And if you add on the last years data its down to 440Gt/y.
But here is a problem. That annual increase follows the 30Gt/y/y line to get there. There is no increase in acceleration.
(I shall upload the updated graph to show the latest data.)

Martin Gisser

Al, there's not enough data yet to read off an exponential shape of the curve. It's just that nonlinear decay is more plausible than linear due to several amplifying feedbacks. And if you do nonlinear, exponential would be the natural choice. A doubling time of 10y would be a conservative estimate supported by current data. And voila, 4m SLR by 2100. Apropos doubling time: Only 5 years back Gavin Schmidt refused to think about more than 1m by 2100. Shifting baseline.

Al Rodger

Martin Gisser,
I would agree that there is not enough data to foretell the future rates. Who knows? This coming melt season could show serious increases in melt-rates. The one problem ahead is that GRACE is getting old and there is no replacement so we'll soon be back to divining ice loss with the tea-leaves.

I'm not clear as to why nonlinear ice loss would make an exponential model the natural choice. And a constant acceleration is also nonlinear. (That 30Gt/y was derived from a regression on this data a few years back now - I'm as surprised as anybody that the melt rate has stuck to that line.)
As for 1m, 1.2m by 2100, there were a lot of papers pointing to such a rise. Has this now changed? Is Gavin now signed up to multi-metre 2100 SLR?

Martin Gisser

Al, hmm don't take me too seriously. It's late and I'm overworked. Just a quick speculation: The melt rate could be 1) proportional to what has already gone: e.g. 1.1) proportional to the height of the ice sheet (the lower the warmer) 1.2) proportional to albedo (more ice gone, more dark debris left at surface) 1.3) proportional to the distance the ice has to flow to reach the calving front. This would hint at the differential equation of the exponential curve. -- If the melt rate were just proportional to a linearly rising ambient temperature we would get a quadratic curve. But 2) I don't think temp would continue rising just linearly: It would accelerate due to e.g. 2.1) sea ice loss 2.2) polar cell dissolution. That would give a cubic curve at least, which might be approximated by the exponential. Third, as this is all just guesswork I would apply Occam's razor and take the simplest nonlinear curve, which is for my taste the exponential.


Calving is going to be the be culprit. Especially in Antarctica. But even in Greenland, those glaciers are starting to brake down structurally and we still do not have a good idea as to at what point they will start braking down entirely.
Just basing on what has happened in the Arctic and what the worse case doom sayers where saying 15 yrs ago, I would think the 5m rise by 2100 maybe on the end of what is going to happen.

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