File this under short term trends matter when we say they matter.
From The Montreal Gazette
BY RANDY BOSWELL, CANWEST NEWS SERVICE
Arctic Ocean ice cover retreated faster last month than in any previous May since satellite monitoring began more than 30 years ago, the latest sign that the polar region could be headed for another record-setting meltdown by summer’s end.
The U.S. National Snow and Ice Data Center had already warned earlier this spring that low ice volume — the result of repeated losses of thick, multi-year ice over the past decade — meant this past winter’s ice-extent recovery was superficial, due mainly to a fragile fringe of new ice that would be vulnerable to rapid deterioration once warmer temperatures set in.
And, driven by unusually hot weather in recent weeks above the Arctic Circle, the polar ice is disappearing at an unprecedented rate, reducing overall ice extent to less than that recorded in May 2007 — the year when a record-setting retreat by mid-September alarmed climatologists and northern governments.
The centre reported that across much of the Arctic, temperatures were two to five degrees Celsius above average last month.
“In May, Arctic air temperatures remained above average, and sea ice extent declined at a rapid pace,” the Colorado-based centre said in its June 8 report.
The centre pegged the retreat at an average of 68,000 square kilometres a day, noting that “this rate of loss is the highest for the month of May during the satellite record.”
Ice loss was greatest in the Bering Sea and the Sea of Okhotsk, “indicating that the ice in these areas was thin and susceptible to melt,” the centre added.
“Many polynyas, areas of open water in the ice pack, opened up in the regions north of Alaska, in the Canadian Arctic Islands, and in the Kara and Barents and Laptev seas.”
Read the rest of the story here
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George, here’s the text from the Barrow web site:
“This is the temperature profile through air, snow, ice, and water. The grayed area indicates the position of the ice (bottom may be off by 0.1 m). The bounds of the red funnel are the highest and lowest temperatures recorded during the past 24 hours. The black line with data points (spaced 0.1 m, 4 inches) is the latest temperature profile. Air, snow, ice, and water can often be discriminated easily in winter and early spring: daily temperature swings are more pronounced in the air than in the snow; the temperature profile in the ice is usually linear and steeper than in the snow; the temperature in the water is approximately independent of depth. Towards summer the ice acts as a heat sink with the coldest temperature registered inside the ice rather than in the air.
Temperature measurements are accurate to approx. ±0.2 °C. Further, measurements in summer may be affected by solar heating of the probe.”
File this under short term trends matter when we say they matter.
I read the article. That’s not what it says. Rather, a scientist quoted in the article separates weather and climate.
Other parts of the article discuss the rapid decline in ice cover over May, but it doesn’t link that to a climate determination. The snark at the head of the top post is unwarranted.
The problem with the Barrow ice, is that it’s a bunch of grounded pressure ridges and stuff, so very little circulation underneath I would imagine.
As of June 18, the Arctic ROOS sea ice extent is equal lowest in the record for this time of year. As this source was heralded as evidence the sea ice had ‘recovered’ a few months ago when extent was near normal, how about an update?
And maybe a comparison with other sea ice extent products that show current extent below the lowest on record for this time of year?
http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
http://www.iup.uni-bremen.de:8084/amsr/ice_ext_n.png
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Extent_L.png
With no more polar ice does that mean no more Polar bears?
So I goofed; seems I made a misteak. Happened once before; in 1971; I thought I had miscalculated a problem ; but I hadn’t; so I was wrong.
But this one is real; I totally blew it.
Nobody seems to have checked my calculation that proved that calving glaciers can melt just by their own collapse.
It’s a simple problem; a mass of ice (m) falling from a height (H), gains an energy m.g.H from gravity, and this energy will essentially all be converted into heat.
The latent heat of melting ice is about 80 calories per gram, at 4.184 Joules per calorie and I used that number to figure out the required collapse height, instead of the 80,000 calories per kg used in the gravitational energy calculation.
So we should have m x 80,000 x 4.184 = m x g x H and g is 9.80665 ms^-2
So H = 80,000 x 4.184 / 9.80665 = 34.13 km and not the 34 metres I said above. So when I said that a 250 foot high calving ice cliff at -8 deg C could melt itself, that was not a very robust theory.
But I was only off by 1000 x
Well I did learn something; now we know why snow falls and doesn’t melt before it hits the ground; well unless it falls from 34 km up.
But no use trying to hide the incline and I am sure Phil would have found it eventually.
It was a good theory; that melting snow is correlated with falling under gravity; but then correlation does not prove causation.
That might be a weakness in the cosmic ray theory too. There ought ot be an effect on cloud formation; but is it enough cosmic ray flux to explain much of cloud cover change. I believe that Leif has raised this caution before, about the sufficiency of cosmic ray flux variations to do much.
But this one is a no brainer; you can’t just brush off a factor of 1000 error. Well much bigger factors have been passed over in the past.
I seem to recall that Jeans brushed off a large factor as being approximately 1, in order to simplify an expression. the factor he threw out was Avogadro’s number; 6E23 or thereabouts.
Well the expression that this annoying quantity was a factor of happened to be factorial of Avogagro’s number; so it was still probably ok. The calculation was in the low temperature specific heats of solids as I recall or something like that.
I guess I should join the 20th century and stop using 80 calories per gram for the latent heat of water.
As soon as I can find an updated value I’ll convert it to Joules per kgram and try to remember that number instead..
So don’t anybody go submitting a paper on the gravitational melting of calving glaciers.
Sorry about that little snafu.
George E. Smith says:
June 20, 2010 at 9:58 am
So I goofed; seems I made a misteak. Happened once before; in 1971; I thought I had miscalculated a problem ; but I hadn’t; so I was wrong.
But this one is real; I totally blew it.
Nobody seems to have checked my calculation that proved that calving glaciers can melt just by their own collapse.
It’s a simple problem; a mass of ice (m) falling from a height (H), gains an energy m.g.H from gravity, and this energy will essentially all be converted into heat.
Hi George, it did seem a little odd but I recalled reading that melt water falling through ice doesn’t refreeze on contact because of the gain in kinetic energy so I didn’t think any more about it. One of the assumptions you make is a bit dodgy too: “this energy will essentially all be converted into heat”, since when you see one of these fall into the ocean a lot of energy is transferred to the KE of the water.
This video is particularly impressive.
I recall the TV program that this clip is from, I’d not want to watch calving from sealevel after seeing this!