This is a continuation of the previous (and now unwieldy) post on the current Arctic situation. We’ll have a proper round up in a few weeks.
Climate science from climate scientists...
Climate science from climate scientists...
This is a continuation of the previous (and now unwieldy) post on the current Arctic situation. We’ll have a proper round up in a few weeks.
Latest (July) ARCUS Expert Assesment now out.
http://www.arcus.org/search/seaiceoutlook/report_july.php
Well, it’s been awfully cold today in Suva (Fiji), where I live, during the wintertime as well as the summertime, so I am not surprised about anything happening up over.
Re: #1
Well 4 of the proejections are already wrong.
Many people seems to be fixed on sea ice extent, which gives no indication of volume or thickness of the ice.
Sure if we get the right wind conditions, the remaining ice can be compacted to below the 2007 minimun.
The best indicator, although not perfect is sea ice area, as it gives a better idea of the condition of the ice, and takes in consideration the concentration for each pixel.
This is why I prefer Cryosphere Today as an indicator of the ice state (this was an unpaid endorsement :) ).
Right now its late August, and surface melt north of 80 will be at a minimun. I figure there is about 0.3 million sq km of ice left to melt in the Fox Basin and Siberian and Labtev sea, which will/should melt due to water temperture.
We stand a good chance of beating last years sea ice area. However I beleive the sea ice extent will end up in the high 4’s million sq km.
The end result, after a particularly cold winter, a greater volume of ice will have melted this year, than last.
With no multiyear ice in the beufort sea, the first year ice that forms will be constantly destroyed by storms, and will be at a much larger scale than last year.
Meanwhile the remaining first year ice, will not become second year ice, as it will be flushed out into the Atlantic by the trans polar current.
We will start 2009 in the same state as 2008, and if the winter is mild, and we get an early summer melt like we did in 2007, then Santa is going to be swimming.
RE: #3
As I understand it, the concentration calculated from the passive microwave data is sensitive to melt ponds as well as to open water. Thus, your claim that the actual ice area for each pixel can be found using this calculation is likely to be incorrect. For this reason, I tend to look only at the extent calculation, not the area. In spite of that, I think an increase in melt pond area would be just as important as an increase in open water area, as the melt ponds have lower albedo than ice or snow.
E. S.
It is clear that the NSIDC graph is correct, and that the 2007 UIUC maps are not precise enough to be used for quantitative analysis.
Comment by Steven Goddard — 21 August 2008 @ 20:17
So pixel-counting seems quite valid to me, and appears to demonstrate that older UIUC images are simply not accurate.
Since these images are widely linked, shouldn’t they do something about it before more unsuspecting pixel-counters are lured to their death?
Comment by dipole
I find that the UIUC maps seem to compare very well with the high resolution images obtained with the AMSR-E imager, see below for a comparison on 8/11/07:
http://iup.physik.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2007/aug/asi-n6250-20070811-v5_nic.png
http://arctic.atmos.uiuc.edu/cryosphere/deetest/deetmp.7104.png
The NSIDC image looks rather similar too to be honest when one considers its lower resolution (for day earlier):
http://nsidc.org/news/press/2007_seaiceminimum/images/20070810_e
The Arctic sea ice is a key indicator of climate sensitivity. I saw a graph the other day of 1979-2007 satellite data projected onto the IPCC scenarios chart for sea ice loss and its worse than the worse scenario. However is 1979-2007 statistically significant enough to warrant a doubling of climate sensitivity. If it is then has anyone run a CGM of when climate sensitivity was doubled and if so, what were the range of scenarios then plotted agaisnt actual satellite data ?
Might it be that albedo feedback will now play a lesser role in AGW destruction of the summer artic ice cap? Blogging as a passive, uneducated observer, it seems to me that wind and wave generation are playing an increasingly important role in the destruction of the summer ice cap. Ozone loss has increased the speed of artic winds and AGW has moved the summer storm track poleward; therefore it could be that increased wind speeds and duration will allow the destruction of the ice cap through wave-driven mixing of surface waters and increased importation on warmer Pacific and Atlantic waters into the Artic Ocean after sun-driven melting has come to a stop. Perhaps the summer melt season is being prolonged by these other than albedo feedback global changes. Perhaps a whole new crop of experts needs to be recruited; that is scientists and engineers who predict wave height and power based on wind speed and duration and fetch.
Re #5. There is a reply from UIUC/CT on Anthony Watts site concerning claims of inconsistency between their images and other published data comparing 2007 and 2008 Arctic ice.
They do indeed confirm their image sequence is generated consistently and suggest that comparisons based on pixel-counting are invalid because of mapping distortion.
I did try to incorporate mapping distortion into my own pixel-counting adventure but was still unable to reconcile the figures. Evidently I was either using the wrong projection, or perhaps made some other error.
Francois Marchand. was it cloudy?
Great report by Cecilia and company. Goddard is a trend setter for his colleagues, they will
use first impression “common sense” one dimensional reasoning to proclaim an “ice recovery”.
While the real argument is why it melted just as much or more than last year with the temperature record cooler?
Remember that Maslowski’s 2013 prediction puts polar bears, walrus, narwhales, and ring seals at risk in the very near future. (see for example http://en.rian.ru/russia/20080818/116103830.html & http://www.marketwatch.com/news/story/multiple-polar-bears-discovered-swimming/story.aspx?guid=%7B9D938E1B-7204-4D4E-8ACF-9EC53B685635%7D&dist=hppr.
Remember that navy is rather careful. A navy captain that runs his ship aground is likely to lose his command. I expect that Maslowski is also careful.
Besides, I got the same result using another approach.
Further more, lack of sea ice puts open water on all sides of Greenland. That means any summer breeze in the Arctic will bring rain to Greenland. And, rain melts ice. That is a subtext that no careful navy man would say these days.
dipole Says: 22 August 2008 at 11:09 AM
> Re #5. There is a reply from UIUC/CT on Anthony Watts site …
Would you mind providing a quote/cite/link?
“There’s a pony there somewhere” just isn’t sufficient motivation to go look.
NSIDC has worked with Mr. Goddard to get to the bottom of the issue with the UIUC and NSIDC images and as has been mentioned in the comments above, he has posted a correction. I thank Mr. Goddard for his cooperation in this matter.
Regarding sea ice area, as Eric Swanson (#4) responded already, yes area estimates can have potentially large biases because of surface melt. This tends to make the area calculations too low. It still can give reasonable results for comparisons between years, though some of the difference between years can be changes in melt instead of changes in real area. Extent is more stable and consistent because, while the sensor may underestimate the specific concentration, it does a good job capture the threshold between ice and water (using a 15% concentration for the threshold).
Another issue with area for long-term tracking is that you can’t estimate the area within the pole-hole around the North Pole. This is a problem because different sensors, with different sized pole-holes exist between 1979-1987 and 1987-present. So you can’t do a 1979-present trend with area (this cropped up in some blogs earlier, saying 1980 area was the same as this year, but neglecting the fact that the pole hole was larger in 1980). For extent, we can safely assume that the pole-hole is filled with at least 15% ice. This is a very safe assumption. Or it least it has been – it may not be for much longer, though I think we’re pretty safe now for this year.
Walt Meier
Research Scientist
National Snow and Ice Data Center
Here’s the opening of William Chapman’s post on wattsupwiththat dated 22/08
William Chapman (07:27:26) :
Hi Folks,
There is no difference between the data or the way the 2008 and 2007 images were produced in the comparison images on the Cryosphere Today. The apparent differences Mr. Goddard observed between the NSIDC values and those produced comparing images from the CT are almost entirely due to the mistake of using pixel counting to compute area on severely distorted satellite projections………….
I’d be interested in knowing some details on how the Cryosphere Today images are created. I found it quite easy to discover on the NSIDC site to understand where the data came from and how it was processed, but I wasn’t able to do that from the UIUC site. Could well be I just overlooked it or that it’s described elsewhere. Does anyone know?
Plea to the Contributors — you’ve locked the prior thread with the last 2 posts being vehement affirmations of the now-discredited pixel-counting method. Could you all at least place a pointer there at the end to this continuation?
Else — as I notice happens quite often — the last few postings in the closed thread leave a quite wrong impression.
For the lazy or naive or new reader coming along later, who might not find all the scattered bits, it’d be a kindness not to leave that misapprehension easy to fall into.
It looks to me that the Northwest Passage will open in a week
The I look at
Daily Updated AMSR-E Sea Ice Maps
http://www.iup.physik.uni-bremen.de:8084/amsr/amsre.html
It look to me that also Northeast Passage will open
Yesterday and day before was line of open water all the way
The losses have failed to slow down in the last few days, but the current ice extent is still well above 2007. Closer to 2005 than 2007. The slow down could start any time. The regrow is due in a month. So it aint over until the fat lady sings!
I think I have figured out what is going on with the UIUC images. I am pretty sure that the archived images are actually showing the extent of ice at 50% cover or more; and that more recent images are showing the extent of ice at 30% cover or more.
To check this, I have taken NSIDC satellite data, and made my own images. I have projected them on the globe using a viewpoint above the pole which has a tangent to the surface at about latitude 27. This gives a very close match for the land masses in the UIUC images. I can overlay bit maps and get quite close agreement.
I can then compare the area weighted sum of NSIDC satellite data (f13 channel, ~25km grid) with an area weighted pixel count of UIUC images; also with the reported data at JAXA.
For 12-Aug-2007
36683 pixels of ice on the UIUC image
4469014 sq km projected area
4201452 sq km at 50% or more, by simple count of NASA data
5057390 sq km at 30% or more, by simple count of NASA data
5679174 sq km at 15% or more, by simple count of NASA data
5421094 sq km at 15% or more, reported by JAXA
Some small differences are to be expected from processing differences; but basically the UIUC projected area lines up well with the extent of 50% ice, and JAXA lines up with the extent of 15% ice as reported.
For 11-Aug-2007
47822 pixels of ice on the UIUC image
5882718 sq km projected area
4612971 sq km at 50% or more, by simple count of NASA data
5783576 sq km at 30% or more, by simple count of NASA data
6462289 sq km at 15% or more, by simple count of NASA data
6291563 sq km at 15% or more, reported by JAXA
This time the UIUC projected area lines up well with the extent of 30% ice, and JAXA still lines up with the extent of 15% ice.
Furthermore, I have projected the NASA data onto bitmaps, projected to align with UIUC images, and I get close agreement with the images using 50% for 2007 and 30% for 2008.
I’m going to stick my neck out and predict that the UIUC archived images are actually showing the extent of ice at 50% or more, and that the recent UIUC images are showing the extent of ice at 30% or more.
Re: 16
About Northwest passage: Polarstern is now crossing it. Meteorological reports: http://www.awi.de/en/infrastructure/ships/polarstern/current_meteorological_data/
Position: http://www.sailwx.info/shiptrack/shipposition.phtml?call=dblk and http://www.iup.uni-bremen.de:8084/amsr/Polarstern_visual.png
Ice report (2008/08/22, 21:00UTC): 44092 :
4 — Close pack ice 6/8 to
Oops. In my previous comment, the second set of figures should be labelled 11-Aug-2008.
Here are the sources of data I used.
UIUC images are obtained from UIUC Compare daily sea ice, gives a side by side of any two days.
Extent of 15% cover sea ice is reported at IARC-JAXA
Satellite data in near real time for recent dates, available from DMSP SSM/I Daily Polar Gridded Sea Ice Concentrations, data from NASA and made available through NSIDC.
Older (and better reviewed) satellite data from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data, data from NASA and made available through NSIDC.
#16 NW Passage:
Called first here last year (#77 and #89) for 10 August, although NSIDC subsequently put the historic event at 11 August 2007. Looks like the McClure Strait route will open 2-3 weeks later this year.
Re: #12
I can understand how sea ice area can be biased because of melt ponds, however this should only be an issue in July and August for the most part. By the time of the September minimun, my understanding is that the melt ponds would be frozen, and most likely snow covered.
Likewise in the fall, the sea ice extent can be biased by wind conditions that can force the compaction of the ice or vice versa loosen the ice over a wider area, making year to year conditions more biased to weather conditions.
I would think that sea ice area would be a better predictor of ice conditions, when it comes to determining the true sea ice conditions at the time of the sea ice minimun.
# Hank Roberts Says:
22 August 2008 at 12:22 PM
“Would you mind providing a quote/cite/link?”
Sorry about the delay in replying. The thread in question is this one, which I see is also the subject of a couple of other recent posts here:
http://wattsupwiththat.wordpress.com/2008/08/15/arctic-ice-extent-discrepancy-nsidc-versus-cryosphere-today/
But looks like discussion is not dead yet.
Just read Jim Hansens’s report from a recent trip to Germany and a meeting with the German Minister of the environment Sigmar Gabriel. Jim Hansen has an excellent way of condensing information and presenting it in a very digestible form. His emphasis or rather crusade is to leave as much as possible of the remaining fossil fuels in the ground and fast track alternative energy sources..he touts a new revolutionary 4th generation IFR or Integral fast breeder reactors which eliminate almost all the negative aspects of current reactors..ie 99% of the fuel rods are utilised..the remaining 1% can be easily stored on-site and can not any more be used for weapons grade material. It does not need water cooling and is much more earthquake resistant than any other station..and here’s the knockout….we have enough existing fuel rods even spent fuel rods to power these stations for a few centuries!!.
World’s energy problem..sorted!!!
In Jims article there is also a fantasic counter to the contrarian angle that the world is now actually cooling and an ice age is imminent.
What he also says is that even if we stop coal use tomorrow and only use oils and gas until they dry up that will still irreversably melt the remaining ice with the resultant consequnces we all all aware of. Here’s the link for that report..GREAT READING!!…http://www.columbia.edu/~jeh1/mailings/20080804_TripReport.pdf
I have also come across a website which daily maps the ice melt in the arctic and antarctic..very interesting indeed!! Here’s the link… http://www.iup.uni-bremen.de:8084/amsr/arctic_AMSRE_nic.png
Been reading about Greenland’d Ilulissat glacier and it it now travelling at over 2metres/hour- much much fater than at any time in the past; this glacier also has significant numbers of moulins futher up onto the landmass so the melt water lubrication of the bedrock is significant. Those glaciers with fewer moulins tend to move slower than the ones with more melt water pond and moulins. The IPCC predictions of sea level rise only took into account the forcasted rise in greenland temps and thus the consequent increase of the ice melt but not the amount of water vanishing into these huge holes in the pack ice. When this is factored in the rate of glacial ice becomming floating ice will definately and significantly narrow the time frame for serious sea level rise mitigation action on a global scale.
Fret not too much about the small stuff. Over-analysing this year’s ice extent is like looking at ‘weather’. We need to look at the longer trends to pick out the ‘climate’ of the artic ice.
We have watched the multi-year ice practically vanish over the last 12 monts, and as others have said, the ice that remains will be like fluff in front of the weather this coming winter.
If I was a polar bear I would be renting a place on solid ground sometime soon, and plotting the annual ice area running averages on the wall.
#22 LG Norton,
I was already aware of the issue Walt Meier has stated. However as I’ve already said before I still think Extent runs the risk of overlooking increasing areas of less than 100% concentration, due to thinner ice. AFAIK there will still be melt ponds around the time of the minima. But whatever method one chooses when using imperfect data one has to compromise.
For my own purposes and considerations I continue to use Area with “advice” from NSIDC’s extent, AMSRE/Terra/Aqua and all the other information available. But it’s crucial that anyone talking about this understands the indices and associated caveats.
PS useful page at Hamburg University supplementing their ARCUS outlook: http://www.ifm.uni-hamburg.de/~wwwrs/seaice/amsr-e.html
So the same people who think that photographing weather stations gives better information than measuring temperature also seem to think that counting pixels on a map projection “proves” that graphs generated from the underlying data are wrong?
Cryosphere Today should switch to a mercator projection. Voila! More ice in the north than ever before! Just count those pixels!
Dipole, sorry, same problem. You link to the thread.
At the top of the thread it says “see correction below – Anthony”
Search “correction” and you find —- no pony. I’m sure there’s one there somewhere. Where, exactly?
Did wossname publish a correction in the Guardian? Anyone have a direct link to that and a quote?
29, Nigel,, it is good to micro-analyze, otherwise someone will count pixels (mixing water mixed with ice) as to make a picture mean something other than what happened. Its good to see how innocent and fragile contrarian theories are. They get blown away by the smallest wind.
#28 Lets see now, people taking pictures of weather stations? Fascinating! How they do figure out temperature from taking a picture of a silly weather station? Geography lesson. Longitude shrinks as one approaches the pole, so area is smaller where the ice is.
Hank Roberts:
Right at the bottom of Mr. Watts’ post is this added correction (however be aware that Bill Chapman has asserted the UIUC maps are correct, according to his post there, and Mr. Chapman claims that Mr. Goddard’s projection is incorrect):
NOTE OF CORRECTION FROM STEVEN GODDARD:
The senior editor at the Register has added a footnote to the article with
excerpts from Dr. Meier’s letter, and a short explanation of why my analysis
was incorrect.
To expound further – after a lot of examination of UIUC maps, I discovered
that while their 2008 maps appear golden, their 2007 maps do not agree well
with either NSIDC maps or NASA satellite imagery. NSIDC does not archive
their maps, but I found one map from August 19, 2007. I overlaid the NSIDC
map on top of the UIUC map from the same date. As you can see below, the
NSIDC ice map (white) shows considerably greater extent than the UIUC maps
(colors.) The UIUC ice sits back much further from the Canadian coast than
does the NSIDC ice. The land lines up perfectly between the maps, so it
appears possible that the UIUC ice is mapped using a different projection
than their land projection.
Click for larger image
Because the 2007 UIUC maps show less area, the increase in 2008 appears
greater. This is the crux of the problem. I am convinced that the NSIDC
data is correct and that my analysis is flawed. The technique is
theoretically correct, but the output is never better than the raw data.
Prior to writing the article, I had done quite a bit of comparison of UIUC
vs. NSIDC vs. NASA for this year. The hole in my methodology was not
performing the same analysis for last year. (The fact that NSIDC doesn’t
archive their maps of course contributed to the difficulty of that
exercise.)
My apologies to Dr. Meiers and Dr. Serreze, and NSIDC. Their analysis,
graphs and conclusions were all absolutely correct. Arctic ice is indeed
melting nearly as fast as last year, and this is indeed troubling.
– Steven Goddard
http://wattsupwiththat.wordpress.com/2008/08/15/arctic-ice-extent-discrepancy-nsidc-versus-cryosphere-today/
Uh, it’s the UIUC that makes the projection – that’s how you take the spherical earth and smooch it down to a flat piece of paper or digital image for viewing on a computer screen.
Is it really hard to understand that the map can be correct but trying to analyze the underlying data from the pixels, rather than directly from the data, is … ill-advised?
Is it really hard to understood that the maps aren’t generated without the notion in mind that someone will try to invert it to retrieve the original data, because no one sensible will do that?
Is it really hard to understand that counting pixels on a projection, without taking the distortion inherent in any map projection into account, after it’s been JPEG’s once, etc etc … and then taking that so-called “analysis” and shouting to the world “the NSIDC graph generated from REAL DATA is wrong!” is just … STUPID?
captcha is “Sherman found”, odd, because in my case it’s “Sherman lost” (having moved recently from my old house on Sherman street!)
An computer-generated image, where you don’t know just how it’s been processed, is “raw data”?
Goddard ought to just give up on trying to justify his pixel-counting analysis. Even Watts admits that the original image that Goddard worked from had been JPEG’d once before ending up on the website in PNG format. Even if it hadn’t, what guarantee would one have that it hadn’t been (if it were me, I’d just put it up in JPEG in the first place, just to make the silliness even more apparent)?
A map projection is not raw data, regardless of postprocessing, and when you don’t know that postprocessing doesn’t include lossy compression …
Geez.
I just thought someone should point out that ice area looks like it might be bottoming out: it was 3.653 million km2 on 19th Aug and now (23rd Aug) it is 3.669. Note that it bottomed out at this point last year as well. If the 3.635 of 2 days ago were to be the lowest of the season, then this would be 24% more than the 2.92 a year ago. Even if it drops to 3.50, this is still 20% more.
In this light, Goddard may have been onto something after all (somewhat fortuitously I admit) and statements like the following I noted above may turn out to have been somewhat premature.
“We have watched the multi-year ice practically vanish over the last 12 monts, and as others have said, the ice that remains will be like fluff in front of the weather this coming winter.”
Walt, Great to see you in here!
I apologize for missing out on this continued thread for so long. And please pardon my ignorance of the discussion thus far. I see a lot about pixel counting and what not.
If I may summarize my own perspective, naive though it may be. We’re losing the sea ice. Volume is on a decreasing trend and existing forcing levels combined with the ups and downs of natural variability are playing a role.
The media of course continues to cherry pick data out of context due to their own lack of understanding the context.
Generally speaking, we are talking about loss of the ice and in my mind that should be getting us to think about other things like the degree of positive feedback that will cause as more and more dark water is exposed during Arctic summer.
And what is that going to do the the circulation patterns?
These are the questions that I would love to talk about.
How much will global warming accelerate, especially when you consider that the Schwabe cycle is going to be getting back in gear soon and at the same time as more dark water is exposed?
Again, my apologies for not keeping up on the thread and jumping in late. Honestly, I did not realize there was such a debate in the thread till the continued page popped up :)
RE # 34
Chris, you said;
[Even if it drops to 3.50, this is still 20% more.]
I am not hair-splitting when I say the 2008 ice extent began melting from an area of 13.8 MM sqkm versus 13.2 MM sqkm in 2007. If 2008 melt stops at 3.5 versus 2.92 last year, total melt in 2008 would be about 10.3 MM sqkm compared to 10.28 MM sqkm last year. About the same, would you not agree?
Lots of heat released and lots of fresh water entering the Arctic ocean.
John McCormick
Re: #22, LG Norton
You make good points. Yes, melt pond and surface melting effects occur primarily during mid-June through mid-to-late August. By September, even though there may be melt occurring at the edge, much of the surface of the pack ice has begun to refreeze..
And extent can be affected by winds. Winds played a role in the late dip in 2005 (making the extent minimum among the latest on record) and in last year’s record. But generally the impact of this isn’t terribly large.
There are also other factors that affect area more than extent, namely atmospheric emission, changes in other surface properties beyond melt (e.g., ice thickness, snow cover, frost flowers, etc.). All these lead to false variability in the area estimates.
In reality, both area and extent can yield insight into the ice conditions (using both area and extent can give a sense of the compactness of the ice, at least outside of the peak melt period) and both generally give consistent information in terms of trends, variability.
However, NSIDC feels that using both area and extent can lead to confusion in the public and that extent is a more stable, more consistent parameter to measure.
John Reisman (#35) – hi John! – makes some good points. Despite the confusion and some skeptical viewpoints, the reality is that Arctic sea ice is decreasing, the volume as importantly as the extent/area, and there will be some substantial impacts of this fundamental change in the character of the Arctic.
For any that might not be aware, there’s discussion on the ice thickness/volume, along with extent/area on our NASA-funded sea ice analysis web site:
http://nsidc.org/arcticseaicenews/
Look for our next update in the next couple of days.
Walt Meier
NSIDC
Not really. Remember, his claim was that this map, using pixel counting to compute ice extent, proves the NSIDC graphs of ice extent to be wrong …
Extent. Not Area.
The last poster mentioned positive feedback from water exposed during the Arctic summer. I don’t want to diminish from the possible effects of this over a period of years. However, I would like to add a perspective that some may not have considered re: this past year. If you compare Arctic ice area http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.jpg with Antarctic area http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.south.jpg over the past year, you will see that the Arctic anomaly has averaged ~ -1 million km2 while the Antarctic anomaly has averaged ~ +1 million km2, and the values for the midsummer months have been close to those averages.
I’m aware that the positive anomaly in the Antarctic may just have been a blip. However, the interesting point to note here is that the ice boundary in (SH) midsummer in the Antarctic is at a significantly lower (i.e. further from the pole) latitude than the ice boundary in (NH) midsummer in the Arctic (there’s a whole continent before you get to the sea ice!) Thus, the cooling albedo effect in Antarctica per km2 of extra ice at the margin is likely to have been greater than the warming effect in the Arctic per km2 of extra open water, and so for the past year at least, the net global positive feedback from ice albedo changes looks to have been (surprisingly) minimal.
Addressing the pixel-counting issue:
A proper description of it is, as someone above named it, “ill-advised”. However, if the projection isn’t too distorting, it is a relatively easy back-of-the-envelope calculation that provides a decent rough estimate. If it’s an equal-area projection, then it will actually give the correct value. NSIDC’s standard sea ice products are not equal-area, but the polar stereographic grid used is true at 70 N. Thus, with summer sea ice historically having its ice edge near 70 N, such a pixel-counting method can work reasonably well. In fact, I and others, in collaboration with the NSF-funded Science Education Resource Center, helped develop an educational module to work with our data, using the approximate pixel-counting method.
One key thing about the exercise is that it uses the actual data and is a count of the data pixels, not pixels in an image, which has less chance of further distortions that can occur in producing an image. The problem with the UIUC images is that the projection is more distorted, as well as other issues with the images, that Mr. Goddard and others have discussed in previous posts.
Walt
Re #36 John
There are lots of statistics that can be presented here, including the one I cited re: absolute minimums 2007 vs 2008, and the one you cited re: absolute melts.
Ultimately it depends on your viewpoint. I would say that the key issue this year has been what happens in the summer melt season, so I would assign less importance to the brief extra ice that was around on the fringes of the Arctic circle (not in the Arctic Ocean, note) at the end of winter, thus enabling your 10.3MM to match the figure of 2007. Rather I would look at what has happened since the beginning of May, when the melt season gets going in the Arctic itself.
What you will see is that the anomaly never diverged very far from -1MM in May, June and July. It’s only in August that it took a sharp tumble (caused incidentally by persistent anomalously warm southerly winds over the Siberian seas) that has now bottomed out (n.b. the wind pattern has finally changed in the last few days)
So the average anomaly has not been nearly as low as it was last year, it’s just that the ice area was briefly very high at the end of winter, and has been briefly very low in the last couple of weeks. I therefore disagree with your characterisation of the situation as “Lots of heat released and lots of fresh water entering the Arctic ocean.” My characterisation would be something along the lines of “consistently significantly greater ice area and extent throughout the main melt season, albeit with the gap narrowing briefly towards the end”. Also if area is indeed bottoming out now and does not dip below 3.5MM, then I could perhaps add the statistic of >20% more multiyear ice, since presumably any first-year ice from last winter that survives this season becomes multiyear?
#38 Fair point – when I said “onto something”, I simply meant that he may have been onto something with his theme that “Arctic Ice refuses to melt as ordered”. Certainly looks like he was dead wrong in what he said about the NSIDC data,
Walt:
“NSIDC’s standard sea ice products are not equal-area, but the polar stereographic grid used is true at 70 N.”
vs
“Thus, with summer sea ice historically having its ice edge near 70 N”
Must necessarily mean that the products are not equal area.
Rather like saying “the sinusoid is evenly positive and negative around the zero mark, so when we take from 0 to 0.1 it’s pretty accurate to go for that”.
Now that may mean that the overall effect isn’t a lot different, but your statement didn’t say that.
Cheers.
I would say that as far as albedo changes are concerned,the difference between 1 year ice and multi year ice is negligible. It’s all white.
What does matter is how easy it will be to change the ice cover next time.
Lawrence Coleman,
Is the report of Hansen’s trip available on line?
[Response: At his website – gavin]
Enough of Goddard…… He apologized, there is hope after all! There are other ways to see what happens to the ice aside from counting pixels. One must be aware of all 5 major league ice physical vectors to observe (as often as possible) before jumping to any pixel conclusion, namely: ocean current, tides (gravity), momentum, winds, pressure, all to be watched continuously and then there is temperatures for a melt, sea (from multiple layers) and air unfortunately 2 meter height may not be enough, ice temperature, also clouds are important, radiation input, and I am missing a few. Let it be a warning for those who try to outsmart great work such as
http://www.arcus.org/search/seaiceoutlook/report_july.php
and others, but NSIDC 15% extent minima is confusing, and I think 50% or more would be better for the lay. Even studying conservative CT 2008 daily ice map is comparable to 2007. In looks now,
Now that Goddard apologized, the big question remains, since the surface temperature record
shows a cooling compared to last year, why did the ice melt just as much and a litte more (till september 20)? Something somehow must give, Even the winds and clouds were unfavorable…
Then why , anybody has a clue? I already suggested that the weighted temperature of the atmosphere was just as warm as 2007. I am all ears for other ideas.
In case it wasn’t clear, when I called it “ill-advised” I was speaking specifically of doing it to the images published on a website.
Hacking on the data pixels themselves is another thing altogether, and makes a lot of sense.
I just took a look at Goddards article “Arctic ice refuses to melt as ordered”
http://www.theregister.co.uk/2008/08/15/goddard_arctic_ice_mystery/
There are more than a few contextual problems with the perspective representation. I’m glad Walt and Steven were able to get the truth illustrated though.
The real problem in my view is context though. We are in the low end of the Schwabe cycle, so some solar energy .3 W/m2 is removed until the cycle swings back up. That along with things to complex for me to imagine in natural variability are at work in the short term. Context is critical when explaining anything related to the climate and pieces of data.
Other things I noticed include: First “some scientists” are not all scientists regarding the ice free north pole comment. I actually did not here any scientists predict that the polar ice cap would “disappear this summer”.
When he talks about the NSIDC graph, first he states it is “an alarming graph”. Really, it’s just a graph and alarming is an insightful claim that conveniently sets him up for his coup de gras statement, i.e. that the”ice has grown in nearly every direction since last summer”. That is true, but that means nothing to the overarching trend. i.e. no relevant context.
Unfortunately this is cherry picking the data. By taking a single day v. another single day, or even a year and trying to say it proves something is certainly improper when the true contextual relevance depends on the long term trends within the scope natural variability on the new path that we have set our atmosphere on.
https://www.realclimate.org/index.php/archives/2008/07/global-trends-and-enso/#comment-91593
Arguing about the details has some constructive purpose certainly, so that we may all understand this better, but it seems to me that the main problem with the article was not merely cherry picking out of context, but it’s tone out of context with the bigger picture.
Having now read Hansen’s account of his trip, I urge others to do so, but his attitude to “4th generation” nuclear power is not as unequivocal as Lawrence Coleman suggests. He’s recounting his own reading of a book by Tom Blees; and he’s very interested but not wholly convinced. Myself, I’m sceptical – Blees does not appear to be technically qualified, there’s always some new form of nuclear reactor just round the corner that’s going to solve all the problems of waste, proliferation, etc., and none of these “4th generation” plants yet exist or, so far as I can make out, are even planned.
BTW, I was obliged to remove most of my #46 to get it past the ludicrously over-sensitive spamometer – e.g. the title of Blees’ book. Hansen gives it, and parts are available online if you google Blees’ name and the title.
[Response: The book is “Prescription for the planet” (website) (PS. a hyphen will work to defeat the filter – sorry for the inconvenience). – gavin]
Wayne – “…why did the ice melt just as much and a little more…”
As I have been informed, the 2007 melt was caused by warm ocean currents and this year warm winds seem to be the cause for the recent drop.
But more importantly, why is everyone so focused on this years ice extent being a little greater than last year’s? These things fluctuate from year to year, but the long term trend is the important indicator. Since ’79 the trend is down with occasional outlier extents. The last two years haven’t changed that. If anything the trend is accentuated.