Satellite sea ice measurements are comprised of terabytes of data over decades of time and multiple instruments. The literature on the topic is incomplete for those of us who don’t live in the field, yet far better than anything that paleomagicology has ever produced. In my recent sea ice work, I’ve taken the time to correct for leap years in the trend and spent a lot of time insuring that the calculations are accurate. I really want to understand what is happening to cause the melting of the Arctic and growth of the Antarctic and believe I am coming close. I used FileZilla to download all of the EASE grid sea ice data from the NSIDC. If you want the link, send an email and I will give you instructions. We don’t want to download gigabytes of ice data if we are not serious about study.
Anthony Watts was curious about the ice trends above and below the Arctic Circle. It seems reasonable that a large percentage of ice loss would happen at lower latitudes if global warming is the cause of the loss. Contrary to my own theory that warm waters were pushed into the pole, it seems that this general warming is in fact the cause. The jury is not out yet, but IMO the fat lady’s tummy is visible. 😀 So here are some of the plots I’ve generated:
I’m not at all comfortable with the steps in maximum ice considering that the max ice is constrained by land mass.
Consider that the total ice area is this:
The ice anomaly below the Arctic is:
This plot seems to have an artificial step at 1995. There is a significant satellite switch at that point but I haven’t had time to fully research it. Despite my fondness for the massively funded Sea Ice group, I don’t believe right now that it is a non-issue. Long time readers will remember the step in the UAH RSS data.
I’m tired again, hopefully this is enough to start some thought. MUCH more of this has been done and will be posted in greater detail.
the Air Vent 
Thank you, Jeff, for your thoughtful and painstaking work.
“1. The idea of Arctic Warming during 1920–40 is supported in Russian publications by the following facts:
* retreating of glaciers, melting of sea islands, and retreat of permafrost
* decrease of sea ice amounts
* acceleration of ice drift
* change of cyclone paths
* increase of air temperature
* biological indications of Arctic warming
* ease of navigation
* increase in temperature and heat content of Atlantic Waters, entering Arctic Basin.
…
The decrease of sea ice amounts in 1920–1940
The area of ice in the Greenland Sea in April–August of 1921–1939 was 15–20% less than in 1898–1920 (data of Karelin).
In the Barents Sea the area of ice was 12% less in 1920–1933 than in 1898–1920 (data of Zubov).
Vise pointed out that since 1929 the south part of the Kara Sea in September was free of ice, while in 1869– 1928 the possibility of meeting ice there in September was about 30%.
The polar ice very often came close to the coast of Iceland in the last century and in the beginning of this century. During 1915–1940 the situation changed: no ice was observed in that region; negligible amounts of polar ice were noticed there only in 1929.
The thickness of ice determined during the Fram cruise was 655 cm; during the Sedov cruise it decreased to 220 cm (the reason for this was more intensive summer melting of ice).
Before Arctic warming, the strait of Jugorsky Shar froze near the 24th of November, but in 1920–1937 it became frozen two months later—in January.
According to Vise, near Dicson and Franz-Joseph Land the amplitudes of tides increased by 20–30% as a result of a decreasing amount of ice.”
http://mclean.ch/climate/Arctic_1920_40.htm
Bruce,
Those facts are clear teleconnectionless to future CO2 emission. There is no reason for ice to melt without CO2.
To go along with the lack of ice in 1920-40, these Iceland temperature series are interesting. Lots of peaks in the 1920-40 years higher than recent periods.
http://en.vedur.is/media/vedur/myndasafn/frodleikur/medium/sth_hiti_enska.png from http://en.vedur.is/climatology/clim/nr/1213
Oh, that’s very interesting! IMHO the below-Arctic summer sea ice looks too high before 1995.
Another interesting item on these graphs is the variability/noise. Look at the “Arctic Circle Sea Ice Area Anomaly” and “Sea Ice Area North” plots, there’s quite a bit of noise from 1980 through about 1996. Starting in 1996 and running through 2007, the noise quiets down significantly. Starting in 2007, it once again is noisy.
I wonder what the standard deviations are in these groups. Why is the period from 1996-2005 so much quieter than the rest?
Here is a graph from a Bob Tisdale article that matches my anecdotal evidence from #2.
http://wattsupwiththat.com/2011/06/08/on-the-amopdo-dataset/
I rather suspect that the salt cycle is at least partly responsible for these figures on sea ice.
Salt puts a brake on the hydrological cycle. It impeeds both freezing and evaporation. If there is less salt in the Arctic then the ice will freeze faster (other things being equal). Salt is recycled through both the surface and the ocean depths (as cold brine). That later has a medium to long to very long cycle time. The more ice that is made each year the more brine is produced. The less the salt the less the brine.
As the Mediteranean is one of the major evaporation reagions and that is gated by geographical features (the Camarinal Sill) and sea level, the combined effect in the Northern Hemisphere of the salt cycle is complex to say the least.
I should also add that the Northern Hemisphere brine route is also severly gated at both the Fram Straight and the Greenland to Scotland ridge. This just adds to the complexity.
Changing winds and water currents.
My thought.
#10 But what is that causes the changes to wind and water currents?
The currents at least can be put down to, at least in part, the freezing of sea water (thermohaline circulation). The more ice that freezes, the more warm salty water is dragged North. The more salt that is in that water the faster that cycle goes (because the brine return current is larger).
If there is less salt then the sea ice needs can be satisfied more locally with a smaller thermohaline circulation and hence less warm water dragged North to melt the existing ice whilst also it requires more energy to freeze the water when it gets there.
It is worth noting that every year more and more ice is being produced in the Arctic (see the difference between Summer and Winter ice http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seasonal.extent.1900-2010.png). In 1900 each year produced at least 4.5Km sq of ice in the Arctic. Last year it produced 9Km sq of ice. That is a lot of brine and hence a large thermohaline circulation. Perhaps that is all that is needed to create a decade long change?
Why look at the role of thermohaline circulation in sea ice coverage when clearly it is the vast yet largely undetected increase in aerosols which (a) are preventing model-predicted global warming from occurring but (b) must nevertheless be delivering the non-manifest heat to the arctic via phlogiston transport.
Disturbing respectful contemplation of That Which the Consensus Hath Foreseen with tacky, scientific considerations like salt, wind, current and/or observations about possible longer-term cyclical arctic climate patterns is typical smoke and mirrors denialism.
Jeff,
Thanks for the interesting work.
“Anthony Watts was curious about the ice trends above and below the Arctic Circle. It seems reasonable that a large percentage of ice loss would happen at lower latitudes if global warming is the cause of the loss.” That’s something I haven’t heard yet. Good call Anthony. Will be watching for updates.
#11
I don’t know.
I recently watched a good program on television that suggested the cause for the Little Ice Age was partly due to the melting of the Greenland Glaciers and all of the extra cold water cooled the Gulf Stream and pushed the North Atlantic Drift more south. The earth is 70 % ocean and that’s a lot of heat content. Just seeing the impact of El Niño/La Niña makes me think plenty of the planet is controlled by the oceans and the sun.
Thanks for this Jeff.
And another one circa 2004?
#15 was me.