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Little Ice Age-to-Modern Warm Period Transition Along the Northern Eurasia Timberline
Raspopov, O.M., Dergachev, V.A. and Kolstrom, T. 2004. Periodicity of climate conditions and solar variability derived from dendrochronological and other palaeoclimatic data in high latitudes. Palaeogeography, Palaeoclimatology, Palaeoecology 209: 127-139.

General circulation models of the atmosphere suggest that CO2-induced global warming should be most pronounced, i.e., greatest and most clearly defined, in high northern latitudes. Hence, this study, which covers nearly all of northern Eurasia that borders on the Arctic Ocean, should be of special interest to everyone concerned about the subject.

What was done
The authors present and analyze two temperature-related data sets. The first is described as "a direct and systematic air temperature record for the Kola Peninsula, in the vicinity of Murmansk," which covers the period 1880-2000. The second is an "annual tree-ring series generalized for 10 regions (Lovelius, 1997) along the northern timberline, from the Kola Peninsula to Chukotka, for the period 1458-1975 in the longitude range from 30E to 170E."

What was learned
The authors' primary objectives were to identify any temporal cycles that might be manifest in the two data sets and to determine what caused them. With respect to this dual goal, they report discovering "climatic cycles with periods of around 90, 22-23 and 11-12 years," which were found to "correlate well with the corresponding solar activity cycles." Of more interest to us, however, was what they learned about the temporal development of the Modern Warm Period (MWP).

Raspopov et al.'s presentation of the mean annual tree-ring series for the northern Eurasia timberline clearly shows that the region's thermal recovery from the coldest temperatures of the Little Ice Age (LIA) may be considered to have commenced as early as 1820 and was in full swing by at least 1840. In addition, it shows that the rising temperature peaked just prior to 1950 and then declined to the end of the record in 1975. Thereafter, however, the Kola-Murmansk instrumental record indicates a significant temperature rise that peaked in the early 1990s at about the same level as the pre-1950 peak; but after that time, the temperature once again declined to the end of the record in 2000.

What it means
The latter of these findings (that there has been no net warming of this expansive high-latitude region over the past half-century or so) is in harmony with the findings of a number of other studies of both the Arctic (Overpeck et al., 1997; Przybylak, 2000; Zeeberg and Forman, 2001; Comiso et al., 2001; Przybylak, 2002; Polyakov et al., 2003; Chylek et al., 2004) and Antarctica (Comiso, 2000; Doran et al., 2002; Thompson and Solomon, 2002). Likewise, the former finding (that the thermal recovery of this climatically-sensitive region of the planet began in the first half of the nineteenth century) is also supported by a number of other studies (Esper et al., 2002; Moore et al., 2002; Yoo and D'Odorico, 2002; Gonzalez-Rouco et al., 2003; Jomelli and Pech, 2004), all of which demonstrate that the Little Ice Age-to-Modern Warm Period transition began somewhere in the neighborhood of 1820 to 1850, well before the date (~1910) that is indicated in the Mann et al. (1998, 1999) "hockeystick" temperature history that is promulgated by the IPCC and its climate-alarmist friends.

This difference is very important, for it indicates that the LIA-to-MWP transition was likely halfway or more complete before the Mann et al. temperature history suggests it even began, demonstrating that the major portion of the transition occurred well in advance of the vast bulk of man's historical CO2 emissions to the atmosphere. Add to this the fact that there has been no net warming since somewhere in the 1930s or 40s ? in the places where CO2-induced global warming is supposed to be most evident ? over the period of time when the vast bulk of man's historical CO2 emissions occurred ? and it becomes abundantly clear that anthropogenic CO2 emissions have had no discernable impact on any part of the LIA-to-MWP transition, which is the "global warming" that climate alarmists continue to claim can be stopped by reducing CO2 emissions. Without question, that claim is absolutely false.

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

Comiso, J.C. 2000. Variability and trends in Antarctic surface temperatures from in situ and satellite infrared measurements. Journal of Climate 13: 1674-1696.

Comiso, J.C., Wadhams, P., Pedersen, L.T. and Gersten, R.A. 2001. Seasonal and interannual variability of the Odden ice tongue and a study of environmental effects. Journal of Geophysical Research 106: 9093-9116.

Doran, P.T., Priscu, J.C., Lyons, W.B., Walsh, J.E., Fountain, A.G., McKnight, D.M., Moorhead, D.L., Virginia, R.A., Wall, D.H., Clow, G.D., Fritsen, C.H., McKay, C.P. and Parsons, A.N. 2002. Antarctic climate cooling and terrestrial ecosystem response. Nature advance online publication, 13 January 2002 (DOI 10.1038/nature710).

Esper, J., Cook, E.R. and Schweingruber, F.H. 2002. Low-frequency signals in long tree-ring chronologies for reconstructing past temperature variability. Science 295: 2250-2253.

Gonzalez-Rouco, F., von Storch, H. and Zorita, E. 2003. Deep soil temperature as proxy for surface air-temperature in a coupled model simulation of the last thousand years. Geophysical Research Letters 30: 10.1029/2003GL018264.

Lovelius, N.V. 1997. Dendroindication of Natural Processes. World and Family-95. St. Petersburg, Russia.

Mann, M.E., Bradley, R.S. and Hughes, M.K. 1998. Global-scale temperature patterns and climate forcing over the past six centuries. Nature 392: 779-787.

Mann, M.E., Bradley, R.S. and Hughes, M.K. 1999. Northern Hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations. Geophysical Research Letters 26: 759-762.

Moore, G.W.K., Holdsworth, G. and Alverson, K. 2002. Climate change in the North Pacific region over the past three centuries. Nature 420: 401-403.

Overpeck, J., Hughen, K., Hardy, D., Bradley, R., Case, R., Douglas, M., Finney, B., Gajewski, K., Jacoby, G., Jennings, A., Lamoureux, S., Lasca, A., MacDonald, G., Moore, J., Retelle, M., Smith, S., Wolfe, A. and Zielinski, G. 1997. Arctic environmental change of the last four centuries. Science 278: 1251-1256.

Polyakov, I.V., Bekryaev, R.V., Alekseev, G.V., Bhatt, U.S., Colony, R.L., Johnson, M.A., Maskshtas, A.P. and Walsh, D. 2003. Variability and trends of air temperature and pressure in the maritime Arctic, 1875-2000. Journal of Climate 16: 2067-2077.

Przybylak, R. 2000. Temporal and spatial variation of surface air temperature over the period of instrumental observations in the Arctic. International Journal of Climatology 20: 587-614.

Przybylak, R. 2002. Changes in seasonal and annual high-frequency air temperature variability in the Arctic from 1951-1990. International Journal of Climatology 22: 1017-1032.

Thompson, D.W.J. and Solomon, S. 2002. Interpretation of recent Southern Hemisphere climate change. Science 296: 895-899.

Yoo, JC. and D'Odorico, P. 2002. Trends and fluctuations in the dates of ice break-up of lakes and rivers in Northern Europe: the effect of the North Atlantic Oscillation. Journal of Hydrology 268: 100-112.

Zeeberg, J. and Forman, S.L. 2001. Changes in glacier extent on north Novaya Zemlya in the twentieth century. Holocene 11: 161-175.

Reviewed 25 August 2004