The warming event in details

Exceptional temperatures

pozaK1[1]Observational data series show that the global surface air temperature (SAT) has increased by 0,6ºC since 1861[1], while the increase in the Arctic was higher, particularly during the decade from 1920 to 1940, and according to Polyakov et al.[2] the period from 1918 to1922 displays exceptionally rapid winter warming in the circum-Arctic region. The proportions of the warming are illustrated in almost every Arctic temperature graphic. Confining the date of the warming-up period to the year 1918 is very precise and important, while describing the warming-up area to “the circum-Arctic region” is rather superficial. On the other hand V.F. Zakharov stated with reference to Russian researcher: “Indicating that while high latitude play a special role in the climate changes over the hemisphere, the Atlantic sector plays a special role in these latitudes themselves. This important aspect of spatial structure of polar forcing should not, of course, be omitted when explaining the causes of the present day climate changes”[3]. These changes started in the late 1910s, and for this reason the Atlantic sector will be a focal point in our further investigation, as recommended by Zakharov[4].

Distant warming

pozaK2[1]Distant warming refers to regions in the “reach” of Spitsbergen, whereby the Arctic region shall here be understood as the Arctic Basin, respectively north of 80º North and north of the all continents[5]. In addition to the exclusion of the landmasses, it seems that also the Northern Pacific Ocean region can be excluded. At least this research has not come across any data, which indicates that an increased warming at the Aleutian had been observed within the time frame of this investigation. As the Pacific limits are at the latitude of 50º North, that is about 2,500 km south of Spitsbergen, respectively on the same latitude as London, Astana, and Vancouver, the region is geographically not comparable with the Northern North Atlantic. The very different oceanic conditions between the two-ocean entrances to the Polar Basin are even more significant. The water inflow from North Pacific to the Arctic Ocean is less influencial than the warm water masses, which arrive via the Norwegian and Spitsbergen Current at Spitsbergen and flow into the Arctic Basin.

Arctic Ocean

pozaK3[1]Due to insufficient data series, any specific warming of the Arctic Ocean from 1918 to 1939 is difficult to assess. There is, on one hand, clear indication that the whole Polar region warmed up over these two decades more than any other worldwide regions, but, on the other hand, the information available provides little hindsight on the hypothesis questioning whether the observed Arctic warming is the result of “summarized” temperature statistics on a decadal basis, or whether certain particular warming spots could be identified.

According to Johannessen et al. 2004[6], the most pronounced warming area from 1920-1939 covered a region from the East coast of North Greenland (60º West) to Severnaya Zemlya Island (100º East)[7]. This was already observed since the 1930s by a number of researchers, and again confirmed by H.H. Lamp (1982) who noted that “the change of prevailing temperatures seems to be the greatest in the regions affected by changes in the balance between the warm northbound Atlantic water and the cold polar current at the ocean surface in the Norwegian-Barents Sea-east Greenland region”[8]. Comparing the location and the extent of this warming area within the wider Polar region, a substantial distinction can be made. The pronounced warming area covers less than 1/3 rd of the Arctic area, but extents well into the northern parts of the Greenland-, Norwegian-, and Barents Sea.


pozaK4[1]It is widely acknowledged that Greenland went through a significant warming-up period. This is well demonstrated in the research work of R. Scherhag, in 1936[9], which indicates that temperature had increased with more than + 3ºC from 1921-1930. The warming of the East of Greenland, after 1920, could be possibly related to the findings of Bjerknes[10], in 1958, sustaining that the Labrador Current[11] had shown a brisk upward trend, starting as late as 1920. It is certain that a substantial warming of Greenland took place after 1919.

One can also be sure that the warming period of Greenland was limited to about one decade. The indicated period of time in question is from 1920 to 1930/32. Bjerkness[12] assessed seawater temperature data in the North Atlantic as it follows:

  • “North of about 57° North the trend in sea temperature has been slightly upwards. Actually this change resulted from a brief but strong upward trend in the 1920s
  • Essentially, it lasted only from 1920 to 1930 in Greenland waters”.

According to Kirch[13], at one East Greenland station[14], where records were registered since 1922, the summer average temperature had shown a typical warming trend, lasting until 1930/39, with a maximum of 3.29°C. Manley reported that in the Greenland Sea the last ‘bad ice year’ was 1923[15]. Due to Kirch’s research, the winter data indicated a warming trend starting with the winter of 1923 and lasting until 1933. Unfortunately Kirch provided only statistics on a decadal basis, which merely indicates that a cooling started in 1931/40. As for this investigation, the exact ending of the Greenland warming is not an imperative; it is enough to understand that it was a significant but short period event of about one decade.

pozaK5[1]Of much more relevance is the exact time of commencement. This is difficult to establish as many observation stations were installed only in 1920 or later, like Myggbukta/East Greenland (1922) or Jan Mayen (1920)[16]. For the important time period of 1918-1920, no temperature records for the Greenland region had been at hand for this investigation. The literature don’t offer a more precise assertion as well, so it seems that everything points out that the Greenland warming had started in 1920.

To understand the warming process, it is important to know whether the warming of Greenland started exactly at the same time as in Spitsbergen (1918/19) or later. On the other hand, the exact date is not so important for the explanation of the warming cause, as this warming derives presumably from the same source as the Spitsbergen warming. The only question, which cannot be answered presisely, is whether there was a delay of weeks, months or a year. It seems that the East coast of Greenland received the warming push some months, if not one year later than Spitsbergen. This would be a reasonable explanation, as water brought northwards by the West-Spitsberge Current would presumably need only a short time to reach Greenland’s East coast, and even the current system south-east of Greenland, including the Labrador Current (see Bjerknes, above). On the other hand, the information given by Kirch and Manley (previous paragraph) indicates that Greenland had not been affected as suddenly and as early as Spitsbergen.

Barents Sea

pozaK6[1]The fact that a zone over the east Greenland-Norwegian-Barents Sea region indicates a sudden significant temperature rise does not necessary means that the Barents Sea contributed significantly, if at all, in the initial phase. In addition to the remarks in the previous section (relative shallowness, inflow of polar sea water, etc), the eastern part of the Barents Sea was usually fully ice covered during the core winter season 90 years ago ( see: Annex C). Particularly the high temperature rise at Franz-Joseph-Land, and at Novaya Zemlya observed in the 1920s may simply have come with the West wind from Spitsbergen. The usually extent of sea ice hardly allows any other explanation, at least for the winter period. The distant from Spitsbergen (West coast) to the West coast of Franz-Joseph-Land is ca. 800 km, respectively less than 2000km to Novaya Zemlya. From this region a contribution to the initial warming period can be excluded. However, Kelly et al[17] assumed that in the Barents Sea and Kara Sea the warming consisted of 2° annually until the mid of the 1920s.

pozaK7[1]Only since 1920 temperature observation was taken at Boar Island, a location roughly half way between the North Cape and Spitsbergen. According to Kirch[18], the recorded winters of 1920 and 1921 (January/February) were significantly colder than the following ones, except for the winter of 1928/29, until the winters of 1939/40 and 1940/41. In so far, the warming started with the winter of 1921/22. The annual means are fairly equal (1° to 3.2°C, between 1920 and 1932), getting warmer only after 1932 until 1939.


In Europe the temperatures increased only very slowly but steadily since 1919 until the winter of 1939/40. It went so far that autumn 1938 was the warmest, together with 1772, 2000 and 2006, in the last 500 years[19]. Summer temperatures also had risen substantially; with 1ºC. Autumnal temperature rises in the 1930s were local and observed in Scandinavia and western part of maritime Russia only.[20] No other continental Northern Hemisphere region experienced a similar rising trend. The United States data records, which had a modest warming until 1933, saw a decrease in temperatures since then.

Although it can be assumed that at the end of the 1930s Europe experienced the highest annual temperatures in 100 or 200 years, it can be questioned whether there had been an exclusive connection between the Arctic warming and the warming in Northern Europe.

pozaK9[1]Even more revealing is the data set for Norway by Gordon Manley[21], demonstrating that the difference between Spitsbergen and Tromsö (North Norway) (ca. 800 km) is tremendous. The slowly advance of rising temperatures at Bergen and Oslo could represent a clear indication that not one but two forces had been at work, one from the North and one from the South, respectively from the East. This is indirectly confirmed by Bengtsson et. al[22], who observed that the NAO (North Atlantic Oscillation) has weakened during the 1920s and remained weak for the whole period of the warm Arctic anomaly. Therefore, the middle Atlantic seems to have played no significant role in the warming of Europe[23]. The air temperatures over North Europe from 1936-1938[24] indicate that higher temperatures were observed in the Baltic Sea region.

Although the warming of Northern Europe between the two World Wars is evident, there is no plain explanation on how, and from what direction the warming of Europe had developed.

Is Spitsbergen the only heating-up spot?

pozaK10[1]If one asks whether the heating-up spot is to be found at Spitsbergen, we would answer ‘yes’; information supplied previously sustain this affirmative answer. Nothing demonstrates this better; than the data record taken at Spitsbergen since 1912, see Table, Annex A. If one reviews the January/February temperature difference between the winters of 1913/14 and of 1919/20 (ca. + 15ºC), or from the winters of 1916-1917 to the winters of 1919-1920 (ca. + 22ºC), the results are not only extraordinary different, but they reveal that the ‘shift’ took place in 1918, respectively in the winter of 1918/19[25]. This is emphasised by the comparison between the data recorded since 1912, before WWI ended in November 1918 (ca. – 4,3ºC), and thereafter (ca. +3,8 ºC), including the winter of 1925/26.

Already in the summer of 1918 the seawater temperatures had reached unusual values: +7ºC to +8ºC at the West coast of Spitsbergen[26]. During the winter of 1918/19 the temperatures varied considerably. There were long periods in November and December 1918 with temperatures close to zero degrees, 4 days with temperatures above zero in November and 7 days in December[27]. In January 1919, the temperatures did not reach –5°C for 14 days, and five days were frost-free. The annual mean (1912-1926) with minus 7.7°C suddenly jumped to an annual average of minus 5,4°C in 1919, a plus of 2.3 degree. The corresponding figures provide for January a difference + 8,6°C, which indicates that the sea was able to transferred a lot of heat to the air. However, during February–April 1919, the temperatures were well below the average (ca. -6°C), with a large ice-cover far out into the sea (Annex C). But that did not affect the significant warming that started a few months earlier.


pozaK11[1]The interpretation of the reference material indicates that an outstanding warming-up phenomenon can be located with precision at Spitsbergen, and the exact timing is within a range of a few months. Such a precise date cannot be provided for other location. As there was no simultaneous temperature jump during the corresponding time period elsewhere, it is possible to assert with certainty that Spitsbergen represents the first place where the Arctic warming started at the beginning of the 20 th century.

The next chapter subsequently will therefore ask: WHY did the ‘greatest yet known sudden temperature rise on earth’[28] presumably occur. After all, the ‘Severe Warming’ at Spitsbergen in 1918 did not come from “nowhere”, nor did the subsequent ‘climatic change’. The event needs to be explained, either that the sudden change was due to internal dynamics of the sea body, or due to an external force, or a combination of both. The war at sea between 1914 and 1918 unleashed military forces, powerful enough to alter the status of huge seawater bodies, and to have acted as an external force.


[1] Polyakov, I.V., Bekryaev R.V., et al., ‘Variability and Trend of Air Temperature and Pressure in the Maritime Arctic, 1875-2000, 2003, American Met. Society, Vol. 16, p.2067-2077

[2] ditto, p. 2072

[3] Zakharov, V.F.; 1997, ‘Sea Ice in the Climate System’, Arctic Climate System Study, WMO/TD-No. 782, p. 70.

[4] Ditto, p. 71; in the section “On the nature of ‘polar forcing’”, Zakharov asks the following question: (1) Why are the maximum climate fluctuations confined to the Atlantic sector of the Arctic?”; (2) Why are these fluctuations pronounced, first of all, right here?”; (3) Should the Atlantic sector of the Arctic be considered as a centre of some kind, a source of climate change over the Hemisphere?”.

[5] According the International Hydrographic Organization the Arctic Ocean proper extents well over land and other sea areas, see:

[6] Johannessen, O.M., et al.; “Arctic climate change – Observed and modeled temperature and sea ice variability”; Tellus 56A (2004), p. 328 –341, Figure 2a.

[7] The distances to Spitsbergen are roughly ca. 1200 km each.

[8] Lamp, H.H.; in: Louis Rey, The Arctic Ocean, „The Climate Environment of the Arctic Ocean“, Comite Arctique International, p. 148, Fig 7.10(a to d)

[9] Scherhag, R.; Die Zunahme der atmosphärischen Zirkulation in den letzten 25 Jahren’, Annalen der Hydro & MartMete., 1936, p. 397ff, Tafel 58.

[10] Bjerkness , J; ‘The Recent Warming of the North Atlantic’; in: Bolin, Bert, ‚The Atmosphere and Sea in Motion’, Oxford 1959, p. 65ff.

[11] The Labrador Current originates from East Greenland Current, continues as West Greenland Current (NW), than as Baffin Island Current (SW), and subsequently the Labrador Current (SW), which transports cold Arctic and sub-polar water south along the Atlantic Canadian coast to the Grand Banks (Newfoundland) where it divides, the East branch joining the North Atlantic Current and the West branch flowing into the Gulf of St. Lawrence. The International Ice Patrol had first quantitatively studied the Labrador Current in 1937.

[12] Bjerknes, op.cit.

[13] Kirch, Regina; ‚Temperaturverhaeltnisse in der Arktis waehrend der letzten 50 Jahre’, in: Meteorologische Abhandlungen, Bd.LXIX Heft 3, Berlin 1966.

[14] Myggbukta/East Greenland, 73°29’N, 21°34’W, data recording since 1922;

[15] Manley, Gordon; ‚Some recent contributions to the study of climatic change’, in: Quarterly Journal of Met. Soc., Vol. 73, 1944, p. 197-219.

[16] Kirch, op.cit.

[17] Kelly, P.M., Sear, Cherry and Tavakol; ‘Variations in Surface Air Temperatures: Part 2. Arctic Region, 1818-1980’; in: Monthly Weather Review, Vol. 110, 1982, p. 71-83.

[18] Kirch, op.cit.

[19] Xoplaki, Elena; “August 2006 is Warmest of Over More Than Half a Millennium”, “” on

Dec.23, 2006.

[20] Igor V. Polyakov, Roman V. Bekryaev, Genrikh V. Alekseev, Uma Bhatt, Roger L. Colony , Mark A. Johnson, Alexander P. Makshtas, and David Walsh; Variability and trends of air temperature and pressure in the maritime Arctic, 1875 – 2000; 2003; Journal of Climate, Vol. 16, p. 2067-2077, 2003 (p.2072).

[21] Manley, Gordon; ‚Some recent contributions to the study of climatic change’, in: Quarterly Journal of R.Met. Soc., Vol. 73, 1944, p. 197-219, Fig.4.

[22] Lennart Bengtsson, Vladimir A. Semenov, Ola M. Johannessen, The Early Twentieth-Century Warming in the Arctic—A Possible Mechanism, Journal of Climate, October 2004, page 4045-4057.

[23] For example: At Iceland there had been defiantly a temperature rise since ca. 1920 but only modestly; see: J. Eythorsson, ‘Temperature Variation in Iceland”, Geografiska Annaler, 1949, p.36-55, Fig. 1-5.

[24] See: Scherhag, R.; ‘Die Erwärmung des Polargebiets’, Annalen der Hydrographie und Maritimen Meterologie, 1939, p.57-67, Fig.2.

[25] See also: Hesselberg, Th., and Johannessen, T.W.; in: R.C. Sutcliffe (ed), Polar Atmosphere Symposium (Oslo 1956), “The Recent Variations of the Climate at the Norwegian Arctic Sectors”, London, 1958, p18-29, Fig.2.

[26] Weikmann, L.; ‚Die Erwärmung der Arktis’, Berlin, 1942.

[27] Average temperatures (1912-1926) for December minus 14,4ºC: in December 1918 minus 7ºC.

[28] Birkeland, B.J.; ‘Temperaturvariationen auf Spitzbergen’, Meteorologische Zeitschrift, Juni 1930, p. 234-236