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Is the Recent Greenland Temperature Increase Evidence of Man-Induced Global Warming?
Volume 9, Number 26: 28 June 2006

Chylek et al. (2006) recently studied the characteristics of two century-long temperature records from southern coastal Greenland - Godthab Nuuk on the west and Ammassalik on the east, both close to 64°N latitude - concentrating on the period 1915-2005. What did they find?

As they describe it, "although the whole decade of 1995-2005 was relatively warm, the temperatures at Godthab Nuuk and Ammassalik were not exceptionally high," as "almost all decades between 1915 and 1965 were warmer than, or at least as warm as, the 1995 to 2005 decade, suggesting that the current warm Greenland climate is not unprecedented and that similar temperatures were [the] norm in the first half of the 20th century." They also note that "two periods of intense warming (1995-2005 and 1920-1930) are clearly visible in the Godthab Nuuk and Ammassalik temperature records," but that "the average rate of warming was considerably higher within the 1920-1930 decade than within the 1995-2005 decade." In fact, they report that the earlier warming rate was 50% greater than the most recent one.

In comparing the southern coastal Greenland temperature record with that of the entire globe for the same time interval, Chylek et al. note that "while all the decadal averages of the post-1955 global temperature are higher than the pre-1955 average, almost all post-1995 temperature averages at Greenland stations are lower than the pre-1955 temperature average," which observation causes us to wonder how that can be, if CO2-induced global warming is supposed to be earliest and most strongly expressed at high northern latitudes, as claimed by climate alarmists on the basis of a long history of climate modeling. This canary in the coal mine concept of theirs is seen to be even more perverse, when, as noted by the three researchers, "the summer temperature at the Summit of the Greenland ice sheet shows a decreasing tendency since the beginning of the measurements in 1986 (Chylek et al., 2004)."

In light of these several observations, Chylek et al. say: "An important question is to what extent can the current (1995-2005) temperature increase in Greenland coastal regions be interpreted as evidence of man-induced global warming?" In answering this question, they note that "the Greenland warming of 1920 to 1930 demonstrates that a high concentration of carbon dioxide and other greenhouse gases is not a necessary condition for [a] period of warming to arise," and that "the observed 1995-2005 temperature increase seems to be within [the] natural variability of Greenland climate." In addition, they say that "a general increase in solar activity (Scafetta and West, 2006) since [the] 1990s can be a contributing factor, as well as the sea surface temperature changes of [the] tropical ocean (Hoerling et al., 2001)."

With respect to an important implication of their findings, Chylek et al. say that "glacier acceleration observed during the 1996-2005 period (Rignot and Kanagaratnam, 2006) has probably occurred previously," and that "there should have been the same or more extensive acceleration during the 1920-1930 warming as well as during the Medieval Warm Period in Greenland (Dahl-Jensen et al., 1998; DeMenocal et al., 2000) when Greenland temperatures were generally higher than today."

To summarize, as Chylek et al. put it, "we find no direct evidence to support the claims that the Greenland ice sheet is melting due to increased temperature caused by increased atmospheric concentration of carbon dioxide."

Sherwood, Keith and Craig Idso

References
Chylek, P., Box, J.E. and Lesins, G. 2004. Global warming and the Greenland ice sheet. Climatic Change 63: 201-221.

Chylek, P., Dubey, M.K. and Lesins, G. 2006. Greenland warming of 1920-1930 and 1995-2005. Geophysical Research Letters 33: 10.1029/2006GL026510.

Dahl-Jensen, D., Mosegaard, K., Gundestrup, N., Clow, G.D., Johnsen, S.J., Hansen, A.W. and Balling, N. 1998. Past temperatures directly from the Greenland Ice Sheet. Science 282: 268-271.

DeMenocal, P., Ortiz, J., Guilderson, T. and Sarnthein, M. 2000. Coherent high- and low-latitude variability during the Holocene warm period. Science 288: 2198-2202.

Hoerling, M.P., Hurrell, J. and Xu, T. 2001. Tropical origins for recent North Atlantic climate change. Science 292: 90-92.

Rignot, E. and Kanagaratnam, P. 2006. Changes in the velocity structure of the Greenland Ice Sheet. Science 311: 986-990.

Scafetta, N. and West, B.J. 2006. Phenomenological solar contribution to the 1900-2000 global surface warming. Geophysical Research Letters 33: 10.1029/2005GL025539.

Vinther, B.M., Andersen, K.K., Jones, P.D., Briffa, K.R. and Cappelen, J. 2006. Extending Greenland temperature records into the late eighteenth century. Journal of Geophysical Research 111: 10.1029/2005JD006810.