Arctic Warming 1920-40
|This is the abstract of a paper
November 10-12, 1997
University of Washington
This report is available in full on the Internet at http://psc.apl.washington.edu/publication/Arctic_Change/arctic.pdf.
A Brief Review of Old Russian Publications
Sergey V. Pisarev
P.P. Shirshov Institute of Oceanology
Russian Academy of Science
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.
2. The reasons of Arctic Warming (according to old Russian publications).
3. Cooling in 1950–1960.
Retreating of glaciers, melting of islands, and retreat of permafrost
During the Persey cruise in 1934 Zubov noticed that the glaciers of Jan-Mayen and Spitsbergen were considerably reduced, relative to their sizes adduced in British sailing directions of 1911. Retreat of glaciers was observed also at Spitsbergen, Franz-Joseph Land, and Novaya Zemlya. The ice bridges between some of Franz-Joseph islands melted.
Alman explored the glaciers of Spitsbergen in 1934 and came to the conclusion that they were melting. The observations of 1935–1938 showed that Iceland glaciers were melting too.
According to Sumgin, the south boundary of permafrost shifted to the north by 40 km during 1905–1933.
The disappearance of Vasilievsky Island in the Laptev Sea and washing away of the Lyakhovsky islands were phenomena of the same type.
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.
The acceleration of ice drift
In spite of the fact that the amount of Arctic ice transported to the Greenland sea increased (established by Soviet expeditions in 1920–1940), the amounts of ice in that sea decreased because of the influence of factors promoting destruction and melting of ice:
* an increase in the velocity and temperature of the Norway and Spitsbergen currents
* an increase in the velocity of winds, connected with common intensification of atmospheric and hydrospheric circulation.
The velocity of the drift of North Pole station in 1937 was 2.4 times greater than the velocity of Fram’s drift.
Change of cyclone paths
Vise noticed that cyclones’ paths changed. They moved significantly northward from their paths before the Arctic warming and so the wind regime changed: After 1920 the prevailing winds in Jugorsky Shar changed from cold east winds to warm southwest winds.
The increase of air temperature
According to Vise, in Varde (northeast of Norway) since 1918 the average annual air temperatures were higher than the average air temperature of the previous century (the exception was 1926, when the average temperature was lower by 0.2°C).
Beginning with 1930, not one negative anomaly of average yearly or monthly temperature was observed in the whole Arctic sector from Greenland to Cape Tcheluskin, and during the same time the positive anomalies reached significant values: 1934/35 ± (4–10)°C, November in Spitsbergen ± 10°C.
Vise noticed, that the average annual temperatures observed during the Fram cruise (for the period of November 1893–August 1895) were lower by 4.1°C than those observed during the Sedov cruise (for the period of November 1937–August 1939), although the Fram and Sedov locations more or less coincided (Fram, 81°59'/113°26'; Sedov, 82°43'/121°30).
At the station Tikhaya (Franz-Joseph Land), temperatures below 40°C were never observed after 1929. But 10 expeditions in the archipelago before 1929 observed such temperatures every winter, except 1896.
Biological indications of Arctic warming
Knipovich, in 1921, was the first who paid attention to the changes of Arctic fauna. Marketable species of fish spread to the north after the beginning of the 20th century and fisheries in the north became more intensive.
Some benthos species spread to the north.
The ornitofauna of the Arctic region changed: some species of birds (White Gulls) left their places of habitation, and some southern species were noticed in the far north (swans in Iceland).
Uspensky stated that 40–50 species of birds moved to the North during 1890–1930.
Ease of navigation
The sailing conditions in the Arctic region became much more favorable in 1920–1940. This can be proved by the following cruises:
* Knipovich, 1932 (round Franz-Joseph Land)
* Sibiryak, 1932 (round Severnaya Zemlya)
* sailing of non-icebreaking ships along North Sea Route in 193—no ice met
* possibility for non-icebreaking ships to double Novaya Zemlya every year since 1930.
The severe conditions of navigation in previous years can be proved by the following cruises:
* In 1912, the ship Foka, a member of the Sedov expedition, could not reach Franz-Joseph Land.
* In 1912, the ship St. Anna, a member of the Brusilov expedition, was trapped in ice near Yamal and carried out with the ice to the central Arctic.
* In 1901, the icebreaker Ermak failed to double Novaya Zemlya.
Increase of temperature and heat content of Atlantic Waters entering the Arctic Basin
The waters of Nordcape Current (Zubov) became warmer by approximately 0.7°C in 1940–45 compared to the beginning of this century.
In the regions adjacent to Spitsbergen and Franz-Joseph Land, the lower boundary of the cold intermediate layer rose from 150–200 m in the beginning of the century to 75–100 m in 1940–45.
Not one station made during the Fram cruise showed Atlantic Waters exceeding a temperature of 1.13°C, but in 1935 (Sadko cruise) Zubov observed Atlantic Water temperatures reaching 2.68°C, and in 1938 (Sedov cruise) even in the places situated to the north and east of Fram’s drift (it must be colder there) the temperatures reached 1.8°C.
According to Shokalsky, “the temperature of surface waters of the Gulfstream steadily rises from the beginning of our century.” The increase of surface waters’ temperature can also be seen (Shokalsky) in the other regions of the ocean subjected to the influence of the Gulfstream and the Atlantic Current.
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