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The old man has been recovering recently, so a lot of discussion has gone by the board; apologies if this has already been discussed.
Fettweis et. al. have a new paper under discussion in The Cryosphere (Copernicus open access). Link here. if that doesn’t work, try: http://www.the-cryosphere-discuss.net/2/225/2008/tcd-2-225-2008.pdf
The conclusion (which has a large uncertainty), based on a modelling of the GrIS surface mass balance fron 1900 -2100, using the AR4 GCMs, is that the contribution to sea level rise is likely to be around 4cm by 2100. This, however, assumes no change in the rate of iceberg calving or basal sliding.
It also derives from an analysis of the models which shows a temperature increase in Greenland (area 1) of around 2 degrees, which is offset by greater precipitation.
Apart from concern over the idea that calving and sliding is likely to remain consistent (I’d suggest that reactions are more likely to be non-linear), there is the question of the implications of findings such as Rignot’s on the changes in key discharge glaciers.
An interesting and challenging conclusion of the reanalysis is that there were more rapid changes in the 1930s than there have been recently (which would be consistent with the Jones et al temperature analyses). This might suggest to a cynic that the impacts of AGW are within natural boundaries (& therefore, supposedly, not a matter for concern). This, though, ignores the cumulative effect of the changes over the longer time scale, a flaw which also appears to be in the paper.
I have some doubts about the Fettweis material, but am not qualified to say more than this; perhaps a Connolley or a Benestad can help explain what the paper appears to be missing. My suggestion is that, whilst this is a comprehensive and scientifically sound piece of work on the surface, there are some assumptions embedded within it which might not be sustainable given other work which the paper does not consider.
It also occurs to me that a change in accumulation to compensate for mass loss through melting, whilst it would help stabilist the GrIS mass balance, does not reduce the rate of melting per se; therefore, it may be that Fettweis’s SLR estimate is much too low.
I’d appreciate it if spome of you read the actual paper and gave us some hints where we (or Fettweis) are going wrong.
I’m still cnsidering the prospect of a global SLR of a metre or more, with a GrIS contribution of perhaps 10-20% by the end of the century.
Two streams of thought arise from the announcement from the BAS that yet another chunk of the Peninsula’s long-term ice shelf is on the verge of splitting off permanently.
The first is to wonder why there are still people who can honestly (inasmuch as they believe it, even though it’s misguided) claim that GW is not really happening. In this category go all the people who spend endless hours attempting to undermine the temperature record in one way or another.
If all that’s left in my gooey grasp is a lolly-stick, there doesn’t seem to be much point in wondering whether the lolly has melted temporarily or on a more long-term basis. There doesn’t seem to be much point discussing whether or not lolly-melting temperatures have been synthetically arrived at by a cabal of lolly-scientists in search of hoards of lolly, or whether the official body responsible for lolly checking is staffed by political radicals with dubious sexual tendencies and atheistic views.
Not much point, because the lolly has gone. No lolly. Bye-bye, cold stuff.
The other stream is the one about what, in the face of the scale and enormity of the problem of climate change, we should or shouldn’t be bothered to do as individuals or consumers (in contrast to institutions and industry). It is easy to understand why some people feel that action on climate change is somewhat pointless, and that token behaviour is simply hypocritical, or perhaps simply self-deluding. It is also easy to see that such an attitude stems, ultimately, from the conception of the world as constituted of many individuals (including ourselves), none of which has substantive power, as opposed to being made up of loosely cohesive groups of people with common desires, aims and beliefs.
You don’t have to join a club to be a part; by doing you are being a part. You don’t have to wear woollen clothing or eat vegetables; there are very few things you might feel compelled to do, unless perhaps it is such things as consuming with thought, travelling with the cost in mind, ending the inclination to waste or replace. You don’t have to sign up to anything, or pay anything. First off, you need to work out whether you belong to a society or are distinct from it. Are you a part, or apart? If you can come to terms with your relative place in the world, then you can start to see the value in your own actions.
Aargh! Just as the Arctic sea-ice anomaly was settling down to a reassuring ~1.25Mkm2, after the rapid October recovery from it’s record low level, suddenly it has done another triple back-flip and colliwobble. CT’s current number is -1.759 Mkm2 (here’s the graph).
I was just thinking the other day that we might see a mean decline in Winter Season ice area of something in the region of 10%, when this happens. It’s probably a temporary blip. Perhaps.
In case you don’t realise, the difference between a Winter (October-December by CT’s reckoning) seasonal anomaly of, say. 1.5, rather than 1.25 Mkm2, is really quite substantial. Winter anomalies have generally been slight and slow (though still statistically significant), even as Summer sea-ice records are shattering all around us (2005, 2007). Whilst the absolute amount lost is relatively smaller than in Summer, the rate of decline, if the anomaly this Winter were to be around -1.5 on average, is much faster than previously.
Ray Pierrehumbert reports substantially on the Sea Ice bit of the AGU, including on Mark Serreze’s rather bleak observations about rates of change and the implications for sea level estimates. Perhaps we are seeing another example of the ’state-change’ of conditions which is currently concerning most of the Cryospheric fraternity.
Now, back to that bet… I wonder if Joe is looking like a better bet than he was a week or two back?
In ACPD this week, a new paper by P.K.Quinn et. al. (co-authors include Shindell), looks at the things which effect the Arctic climate in the short-term (anthropogenic forcings other than CO2), and discuss possible strategies for mitigation. Link to the abstract here, from where you can download the discussion paper.
The paper focusses on Methane, Tropospheric Ozone and Aerosols (with an emphasis on black carbon in the latter part). For those who can’t be bothered, here’s what the abstract says:
Short-lived pollutants in the Arctic: their climate impact and possible mitigation strategies
Abstract. Several short-lived pollutants known to impact Arctic climate may be contributing to the accelerated rates of warming observed in this region relative to the global annually averaged temperature increase. Here, we present a summary of the short-lived pollutants that impact Arctic climate including methane, tropospheric ozone, and tropospheric aerosols. For each pollutant, we provide a description of the major sources, the mechanism of forcing, seasonally averaged forcing values for the Arctic, and the corresponding surface temperature response. We suggest strategies for reducing the warming based on current knowledge and discuss directions for future research to address remaining uncertainties.
The most powerful forcing is still related to tropospheric aerosol indirect effects, though it is interesting to note that, whilst the biggest factor by far is in Summer, the largest net effects are felt in other seasons, notably Winter. The table at the end of the paper provides a useful summary.
There may be some questions about the forcing values of cloud longwave emissivity; I am not sure that this is an entirely convincing part of the paper, but I’ll hope that one of you can provide a reasoned discussion of this section.
Another slightly surprising result of their analysis is the (relatively) low values of forcing from Methane to date. The paper does, however, point out that this variable is particularly open to sudden changes as a result of changes in land - permafrost degradation and wetland production, as well as vegetation typology - and still contains a degree of uncertainty. My intuition is that this particular forcing has considerable potential for non-linear, rapid change in the coming decades, and may play a more significant role than is implied in the paper’s estimates of current relative forcing values.
The paper is worth reading for anyone who is interested in looking for an explanation of why, for example, 2007 might have been such an exceptional year for Summer sea-ice loss. The unusually high number of boreal forest fires in Siberia and Alaska in 2006 may well have been an exceptional factor affecting ice-melt onset, and thus the ensuing record low.
This is a rich paper with much to consider, not least in the implications for our expectations of future changes in the Arctic, and possibly for those of you who have taken a bet with William. I’d appreciate some feedback from those in the know…
A bit sideways, this one, but just something I noticed. Here is a new paper (under discussion), from The Cryosphere. The subject matter is the mass balance of the McCall glacier, Alaska.
The paper is interesting in itself, and at only 25 pages, worth a read, not least for the work on internal accumulation and its relation to mass balance, which seems to be quite original.
But the main reason for posting it id to draw your attention to the graphics in the latter part of the paper. No surprise to learn that the glacier has been shrinking for some time now (100 years, in total), nor that the rate of change of mass balance has accelerated since the 1980’s. What is interesting is that the graphs bear an uncanny resemblance to others I have seen recently, such as the ones showing long-term ice extent trends for the Arctic on Cryosphere Today.
In fact, the shape of the graph is similar to very many of those showing changes related to climate in the Arctic. On the principle that coincidence may be plausible for two discrete measurements, but not for a whole set, it may be acceptable to conclude - tentatively - that the consistency carries for a number of measures and data. This, again, probably comes as no surprise to those of you who observe the progress of the Cryosphere.
But it does have implications. The shape is suggestive of the first part of a hyperbolic curve, where increase goes from negligeable, to noticeable, to substantial, in a logarithmic (?) relation. The question we could be asking, then, is whether the line of best fit for likely future changes in glacier mass balance, sea-ice area, GIS mass balance, should continue along this curve.
I cannot say that this should be the case, nor claim that it is likely, but it is plausible. If so, this suggests that the impacts of climate change for glaciers, sea ice, and other elements of the cryosphere, is starting to accelerate rapidly. This in turn has implications for the estimates of 21st Century sea level rise, and also for water resource availability in the next ten-twenty years.
I would be interested to know if there are scientists out there, or knowledgeable amateurs, who are willing to speculate that this is the case, and, if so, what the implications might be.
If you decide to post a comment, it won’t go up ’til Sunday, as I’m off line for two days, but don’t let that stop you if the mood takes you: I’ll update as soon as I get back.
Enjoy the weekend.
Here is a long post: I have taken a selection of extracts from the NSIDC press releases, going back to early August, to provide an overview of the season so far.
More remarkable, perhaps, is the figure from CT, regarding the number of days below 7 Mkm2 ice area this year; nearly twice the long-term average, and nearly three times the number compared to 1980.
NSIDC, 10th August:
July 2007 showed the most extreme ice-loss anomaly ever seen since the satellite record began in 1979, with a monthly average extent of only 8.1 million square kilometers (3.13 million square miles).
The absolute minimum usually occurs during the second week in September, but as of only August 9, sea ice has already sunk below that mile-marker. In fact, the daily extent fell below the long-term average absolute minimum back in mid-July.
Record rate of sea ice decline, July:
NSIDC, 17th August:
Yesterday and today, Arctic sea ice surpassed the previous single-day (absolute minimum) record for the lowest extent ever measured by satellite. Sea ice extent has fallen below the 2005 record low absolute minimum and is still melting. Sea ice extent is currently tracking at 5.26 million square kilometers (2.02 million square miles), just below the 2005 record absolute minimum of 5.32 million square kilometers (2.05 million square miles).
NSIDC, 4th September:
August in review
The low ice extent for August 2007 stands out sharply compared to all previous Augusts. The August 2007 monthly average extent was 5.32 million square kilometers (2.05 million square miles), falling well below August 2005 extent, which was 6.30 million square kilometers (2.42 million square miles). Additionally, August 2007 ice extent is 31% below the long-term average of 7.67 million square kilometers (2.95 million square miles).
Even more stunning is that the August 2007 monthly average is the lowest extent in the satellite record for any month, including any previous September, which is typically the lowest month each year. September 2005, the previous record, had a monthly mean extent of 5.56 million square kilometers (2.14 million square miles).
Current Sea Ice Conditions: September 9, 2007
Figure 1 provides the updated map of sea ice extent for September 9, 2007. Sea ice extent now stands at 4.24 million square kilometers (1.63 million square miles). The magenta line shows the median September monthly extent based on data from 1979 to 2000.
The Northwest Passage is still open. The Northeast Passage, along the coast of Siberia, is still closed by a narrow band of sea ice.
17th September:
Sea ice is still declining, although the rate is very slow at present. Sea ice extent at this time of year can vary from day to day, as regions within the Arctic have small episodes of melt, freeze, or wind movement of the ice, just before the strong autumn cooling. As of September 16, sea ice extent was 4.14 million square kilometers (1.59 million square miles), surpassing the previous one-day record of September 20–21, 2005, by more than 1.2 million square kilometers (461,000 square miles).
20th September:
The long-term average minimum, based on averaging data from 1979 to 2000, is 6.74 million square kilometers (2.60 million square miles) and occurs on September 12. Compared to this average, five-day mean ice extent for September 16, 2007, was lower by 2.61 million square kilometers (one million square miles), an area approximately equal to the size of Alaska and Texas combined, or the size of ten United Kingdoms.
The minimum for 2007 shatters the previous five-day minimum set on September 20–21, 2005, by 1.19 million square kilometers (460,000 square miles), roughly the size of Texas and California combined, or nearly five United Kingdoms.
Current sea ice conditions: October 17, 2007
Figure 1 provides an updated map of sea ice extent for October 16, 2007; the magenta line shows the median October monthly extent based on data from 1979 to 2000. Sea ice extent is 5.65 million square kilometers (2.18 million square miles), an increase of 1.52 million square kilometers (590,000 square miles) since we reached the minimum extent of 4.13 million square kilometers (1.59 million square miles) on September 16.
While sea ice is again growing, we didn’t actually get above the previous absolute minimum record extent, set on September 20–21, 2005, until October 14 of this year.
An astonishing figure from Cryosphere Today:
The number of days with sea ice area below 7 Million Km2 was 42 in 1980, and as low as 39 as recently as 1996. 2006 saw a record 89 days below 7.0 Mkm2. So far in 2007, (my estimate), we have had 110 days below this figure. We can expect another 30 days, give or take, perhaps 140 days.
The current areal anomaly is close to -3 Mkm2. The most recent figure (from Walt Meier) for extent anomaly was ‘close to’ -3 Mkm2, slightly up from the absolute limit around October 14th.
This looks like bad news for the USA…
Current and future U.S. weather extremes and El Niño
…Future El Niño teleconnection patterns over the U.S. are projected to shift eastward and northward due in part to the different midlatitude base state atmospheric circulation in a warmer climate. Consequently, projections for the changes in the patterns of extremes over the U.S. during future El Niño events include: decreases of frost days over the southwestern U.S expand northward and eastward; increases in intense precipitation in the SW U.S. expands eastward and areas in the SE U.S. become stronger; and decreases of heat wave intensity over much of the southern tier of states turn to increases.
Whilst this at least is good news; at least some tundra types should act as a carbon sink as conditions change in the far North; and remember, there’s a lot of tundra…
The wet polygonal tundra of the Lena River Delta was observed to be a substantial CO2 sink with an accumulated net ecosystem CO2 exchange of −119 g m−2 over the summer and an estimated annual net ecosystem CO2 exchange of −71 g m−2.
http://www.biogeosciences.net/4/869/2007/bg-4-869-2007.html
But some less good news for those guys who were trying to get funding to try geoengineering a solution by dumping millions of tons of iron into the oceans; it don’t work…
http://www.biogeosciences-discuss.net/4/3863/2007/bgd-4-3863-2007.html
…Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean’s biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.
And back to a popular subject here at the cave; how good are the models of the cryosphere?
Atmospheric forcing validation for modeling the central Arctic
…Our analysis shows an excellent agreement between observed and reanalysis sea level pressures and a relatively good correlation between observed and reanalysis surface winds. The observed temperature is in good agreement with reanalysis data only in winter. Specific air humidity and cloudiness are not reproduced well by reanalysis and are not recommended for model forcing. An example sensitivity study demonstrates that the equilibrium ice thickness obtained using NP forcing is two times thicker than using reanalysis forcing.
This is a disparate bunch of stuff which caught my attention as I trawled the net. They all have uses, though the US projections and the iron thing stand out. To readers, please note, an interesting but obscure paper is always a welcome thing here at the cave, especially if you understand its implications…
Is so much easier if you can take advantage of expert opinion. So I did some back-of-the-enveloping, then decided to ask someone who would know much more than me.
Who best to ask? WTF: I emailed Mark Serreze the following enquiry:
I have noticed that Bill Chapman’s site at CT/UIUC is currently showing a negative areal anomaly of more than -2.7 Million Km2, which as far as I can ascertain is the largest recorded anomaly for this metric in satellite records.
Can you tell me if the same is true for your method of calculating extent, i.e., if the present anomaly (for the past 5 days, for example) is now larger than it was during the week of minimum extent, Sept. 16th?…
…I am also curious to know how far you think the anomaly might go before next April; is there any chance we might see a total areal anomaly of -3.5Mkm2, or even more?
Never let it be said that scientists aren’t good, decent considerate folk. Heck, these guys have their jobs to do, as well as handle the press, and could do without dumb emails from the likes of the Old man. So I wasn’t surprised when Mark replied, though I was extra pleased by the bonus email from Walt Meier. Here are a couple of extracts from their replies:
Fergus:
… in terms of ANOMALIES, yes, I would not be surprised if we still had a record, both in terms of ice area and extent. Check our last posting, you will see that extent is still way below normal.
Walt: do you have the numbers handy in terms of current ice extent anomalies?
Ice extent and area are increasing only slowly this autumn, the reason being that there is still so much heat in the Arctic Ocean. Will anomalies grow through this winter? I just don’t know. However, the ice we have by April will likely be pretty thin, setting us up for another big loss next summer.
CheersMark C. Serreze
And Walt replied, too:
Hi Fergus,
Yes, we have been tracking the extent anomalies relative to the climatology (1979-2000) and indeed it did continue to grow well after the minimum extent was reached on Sept. 16.
In fact, it reached as much as -3.25 million sq km about a week ago. Since then it has moderated some, but it’s still nearly -3 million sq km.*
This isn’t too surprising. There was such a huge area that was ice-free, allowing the ocean to warm up. This means it’s going to take longer to cool to the freezing point allowing ice to form. I would expect that the anomaly magnitiude will decrease through the winter**, but may still stay larger than the previously anomalies of ~1 million sq km we’ve seen the past couple of years. Also, as Mark mentions below, if where there is ice, it will be thinner.
walt
* a quick technical point; the numbers I use are for the CT ‘area’ metric, Walt’s are the NSIDC ‘extent’ anomaly numbers.
**walt emailed to mention the typo, where he put ’summer’ rather than ‘winter’; it has now been adjusted.
So, the anomaly did increase after the minimum was reached, by both measures. CT is still going downwards, though this could change within a week; to answer a potential disagreement on the earlier thread, my ‘eye’ estimate reads the ‘tale of the tape’ showing an areal anomaly of -2.75 Mkm2 +/- 0.05.
From this, plus my unique method of pseudo-straight-line analysis, I will now estimate the forthcoming seasonal mean extents for Autumn (October-December) and Winter (January-March). This can be compared against the fourth of the top-line graphs at CT - the one with the pretty colours.
The OND mean extent will probably not exceed 10Mkm2, and is more likely to be as low as 9.3Mkm2, +/- 0.2.
JFM should be below 13.5; my guess is 12.8 Mkm2 +/- 0.4. The mean annual extent, calculated at the end of Autumn, will be below 11 Mkm2, perhaps as low as 10.2.
I couldn’t work out how to estimate the Spring mean.
This sets the scene nicely for the bets between William, Eli and the others over at Stoat, for next Summer’s minimum. There is a very good chance that the maximum in March will be down by more than 1 Mkm2, and it could be as much as 1.5. The ice in April will be thin, and will melt or dissipate more rapidly as a result. Next year’s minimum might be very close to this year’s all-time record decline. I don’t know which side of the line it will fall, but I’ll hazard that it will be considerably lower than the 2005 (former) record minimum.
If anyone thinks my estimates are likely to be out by more than 1 Mkm2 either way, I’m willing to consider a small wager…
My sincere thanks go to Mark and Walt, and the excellent people who work at both the NSIDC and the UIUC to produce the data; you’re all heroes.
This is getting silly. Maybe scary is better. CT’s Northern Hemisphere sea ice area anomaly used to go down to -1.5 Million Km2.
Back in June/July, they had to change the graph and add a white bit to the bottom, to allow for the unusually low numbers, so they stretched thw white bit to -2 Mill.
Then a month or so back, it went to -2.5Mill.
Just last week (thanks for the heads up, Steve), thanks to the fact that the ice still isn’t there, when it should be, even more white was added to the bottom of the graphic, to allow for the new lowest ever anomaly of -2.7 Million Km2.
Here is the ‘tale of the tape‘ as it currently stands. Aw, shucks, the darned needle’s gone and fell right off the bottom again. Below -2.7 Million Km2.
Two obvious things to note here. First, the way the loss of sea ice has fallen below long-term averages this year has caught out the team at CT (who know much more about the subject than amateurs, like me) not once, but four times, in six months. Second, the only increase in white stuff as far as the Arctic sea ice is concerned is the extra white sections being pegged onto the graphs to allow for the ever-increasing anomaly.
There’s a chance for a good old-fashioned spread bet here. How much extra white space should CT add to its anomaly graph this time? Will -3 Mkm2 be the limit of the anomaly between now and next Spring? Anyone care to take a punt at -3 to -3.5 Mill.? I might be tempted to offer odds against a spread of -3.5 to -4 Mill. between now and April, but someone might want to take the spread even further. Is this as far as the anomaly will go this year?
I’d like to know what readers are willing to suggest will be the largest sea ice anomaly of 2007, and the largest anomaly between October 1st, just gone, and April 1st 2008. I’ll publish my forecast in a couple of days time.
Oh: and here, for the sake of completeness, is the NSIDC briefing from October 17th. I’ve emailed to ask what their measurement system shows the anomaly as. The comment below is from that briefing:
The differences from climate norms for the previous century continue to increase, even though the 2007 melt season has ended and the ice has begun its seasonal recovery. As of October 16, the extent was 3.20 million square kilometers (1.23 million square miles) below the long-term average.
Since the NSIDC produced its press release on the first of October, with the end of the ‘melt season’, there have been some comments on the blogs about the past season, but nobody seems to have noticed this.
The sea ice area anomaly exceeded -2.3 million km2 in September, during the period of minimum cover. But in the past couple of days, it seems to have gone even lower than that; the current anomaly is as great, if not greater, than it was last month.
The sea ice is returning, with some areas seeing reasonable refreezing rates, but overall, there is a lower ice area relative to the long-term date average than ever before, or so it looks. The simple explanation is that it is taking longer than usual for the refreeze to happen, which under the circumstances is not a great surprise.
It’s only a few weeks into the Arctic cold season yet, so what the Winter will bring is unknowable (seasonal variation really is a very strong signal) , but the start does not augur well. My suggestion is that we keep our eyes on the progress of the refreeze for a while yet. Historically, the Winter anomalies have been less extreme than the Summer ones, so we should expect, on average, to see that area anomaly rise, sooner or later. But that ’sooner or later’ is also significant, as the final level of recovery will likely be affected by the timing of the refreeze.
Keeping my eyes on this one…
Here is another example of something I frequently find myself cautioning against; the relationship between fact and fantasy in the media. This example is from the BBC.
So, now that the North West Passage has had a few clear weeks, and many people seem content to assume that this will be the case for many years to come (isn’t it a bit soon to make this assumption?), David Shukman reports that Canada is ‘asserting its control’ over this part of their territorial waters:
In another sign of potential friction in the warming Arctic, Canada has warned that it will step up patrols of the North West Passage. Record summer melting of sea-ice has cleared the passage for the first time; and immediately escalated a dispute over who controls the route.
Canada maintains the waterway that connects the Atlantic with the Pacific lies within its territorial waters.
It has backed that up with plans for a new military base in the Arctic.
However, the United States, and other countries claim international rights to use the route for shipping.
note the language use to emphasise the message that this represents a ‘threat’: ‘friction’, ‘warned’, ’step up’, ‘patrols’, ‘escalated’, ‘dispute’, and the classic ‘plans for a new military base’.
But the lack of details in certain key areas makes me suspect there is perhaps less to this story than Mr. Shukman is making out. I’m not saying he’s lying about this, not at all; it may well all be both true and accurate. It’s important to recognise that part of the job of experienced journalists is to recognise the underlying reality, when on the surface, not much is stirring. But the question of how the North West Passage is to be used, and who is responsible (and who is to profit from it, we imagine) for this new shipping route, is here being specifically ‘framed’ in terms of a potential international ‘conflict’. What evidence is there that there is going to be anything more dramatic than diplomatic discussions, at worst a political dispute over the use of the NWP? Apart from the statement that ‘the USA and Europe’ are promoting the status of the passage as an ‘International Water’, not a lot. The impression from the article is that this is a military conflict-in-waiting, which is hardly credible.
As for the details that Mr. Shukman does provide: What sort of ‘military base’ is Canada planning, exactly? Where? And what is it’s intended purpose? Are they planning a large Naval installation, or a twenty-man research base? Details, please…
It is also hard to understand under what circumstances any other nation might claim that the NWP represents ‘International Waters’; it is surrounded by the Canadian Archipelago (is there some dispute about which country Ellesmere Island, or Banks Island belongs to?) , and as such, exists entirely within Canadian territory, as much as the Panama Canal is within Panama, or the Suez within Egypt. (Don’t even go there…); how this could then be ‘disputed’ water is at least a matter of curiosity to me.
I don’t doubt that there will be some interesting manoeuvring going on in the Arctic Ocean, should the climate change for long enough to allow detailed research and exploration of potential resources, but the idea that Canada is ‘flexing its military muscles’ seems faintly incredulous. Id’ be happy to be proven wrong.
Thanks to the inimitable resource that is Wikipedia, I learn:
Northwest Passage
Northwest Passage routes
The legal status of a section of the Northwest Passage is disputed: Canada considers it to be part of its internal waters, fully under Canadian jurisdiction, arguing that they are archipelagic waters under the United Nations Convention on the Law of the Sea.[24] The United States and most maritime nations,[25] consider them to be an international strait,[26] which means that foreign vessels have right of “transit passage”.[27] In such a regime, Canada would have the right to enact fishing and environmental regulation, and fiscal and smuggling laws, as well as laws intended for the safety of shipping, but not the right to close the passage.[28][29]
So maybe there is an argument going on, but really; will it ever be more than posturing? 
Here is the summary of the Summer melt season from the NSIDC.
And here is a graph.
Interesting explanation about the North West Passage; this year’s event truly is exceptional. Shame about the Northern Sea Route, though.
Though I think it may be slightly contentious, the observation of a decline of 10% per decade, for five decades, (or even if you choose to allow lower numbers and less time) probably counts as a definitive trend.
EDIT: Andy Revkin’s article for the NY Times says it so much more eloquently than I have managed… and note that statistic at the end; ‘Old ice’ down from 80% to 2%…
Slightly slower than usual, here’s the NSIDC release for two days ago. In a couple of weeks, they’ll be producing their summary of September, and probably drawing the page to a close for the year not long after that. Before the monthly means are posted, though, these are the numbers we have so far for this year.
At it’s lowest, sea ice extent reached around 4.13 Mkm2, during the week of the 16th September; not especially late (the previous week has been the average over recent years), and earlier than some years. What is unusual about this month is the ‘flat-line’ appearance of the ice extent; normally, the refreeze starts as soon as the thaw has ended, and we get the familiar curved graph of extent; this month, the ice has persistently refused to start increasing in extent, in spite of the steadily decreasing temperatures. As a result, the September monthly mean is likely to come in around 4.2 Mkm2. How does this compare to previous years?
The Long-term mean Summer sea ice extent is 7.7 Mkm2. So, this month will have been around 3.5 Mkm2 lower than that mean; around 45% less. The previous lowest ever was two Septembers ago: 5.32 Mkm2. We’re around 1.1 Mkm2 lower than that; about 21% down.
In the meantime, ice extent in the Antarctic has pushed close to record high anomalies; more than 1 Mkm2+ at its’ height. I haven’t yet seen any analysis of the data from here, or any novel explanations, but it still doesn’t look like the Antarctic is trending positively in a consistent way much beyond it’s natural variability; I’ll look for more on this later.
Ignoring the plight of Polar bears and local inhabitants for the moment, does the change in sea-ice matter? It does seem to be prima facie evidence of the ‘Polar Amplification’ hypothesis - not just this year’s low, but the trend over nearly thirty years, and the apparent (this year and 2005 could still turn out to be exceptional, rather than habitual) acceleration of the rate of decline in the NH.
But this year, at first glance, it at least looks as if the conditions in the Arctic are, somehow, different to previous years, not least because of the loss of a chunk of perennial sea ice in the Central Arctic Ocean, and the exceptionally low quantity of multi-year ice in the ocean as a whole, as well as the apparent inertia in the system this month.
What I am confused about, though, is how the huge amount of heat-loss from the ocean compared to previous years will effect the area next year. One the one hand, we may well see a slow and deficient refreeze throughout the Autumn and Winter, with a very large extent of vulnerable first-year ice. On the other, a vast amount of the heat transported in to Arctic Ocean via the NwAC and the Bering Strait will probably be removed from the climate system into the stratospher over the coming months. This is likely to have an impact on this Winter’s weather in Siberia and Northern Canada/Alaska, and more so in the Chukchi Sea area than anywhere else. There is also the possibility that the internal downwelling and upwelling circulation, as well as the boundary layer heights, will be affected.
It is far too soon to be claiming a systemic change in the Arctic yet, but the next four seasons may be critical in helping us understand what is and isn’t happening, and how the global climate system might respond.
Since it is a subject dear to my heart, I thought you’d like to know that today is International Polar Day, part of the IPY.
The IPY website now has a load of snazzy links to lots of useful stuff about sea ice, here.
Update on current sea-ice extent: the latest NSIDC press release is here. It looks as if the past week has seen the minimum, though as the release points out, it’ll be a couple of weeks before this can be confirmed. On scale of losses this year, the NSIDC says that the anomaly compared to the previous lowest figure is the size of Texas and California combined, or five UKs.
For the full horror story, the animation at the bottom, of minima from 1979-present, is the eye-opener.
The NSIDC has released it’s latest update; Arctic sea ice extent is still declining, though more slowly now. The figure they are giving today is 4.24 million km2. Looking at that curve and taking into account the date, a final figure of between 4.1 and 4.2 seems likely.
There is an interesting discussion on the page about the whys and wherefore, citing work from Polyakov and Shimada which respectively deal with the Barents and Bering Sea processes. Most obvious is the connection between temperature anomalies and sea level. As they point out, with no ice to prevent heat loss from the ocean, the ice level and temperature feed off each other.
The NSIDC also reminds us that the albedo feedback effect, which is pretty clearly what is happening in the East Siberian and Chuchki Seas, and could be having an effect on keeping the North West Passage open, has long been expected from the output of global climate models. On the face of it, the cureent situation in the Arctic looks like straight evidence that climate models can (and have) correctly model (or project!) large-scale climate processes.
From the blog data, it is clear that some of you are interested in the state of the Northern Sea Route, which I have been incorrectly referring to as the North East Passage (apparently, this terminology is antediluvian). Thanks to Hank Roberts ans Steve Bloom, among others, we can now keep a close eye on the satellite images from the MODIS rapid response near-time image bank. The TERRA image for 12.35 today should show the Taymyr Peninsula, the ‘bulge’ in the mainland, next to which a number of small boats are trying to make a passage (see other posts for links).
There are still strong Sea Surface Temperature Anomalies (from the AARI) in the Laptev Sea, and, though the ice drift forecast is now a few days old, it still shows a Northward drift in the area. This is too coarse to show local eddies or back currents, so it’s hard to be sure, but conditions should remain adequate for a few more days for the passage to clear to a level of less than 30% concentration, of ice less than 1ft thick. It would seem unlikely that the entire passage will clear in the way the NWP has, but if it is navigable, without icebreaker assistance, by a non-commercial or small commercial vessel, this should count as being ‘clear’ for the sake of the argument.
As has been said elsewhere, don’t be fooled into thinking that we’re talking about an ordinary ocean trip here: temperatures are still incredibly low, there is not much daylight (though still some twilight), and conditions can go ‘bad’ very quickly. Even if a small boat could get through, there is danger from ‘bergy bits’ and ‘growlers’, large chunks of very hard ice which are hard to see until they are very close.
For some years, shipping companies, and the Russians in particular, have been looking into the viability of the Northern Sea Route. If the sorts of conditions we have seen this year persist into the coming decades, then this will become an important and economically viable route for major shipping between the Atlantic and the Pacific. This would have ramifications in all sorts of places, from Panama to the Suez to the many ports which rely on the huge international shipping business for their livelihoods. It would also suggest that new ports would need to be opened on the Siberian coast; this in turn would stimulate development along the North of Canada and Alaska, which means a northward population shift and other side-effects.
I’ll keep an eye on things and post regular updates. For a fascinating (but often technical) discussion of the Arctic sea ice, RealClimate has a thread which has been active for weeks now, with hundreds of comments.
http://www.seaice.dk/iwicos/latest/amsr.n.comb.20070909.gif
The North-East Passage will be open for business. (I sometimes have trouble linking to that site; I hope it works for you…)
EDIT: From the comments, llewelly usefully points out that each of these is a single image, so:
That site only keeps each image of the sea ice for about a day. On the 10th (more or less - I’m not sure of the time of day the change takes place) your readers will need to look at http://www.seaice.dk/iwicos/latest/amsr.n.comb.20070910.gif . On the 11th they will need to look at http://www.seaice.dk/iwicos/latest/amsr.n.comb.20070911.gif .
Thanks for pointing this out.
Edit again: following on from the previous comment about the circumnavigation, here’s just the boat for the job.
Edit again: If you want to look at satellite images, they are all available on the DTU Interactive Java page on the IWICOS site. To see the images, you need to open the Java applet, then go back one day (-d at the bottom of the page). Then the top dropdown menu will give you a list of all the images available. You may need to use the menu on the left to zoom out, to get a better picture. Once you have your bearings, you can shift and zoom to your heart’s content.
The best images of the Laptev Sea are low down on the dropdown list; the MERIS.Laptev D22 (zoom out) is great, but the critical place is covered with cloud atm, by the look of it, and the ASAP.Laptev 3D 1km is also a good image.
The menus are not intuitive at first, but with a bit of effort you can find what you want; but remember to go back one day first - it makes the rest relatively easy.
The NSIDC update of September 4th speculates on the possibility of the North-East Passage opening this year. If it did, this would allow a very, very fast boat to circumnavigate the entire Arctic Ocean (no, it’s not really feasible, this year).
Will the NE Passage open? It looks like it’ll be a close-run thing.
CT’s image is a bit coarse to see in detail what’s going on, but the IWICOS/IOMASA/Polarview/Damocles site has excellent high definition images extracted from satellite data, and in the ‘interactive’ section, an opportunity to choose the satellite and date of your choice and view the actual images. the best seem to be yesterday’s MERIS images.
All depends on whether the ice clears in the Laptev Sea, close to the coastline. From the overview image you can see that there is a substantial amount of open water there already. TBH, it’s hard to tell from the satellite images how much there is. But going back to CT, if you select the Laptev sea button, you’ll notice that the sea ice area has gone up a fraction in the past few days, which would suggest, on first impression, that it ain’t gonna happen.
Luckily, the Russian Met has it’s own website (English version, too) which has some sea ice pages. Most usefully, there is a forecast of ice drift for the next six days. This shows a slight drift towards the coast for the next two days, followed by three days of strong drift Northward, parallel to the key area. If this forcast is accurate, the ice currently in the Laptev area of the passage could clear away from the coastline.
It’s hard to give odds on this, but I’d say that there’s a fair-to-middling chance that the North East Passage will open, if only for a few days, from Monday to Wednesday of next week.
Anyone got the boat ready?
Regular visitors to Cryosphere Today will have noticed that the headline graph of sea ice area covering the whole Arctic has developed a funny little squiggle at the end, and the sea ice loss appears to have come to an abrupt stop, at least for the time being. So what is going on?
If you look at the various regional graphs, something emerges. Almost every area has flatlined at or near zero. It’s hard to reduce ice in areas where there is next to none. The Arctic Basin has increased its sea ice cover. two possible explanations: as it’s the first area where refreezing begins, and surface temperatures are at their lowest, it is possible that some consolidation of the ice pack has occurred, and there are fewer pools or polynyas in this area at the moment. The whole of the Arctic ice also drifts around a bit. With so much open water this year, it is likely that the currents have pushed what little ice was outside the area into the Basin. Indeed, if you then check out the Kara and Laptev seas, you’ll see that the ice area here has continued to decline; some from drift, and some from melt, perhaps.
Two other areas where there have been changes recently are the Canadian Archipelago/Beaufort Sea and the Greenland Sea. The first of these suggest that the ice melt is continuing, and pack ice is drifting towards the Pole. The second is a lot more worrying in its implication.
If you go back to the NSIDC illustration of the season’s ice movement, there’s a strong pattern of motion across the North of Greenland and around the corner, into the Greenland Sea. Using CT’s large file of satellite images, or the NSIDC image, a lot of this looks like multi-season (old) pack ice being flushed out of the Arctic and into the North West Atlantic.
All of this means that it is possible that we may have already seen the minimum ice area day pass. I’d expect, though, to see a few more days of losses at least from that Kara/Laptev area, so there may yet be a slight dip before the thaw ends and the refreeze proper begins.
This Winter, then, the sea ice area will go back to its larger value. How much the maximum will be is dependent on a lot of factors, but a recovery to near-average maximum seems less than likely as things stand. And much more of the Winter ice will be first-year ice. Vulnerable ice. Even if the Winter was to see a return to nearer-normal average areas, the picture for next Spring’s melt season looks ominous already. Unless another major variable comes into play, and suppresses the sub-Arctic SST anomaly, reduces the Bering inflow, or cools the whole region by a few degrees compared to the past six years, then ice loss will be rapid and comprehensive early in the season.
It is not clear what impact this will have on the Northern Hemisphere’s climate or weather, nor what the feedback effect is likely to be. I can’t see that it’s likely to be good for us.
All of this is pure speculation. Unless it happens.
Stay cool.
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