Last year the north pole experienced a truly astounding redution in sea ice. As a result, much of the older, thicker sea ice melted. The ice present now is mostly 1st-year ice, thinner than was present before; as a result, the new ice is more vulnerable to melting during the summer heat. This raises the possibility of similar dramatically low sea ice values this summer. In fact scientists have made numerous predictions covering a wide range of possibilities, but my reading of the prognostications is that there’s about a 50-50 chance that this year’s minimum sea ice extent will be lower than last year’s. Members of the Polaris Project, for example, are split 4-to-2 against this year’s record breaking last year’s.
Monthly average sea ice extent for the northern hemisphere, as measured by satellite observations since late 1978, are available from the NSIDC (National Snow and Ice Data Center):
There are large ups and downs due to the annual cycle of melting and re-freezing caused by the seasons. But there’s also a distinct decline superimposed on that annual cycle. We can see this plainly by computing sea ice anomaly, the difference between a given month’s extent and the average for that month during some reference period. In this graph, the reference period is the entire time span of data, so the numbers aren’t the same as other sources which use a different reference period (usually 1979 to 2000) but the changes are the same (Note: I can’t seem to get this graph to display on the page — but if you click on it you’ll see the graph):
Another way to isolate the trend from the annual cycle is to compute the “mean” value using a wavelet transform:
This graph tells basically the same story as the previous one, which is evident if we plot them together (but using different axes; the left axis is for anomaly, the right axis for mean extent):
The decline is evident, and is unprecedented for the time we’ve been tracking sea ice; prior data (not from satellites) confirm that the rapid decrease of northern hemisphere sea ice is confined to the last few decades.
Not only has arctic sea ice been in decline for decades, the decline is accelerating. The anomalies don’t just show a decline, they show a statistically significant greater rate of decline now than for the first two decades of satellite obserations. This result isn’t just due to the dramatic 2007 dip; even if we eliminate data after 2007, using only the data up to the end of 2006, the recent increase in the decline rate is still statistically significant.
Will this year’s minimum be even lower than last year’s? The issue isn’t yet decided; the annual minimum in sea ice extent for the northern hemisphere tends to occur around early September, although last year the minimum didn’t happen until Sept. 24th — so we won’t know for nearly another two months how low the extent will go this year. Some maintain a continual watch on the ice cap, reporting daily whether it’s up or down compared to last year; to me that seems rather like watching the grass grow because you’re wondering whether or not the lawn will be as full and green this year as last.
The unusual wind patterns seen last year haven’t occured this year (yet), so ice reduction isn’t as great so far this year as last year. But there’s still nearly two months of the melt season yet to go, and the ice is indeed thinner than last year, so it’s possible we may yet exceed last year’s record.
I managed to locate daily data for sea ice extent from mid-2002 to the present. These data are processed by a different algorithm than those from NSIDC. So, the numbers are different; nonetheless the changes indicated are extremely similar. Here’s the daily data:
We can directly compare the year 2007 to 2008 (so far):
This is essentially the same as the graph updated regularly on NSIDC.
While it remains to be seen whether this year’s minimum extent will be even smaller than last year’s, we already observe that arctic sea ice is in decline and that the decline has gotten faster recently. In my opinion, whether or not we break the record again this year is a less important scientific question than whether or not the trend will continue. But clearly, in the press and in the public eye breaking the record has more influence than continuation of a trend. Therefore, a new record low might have significant impact on the “propaganda war” over global warming. As for the actual result … we’ll just have to wait and see. We won’t have to wait very long.
76 responses so far ↓
Joseph // July 17, 2008 at 10:56 pm
Out of curiosity, if the trend were to continue, when do you project there will be zero ice?
[Response: The linear trend in summer minimum will hit zero in 2087. But using the greater rate recently, the summer minimum will hit zero around 2050]
Bill Illis // July 18, 2008 at 1:55 am
But since global temperatures have not increased in the last ten years, how can the northern ice have declined by so much over the last ten years?
Hank Roberts // July 18, 2008 at 4:04 am
Bill, you should read a bit and check your assumptions. You’ve got one wrong in that sentence.
Bob North // July 18, 2008 at 4:52 am
Hank - Perhaps the correct question is a little different. Maybe it should be”Given that the available data from long term stations, albeit limited, suggested that the Artic region was as warm or warmer in the past (late 1920s thru early 40s), why is the ice melt much greater now?” If, in fact, the ice melt is much greater than in the 30s and 40s (again very limited data available), my guess is that it is something other than CO2 induced atmospheric warming that has caused ice loss, perhaps changes in albedo of the ice due to particulate deposition. This just means that we need to be looking at all potential causes and issues with pollutants rather than focussing too much on a single issue (GHGs) to the determint of addressing others.
BTW, the citation for my statements regarding the historic warmth of the Artic is my personal review of Artic stations (GISTEMP) with long term data availability (from at least 1930). Unfortunately, there are only a relative handful, but all of them indicate a distinct “warm” period in the 1930s through the early 40s which was in many cases warmer than the current temperatures. Since this data is publicly available, you can check it yourself.
Greg Simpson // July 18, 2008 at 4:55 am
Even if temperatures had stayed the same over the last ten years, that temperature was enough to cause a net melting of sea ice most years, so it would be reasonable for it to continue to do so now. It’s not obvious why this wouldn’t continue, a little more ice melting each year until the arctic ocean is ice free in summer.
Steve Bloom // July 18, 2008 at 6:49 am
Bob, I think a careful review of all the data shows greater warming now, and indeed that’s what the experts seem to think. One big difference to bear in mind is the intrusion of warming currents into the Arctic; there’s no evidence that any such thing happened circa the ’30s. There are also some phenology results (this paper e.g.) unrelated to ice.
Timothy Chase // July 18, 2008 at 7:16 am
Bob North wrote:
Alert,N.W.T. — 82.5 N, 62.3 W, rural area, 1950 - 1991 seems to go with your assertion, Eureka,N.W.T. — 80.0 N, 85.9 W, rural area, 1947 - 2008 not so much. If the record extends beyond 1995, it tends to show more warming more recently — particularly if it extends beyond 2000. But 1990 was cooler than the peak around 1940.
For more, please see:
http://data.giss.nasa.gov/cgi-bin/gistemp/findstation.py
Bob North wrote:
Hansen and others are:
http://data.giss.nasa.gov/modelforce/
http://data.giss.nasa.gov/modelforce/RadF.txt
However, could I also suggest that with respect to the arctic, we shouldn’t simply be considering the effects of the atmosphere — but of ocean circulation.
The largest part of the melting of the ice takes place below the surface of the water.
Timothy Chase // July 18, 2008 at 7:18 am
Ps to the above
I meant Alert,N.W.T. to be hyperlinked — but improperly formatted it.
michel // July 18, 2008 at 7:26 am
One sees that since 1975 there is a distinct slight downward trend. The trouble with reaching any conclusions from it is surely that its only 35 years worth of data? If we don’t know what is normal and what the time period is for any cycles that may exist, how do we know what, if anything, this means?
It seems a bit like observing the last 10 years and claiming that its not warming, when in fact, take a longer period, and it obviously is. Or, its a bit like taking the period up to 1975 and claiming that it was cooling, which it was, but it was about to reverse, though you could not see that in the data to hand.
How worried should we be about climate events which are only unique in a 35 year span? These are long tailed distributions, are they not?
[Response: There are several things wrong with your claims. First, as I pointed out in the post, we do have data before the satellite era, which indicates that the decline we're seeing is unique in a span of a century or more. Second, the analogy with the temperature data is false; one fails statistical significance while the other passes.]
Richard // July 18, 2008 at 7:38 am
There is no way that the minimum for 2008 will be lower than 2007. In fact, the way things are going, the 2008 minimum will be around the long term average.
Your graphs and those of NSIDC are misleading in that the scales chosen will emphasise the decline inordinately. Try making your Y axes start at zero and then see how they look.
As the time period is only 29 years for the satellite data, there is no confidence that the decline is an ongoing and permanent process. After all, Roald Amundsen was the first to navigate the Northwest Passage in 1908. One can only assume that the summer ice minimum was similar then to now. And there is no evidence to suggest that it was never less that it is now.
dhogaza // July 18, 2008 at 7:42 am
Got any evidence for this guess? This common denialist claim hasn’t gotten any traction among mainstream scientists for the basic reason that there’s no evidence to support it beyond the typical “if it’s CO2, we might have to take action certain segments of society find distasteful”.
dhogaza // July 18, 2008 at 7:48 am
This is common knowledge, of course, no need to compute it yourself. Perhaps you’re unaware that the climate science community is fully aware of Arctic warming during that time?
There’s a major difference between that warming and current warming, though, that makes handwaving dismissal of the significance of current warming a bit over optimistic.
I’m sure you can tell us what that difference is …
Nick Barnes // July 18, 2008 at 9:06 am
Watching this grass grow is about as exciting as watching the US presidential campaign, or the Tour de France. It keeps us off the streets, and gives us something to gamble about. And it’s educational too: I know where Kugluktuk is now, and the Dolphin & Union Strait.
null{} // July 18, 2008 at 11:22 am
The actual physical causality is almost always ignored whenever the Arctic Sea Ice is discussed. Instead, “the Great Global Average Temperature is Increasing Everywhere,” SOP is usually implicitly invoked.
Arctic Sea Ice is 90% underwater. Water-to-Ice energy exchange is very likely one of the more important physical processes. Changes in albedo have also been noted.
Stats without causality is not science.
Bob North // July 18, 2008 at 1:55 pm
Tim -
Neither of the stations you listed (Alert, Eureka) cover the time period of interest. I looked only at those stations with the longest possible records, starting no later than the early 1930s. This includes stations such as Akureyi, Jan Mayen, Tromo Skatto, Angmaggsalik, Clyde NWT as well as others. While there is no doubt there has been significant warming since the 60s and 70s, it is also clear that the “warm” period during the 30s/early 40s was similar in duration and magnitude.
My point really was , if the ice retreat seen over the last couple of decades is unprecedented, then we should be looking harder at causes other atmospheric warming since such warming does not appear to be unprecedented. I agree that changes in ocean currents, particularly those that bring warmer water under the ice, and the cause(s) of such changes, need to be considered.
Timothy Chase // July 18, 2008 at 2:53 pm
null setwrote:
There is also increased poleward ocean circulation from the lower latitudes. Maslowski discusses the importance of accurately modeling ocean circulation here:
And we now know, for example, that hurricanes are responsible for some of this circulation. If you increase the strength of the hurricanes, you increase the poleward circulation and thus the heat that the Arctic Ocean receives from the lower latitudes.
Timothy Chase // July 18, 2008 at 3:30 pm
Bob North wrote:
You could try Jan Mayen at 70.9 N Lat covers 1920-2008 — but it is a lower latitude. But that is the highest latitude that includes 1940-2000, and the strongest multiyear arctic warming would appear to have been since 2000.
Other station data is available by clicking station data at:
http://data.giss.nasa.gov/gistemp/
… then clicking the map. But as I have said, you won’t find much anything farther north for 1940-2000.
Akureyi - doesn’t come up. Spelling?
Jan Mayen? Just above - but 70.9 N.
Tromo Skatto - doesn’t come up.
Angmaggsalik? 65.6 N. And like most of the other stations you are picking, Greenland — which is large enough that it creates its own climate zone.
Clyde? Not in Greenland, but it is lower than Jan Mayen - at 70.5 N and its record appears a little patchy towards the end. However, unlike Jan Mayen, it appears warmer around 1940.
*
In any case I would suggest looking at poleward oceanic advection. As Null {} points out, most of the melting is taking place under water, and a lot of warm water seems to be coming from the lower latitudes these days.
dhogaza // July 18, 2008 at 4:28 pm
Read about his voyage and then come back and tell us why his account supports yoru statement that the summer ice minimum was similar to 2007.
And you might also ask why those rabid enviros driving US nuke subs under the arctic ice have added more faked data to the fraudulent global warming scam, claiming, undoubtably while under the influence of increased CO2 inside those sealed underwater cans they live in, that polar ice VOLUME is about 1/2 what it is today.
dhogaza // July 18, 2008 at 4:29 pm
sigh - about 1/2 what it was 50 years ago (gotta stop posting while in the midst of other stuff)
Aaron Lewis // July 18, 2008 at 4:57 pm
Also, thick ice has broken up into little pieces, thereby increasing its area as measured from above and its rate of heat transfer to sea water.
My guess is that the VOLUME of ice in the Arctic will be less in at the end of this melt season than it was at the end of the 2007 melt season.
With all the exercise that polar bears are getting by swimming from ice patch to ice patch and then to shore, we will not have to worry about them getting too fat this year.
Hank Roberts // July 18, 2008 at 5:06 pm
http://www.realclimate.org/index.php/archives/2004/12/the-arctic-climate-impact-assessment/
“… the conclusion of the ACIA study that the recent warming is due to anthropogenic greenhouse gases is of course not based on one particular time series, but on a host of further scientific data. For example, looking at all the temperature data rather than just one time series reveals that the pattern of warming of the 1930s was very different from the recent warming. In the 1930s, warming was localised to the high latitudes, consistent with this warming being the result of a natural oscillation (the so-called “Atlantic Multidecadal Oscillation”). Very similar natural oscillations are also found in climate models. The recent warming, in contrast, encompasses most of the planet; this is consistent with it being the result of a global forcing. A very similar pattern of warming is found in climate models as a result of rising greenhouse gases. (For full details, see the publication of Johannessen et al., Tellus 2004). Many other lines of evidence demonstrate convincingly that anthropogenic forcing was very likely the dominant factor in the warming of recent decades….”
You can look this stuff up.
Hugh // July 18, 2008 at 5:31 pm
TC, for info:
Akureyri, Iceland, use latitude 65°41′N (it’s in the north of the island)
Bob North // July 18, 2008 at 5:38 pm
Tim - there are other far northern stations, particularly along the northern coast of Russia, such as Gmo. Im.E.K (77.7 N, 104.3 E) (1933-2008), Ostrov Kotel (76.0N, 137.9E, 1933-2008), Ostrov Dikson (73.5N, 80.4E, 1916 - 2008), Hatanga (72.5N, 102.5E, 1929-2008), Cokurdah (70.6N, 147.9E). In addition, there are several in the 65-70N range with long term records.
Dhogaza - I seem to recall a very recent article and discussion regarding the impacts of particulate deposition at levels as low as a few ppm increasing ice melt rates. In addition, Hansen raised this issue himself - http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=327163
Like I have said, the point is to look at all potential causes (some of which may be interactive) such as soot and ocean currents in addition to slight increases in near surface atmsopheric temperatures.
Bob North // July 18, 2008 at 5:42 pm
Tim - PS, a couple of typos
Akureyri (65.7N, 18.1W, 1882 -2008)
Trommo/Skatto Norway (69.5N, 19.0E, 1880-2008)
luminous beauty // July 18, 2008 at 6:01 pm
Bob North,
“…it is also clear that the “warm” period during the 30s/early 40s was similar in duration and magnitude.”
My calculations for decadal average temperature anomaly for 64˚N - 90˚N:
1937 - 1947 (11 years to include all the highest temps.): .64C
1998 - 2007 : 1.27C
Not so clear, Bob. Perhaps you’d like to compute the last decadal period in which the anomaly fell below the 37 - 47 max.
Nick Barnes // July 18, 2008 at 6:32 pm
What makes you say that? The NSIDC extent graph has 2008 tracking very consistently about a million square kilometres below the long-term average. CT has the ice area anomaly consistently between 0.5 and 1.5 million square kilometres below the long-term average.
In other words, do you want to bet?
Eliot // July 18, 2008 at 9:09 pm
Tiamo, on this topic and more generally, id be interested in your assessment of the following, from your very own Andrew Bolt:
http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comments/column_seven_graphs_to_end_the_warming_hype/
Was wanting to email this to you but didn’t see a link. It seems like the presented data might be (convieniently) confusing what some of the predictited scenarios might be in the future, with the general alarmism that abounds - its easiest to attach the latched on environmental firebranders than the more careful science.
Anyway, lots of graphs and lots of statements made, thought they might benefit from your inspection.
[Response: I already saw a link to this on another blog, and I'm considering doing a blog post about it.
Short answer: cherry-picker's jubilee.]
Eliot // July 18, 2008 at 11:00 pm
Cheers, hope to see a response from you. There is a lot of mileage that can be made from this sort of info as it seems very rarely that someone credible takes time to rebut and challenge assumptions. Its good to see both arguments next to each other!
Richard // July 19, 2008 at 3:27 am
dhogaza.
I realise that Amundsen took 3 years to traverse the northwest passage (1903 not 1908). But you must remember he did it in a 70ft wooden fishing vessel. Not an ice breaker. For that vessel to be able to progress along at all, required the summer ice extent to be reduced enough to allow a wooden sailing vessel to traverse in open water.
Inductive reasoning would lead one to the conclusion that if the opening of the NW passage occurred in 2007 for the first time since satellites started measuring the ice extent, then for a wooden sailing vessel to be able to navigate that waterway would require similar levels of ice reduction. I am not saying it was the same as 2007 but of a similar condition to the current one.
Richard // July 19, 2008 at 3:31 am
Nick.
Look more closely at the graph. You will notice that the trend is toward the long term average and diverging away from the trend for 2007 (http://www.nsidc.com/data/seaice_index/images/daily_images/N_timeseries.png)
Hank Roberts // July 19, 2008 at 5:12 am
Inductive reasoning should consider the draft of the vessel involved when concluding by logic that last year was similar to 1905-6: “In August 1905, the scientific work was completed and the “Gjøa” resumed its westerly course through fog and drift ice. So shallow was the channel that at one point the vessel had only one inch of water beneath its keel…. After three weeks of mounting tension and excitement the expedition sighted a whaling ship out of San Francisco. The “Gjøa” had successfully navigated the Northwest Passage, the first vessel to do so. But shortly after this it froze into the ice, where it remained all winter.”
http://www.mnc.net/norway/Amundsen.htm
Hank Roberts // July 19, 2008 at 6:38 am
http://www.earth.ox.ac.uk/~helenj/at_sea.html
dhogaza // July 19, 2008 at 6:48 am
When people speak of the Northwest Passage being opened, we’re not talking about using ice breakers, nor taking three months, nor sailing through partially-opened channels with ice under our keel.
People are speaking of clear-water sailing.
I’m looking, and to my eyes it appears that the rate of decrease has settled down to tracking the average rate of decrease for the years 1979-2000, which means that at the end of the season the extent will be below the average.
It’s true we’re not seeing the July uptick in melt that we saw last year and that if the current situation doesn’t change, that the extent will be above last year’s record minimum.
Above last year’s minimum … below the 1979-2000 average … unless melting accelerates …
Yeah! Exactly what everyone except Richard is saying! Hoo-rah!
Timothy Chase // July 19, 2008 at 7:01 am
Bob North wrote:
I will take your Hansen (2003) and raise you four years.
Hansen, J et al. (2007) Climate simulations for 1880-2003 with GISS modelE. Clim. Dynam., 29, 661-696
http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_3_small.pdf
The magnitude of soot’s contribution was reassessed. It is still regarded as a positive forcing but much less so (by a factor of three if I remember correctly) than what they calculated back then.
Bob North wrote:
Glad to see you are thinking about ocean currents. It is much better at conducting heat than air, and sea ice is nine-tenths below water.
Now what has been warming the ocean? Dark soot on dark ocean? Or do you suppose backradiation might have something to do with it — such as what you get from increased levels of carbon dioxide, methane and levels of water vapor that rise with the rising temperature?
By the way — Hansen (2007) isn’t looking at just greenhouse gases. But they do appear to dominate, with greenhouse gases having been the major positive forcing ever since 1880 relative to 1880 but for one year: 1881.
Timothy Chase // July 19, 2008 at 7:09 am
Richard wrote:
I have been noticing the same thing — pretty much for the past two weeks.
At the same time, last year I calculated that if the reduction in sea ice extent minimum is as great every two years as it was from 2005 to 2007, we would see the minimum first reach zero by 2013. But I think I prefer Maslowski’s way of calculating things — a high resolution climate model.
Richard // July 19, 2008 at 7:12 am
So? What are you trying to say? Was the draft that shallow for the whole journey? I would say not. Then consider the journey of the St. Roch in 1944 which was a much northerly route. The St. Roch whilst a steel hulled vessel was still no ice breaker. You seem to be grasping at straws to belittle the achievement of Amundsen and lessen the importance of ice free conditions at that time.
Richard // July 19, 2008 at 7:16 am
By ice free, I mean water that is less than 15% ice. This is the figure used by NSIDC to define ice extent. Drift ice is common in that region of the world at all times of the year.
michel // July 19, 2008 at 9:02 am
Tamino, I am aware of the Hadley material. It leaves one unconvinced, because we’re comparing very precise estimates from satellites with estimates which (pre 1870 or so) se know are wrong - the extent cannot have been a straight line with no fluctuations. And in the period before satellites, very loosely based estimates. There just were not enough observations.
It is clear that something remarkable in the last 35 years did happen in 2007. As to whether it was remarkable in a 100 year timescale, I think we just do not know. And as to whether it was remarkable in 1,000 years, same thing in spades.
I do agree however that a few years of 2007 type melting, or greater, and with no recovery, and one would start to be very seriously concerned. Its just that one year in 35 alerts rather than convinces.
Nick Barnes // July 19, 2008 at 11:56 am
Richard, I look at that graph every morning when I open my web browser, and have done so since the NSIDC first put it up.
The 2008 line is parallel to the long-term trend, not tending towards it to any significant extent. The 2007 numbers fell away from the last week of June onwards. Looking at the MODIS shots and the Canadian weather charts (every day, again) the reasons for this are fairly clear - we haven’t seen a repeat of last year’s persistent anticyclones over the Chukchi and East Siberian seas.
I have money riding on this year’s sea ice, you see. If you believe that the 2008 minimum extent will be close to the long-term trend (say, within half a million square kilometres) then I will be happy to take your money too.
dhogaza // July 19, 2008 at 4:18 pm
Pointing out that Amundsen achieved his passage when it was NOT ice free, that it took months, that he had ice under his keel at times, and that his ship got frozen in before he could get back out, is hardly “belittling his achievement”.
If there’s any belittlement going on, it’s by you, by insisting that there was as little ice in the Arctic sea then as there was last year …
But then again denialists are skilled at scoring own goals, don’t worry, we’re used to it.
And, as Nick and I both point out, you’re not so hot at reading graphs, either.
Hank Roberts // July 19, 2008 at 5:28 pm
Here’s the 2007 reference image:
http://modis-snow-ice.gsfc.nasa.gov/091507ar.html
____caption_____
On September 15, 2007, at the time of the Arctic sea ice minimum, the MODIS on NASA’s Terra satellite captured an unusually clear view of the open Northwest Passage. Although clouds appeared over some of the Arctic in mid-September, skies were clear enough to allow Terra’s MODIS sensor to observe much of the sea ice and open ocean throughout the Arctic.
This image is a mosaic of Terra observations of the Arctic, taken on September 15-16, 2007. Overlain onto the image are sea ice minima from 2007 (medium blue), the previous record from 2005 (light blue), and the long-term average from 1979-2000 (gray). The 2007 minimum, which correlates closely with the ice visible through clouds in this image, fell substantially below previous records. In 2007, all Arctic sea ice records were broken in August, more than a month before the end of melt season.
Lee // July 19, 2008 at 5:51 pm
Richard says:
“Inductive reasoning would lead one to the conclusion that if the opening of the NW passage occurred in 2007 for the first time since satellites started measuring the ice extent, then for a wooden sailing vessel to be able to navigate that waterway would require similar levels of ice reduction. I am not saying it was the same as 2007 but of a similar condition to the current one.”
As it happens, I’m somewhat plugged into the sailing/yachting community, and I’ve spoken to a sailor who has transited the Northwest Passage in a private yacht. Private yacht transits of the NW passage are becoming more frequent, in large part due to modern ice mapping and communications, but also due to the loose-ice season being longer, and to there being more stretches of open water.
Passages of the Channel do NOT require it to be ice free, or even ice open. Historically, part of the art of transiting the channel has been to pick good leads through the ice, and to being prepared to wait it out when one does get caught in the ice. Here are a coupel fo good examples for Idlewylde’s transit in 2005:
http://www.trawlersandtrawlering.com/news/Resources/pxidleiceallaoun.jpeg
http://www.trawlersandtrawlering.com/news/Resources/pxidletroyroutep.jpeg
From this story:
http://www.trawlersandtrawlering.com/news/idlewildpassage.html
2007 was much different. The Northwest Passage was open from end to end, in one swoop. I know of two sailing yachts that transited the passage in 2007 - at least one of them simply sailed through, without ever having to do any ice navigation except for mounting a 24 hour iceberg watch. The channel was simply open.
Compare this with the accounts of Mundsen, and other early explorers of the NW passage, their tales of struggling to find open paths through the ice, getting stuck in the ice, waiting for ice to fracture and free them, over-wintering because they got stopped by ice, to get an idea of how extraordinarily different last year really was.
Hank Roberts // July 19, 2008 at 6:31 pm
By the way, that wasn’t inductive reasoning above. Here’s a good lesson in
_______excerpt_follows_______
http://geography.berkeley.edu/ProgramCourses/CoursePagesFA2005/Geog40/Lecture32.pdf
“… Typical scientific arguments are inductive
All evidence presented, assessed, and conclusion drawn. (inductive scientific approach)
vs.
Conclusion drawn. Evidence drawn to support that conclusion, evidence cited to contradict contrary conclusion (deductive argument approach).”
Outline from that page, good background info on how this works:
I. The process of scientific inquiry
A. Scientific terminology
B. Scientific method
C. Deductive vs inductive reasoning
…
II. Making an argument
A. Deductive vs. inductive arguments
B. 2 great fallacies in non-critical thinking
C. Other logical fallacies
D. Science is typically inductive
…
Arch Stanton // July 19, 2008 at 6:43 pm
Nice post Lee.
Dave Andrews // July 19, 2008 at 8:52 pm
Lee,
Private yacht transits of the NW passage are becoming more frequent, in large part due to modern ice mapping and communications, but also due to the loose-ice season being longer, and to there being more stretches of open water.
But the private yachts, the modern ice mapping and communications were not available in the 1930’s for example, so how do you know that if they had been it would not equally have been possible to traverse the passage?
Early explorers of the Arctic were also undertaking that exploration at a time the Arectic was coming out of the LIA.
B Buckner // July 19, 2008 at 8:54 pm
Tim Chase,
Your discussion of ocean currents/heat appears to make a lot of sense:
“Glad to see you are thinking about ocean currents. It is much better at conducting heat than air, and sea ice is nine-tenths below water.”
Are you aware of any data or papers that compare ice extent/volume to arctic ocean SSTs. Is there a data set of SSTs below an ice sheet? Anyway I would like to read up on this and explore it further, and would appreciate it if you could be of any help.
Phil. // July 20, 2008 at 4:30 am
BBuckner: You could try here:
http://www.crrel.usace.army.mil/sid/IMB/newdata.htm
Phil. // July 20, 2008 at 4:55 am
michel // July 19, 2008 at 9:02 am
Tamino, I am aware of the Hadley material. It leaves one unconvinced, because we’re comparing very precise estimates from satellites
What are these very precise estimates of which you speak? Are you sure you don’t mean accurate?
Compare the data from SSMI and AMSRE:
http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=07&fd=19&fy=2007&sm=07&sd=19&sy=2008
http://iup.physik.uni-bremen.de:8084/amsr/arctic_AMSRE_nic.png
Timothy Chase // July 20, 2008 at 5:50 am
B Buckner wrote:
Well, I am no expert in the area. However, I do remember that most of the melt appeared to have been driven beneath the surface — four meters as opposed to a meter above surface, if I remember correctly. Likewise, the arctic sea ice is normally insulated from much of the heat content of the ocean due to a fresh water layer, and much of that fresh water had been flushed in 2007, resulting in more heat exchange.
But mostly what I am going off of is simply what I remember reading on Maslowski. They employed a finer grid than earlier models of ocean circulation and found that the arctic became ice free during the summer by 2013. And this was without taking into account what transpired in 2007.
Anyway, I can do some digging — Google Scholar might help. I can also look up the article that shows how hurricanes appear to be responsible for as much as 15% of poleward oceanic advection. I know I have that on my hard drive.
Let’s check…
Found it — and this part looks interesting:
Anyway, I will look to see what I can find.
Richard // July 20, 2008 at 6:44 am
Hank,
I have read the lecture you refer to. I see no contradiction between it and my inductive reasoning. Vis a Vis:
1. Real World. We see changes and speculate the causes.
2. Observation and Measurements. Namely the satellite observations and correlating the conditions evident when the NW passage opens (only once in the satellite series).
3. INDUCTIVE REASONING. Build a conceptual model of when the NW passage opens. I postulate that this occurs when the ice extent approaches that of 2007.
4. Hypothesis. Therefore, all openings of the passage require similar environmental conditions to 2007.
5. Experimental observation. The hypothesis is tested by continued observation and by analysis of proxy data (i.e. sedimentary analysis etc.).
6. Accept the hypothesis or the null hypothesis depending on observational data.
7. Theoretical acceptance if the hypothesis once accepted stands up to further scientific rigour.
My hypothesis is disprovable. Disprove it! I can’t conduct the experiments to determine the validity of my hypothesis as I don’t have access to the necessary resources (perhaps when I do my Ph.D.).
dhogaza // July 20, 2008 at 7:36 am
What we do know for sure is that Amundsen’s passage wasn’t clear-water sailing, as was possible last year, no matter how strongly Richard insists the two situations were equivalent.
You’ve moved the goalposts. Don’t have to answer that one in order to show that Richard’s full of shit.
And, of course, you follow-up with the just-in-case backstop - “it was coming out of the LIA!”.
Trying to have your cake and eat it, too.
If I owned a hockey stick, I might admit it were broken … after applying it forcefully over your dishonest head.
dhogaza // July 20, 2008 at 2:00 pm
But, of course, the historical record provides no support for your postulate, as has been shown earlier. You *imagine* that Amundsen’s perilous voyage somehow shows that he experienced nearly ice-free conditions as was seen last year, yet his own words make it clear that it was a close-run thing.
luminous beauty // July 20, 2008 at 3:46 pm
Richard,
“4. Hypothesis. Therefore, all openings of the passage require similar environmental conditions to 2007… My hypothesis is disprovable. Disprove it!”
Read my comment @July 18, 2008 at 6:01 pm.
That should cover the period in question. Evidence from varves, boreal tree-rings, glaciers, palynology, etc. indicate present Arctic conditions haven’t been approached since the Holocene maximum, about 8000 years ago.
I hope that helps.
Lee // July 20, 2008 at 4:17 pm
“3. INDUCTIVE REASONING. Build a conceptual model of when the NW passage opens. I postulate that this occurs when the ice extent approaches that of 2007.”
Problem is that facts already in evidence in this thread show that your ‘conceptual model’ and ‘postulate’ are utterly at odds with the facts.
Let me add more. Amundsen’s transit of the NW Passage started in 1903, and ended n 1906. He overwintered 3 winters there, stuck in the ice. One of his most successful ice navigation tricks was to stay near shore and wait for offshore winds to break the pack ice and open a small lead of open water right at the shoreline - he frequently sailed a few hundred feet off the coast in water as shallow as 3 feet, right along shore. He spent so much time dealing with ice that it was in this sailing transit of the NW Passage that he learned the dog sledding skills that he used in his later high-latitude expeditions.
In 2007, at least one yacht sailed straight through in open deep water without ever encountering pack ice.
If you believe that ice conditions are equivalent in those two periods, as you propose in your ‘postulate,’ then you are badly misleading yourself.
Dave Andrews // July 20, 2008 at 10:31 pm
Dhogaza,
I was responding to a comment by Lee.
I know Admunsen’s journey took 3 years because he was ice locked for much of the time. But the Arctic was warmer in the 1930s and I just wondered whether modern yachts with their equipment etc might have been able to traverse the passage if they had been available at that time?
As to the LIA, I understand you might have a problem with that given your belief in the h.s.
Hank Roberts // July 20, 2008 at 11:34 pm
Dave, when you write
> the Arctic was warmer in the 1930s
you need to be more specific. What’s your source? I only find mention of springtime warming, not year-round and not for the decade, and that’s air temperature not sea ice conditions.
Have you any sea ice information or are you using logic?
This is as close as I can come to finding support for what you’re saying. It’s not as simple as you’re describing it, not even close. Have you a better source?
Seasonal and Regional Variation of Pan-Arctic Surface Air Temperature over the Instrumental Record
Overland, J. E. Spillane, M. C. Percival, D. B. Wang, M. Mofjeld, H. O.
JOURNAL OF CLIMATE 2004, VOL 17; PART 17, pages 3263-3282
AMERICAN METEOROLOGICAL SOCIETY
Quoting:
“1. Introduction
In this paper we further the analysis of Arctic variability by reexamination of the surface
air temperature (SAT) from major weather observation stations with long record lengths. We focus on changes in each season and in different regions of the Arctic, rather than concentrating on annual zonal averages, because extensive averaging can often obscure the underlying physics….”
and
“Several authors show that the increase in European winter temperatures in the 1920s were
associated with increased westerlies across the North Atlantic producing warm air advection into Europe; at the same time Baffin Bay was cold, suggesting an NAO connection (Rogers 1985, Fu et al. 1999). Fu et al. (1999) notes considerable strengthening and northward movement of the North Atlantic high pressure region during this period, suggesting the influence of NAO midlatitude processes. Our PCA and Fig. 2 indicate that the Baffin Bay region in the recent half century was out of phase with Scandinavia, showing a continuing interdecadal pattern as earlier in the century. Temperatures over the sea ice in the central Arctic during the 1980s and 1990s also have this wintertime seesaw pattern (Rigor et al. 2000); there was a warming in the European sector of the Arctic, but a cooling trend in the remainder of the Arctic….”
Eli Rabett // July 21, 2008 at 1:51 am
The issue is how thick the ice is. If the ice has been thinning over 50 years or so, at some point you expect a collapse such as was seen last year.
Richard // July 21, 2008 at 3:48 am
Dhogaza,
Ad hominem attacks such as yours cheapens your argument. You lose all credibility when you attack the person and not the reasoning.
Hank Roberts // July 21, 2008 at 4:40 am
Sorry, Richard, I can’t make sense of your claim to have collected facts. You state your beliefs.
Start by listing your facts, what they are, where you found them, how to look them up, and what’s found in the subsequent citations of those papers to see what’s been published since. The point is if you want to use this approach you have to look at all the available information. This indeed does amount to work suitable for a PhD and a postdoc. Much less is just armwaving.
Petro // July 21, 2008 at 5:02 am
Richard: As a presenter of hackneyd false arguments, which has been explained to you a hundred times, you deserve an occasional harsh language from dhogaza. Would you stop presenting lies as premises, you might get some credibility yourself. Currently, you have none.
michel // July 21, 2008 at 7:23 am
Phil asked “What are these very precise estimates of which you speak? Are you sure you don’t mean accurate?”
Yes, it was careless. I meant to say that the satellite observations on which we base current estimates are probably a lot more accurate. Or better founded. They cover the full extent and are systematic. For earlier periods, we are relying on scattered observations from very restricted set of points.
I’m not convinced that we know, based on one year’s data, that something catastrophic is happening, because while I am convinced that we’d have known about it, if it had happened before in the satellite era, and probably if it had happened post WWII, I am not at all sure we’d have known about it had it happened earlier than that.
It will take more than one year to be convincing. If 2007 repeats several years in a row, that will be different.
I am not clear why this is controversial. One year’s cold summer does not throw doubt on the warming trend. Neither really does a ten year stasis in the progress of warming. So why should 2007 by itself be so convincing, in the absence of a long term history to show for sure that it is unusual on a time scale of centuries?
Richard // July 21, 2008 at 9:39 am
Petro,
No one deserves to be called “full of shit”. Respect for anothers view whether informed or not, whether right or wrong is paramount for erudite people contributing to a discourse. Dhogazas’ language says more about him than it does me. A number of contributors have sought to answer my contributions with science, not denigration.
And for your information, I made no claims. Merely a hypothesis. Testable and disprovable (and may well be wrong).
dhogaza // July 21, 2008 at 11:41 am
Richard, I said you’re full of shit. That’s not an ad hom, it’s an attack on your knowledge and argument, not your person.
Get your terms right, please.
“Al Gore is fat” is an ad hom argument.
dhogaza // July 21, 2008 at 1:31 pm
Michel:
Of course we don’t. That’s a strawman, and a horribly stupid one, at that.
What we have is a long-term trend measured by two independent methodologies:
1. satellite data going back about 30 years that shows declining ice coverage.
2. submarine ice mapping data that goes back about 50 years that shows declining ice VOLUME, to the tune of something on the order of 50%. Broken out of the classified data bin largely due to that bogeyman of the denialist world, Al Gore.
Ice experts have been concerned because the pace at which the arctic ice cap is diminishing appears to be WORSE than models project, and the minimum reached in 2007 was far lower than anyone expected for the next decade or two.
Look, if a wing falls off an airplane, it doesn’t necessarily mean there’s a design flaw involved.
But it sure as hell gets the attention of the experts.
Richard:
Where is it written that I must respect a liar’s point of view? My hard-assed fundy xtian mother taught me just the opposite. Lying’s a sin. Sin deserves no respect.
luminous beauty // July 21, 2008 at 2:08 pm
Richard,
You have made an hypothesis for which you have no supporting evidence and for which all the existing evidence would indicate the contrary.
The scientific term for this is ‘full of s–t’.
Don’t take it personally.
Petro // July 21, 2008 at 2:18 pm
Richard:
In Internet, there is no way of knowing who the other is, it is the arguments which are evaluated. When your arguments are illogical, irrelevant or lies, then it is ok to call your character to be “full of ‘your favorite brown matter’” occasionally. I don’t claim it is polite, but similarly it is not polite,when you repeat lies as facts again and again.
Your arguments or hypotheses or whatever are in stark contrast with plain observations and scientific results. It takes two week for you to go through a basic readr in climate science. If you are not willing to do that work, you get the basics in two days from AR4 or in two hours from Inconvenient Truth. This not rocket science and is well within your intellectual capacity.
But it is a different challenge, if your political, economical or religious conviction or your psychological character prevents you to accept scientific facts. For example, just look how pathetically Nanny still nags with the same old, same old for two years. It is your desicion to avoid such destiny.
Hank Roberts // July 21, 2008 at 5:16 pm
Michel, you state as though it were true:
> in the absence of a longterm history
You can look this stuff up. All you need is an hour or two spent learning the words.
Alternatively, point and click, but you’ll still have to learn the words:
http://scholar.google.com/scholar?sourceid=Mozilla-search&q=arctic+sediment+climate
Lee // July 21, 2008 at 6:07 pm
Richard: “And for your information, I made no claims. Merely a hypothesis. Testable and disprovable (and may well be wrong).”
Te reason your ‘hypothesis” is getting savaged, Richard, is not only that it “may well be wrong,” but that is is in stark, glaring disagreement with the fact you cite as the basis for your “hypothesis.”
It would be as if I said, ‘yesterday I opened my freezer and the ice cube tray was full of ice cubes. Today I opened the freezer, and the ice cube trays were full of liquid water. Because I could look into the freezer both days, I hypothesize that the conditions there yesterday were the same as today. I may be wrong, of course - its just my hypothesis. Disprove it.”
To which the only possible response - the same one we’ve given you, Richard - is that the evidence I list as the basis for my hypothesis (and yours, Richard) ALREADY disproves the hypothesis.
Eachran // July 24, 2008 at 5:05 pm
Tamino, I quite like your stuff : you seem to me an honest man and dont get upset about your Jury Duty piece. I think that you are an admirable person for doing Jury Duty : forget about the critics, they are not serious people.
But on this thread?
I am quite interested in the idea of putting ones money where ones mouth is, and therefore : apart from Nick Barnes, who I believe has already some spondoolies with Mr Connelly, is there anyone else on the thread who is prepared to stick their neck out on Arctic sea ice extent for 2008.
Or do you all think that betting is vulgar?
I follow the climate issues with interest but I am not an expert : I am currently wrestling with oceanic pH changes and what I read I dont like the look of. But Arctic sea ice seems to me important too.
Lee, I liked your posts.
[Response: I don't regard betting as vulgar, but I've found that life is simpler and happier if I use my money for things like food, rent, etc. That's for me, others should decide for themselves.
The experts do seem to be split, about 50-50, on whether we'll see a super-low in arctic sea ice this year like last year's. From my perspective, it's not likely because the data so far this year don't match the decline of last year. But that ignores the fact that the ice is truly a lot thinner, so "I wouldn't bet on it." And of course I'm certainly not an expert on the cryosphere.]
David B. Benson // July 24, 2008 at 8:37 pm
Eachran // July 24, 2008 at 5:05 pm — Betting on Arctic sea ice extent seems to be centered here:
http://scienceblogs.com/stoat/
Petro // July 25, 2008 at 4:35 am
Compared to year 2007, this year sea ice has packed to the shores of Siberia. This seems to have happened at the expense of the ice in North of Greenland, the old ice is no more contact the land meaning that even though the area of ice is not diminishing, it is getting thinner.
Also, there is still 1.5-2 million km2 loss in pipeline for next month, mainly from the Arctic basin, meaning that this year the second lowest sea ice area is reached. Would melting period last to the first week of September, which two weeks longer than last year, the record should be reached.
Eachran // July 25, 2008 at 1:42 pm
David B. Benson, thanks.
I follow the blogs of Messrs Connelly and Annan from time to time because they seem to me intelligent and serious people and tend to get it right. I also read realclimate regularly, and others, and tend to follow up on links from people I regard as reliable.
I recognise most of the names of posters.
From time to time I look at stuff like climate audit (is that it?) but frankly I like neither its house style nor its logic.
Tamino, thanks for reading my post : dont weaken.
David B. Benson // July 26, 2008 at 1:01 am
Eachran // July 25, 2008 at 1:42 pm wrote “… but frankly I like neither its house style nor its logic.” I’ll say that indicates clear thinking, good sense and taste.
Paul Swanson // July 27, 2008 at 6:10 am
If the 2008 sea ice extent minimum is to be lower than that of 2007, when would you anticipate the current sea ice extent to be less than that of 12 months previous? The 2008 sea ice extent has yet to be less than that of the corresponding 2007 values.
[Response: Not quite correct. From June 9th to 13th, 2008 shows lower extent than 2007.
IF this year's minimum dips below last year's, I'd expect it to be below 2007 values around mid-September.]
Paul Swanson // July 27, 2008 at 5:55 pm
That would explain the flurry of MSM articles in June predicting a total melt off. Still the difference between the 2008 and 2007 data for June 9th to 13th is so miniscule, I would venture to guess that it falls within the error bars of the measurement.
Hank Roberts // July 27, 2008 at 6:22 pm
> error bars of the measurement
Depends on whose. Satellite measurements available to the public? Navy submarine measurements made from below?
Note the many climate model articles coming out of the Navy Postgraduate program, where they can publish conclusions even from classified details. Note the last bit of Wegman’s caution about polar temperature.
Some of the Navy scientists have figured out that defending the country may require defending the whole world, and that they’ve got data.
http://scholar.google.com/scholar?q=arctic+sea+ice+navy+submarine+sonar&num=20&hl=en&lr=&newwindow=1&scoring=r&as_ylo=2003
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