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Norway’s extreme winter 1940/41.
Cold pole Skagerrak! Did man contributed?

By Arnd Bernaerts, 04 November 2010





Fig.1, 2 & 3

Many believe in natural climate variability. It seems the Norwegian too. 70 years ago the year and winter in Norway was extreme cold[2]. Actually the regions adjacent to the Skagerrak, South Norway, West Sweden, and North Denmark experienced the lowest temperature in winter 1940/41 for many decades. From a global perspective the world was warmer than the average from 1900-1939, but colder from Great Britain, via Scandinavia, and north-east wards (see: Fig.1, D/J/F, Giss) The last very cold winter 2009/10 was almost modest compared with what happen at that time. At Oslo/Blindern the mean winter temperatures (D/J/F) had been more than 3°C colder as in winter 2009/10[1].  The lowest temperature in last winter was -20.5 °C (9. Jan. 2010)[3]. (see Fig.2 annual,, Fig. 3, D/J/F, Giss) Only few years later Hesselberg et al. stated that many low temperatures all over Norway had been the coldest ever observed in January 1941.[4] What do the Norwegian think about this winter? It was definitely a remarkable winter for the Skagerrak region, but presumably chopped down as ‘natural climate variability’, as the reasons for the event have been never scientifically investigated and explained. A mistake? 

   Fig.4 & 5                  The assumption of a mere ‘natural climate variability’ event, would be certainly an unforgivable flaw, if human activities contributed to the cause Lets briefly recall that the 1930s had been the warmest since the Little Ice Age. That turned suddenly to the coldest winters in Europe in the moment World War II started in September 1939. The first war winter became the coldest in Northern Europe for more than 100 years. The third even succeeded the 1st war winter in some parts. Towards the end of this two winters naval activities run high in the North and Baltic Sea. That was quite different prior the winter 1940/41. The Baltic Sea had had a year without belligerent activities. The naval activities and fights took place elsewhere. In early April 1940 the Germans occupied Denmark, and moved forward north ward in the so called Norwegian Campaign (see Fig.4). 100 naval vessels and 1’000 air planes were sent north wards to take Norway as well. For the rest of the year the sea areas along Norway was a battle ground from the Skagerrak to Narvik. Uncountable naval activities penetrated the sea over considerable depths, which may have contributed that the winter in the regions were record cold in the winter that followed this onslaught.
For details see: ”Occupation of Norway - Return of Ice Age (3_11)” at:

The center of the  wintry cold reached from London to Stockholm (See: Fig.1). The cold could have happen only due to a lack of heat reserve in the sea area from Dover to Bergen. Presumably the Skagerrak has contributed as well. That is easily achieved by huge naval activities during the autumn and early winter season. Further more, the southern coast of Norway the sea has a depths of up the 700 meters, with a temperature difference to the surface of more than 10°C  in August (see Fig.5). Any mixing up side down would cool the surface layer as well. Has this combination contributed to the record winter conditions in the countries around the Skagerrak? (see Fig.6) That was 70 years ago, and we do not know. For decades we talk about human induced climatic changes, and we do not know whether the Norwegian Campaign and other naval activities in Western European seas areas should be partly been blamed for the event to happen.

Fig. 6        In January 1941, southern and middle parts of Sweden had been colder than during January 1940, and in some locations colder than even 1860. The greatest heat deficit was observed in the inner parts of Götaland and northern Dalarna. Denmark recorded the coldest January since 1874, whereby northern Jutland was about 6°C colder than southern Jutland, with record low temperature of –30°C measured at a station near Viborg on 29 January 1941. As already mentioned, the southern coast of Norway was caught up in the cold as well. All stations reported great deviation form the mean: Oslo/Blindern  –8.3°C; a few miles south of Oslo  – 9.6°C; Ferder at the entrance to the Oslofjord -7°C; Lyngor (between Ferder and Kristiansand) –7.9°C, and Oksoy (near Kristansand) with –7.3°C.[5] Was it a “great event”?

Was the winter 1940/41 a “great event”? One shivers by considering any time of WWII, the Norwegian Campaign, and the occupation of Denmark and Norway, a “great event”, as one event was more horrible than the other, and in a no ending number. But from a far distant and a climatologically point of view, the event possibly marks a great failure of atmospheric science. For science the war activities at sea could be regarded as a human experiment on the interchange between the sea and the atmosphere. Did naval activities in 1940 have anything to do with the extreme cold from London to Stockholm, and the a cold center around the Skagerrak? (see Fig.6) If that would be proved one day, it would be shocking. Human activities moderated the winter 1940/41 seven decades ago, and science and the general public do not know. Man or ‘natural climate variability’ that is a great question.

More about the subject: 
“Climate Change & Naval War” (2005),Victoria/CA, pages 326.


[1] The calculation is based for 1941 on data from Jahrbuch des Norwegischen Inst. (deviation from average 1901-1930), and for 2009/10 from Met/No the difference between monthly average and “Normal” (Source: see Fn. 3).   

[2] Hesselberg, TH., and Birkeland, B.J. (1944); ‘The continuation of the secular variations of the climate of Norway 1940-50’, in: Geofysiske Publikasjoner Vol. XV. No. 5. , Bergen 1944-56; p.14, Table C.   

[3] Meterologisk Insitiute, Norway, Olso/Blindern at:  

[4] Hesselberg et al.,  op. cit. 

[5] Information and data from: ”Occupation of Norway - Return of Ice Age (3_11)”, at: