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1,000 Years of Treeline Change in Northwest Finnish Lapland

Paper Reviewed
Helama, S., Kuoppamaa, M. and Sutinen, R. 2020. Subaerially preserved remains of pine stemwood as indicators of late Holocene timberline fluctuations in Fennoscandia, with comparisons of tree-ring and 14C dated depositional histories of subfossil trees from dry and wet sites. Review of Palaeobotany and Palynology 278: 104223.

Evidence for the Medieval Climate Anomaly (MCA) has been presented from all corners of the globe (see the many links under the heading Medieval Warm Period in our Subject Index), but much of it is found in Northern Europe, where a 2020 study by Helama et al. was conducted. Focusing on the area encompassing northwest Finnish Lapland, the three scientists examined 172 samples of subfossil wood and 1071 samples of living trees from forested and treeline sites to deduce pine (Pinus sylvestris) treeline fluctuations in the region over the past millennium.

Results of the analysis revealed there were two major phases of increased pine recruitment, one from AD 1000-1200 that corresponded with the warm temperatures of the MCA and one from AD 1400-1600 that corresponded to a warm period sometimes referred to as the Little Medieval Warm Period . In contrast, pine recruitment was, in the words of the authors, "generally impaired by cooler summer temperatures" during the cold phases of the two-stage Little Ice Age (AD 1200-1400 and 1600-1900). Helama et al. also report that since 1930, the modern rise in temperatures during the Current Warm Period has led to an altitudinal advancement similar to that observed in the two prior pulses of the past millennium, putting "the recent changes in a long-term context." And that context reveals there is nothing unusual, unnatural or unprecedented about the current level of warmth in northwest Finnish Lapland.

Posted 22 January 2021