ИСТИНА

Volcanic activity is considered to be one of the most important factors of climate variability throughout the Holocene prior the industrial period. Volcanic eruptions emit huge amounts of volcanic dust, sulfur dioxide and water vapor into the atmosphere, which, through the formation of an aerosol layer, can change the radiation balance of the atmosphere, thus impacting climate. Sulfate aerosols that enter the stratosphere after powerful volcanic eruptions exist there for several years. The aim of this study is to verify a hypothesis concerning the possible climatic response in polar region (Kola Peninsula and Finnish Lapland) to the most powerful volcanic eruptions (VEI>4) during the last millennium. The analysis was based on the Kola (1445-2005) and Finnish supra-long ( ~ 7500 years) tree-ring chronologies. These chronologies were developed from Pinus sylvestris L. (scots pine) samples collected near the northern tree line at Loparskaya station (68.6 N, 33.3 E) and Finnish Lapland (68-70 N, 20-30 E), respectively. It was shown that sometimes volcanic eruptions may mask or enhance the action of solar activity, depending on the time of the event. The 1815 eruption of Tambora in Indonesia (VEI>7), which was the most powerful over the study period, occurred during the Dalton minimum of solar activity and seemed to intensify the regional climatic response. A superposed epoch analysis indicated a significant decrease in polar tree-ring growth over 7 years after the eruptions with subsequent recovery to its normal level. Our results showed that the most powerful eruptions of low-latitude volcanoes lead to a tree growth depression above the Arctic Circle. For example, the 1600 Huaynaputina eruption (VEI=6), which was the largest volcanic eruption in South America over the past 2000 years, caused the most significant (by 25% relative to the previous year) depression in tree growth. By contrast, eruptions of high-latitude Icelandic volcanoes (Katla (1721, 1755); Laki (1783); Askja (1875)) had no significant impact on the climate of Kola Peninsula and Finnish Lapland. Possible reasons for the lack of a regional response to the eruptions of Icelandic volcanoes were considered. The results open new possibilities of using polar tree-ring widths as indicators of volcanic activity above the Arctic Circle.