Saturday, October 30, 2010

Is a changing wind responsible for melting Arctic ice?

Where is it hot?  Where is it cold?

The latest big picture url:

Read about it here:“arctic-report-card-update-for-2010”/

The first 7 months of 2010 achieved a record high level of global mean air temperature, but this could moderate for the rest of the year due to La Niña influences. The warmest temperature anomalies for the Arctic in the first half of 2010 were over north-eastern Canada”, which may be relevant for January to June temperature in NE Canada, but is of little concern to the Arctic Ocean.

However the report does describe an interesting phenomenon, described here in direct quotes:
  • Winter 2009-2010 showed a major new connectivity between Arctic climate and mid-latitude severe weather, compared to the past.”
  • “…winds tend to blow from west to east, thus separating cold arctic air masses from the regions further south.” but “in December 2009 (Fig. A7b) and February 2010 (Fig. A7c) we actually had a reversal of this climate pattern, with higher heights and pressures over the Arctic that eliminated the normal west-to-east jet stream winds. This allowed cold air from the Arctic to penetrate all the way into Europe, eastern China, and Washington DC.
  • This change in wind directions is called the Warm Arctic-Cold Continents climate pattern and has happened previously only three times before in the last 160 years.
  • The section concludes “While individual weather extreme events cannot be directly linked to larger scale climate changes, recent data analysis and modelling suggest a link between loss of sea ice and a shift to an increased impact from the Arctic on mid-latitude climate.”

Three times “in the last 160 years”! – yet the years are not mentioned, nor any historical context.   Instead the section ends with the conclusion that:
“Models suggest that loss of sea ice in fall favors higher geopotential heights over the Arctic.  With future loss of sea ice, such conditions as Winter 2009-2010 could happen more often.  Thus we have a potential climate change paradox.  Rather than a general warming everywhere, the loss of sea ice and a warmer Arctic can increase the impact of the Arctic on lower latitudes, bringing colder weather to southern locations.”
In the ocean section, the authors tend to focus on 2007 to 2009, not even mentioning the winter 2009/10, or any period or month in 2010.  They report that summer sea surface temperatures fell over the period, and also discuss wind driven circulation and salinity.  Astonishingly, this section (a two page long text of about 1300 words) required 15 authors from 8 institutions and 5 nations for its preparation.
The one text-page long section on sea ice cover starts with the remarkable sentence: “Sea ice extent is the primary parameter for summarizing the state of the Arctic sea ice cover.”, and regards as “Highlights” of 2010:
  • “September minimum sea ice extent is third lowest recorded.”
  • “Loss of thick multiyear ice in Beaufort Sea during summer.”
The main discussion is about the difference between 2007 and 2010, culminating in the information that:
  • “Winter 2010 was characterized by a very strong atmospheric circulation pattern that led to warmer than normal temperatures.”
  • “A strong atmospheric circulation pattern during winter 2010 kept most of the 2-3 year old ice in the central Arctic, and during June helped push the ice edge away from the coast.”
A post by one of the four authors, Dr. Walt Meier, at WUWT (21. Oct.): “Summer 2010 in the Arctic and other Sea Ice topics”, was more informative, i.e. mentioning the importance of bottom and lateral melt, which depends on the ocean temperatures.
Figure 5. GISS DJF 1939/40
The report has some value, at least with a basic analysis and explanation concerning the phenomenal change of wind direction during winter 2009/2010. While it may be risky to guess about three events, I can bet on one without any hesitation, namely winter 1939/40, the first World War II winter, which has been a subject of considerable research for some time (  (See Fig.5 (left)). At the end of the 1930s the NH temperature had been very high, but suddenly Europe was confronted with the coldest winter since the Little Ice Age. This included an interesting change in wind direction, for example in Great Britain (see Fig.4) during the winter seasons 1814, 1841, and 1939/40. One of the leading German meteorologists at the time, R. Scherhag explained the sudden change few years later:
The temperature anomalies which were observed in the northern hemisphere in January 1940 can easily be explained by the occurrence of the pressure deviations.”(Richard Scherhag, 1951, “Die große Zirkulationsstörung im Jahr 1940”; Annalen der Meteorologie, Vol. 7-9, pp. 327-328). In the same way he tried to explain the Arctic warming (1919 to 1939) In the 1930s. C.E.P. Brooks (1938) felt it necessary to provide a reason: “Attributing the recent period of warm winters to an increase in the strength of the atmospheric circulation only pushes the problem one stage further back, for we should still have to account for the change of circulation.” (in: “The Warming Arctic”, The Meteorological Magazine, 1938, p.29-32.).  And the answer regarding the change in circulation?  It is the ocean that matters.
So here we are, 70 years later. NOAA presents a report with a fanfare, but there are few new facts, meagre explanations and claims that scare. No wonder – if we cannot explain the early Arctic warming since 1919, and the onset of the global cooling since Winter 1939/40, we are unlikely to explain convincingly the mechanisms that drive the conditions in the polar region today. The oceans should be the prime factor; instead the NOAA Report puts the atmosphere and sea ice cover first.

(Click for animation)
NOAA: “Arctic Report Card 2010”,
“Arctic Report Card: Update for 2010 – Tracking recent environmental changes” Richter-Menge, J., and J.E. Overland, Eds.: Arctic Report Card 2010, (Full report)
The various essays shall cite the mentioned authors (In total about 69) (in PDF: 7.5 MB)
NOTE: The Table of Contents is only available by titles, subtitle, pages and other info added.
Figures on Global Temperature:
  • NASA: GHCN_GISS_HR2SST_1200km _Anom D/J/F_2009/10 & 1939/40 vs 1920-1939 (prepared 25/10/10).
  • Figure: Wind direction Great Britain 1939/40 is based on information from Drummond, A.J.; ‚Cold winters at Kew Observatory, 1783-1942’; (1943)  Quarterly Journal of Royal Met. Soc., No. 69, pp 17-32 (prepared by:

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