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.
#481 CobblyWorlds
Good question: What’s the difference between 21/8/08 A & B?
All I know is that the 1st Ice map of the day appear at the evening and the 2nd with the same date appear in the next morning.
Wayne,
Thinking aloud again.
Forget tidal bores which are simple waves, but here we a talking about a major wave.
However, the shelving amplification of the tidal wave may be amplified by the weight of the ice. If the wave passes under an ice shelf, or solid sea ice it may be amplified just as it would be by a shelving sea bed. If the ice is low concentration, then the tidal wave will break over the ice flows and not be amplified to the same extent.
So I am arguing the opposite to you. It is the thick ice to the north of Greenland that causes the these large waves, which finally burst through the ice at the coast pushing the ice away from it.
When the ice is less concentrated then these large waves will not build up.
OTOH, the tides are the result of the effects of both the moon and the sun. It may be that the maximum tide precesses around the Arctic coast to correspond with the exact time of day when the moon and sun are aligned. The height of the Severn bores seem to be very sensitive to the size of the tide.
I like my first idea better, but perhaps it is a combination of both.
Have you got any records that could be used to test these ideas?
Cheers, Alastair
Alastair, I am in near full agreement with your reasoning. We are not far apart actually. Given the scenario of a resonant continental shelf enhanced tidal wave rushing towards shore, imagine the old days, loaded with ice more than 10 meters thick, interlaced with 5 meter, 2 meter in otherwise a jungle of multi aged ice. The friction at the interface would have been formidable, and like reported by early explorers, there would be a breaking point, which was called the “big lead”. Not so long ago, the big lead was usually 10 to 20 nautical miles away from shore. Now it seems closer. If so, Ward Hunt and other ancient ice shelves are vulnerable. If instead of high friction ice, you have smoother thinner ice, then the coastal impact would be stronger. If also near the coast there is open water, instead of old ice, there is nothing to slow down this wave at all.
Now for data, using recent wave effects:
http://seaice.bplaced.net/buoy-pos/
Click on the recent days before the full moon and observe the impact:
I will do some play by play:
Click on Sept 15. then observe the 16 and 17
This is a good example, look at the ice just frozen off Axel Heiberg, and watch it open
the day of the full moon.
Click on August 16, and look at several days before and after, the opening off Ellesmere to follow was unleashed on about that day.
Click on July 18,,, a middle coast hit
New Moon effects are usually not so violent. They exist but they are more subtle. Higher resolution pictures show them. I would keep on looking at the pictures during the full moons. I am interested in Antarctica, may be they have similar waves?
#501 Eyal Morag,
Thanks for getting back on that.
Normally the only difference I’ve seen between initial and final daily images is a grey band of “no data” that points out towards the Bering Sea. But I’ve not really paid much attention to any of the fine detail between what is for my timezone (UK) the evening preliminary and morning final image. I only got the preliminaries in case I’m too rushed to get the morning images (now I’ve stopped collecting them).
My best guess is that the difference in the images is down to processing of final data. I still think that’s some form of spurious response due to weather, but as I said before I couldn’t see what the weather was in Hudson Bay at the time.
Regards
Cobbly.
More generally regards AGW…
Recaptcha: “now Gordian”.
Indeed.
The NSIDC has provided an update, and one of the most interesting images, is a comparision of the age of the ice at the end of 2007 melting season as compared to 2008 melting season.
NSIDC Ice Minimun plus multiyear ice survival rate”
We have a lot less multiyear ice now than we did in September 2007.
Sure we have more first year ice this year than last year, however we did manage to wipe out most of the 2nd year ice this year instead.
I suspect that very little of the existing first year will survive as 2nd year ice until the fall of 2009.
“We have a lot less multiyear ice now than we did in September 2007”
I agree, but remenber that already in March 2008 we had a lot less multiyear ice than in September 2007. (From 4 to 2.61 million sq. km. http://seaice.apl.washington.edu/Outlook/2008/)
The ice drift during autumm and winter will determine the amount of multiyear ice remaining for the next melt season´s beginning.
If the northern first year ice has survived its first summer melt season: why won´t survive as second year ice in 2009? The atmosferic patterns will determine it: with a weather as in 2007, all the second year ice will be gone. With a weather pattern as in 2008, probably it will survive.
Re #503,
I’ll make a prediction. Then if I am wrong I can give up :-)
A huge lead developed off the north coast of Greenland on the 1, 2, & 3 rd of September. That coincided with a large bores on the Severn. See
http://www.severn-bore.co.uk/2008.htm
That lead did not re-develop at the next full moon around the 14th of September, nor was a large Severn Bore predicted. The next set of large bores is Sept 29th and 30th. So I predict that a large lead will develop again north of Greenland by the 1st of October.
Now all I have to do is wait and see!
Cheers, Alastair.
Maikdev,
To some degree (although perhaps not as much as last year) the ice in the Arctic now will be further lost by:
1) Outflushing off the coast of Greenland via the Fram Strait.
2) Fragmentation and dispersal into the pack ice of the Beaufort Gyre.
If you follow timeseries of QuikSCAT these processes could be seen in operation last year. The September 2007 surviving ice actually reduced over the course of last winter, to be replaced by fresh winter freeze from the Siberian sector. To some degree the same is to be expected this coming winter, it’s called the Transpolar Drift.
Sheldon Drobot’s graphic stunned me this morning. The region of multi-year ice looks about half what I had guestimated while discussing the matter with Chris previously on this thread.
Way to go Alastair! If its repeatable its science, I would look not only North of Greenland,
but the entire coast. Studying ice movement similarities may make you more precise as well.
Cobbly I have seen that too , rekindling the Volume melt question. But we have only one set of numbers from one model based with some missing data. Competition is good…. We are waiting for more estimates!
CobblyWorlds,
Thank you for your reply.
In my understanding, this coming fall and winter the Arctic could lose 0.4 Msqkm of MYI (through Fram Strait or by fragmentation and mixing with FYI) but still would remain at the same level of March 2008:
Multiyear ice area (million square kms)
2004 Sept. // 2005 Mar. 4.69
2005 Sept. 4.3 // 2006 Mar. 4.23 -0.07
2006 Sept. 4.2 // 2007 Mar. 3.61 -0.6
2007 Sept. 2.9 // 2008 Mar. 2.61 -0.3
2008 Sept. 3.0 // 2009 Mar. ? (2.67?)
Mean MY ice lost during fall and winter: 0.33
September data: yearly sea ice area minimum, when sea ice becomes MY ice, by definition: http://seaice.bplaced.net/nsidc/
The multi-year ice area in March:
Nghiem: Rapid reduction of Arctic perennial sea ice and
http://seaice.apl.washington.edu/Outlook/2008/
Maikdev,
-0.07, -0.6, -0.3, is a very short sequence and seems pretty random to me. I’d not consider it predictive for any more than “the March perennial extent will be less than the preceding September sea ice extent minimum” which considering the ice motion is not much of a surprise. I certainly don’t see your prediction of an increase as any better than guessing (“guess” as in the dictionary definition; no extra meaning implied).
Check out figure 3 of NSIDC September 24, 2008 Sea Ice News: You’ll see the effect of compression by the Transpolar Drift bringing all that first year ice in to replace area covered by perennial the previous September.
Looking at 2007 the light purple region becomes 2008’s region of green, and the areas of deep blue in 2007 become the tracery of light purple in 2008. Much of this year’s large area of first year ice (blue on the 2008 image) may be compressed down against Greenland and Canada, just as the previous year was. How much that happens depends on weather.
Back to the essential definition of multi-year ice: If the conditions in the Arctic are not yet able to maintain a seasonally ice-free state, then figure 3 of Nghiem cannot drop to zero. This is because first year ice will survive in the “haven” of the polar region to become perennial and it would take further warming of the Arctic Ocean (and more GHGs) to remove that polar “haven”. So Nghiem 2007 fig 3 would assume a sigmoid type shape and as the rate of change drops off so we will see an end to the period of year-on-year perennial extent reductions, and enter a new period of a gradual “noisy” reduction in perennial ice (reduction not apparent on a year-to-year basis).
The process of perennial loss has been going on for years, since 2002 there’s been consistent year-on-year loss despite the weather. Whilst it’s possible the phase of rapid loss is at an end I think we have a bit more to go. Rather than a gain I suspect the loss will be less than last year.
For me this is the tipping point, I still think we’re in it, not past it. The end of this rapid loss period would not mean things are OK – just that the scene is set for the final transition to a seasonally ice-free state.
I am curently unconvinced by Maslowski’s “ice-free by 2013” – I’m starting to see this year as telling us that lattitude is still big factor so the region may not be quite warm enough yet to sustain a seasonally ice free state – 5 years to overcome that seems steep to me. For a virtually ice-free state (just a smear of ice off the Canadian Archipelago at the minima) I’m sticking to around 2018 as my earliest bet, but keeping Maslowski in mind as a lower bound.
Wayne,
Considering this year and last it’s quite possible that we’re seeing the limiting effect on melt of lattitude (insolation angle of incidence). Volume isn’t the only factor and I’m not sure it’s the key factor for the future (see above). We are now at a point where for the first time in the record the ice that’s survived the summer is substantially 1 year old – that alone suggests volume is going to be less crucial.
Hi Cobbly,
I have been reading your comments with interest. I think you are right about a tipping point. It seems likely that summer sea ice will not recover its position of a few decades ago and that it is in a terminal decline. The debate is how long a late summer almost sea ice free state will take to achieve. Less than twenty years IMHO.
I hope you don’t mind but I am quoting you on the Science Forum.
Cobbly, I agree with your tipping point assessment. 2008 melt season had everything going for it to make a recovery happen. And it didn’t happen. At this time there is only one big player to consider,
the heat content of the entire atmosphere. Sea temps were cooler, sunlight reflection from cloud cover made it so, but sea temperatures didn’t recover, they are gradually getting warmer, again we must consider total heat content within the Arctic Ocean, which will eventually become the dominant factor during the long night. But this melt season past was driven by weather and atmospheric heat.
Despite cooler surface temperatures. My big question is how maximum heat zones travels, upwards is a given, but sometimes I suspect downwards, which is possible sooner than later. .
Posted in longer form at Tamino’s:
Science 25 August 2006:
Vol. 313. no. 5790, pp. 1061 – 1066
DOI: 10.1126/science.1122593
Trajectory Shifts in the Arctic and Subarctic Freshwater Cycle
Bruce J. Peterson,* James McClelland, Ruth Curry, Robert M. Holmes, John E. Walsh, Knut Aagaard
Manifold changes in the freshwater cycle of high-latitude lands and oceans have been reported in the past few years. …. Fresh water may now be accumulating in the Arctic Ocean and will likely be exported southward if and when the North Atlantic Oscillation enters into a new high phase.
Hello Simeon,
Quote me at your own risk, I’m far from expert. ;)
Good to hear from you again. I’ll be in touch.
Arctic Ocean warming (Wayne) Arctic Freshwater fluxes (Hank) – just 2 more things to read more on if I continue.
#507—Alastair: 27-28 September massive development along the Ellesmere coast, right on with advent of new moon.
http://seaice.bplaced.net/buoy-pos/
load last 6 days… The ice is flowing against the coast as well.
Wayne,
I do not see “massive development” as you state, but I may have been expecting more. I was expecting something like this, YouTube video I did in April for our earlier discussion: http://www.youtube.com/watch?v=l8vi–s1T8E That said, as is also apparent on Cryosphere Today 30 day animation there is the opening of a localised coastal lead from the coast of Ellesmere Island on 28/9/08 westward of the 75degW line of longitude. I take it that this is what you refer to? To me it’s notable because it is not associated with a change in buoy movement in the pack.
Note that there’s an AO -ve excursion starting around 28/29 sept.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif
At that time the buoys on your bplaced buoy position link reverse, moving towards Ellesmere Island as opposed to their typical motion towards Banks Island. This is caused by a change in wind direction:
GFS Wind 28 Sept.
http://seaice.bplaced.net/2008-09-28.12z/wind.2008-09-28.12z+000.png
GFS Wind 28 Sept + 45hr
http://seaice.bplaced.net/2008-09-28.12z/wind.2008-09-28.12z+048.png
There’s an Arctic Bathymetry for the PIPS 3.0 model here:
http://www.oc.nps.edu/~pips3/domain.html
May help you, although I don’t know enough about coastal tides to know if it’s of use.
The coastal lead along Ellesmere may indeed be a tidal effect, I’d be more convinced by something like a plot of tidal vectors in that locality. However with regards the larger scale opening of leads along the Canadian Archipelago such as I refer to in post 489 above. I still think such events are due to changes in wind forcing, not tidal effects.
It would be interesting to see a RealClimate post on black carbon and its potential snow-albedo role in the last few years of surprising rate of Arctic melt and Arctic temperature increase: recent meetings of the Arctic council, hearings on the Hill in the US and legislation introduced by Clinton (S 3489) and Inslee (Climate Action Now bill) make black carbon a fairly hot topic. There’s plenty of recent academic work by Ramanathan, Bond, Boucher, Hansen, and others in the area that could serve as a launching board for this…
Marcus, use the Search box (top of page) for
“black carbon” or “global dimming” — these for instance may have osme of what you want:
https://www.realclimate.org/index.php/archives/2007/11/global-dimming-and-global-warming/langswitch_lang/mo
https://www.realclimate.org/index.php/archives/2008/07/aerosols-chemistry-and-climate/langswitch_lang/mo
There are others you’ll find with a search.
517, Cobbly. You need to go to the site I linked to have a clearer idea. Your April sequence shows “spring break” as it has always happened in the past. Spring break with a new moon is a mad place on the ice, with a full moon, completely wild and dangerous. Synergism plays a huge role in either amplifying or hiding new, full moon ice distortions or openings. In this recent case , ice momentum helped show the new moon tidal wave effect indirectly, and as ice direction momentum shifted its open tracks closed quickly. In the past, I relied on satellite pictures, which were inconsistent in showing everything on a regular basis, now its much better, thanks again to Clarence… The event was massive extending itself over the entire Axel-Ellesmere Arctic Ocean coast, a huge distance, unlike your April break which was a “Mega” usually yearly event, you cant claim this as a local wind event since the opening was amongst a shallow shore line brimming with high mountains, and also the event was highly localized, where as an AO break, if there is such a thing, would be at a much grander distance, much like the spring break. I think I need not try to convince any more, since this is another clear example of a lunar wave, I’ve seen so many of them that its frustrating to read that some don’t understand what is happening. For those who remain skeptical, observe as long as it takes and let nature convince, come back when satisfied by the preponderance of evidence, we will talk about it over a cup of tea. For those who clearly see this wave, as so very obvious on my web page example, its black, its underwater, moving along tide lines, despite the usual difficulties in seeing it well regularly, lets try to explain, its a deep mystery, very exciting as all discoveries are.
Alastair there was something on the 28th North of Greenland, although not as big as next to Ellesmere… There was something.
Interesting to see the retreat on this thread from the dire predictions of a month ago.
I joined in the debate back then mainly to question the assumptions that (i) the accelerated August melt (compared to previous years) would continue through September, and (ii) the date of ice minimum would likely be later than in 2007.
Looking at
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
it turns out I was right to question both assumptions.
As for the future, I believe there are two prevalent assumptions:
(i) The world and hence the Arctic will be warmer in 2008-2018 than in 1998-2008
(ii) In any event, the average age of the Arctic ice is now much less therefore it will not recover to say 1990s levels even if temperatures remain the same.
Re: (i) – leaving aside climate sensitivity to CO2, which is obviously a huge debate in itself, I would ask people how much they would stake on Arctic temperatures not being cyclical (i.e. it’s all very well to talk of ice-free summmers in 2013/2018 etc, but would you really bet on it?)
Here’s graphs from the only stations covering both 1940s and present day on west and east coasts of Greenland, and from the closest stations to the Laptev Sea (i.e. hotspot for methane hydrates ….. incidentally first discovered bubbling from Arctic sea floor in 1940s; also often quoted as having had 4C temperature rises in the last couple of decades……but what about the equivalent 4C drops in the previous decades?…….)
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=431042500000&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=431043600000&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222208910006&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222241430002&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222202920005&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222208910006&data_set=1&num_neighbors=1
I can’t believe all or most of that cooling from the 1940s was due to aerosol effects.
As for (ii), provided it is possible for large areas of first year ice to survive a relatively warm summer and become second year ice (as occurred this year) then the amount of older multiyear ice is far from critical. Think about it: the average age of Arctic ice has never been more than a few years – that’s why average thickness has never reached much more than ~3m in the past century, and there hasn’t been runaway ice thickening! Thus, virtually none of the Arctic sea ice we’ve been analysing in the last couple of years existed before about 2000, i.e all of the ice has been formed during the warmest decade in recent history.
If you look at 2008 global temperatures so far e.g.
http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt
you will see that they are comparable to the 1995-2000 period
(Jan-Aug average anomaly 1995-2000: +0.40C;
Jan-Aug average anomaly 2008: +0.37C)
And in the 1995-2000 period, Arctic ice coverage showed an overall increase, especially in the area which summer 2007 affected so noticeably i.e. the Siberian Arctic Basin – see fig 3 of
http://nwpi.krc.karelia.ru/climas/Ice/Ice_no_sat/XX_Arctic.htm
Note: see fig 3 of
http://www.frontier.iarc.uaf.edu:8080/~igor/research/pdf/ice.pdf
re: fast ice thickness anomaly trends in the 20th century in the Siberian seas
(“The fast ice records do not show a significant trend (Fig. 3). In the Kara and Chukchi Seas trends are positive, and in the Laptev and East Siberian Seas trends are negative. In all of the seas the trends are relatively small, about 1 cm [per] decade, close to the resolution of the measurements. These trends are not statistically significant at the 95 [per cent] confidence level.”
I’m not making predictions as such, I’m just saying that a lot depends on people’s assumptions about the future, and these assumptions should be clear to interested public and policy-makers.
As a matter of interest what difference would it make to the Northern Hemisphere climate if the Arctic Sea did melt away in Summer?
“dire predictions”? Intersting spin on a discussion in which most were quite sure last year’s minimum extent would not be meant.
Also interesting in that ice *area*, as reported by cryosphere today, momentarily reached, for all practical purposes, the 2007 minimum.
Assumptions? These were assumptions? These were questions that were the subject of speculation.
#523 dp Said:
4 October 2008 at 4:02 PM
As a matter of interest what difference would it make to the Northern Hemisphere climate if the Arctic Sea did melt away in Summer?
Imagine yourself to walk outside in black attire on a 45C day say in Dharan, Saudi Arabia. Now picture yourself the next day, same time walking around in white attire. Who gets warmest? The Arctic Ocean will act as a major heat absorbent…. sea water is dark! The knock on effect will be dire.
Do read up on values like “Snow Off Days”. The more of these, the more land can warm up in spring/summer and e.g. help to further the melting of permafrost. Snow is tracked at e.g. http://climate.rutgers.edu/snowcover/
“Imagine yourself to walk outside in black attire on a 45C day say in Dharan, Saudi Arabia. Now picture yourself the next day, same time walking around in white attire. Who gets warmest?”
Interesting. I’ve spent many days in hot summer sunshine, in both dark and light attire. And my temperature has remained stuck at almost exactly 37C.
(Don’t worry, I understand albedo, I just think your analogy could actually be a wonderful illustration of negative feedback! For sweat and hot attire read precipitation and higher surface emissivity/OLR……)
“The Arctic Ocean will act as a major heat absorbent…. sea water is dark! The knock on effect will be dire.”
Really? Most of the Siberian Arctic Basin melted away by the end of summer 2007.
http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2007/sep/asi-n6250-20070901-v5_nic.png
What was the knock-on effect?
In the following you can see the Siberian Arctic Basin on 21st June 2008 after 2 months of peak insolation:
http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2008/jun/asi-n6250-20080621-v5_nic.png
So far nothing dire.
Here it is after a further month of peak insolation:
http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/2008/jul/asi-n6250-20080721-v5_nic.png
So far nothing dire.
Then we had August 2008, and “weather noise” as some like to say, over the Siberian seas:
“A pattern of high pressure set up over the Chukchi Sea, bringing warm southerly air into the region and pushing ice away from shore. August air temperatures in the Chukchi Sea (at 925 millibars pressure, roughly 750 meters [2,500 feet] in altitude) were 5 to 7 degrees Celsius (9 to 13 degrees Fahrenheit) warmer than normal. Ice loss in the Chukchi and East Siberian Seas averaged 14,000 square kilometers (5,400 square miles) per day faster than in 2007.” (NSIDC News, 4th Sep)
The result? It took until at least 21st Aug for the Siberian Basin to contain appreciably more “dark” sea water than in say 1990:
http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=08&fd=21&fy=1990&sm=08&sd=21&sy=2008
And how strong is the sun at 80N on 21st Aug? As a rough estimate, it is between 0 and 20 degrees above the horizon. Similar to a midwinter’s day in the northern US. And of course it is diminishing rapidly over the coming weeks.
In any event, for at least the last century there have always been large areas of open water in the Siberian Arctic Basin by the end of summer. We’ve already seen that the second half of August 08 was comparable to the second half of August 1990 in the region. According to http://nwpi.krc.karelia.ru/climas/Ice/Ice_no_sat/XX_Arctic.htm fig 2, the area of open water in Aug 1990 was at least 1.9 million km2 i.e. ~76 per cent of the area.
In both the 1940s and 1950s it reached at least 1.75 million km2 i.e. ~70 per cent of the area.
“Do read up on values like “Snow Off Days”. The more of these, the more land can warm up in spring/summer and e.g. help to further the melting of permafrost.”
What matters most to the melting or otherwise of permafrost is the mean temperature over the course of the year. In spring, snow insulates the ground below from warm sun, but it also insulates it from frosty nights. In any event, the deeper you go into the ground, and the further north you go, the harder the permafrost is to melt (another negative feedback)
Check out the mean temperatures of the following stations in Siberia (the furthest north, and closest to the Laptev Sea)
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222241430002&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222214320004&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222202920005&data_set=1&num_neighbors=1
http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=222208910006&data_set=1&num_neighbors=1
All below -10C, and showing a cyclical pattern. Absolutely no chance of major permafrost thaw at these latitudes for a very long time. Well, apart from temporarily close to the surface during mid-summer (as it always has done), and the continuation of the slow thawing of the permafrost under the continental shelf seafloors of the past 1000s of years.
http://www.sciencedaily.com/releases/2007/02/070207091024.htm
“According to a recent paper published by MBARI geologists and their colleagues, methane gas bubbling through seafloor sediments has created hundreds of low hills on the floor of the Arctic Ocean. These enigmatic features, which can grow up to 40 meters (130 feet) tall and several hundred meters across, have puzzled scientists ever since they were first discovered in the 1940s.
Paull’s data suggest that pingo-like features are growing in response to warming that started thousands of years ago. Thus, their growth is not a result of human-induced global warming. However, Paull’s research does show that pingo-like features are still growing and releasing methane today.”
>Paull, pingos
Look at the previous temperature pattern — each glaciation ended in a rapid warming to a peak then a long slow cooling. Our last ‘peak’ from the previous ice age was around 8,000 years ago.
http://www.globalwarmingart.com/wiki/Image:Ice_Age_Temperature_Rev_png
Then there’s the warming of the past century or so.
From what I’ve read ‘pingos’ and other areas where methane is escaping are just the surface expression of a complex process — areas lifted up by methane ice. Methane forms in the deep sediment, moves up til it hits an area where it can freeze as a clathrate; the clathrate ice forms til it gets exposed at the surface or to circulating seawater in the upper sediment and some of the methane gets released as gas; usually the gas dissolves before it reaches the surface of the ocean.
Add rapid warming, and this doesn’t cause a sudden change — it just changes the rates at which all these transitions occur. When the rate at which methane enters the water is fast enough, some of the bubbles can reach the surface rather than dissolving. And lo, we see bubbles.
http://www.sciencemag.org/cgi/content/abstract/318/5850/633
This (poking around with Google:
http://www.google.com/search?q=methane+sediment+formation+circulation+clathrate )
seems a good brief summary with references:
http://courses.washington.edu/pcc588/projects/Kennell.doc
Can’t get ANYTHING past the damn spam filter!
It’s my URL the idiot spam filter keeps rejecting. Didn’t realize there was anything spamlike about g e o c i t i e s d o t c o m. I’d to be able to cite my new web site.
Chris writes:
Except that there isn’t any warming that’s been going on for thousands of years. We passed the peak of the interglacial 6,000 years ago and the Earth has been steadily cooling from then until the industrial revolution began.
“Except that there isn’t any warming that’s been going on for thousands of years.” (Barton Paul Levenson)
There might be if you’re hundreds of meters down through the sediment :)
“Over thousands of years, the scientists believe, this “wave” of warming moved downward through the sediment. Eventually it reached the frozen methane hydrates, hundreds of meters down.”
(Only quoting what the article says – my knowledge of this subject is extremely sketchy)
Barton, look at the actual science news cited — the suggestion is that the pulse of warming from the last glacial maximum is still propagating down through the sediments.
“… the seafloor in this area has been gradually warming over the last 10,000 years, after being flooded as sea levels rose at the end of the last ice age…. when the ice sheets from the last ice age melted and the ocean flooded the continental shelves, it caused the seafloor sediment to become warmer.
Over thousands of years, the scientists believe, this “wave” of warming moved downward through the sediment. Eventually it reached the frozen methane hydrates, hundreds of meters down….”
You’d want borehole temperature profiles to check this statement.
Here’s the press release
http://www.mbari.org/news/news_releases/2007/paull-plfs.html
Chris quotes the story, but note Paull is saying the particular pingos he studied are old ones. Don’t take that as a generalization:
http://www3.interscience.wiley.com/journal/112738743/abstract?CRETRY=1&SRETRY=0
http://www.erudit.org/revue/gpq/1998/v52/n3/004847ar.html
http://dx.doi.org/10.1016/j.palaeo.2007.09.015
Barton, Chris is usually long with explanations that don’t add up to much. His recap of the summer ice melt is long as well, misses most of the main features which have happen.
“interesting to see the retreat on this thread from the dire predictions of a month ago.”
Chris, you misread perhaps? When one tries to understand a phenomena as huge as the polar ice cap, some ideas are floated as a way to see what will happen, comparing a hypothesis idea with what has now happened, is a useful tool in seeing if one understands the subject at hand.. Given that there was more spread out ice, it was fascinating to see the latter summer months melt which in the end was very much comparable to last year. The clear distinction in conditions achieving this is equally fascinating and suggests melt mechanisms not fully understood.
“the following you can see the Siberian Arctic Basin on 21st June 2008 after 2 months of peak insolation:”
Insolation doesn’t mean anything when its very cloudy…
This was in brief what happened to the ice cap in 2008: another great melt, with wind and cloud conditions favoring more albedo, with less direct insolation by clouds and by scattering ice instead of compressing it like 2007. Compression of ice in 2007 favored a more intense melt as well, with just exposed water receiving direct insolation from clearer skies. Ice scattering in 2007 reduced sea temperatures as well as surface air temperatures. Yet in the long run, the melt was just as significant as in 2007. Everywhere, not just in one area or another… At the start of the 2008 freeze up there was a significant area of thin ice, along with less thick ice than last year.
finally
“I’m not making predictions as such, I’m just saying that a lot depends on people’s assumptions about the future, and these assumptions should be clear to interested public and policy-makers.”
Policy-makers from around the world have made up their minds years ago, they see the gradual progressive greater summer melt a lot better than some amateur ice experts. And have made plans
and preparing and executing sovereignty policies from this consequence. It is a curious phenomena,
because some countries dont explain why this is happening, but they act to protect their ocean jurisdictions nevertheless.
Chris,
I’m having a break from this issue as I decide whether to walk away from what’s looking to me like a “done deal” (I probably will).
But for what it’s worth:
You won’t yet necessarily “see” wider atmospheric impacts of the reduction of summer ice yet. The response is such that it can be lost in the noise of weather. As Bhatt 2008 (link below) shows, some effects will be scientifically detectable, but initially they may be lost in the noise (weather). Also as Bhatt et al shows the impacts are not the same all around the Northern Hemisphere. However you may like to consider the greater ice cover of 1995 against 2007/2008: I’ve been too busy to look elsewhere (geographically) in detail but the North Atlantic Summer Jetstream position is one I’d suggest watching – in terms of it’s impacts on storm tracks.
I agree, some of the methane release may very well be due to long-term warming since the start of the holocene. This seems to apply to the recent observations off Svalsbaard. However much of the clathrates on the Siberian shelf are not as deep and what is happening there looks more like a recent development.
Check out the recent discussions at Stoat (linked to from Other Opinions – top right of every RC page) “Mr Methane” “Methane Data” and there’s another about Abrupt Climate Change (4th down on recent posts). The methane isn’t going yet at such a rate that it’s affecting Carbon 13 isotope fraction, but from my understanding we are now committed to that happening, and to the other 2 risks (1 & 3) in my post 254. As to how quickly, that depends upon how fast the Arctic transitions to a seasonally ice-free state.
Bhatt et al 2008: “The Atmospheric Response to Realistic Reduced Summer Arctic Sea Ice Anomalies.”
http://www.cdc.noaa.gov/people/michael.alexander/publications.html
Fascinating these vertical heat mechanics… just wonder what heat from the earth’s core does in that same period… steadily coming up.
Relevant to the “Ice scattering in 2007 reduced sea temperatures as well as surface air temperatures.” of Wayne and similar by others posted here, been following the ratio of Sea Ice Area and Extent and found that if comparing AMSR-e JAXA and Cryosphere Today, there was a record 38%+ of water in between the Arctic ice floes during August where 2007 stuck at ~36% for the same month. September year on year also showed ~2% differential. Interestingly if one compares the 5 day average ice extent of October 2007 with 2008 there is ~740,000 km2 more “extent”, but only ~130,000 km2 more Area… ~80% water region added. Now is that a sign of poor ice state? Does a more spread out floating ice help to build more ice during the winter… sort of analogues to the grafted skin on a burns patient, or does it work the other way. One would assume that water turbulences and waves allow greater heat exchange in either direction.
Sorry, forgot. The running October ratio Extent / Area of 2007 v 2008 is for latter ~3% more interwoven water… that what Pugh tried to navigate to 90th north in his kayak. Does not strike me as a good situation having 64% ice instead of 67%. Of course the month is young.
Sorry, forgot. The October running ratio is ~64% ice within the “extent” versus ~64% for same month in 2007. The month is young, still historically this does not seem to bode well with 1995 the only other year
weird, page refresh and the second post did not appear, hence the double: Here’s a little extent/area/water/% Ice table for historical data of October, in millions km2
Period Extent Area Aqua % Ice
1979-10 9,39 7,30 2,09 77,74%
1980-10 9,46 7,61 1,85 80,44%
1981-10 9,19 7,38 1,81 80,30%
1982-10 9,98 7,79 2,19 78,06%
1983-10 9,64 7,89 1,75 81,85%
1984-10 8,84 7,03 1,81 79,52%
1985-10 8,88 7,22 1,66 81,31%
1986-10 9,89 7,96 1,93 80,49%
1987-10 9,29 7,75 1,54 83,42%
1988-10 9,47 7,78 1,69 82,15%
1989-10 9,52 7,21 2,31 75,74%
1990-10 9,35 6,98 2,37 74,65%
1991-10 9,16 7,01 2,15 76,53%
1992-10 9,60 8,00 1,60 83,33%
1993-10 9,19 7,29 1,90 79,33%
1994-10 9,48 7,48 2,00 78,90%
1995-10 8,94 6,22 2,72 69,57% only other
Sekerob, What is fascinating is this:
http://www.cdc.noaa.gov/map/images/rnl/sfctmpmer_30b.rnl.html
A very warm September for Surface air. I am waiting for the official results from NOAA and NASA,
if September is as warm as it seems on the link above, me thinks it shows some erratic surface temperature behavior indicating a fluctuating in altitude warm atmospheric zone.. All numbers Up Here in the high Arctic point to the same thing. I also think that the earth core temp has very little to do with this, otherwise SST’s would be more consistent, besides there is weaker heat coming out from the Earth’s crust.
okay, so core heat coming up is dismissed as a source of thawing the methane deposits in the shallow?/deep? “seabed” rather than heat from above.
The air temps for anomaly and current i follow are:
http://polar.ncep.noaa.gov/sst/ophi/color_anomaly_NPS_ophi0.png
http://polar.ncep.noaa.gov/sst/ophi/color_sst_NPS_ophi0.png
Visited them almost daily and saw consistently above normal temps but for some regions on the central arctic.
And to my previous post that had chopped off table:
Period Extent Area ARXT Ice %
1995-10 8,94 6,22 2,72 69,57% Only other
1996-10 9,39 7,81 1,58 83,17%
1997-10 8,76 6,70 2,06 76,48%
1998-10 8,85 6,96 1,89 78,64%
1999-10 9,10 7,08 2,02 77,80%
2000-10 8,92 6,95 1,97 77,91%
2001-10 8,59 6,90 1,69 80,33%
2002-10 8,81 6,51 2,30 73,89%
2003-10 8,65 6,24 2,41 72,14%
2004-10 8,48 6,66 1,82 78,54%
2005-10 8,45 6,02 2,43 71,24%
2006-10 8,34 6,04 2,30 72,42%
2007-10 6,75 4,51 2,24 66,81%
2008-10 5,52 3,56 1,97 64,41%
Re #534 et seq
A precursor for what might happen to the more fragmented ice would be the fate of the Beaufort seaice this summer. Due to some major breakup over the winter the Beaufort sea had a lot of fragmented old ice (leads in between filled with new ice), this melted quickly in the summer leading to a rapid melt to record lows.
Re #537
Sekerob, the reason your posts are truncating is probably that you’re using the ‘less than’ symbol which has a special meaning in html, if I remember correctly you have to preface ‘lt’ with the ‘and’ symbol to get it to print. I’ll do that here as a test: &
Re #516
Wayne,
Although a lead did appear on the 28-29th of Seprember, my prediction of a giant lead similar to that of on the 3rd September did not materialize. So I deem my prediction to have failed. It is not possible to determine the size of Arctic leads from information on the tidal bore in Southern England.
Of course that conclusion is fairly obvious, but thinking about it has led me a little further.
First, it was a gross simplification to think that a peak tide at one geographical location would coincide exactly with another. Even if the high tides always coincide at two locations, that does not necessarily mean that the heights, or even the peaks will coincide. Longitude and latitude will both play a part in deciding the exact height of the tide. Moreover, the shelving sea bed is also important, and no two sea beds are the same. But using a computer model we can calculate the effects of latitude and longitude on the tide, which can then be calibrated with tidal measurements.
Second, the lead will form when the ice cracks. There will be a threshold tide which can cause that, and that is why the leads form at the highest tides, when the threshold is most likely to be broken. But the thickness of the ice changes, reaching a minimum at the start of September. Thus it is not surprising that the major lead happened then and was not repeated later when the ice had begun to refreeze.
Third, I do not think it is a matter of whether the lead is created by the wind or the tides. Both will have an effect, but the tide is needed to crack the ice and the wind strength and direction will affect the width of the lead.
The wind strength and direction will be affected by the QBO, Arctic Oscillation, atmospheric tides and local weather. I would really like to relate the arctic ice extent to the QBO, but if it is possible then it would probably have been done already by now.
Fourth, it has occurred to me that the tides probably have a strong influence on the Arctic ice because in polar regions the tidal forces are parallel to the surface there, whereas in equatorial regions the gravitational and centrifugal forces are normal to the surface. In the arctic the ice will be pushed around horizontally by the tides, whereas elsewhere the tide mainly lifts the ocean surface vertically.
Fifth, I do have one last thought. Since the lead will only form if the ice cracks, and that will depend on the height of the tide and the thickness of the ice, then it should be possible to determine ice thickness if we know the tidal force. Thus we could use satellites to watch for leads and use that information to calculate the thickness of ice.
But I don’t think it is worth much more investigation since there is unlikely to be any ice at all within ten years.
So that is my 2 cents worth regarding tidally induced leads.
Cheers, Alastair.
Seekrob wrote:
> wonder what heat from the earth’s core does in
> that same period… steadily coming up.
Answer: “steadily” is your answer, because that’s routinely measured; just one example:
http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.earth.28.1.339
(Note, this is an area where you’ll find scientific papers with Google Scholar, but if you search Google using the exact same search string, your first few pages of hits are likely to be rather wild crank articles
Stormier Arctic?
http://www.livescience.com/environment/081006-arctic-storminess.html
#546,, Right now it is with freezing rain… The Upper Air is very warm…
#543 Alastair, you have not failed because you try to understand by hypothesis.
It does not usually give results in a few days.. I suggest waiting for the full moon. Study the ice closely. You might be amazed by the effect, it depends whether ice movement vectors conflict or contribute to a tidal wave. There are many vectors, momentum, wind, sea current, amongst other factors.
I am more than curious about that river of yours, especially the tide anomaly. After many years of watching moon tidal effects I am narrowing down the possibility to a temporary wave/current very damaging if the vectors are right.
During a full or new moon, a deeper underwater current somehow rises and surfs
the ice ocean interface. Its not only a tide but a current as well perhaps clockwise as the gyre, adding to shelf amplification its a powerful event. Problem is, I have never heard of such a tide current, and may be that river of yours as something in common, especially with the tide still surging above the river current. I think there is something like that happening on the Archipelago shelf….
Phil, you need to preface “lt” with an ampersand and follow with a semicolon: <
Wayne,
“The tidal bore is a rare phenomenon found on only a few of the world’s great waterways. It is a wonder that has never been truly understood, although the mechanisms of its passage and size are fairly predictable.” Tidal Bore Research Society.
Wikipedia also has an article entitled Tidal Bore.
I suspect that it is a soliton wave caused by the tide reversing. I believe the mathematics for soliton waves has been worked out but I suspect that the differential equations involved are well beyond me :-)
Cheers, Alastair.
PS I have just read the Wikipedia article on solitons and it cofirms what I thought. The mathematics of solitons is beyond me and thatthe Severn Bore is a soliton. In fact it hints, as you suspect, that there may be solitons in the (Arctic) ocean!
It’s up to you now to take it further :-)
Wayne,
This article has just appeared: Scientists solve fluid puzzle. Not sure if it is relevant but it may be.
Cheers, Alastair.
Thanks Alastair, Well, I have some studying to do! But its kind of a one man research Up Here looking at these waves, keep on with the help! I need all I can get. The only other people keen about this are extreme adventurers who yearly attempt to sledge to the Pole by way of land. They are an important source of information. For those curious about what they have recorded: http://www.thepoles.com has an archive and list of past ice cap adventures.
The warmest low pressure event just occurred in the High Arctic, with Upper Air temperature of +4.8 C, and the Density Weighted Temperature at 258 K , 11 K warmer than October 2007 average,
7 K warmer than October 2007 warmest atmosphere. It rained, and it is not good news to polar animals depending on vegetation. It has been consistently unusually warm in the Upper atmosphere, a low from Alaska Moving NE to Ellesmere in the past was tempered with much colder air.