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The Little Medieval Warm Period in Northern Fennoscandia
Reference
Weckstrom, J., Korhola, A., Erasto, P. and Holmstrom, L. 2006. Temperature patterns over the past eight centuries in Northern Fennoscandia inferred from sedimentary diatoms. Quaternary Research 66: 78-86.

Background
In the concluding paragraph of the summary of reviews we have written about what we call the Little Medieval Warm Period, "we wonder if the widely distributed warming that began somewhere in the vicinity of the 15th century and ended somewhere in the vicinity of the 16th century was an independent phenomenon or perhaps the 'last hurrah' of the Medieval Warm Period [MWP] before it relinquished control of earth's climate to the Little Ice Age." We here review another paper that makes us wonder yet again.

What was done
The authors developed a high-resolution quantitative history of temperature variability over the past 800 years based on analyses of diatoms found in a sediment core retrieved from a treeline lake - Lake Tsuolbmajavri (6841'N, 2205'E) - in Finnish Lapland.

What was learned
In the words of Weckstrom et al., their temperature reconstruction "depicts three warm time intervals around AD 1200-1300, 1380-1550 and from AD 1920 until the present." Of these intervals, they say they "associate the warmth of the 13th century with the termination phase [our italics] of the MWP and the rapid post-AD 1920 temperature increase with the industrially induced anthropogenic warming," the last decade of which climate alarmists typically tout as having been the warmest such period of the last two millennia. Most interestingly, however, Weckstrom et al.'s data indicate that the peak warmth of the AD 1200-1300 termination phase of the MWP was about 0.15C warmer than the peak warmth of the post-1920 period. Even more interesting, the peak warmth of the AD 1380-1550 period was warmer still, at 0.25C above the peak warmth of the post-1920 period.

What it means
This study provides yet another example (see our Medieval Warm Period Project) of a situation where the MWP - in its termination phase, no less - was warmer than the peak warmth of the Current Warm Period. And it indicates that the "Little" MWP, which immediately preceded the Little Ice Age, was no slouch in this regard either, having been the warmest of all three warm periods surveyed in this study.

Reviewed 11 October 2006