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Aaron Lewis

In the old days the ice was cold and strong, now is weaker and subject to more internal work as it is blown around and subjected to shear and flex. That work leaves the ice with more energy (distributed throughout its volume), which makes it weaker. This stuff is more like a "snow cone" than what we traditionally thought of as "sea ice". Our eyes in the sky were not designed to distinguish between fractured ice and solid ice.

This is a feedback that has not been widely discussed.

Neven

BTW, I also feel that the sea ice concentration maps do not catch parts of the Kara Sea well. If for instance you look at the region to the east of Novaya Zemlya on this LANCE-MODIS satellite image you see quite a dispersed bunch of ice floes, whereas all of the SIC maps indicate 100% concentration. Could it be that those fog-like clouds (heat release+higher temps=more moisture?) are fooling the satellite sensor to think there's ice there? Or is there very thin ice between all those floes?

Not that it matters for the final result when the foggy clouds disappear.

Glacierchange.wordpress.com

I was thinking on the same line, Barents Sea being more open and how Novaya Zemlya glaciers on the west coast have been responding. In the post noted we look at Glazova and Nizkiy Glacier

John Christensen

Neven;

Yes, I have previously noted that in the shallow straits between Sweden and Denmark, under certain conditions with no wind, low cloud cover and -5 to 0C, DMI would suddenly indicate ice cover where there is no ice, so not surprising if other satellite sensors do the same..

Steve Bloom

See this new paper (h/t Ari Jokimaki), confirming the bleedin' obvious one might say.

So, what are the ultimate limits to the ability of Atlantic inflow to push back the ice?

Philiponfire

And you can bet your last dollar they are talking about extent when the Barentsz ice is tissue paper thin. MODIS pictures show almost all grey slush/transparent ice. Me thinks the volume figures are far more dramatic than that.
I predict earliest ever ice free Barentsz this year.

Philiponfire

especially if we get off shore winds for an extended period.

Wade

So, with the Arctic 15% and 30% extents and areas being close to "normal," being the 30 year mean, but thickness being so extremely low, isn't this a precursor to a potentially enormous melt season?

At first glance, it might look like a "rebound" year for volume, like 2008, but I don't think that makes much sense.

Based on the data, it seems the volume has degraded so much that heat loss through the ice is allowing re-freezing to occur along the outer edges during March and April, but since this is pathetically thin ice with a very high surface to volume ratio, it should melt extremely fast.

Am I missing anything else?

John Christensen

Wade:

Part of the reason why the sea ice this winter and early spring has been much thinner than ususal was the weather event in Jan/Feb where strong (and unusual) winds pushed the ice towards the Canadian Archipelago and Beaufort Seas (See DMI link for nice graphics, sorry for the Danish):
http://www.dmi.dk/dmi/kold_luft_over_danmark_og_lav_isudbredelse_i_arktis

The compression of sea ice should have increased thickness on the NA side, while enabling cooling of surface waters and rapid development of new sea ice, happening at that time of year.

If (big 'if' here) the water has cooled significantly, it will support the thinner ice in Kara, Laptev, and Arctic Basin for longer in the spring/early summer, and allow for later than usual sea ice increase as well in these areas.

Blend in that top layer waters under the ice is around -2-0C (while ice-covered) and sustains the ice reasonably, while further down the water can be as warm as 4-6C and therefore melts thicker MYI from below (see comments on increase in water temp from the Atlantic elsewhere), so yes; it is difficult to anticipate development in volume in the coming months, as is the case with development in sea ice area.

Chris Reynolds

Steve Bloom,

I can't find the paper paywall free, but there's a set of presentation slides about the paper here.

The recession in the Atlantic isn't so significant when compared to recession in the Pacific and Siberian sectors. As I understand it this is because Atlantic water is more saline and dense so sinks as it crosses into the Arctic Ocean it sinks into the Fram Basin, map. This bathymetric feature 'pegs' the ice edge in the same area meaning it hasn't receded so much.

This Atlantic water is thought to increase stratification in the Arctic Basin, and to lead to longer term warming of the whole basin. Being deeper then Bering strait influx its warming impact is 'integrated'. However I suspect that an increased rate of melt along the Atlantic ice edge may 'make room' for more ice transport from the Siberian sector.

Ole Heinrich

Interesting that the maximum sea ice extent april 1769 where very similar to todays extent §.-) http://www.climate4you.com/images/SeaIceSvalbardSince1769.jpg

Glacierchange.wordpress.com

Steve Bloom, thanks for the references I came across another presentation by same authors, on Barents Sea heat balances

Wipneus

Your graph shows the 1769 extent in August.
(The other years are April maximum extents)

See for example: http://acsys.npolar.no/meetings/final/abstracts/posters/Session_2/poster_s2_050.pdf

Neven

Interesting that the maximum sea ice extent april 1769 where very similar to todays extent §.-) http://www.climate4you.com/images/SeaIceSvalbardSince1769.jpg

Thanks for that, Ole. As Wipneus points out (thanks, Wipneus) that green dotted line is August 1769, not April. It is interesting though to see that early retreat south of Novaya Zemlya in 1995 (as corroborated by the CT comparison page).

I'm trying to find the original image from Barents Sea ice edge variation over the past 400 years author:Vinje, Vinje 1999. I did find another version of it - without the green dotted line for August 1769 - in a subsequent paper by Vinje: Anomalies and Trends of Sea-Ice Extent and Atmospheric Circulation in the
Nordic Seas during the Period 1864–1998
(PDF).

Does anyone know where I can find the original image, as used by Climate4You (linked by Ole, from this webpage)?

Neven

The link on the Climate4You reference list was dead, but I have found the report here. Below the image it says: "The Norwegian Polar Institute has developed a data base on the ice edge in the Barents Sea over the last 400 years. The data are mostly derived from old ship logbooks. The figure shows maximum and minimum ice extent for the month of April in some selected years to illustrate the enormous variation among years."

The other version in the Vinje 2001 paper says: courtesy S. Østerhus. I have found the image in this presentation (p. 18) by Østerhus. There it also says "Extreme southern and northern April ice edge location".

So is it April or August 1769?

Neven

I have found the image referred to in the presentation linked by Wipneus in this paper by Isaksson et al.

I can't find a copy of Barents Sea ice edge variation over the past 400 years author, Vinje 1999, anywhere.

Neven

Thanks, Daniel and Twemoran. I had found Vinje 2001 and the extended abstract of Vinje 1999 already.

The fact that 1) the map in Vinje 2001 doesn't have the dotted green line for 1769 (other than that both maps are identical), 2) Vinje 1999 is explicitly about the "August ice edge", and 3) Isaksson has another version of the map with the August 1769 ice edge, makes me conclude for now that it must be for August 1769, not April.

Let's hope no 'skeptics' are reading along. This map has a very high USS-Skate-at-ice-free-North-Pole-in-1957 potential. It will be plastered all over the Internets in no time flat, until a couple of months later Vinje or Østerhus are asked for an explanation ('No, it was for August 1769. If we had known the map would be used in this way, we would have been more careful, but who could have known in 1999?'). ;-)

Chris Reynolds

Neven,

To be clear, you have a copy of Vinje 2001 "Anomalies and Trends of Sea-Ice Extent and Atmospheric Circulation in the
Nordic Seas during the Period 1864–1998." Otherwise I can't help as I don't have a copy of Vinje 1999.

I don't see as great a problem as you seem to.

Kinnard et al "Reconstructed changes in Arctic sea ice over the past 1,450 years" finds a reduction of extent during the Little Ice Age, 1769 was at the end of this period.

We can't use recent relationships between the AO/NAO for determining what the neutral/low AO/NAO meant for sea ice, because as Kinnard et al note the recent correlation doesn't hold during the preceding 1400 years. However the Atlantic Sector is wide open to the Atlantic so substantial impacts of Atlantic ocean heat transport should be expected.

Vinje 2001 states:
"Temperature variations on the order of 1degC occur in the ocean on a decadal scale. Provided there is positive correlation between the atmospheric and oceanic effects, a considerable expansion or contraction of the ice extent should be expected to occur over periods of a decade or two only. It is possible that such a coincident occurred during the comprehensive advance of ice and fall in temperature during the last decades of the eighteenth century."

Whilst Vinje et al refers to an earlier period than 1769, it is quite feasible that such changes would have happened earlier and may have had a role in the reduction of extent during the LIA noted by Kinnard et al.

It's probably something that will never be known. But I'm very sceptical that the 1769 ice edge really applies to August. That's not a small mistake.

As for the denialists, the one thing we can be sure of is that they'll twist the science to suit their bizarre fantasies. All we can do is continue to be guided by the science.

PS I've just had an email from RealScience stating the proprietor is deceased. If I can't say anything respectful my policy is to say nothing at all. So I'm saying nothing.

Chris Reynolds

To correct my PS above.

Here's what an apparently alive Goddar has had to say:

"I’m fine. I was off at a soccer game when this happened. Basically, someone I trusted went insane and took control of the site. I still don’t have access, as my IP address has been blocked."

Someone went insane and posted false information at Real Science?

No change there then eh?

Tunnulik.wordpress.com

Re the sea ice extent in the North Atlantic in april 1976 - I have a paper "Dansk hvalfangst i Nordatlanten 1771 - 1789" (Danish Whaling in the North Atlantic 1771 - 1789 http://www.fogsgaard.org/Hvalfangst.pdf One of its refences is a paper from Christian Vibe - Arctic animals in relation to climatice fluctuations, The Danish Zoogeographical Investigations I: Meddelelser om Grønland, bind 170, København 1967.

"Two periods with little ice cover stands out from the others in the study. Precisely the period from 1770 to 1780 (and 1845 to 1850) shows the least amount of ice in all the statistical material. From the 1760s the intensity of the ice decrases constantly and almost dramatic, in 1776-1778 to reach an absolute low. From the early 1780s the intensity of ice rises again to reach its highest prevalence among 1783 and 1790."

During the 1760's and 1770's whaling where conducted in Melville Bay already in the month of may. The only conclusion can be that at this time there were less sea ice than now.

Melville Bay, april 22 2011 http://ocean.dmi.dk/arctic/images/MODIS/Pituffik/20110422AQUA.jpg

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