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A 7500-Year Proxy Climate Record for Finnish Lapland
Helama, S., Lindholm, M., Timonen, M., Merilainen, J,. and Eronen, M. 2002. The supra-long Scots pine tree-ring record for Finnish Lapland: Part 2, interannual to centennial variability in summer temperatures for 7500 years. The Holocene 12: 681-687.

What was done
Midsummer temperatures were reconstructed for the last 7500 years using the long ring-width chronology of Scots pine (Pinus sylvestris L.) from northern Finland that was derived by Eronen et al. (2002).

What was learned
The 20th century was indeed warm compared to the mean of the entire record (about 0.6C warmer). However, there were three other hundred-year periods that were warmer still: 600-500 BC, 300-200 BC and AD 1500-1600. Likewise, the difference between the mean temperatures of the 20th and 19th centuries was large; but the difference between the mean temperatures of the16th and 15th centuries was of the same magnitude, while there were three other such century-to-century warmings that were even greater.

What it means
In contrast to the climate-alarmist claim that 20th-century global warming was unprecedented over the past one to two millennia (Mann and Jones, 2003) in terms of both its rate of temperature rise and the ultimate level of temperature reached, the Finnish Lapland record tells a very different story. In addition, the finer-scale record of Eronen et al. (2002) indicates that the apex of the 20th-century's warmth occurred near the mid-century point, and not at its end, as it does in the infamous hockeystick record of Mann et al. (1998, 1999).

It should be noted, however, that Finnish Lapland is but one small part of the world. But it is not the only "one small part of the world" to exhibit such thermal behavior. We have reported on many additional such places on our website; and Helama et al. mention a few others. They state, for example, that "the warmth reconstructed here for AD 1561-1570 overlaps with the warm 20-year period previously reported in northern Sweden (Briffa et al., 1995)," and they say that "coinciding with reported warmth in northwest Siberia (Briffa et al., 1995) are our warm periods in AD 1541-1570 and 1931-1960."

Last of all, we note that the peak warmth of the mid-1500s corresponds closely in time with what we have called the Little Medieval Warm Period, which has been identified in the proxy climate records of a number of other locations. Hence, it is beginning to appear that one need only travel back in time a mere 500 years to find a number of places around the world that were significantly warmer than they are today. And since there was much less CO2 in the air at that time than there is currently, whatever made so much of the world so warm during that earlier era could well be doing the same today, without any help from the elevated atmospheric CO2 concentrations of the present.

Briffa, K.R., Jones, P.D., Schweingruber, F.H., Shiyatov, S.G. and Cook, E.R. 1995. Unusual twentieth-century summer warmth in a 1,000-year temperature record from Siberia. Nature 376: 156-159.

Eronen, M., Zetterberg, P., Briffa, K.R., Lindholm, M., Merilainen, J. and Timonen, M. 2002. The supra-long Scots pine tree-ring record for Finnish Lapland: Part 1, chronology construction and initial inferences. The Holocene 12: 673-680.

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.

Mann, M.E. and Jones, P.D. 2003. Global surface temperatures over the past two millennia. Geophysical Research Letters 30: 10.1029/2003GL017814.

Reviewed 13 October 2004