ИСТИНА

Solar and volcanic activities are considered to be the two most important forcings for 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 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. 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. It was revealed that the level of tree growth in polar region is affected by most powerful low-latitude volcanic events. 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. As it concerned the 1783 Laki eruption, in accordance with some evidence (Thordarson and Self, JGR, 2003; Sonnek et al., Nat. Hazards, 2017), one can assume that a stable blocked high-pressure air pattern over Europe concentrated volcanic gases near the Earth's surface and prevented them to spread into the Kola Peninsula. The results open new possibilities of using polar tree-ring widths as indicators of volcanic activity above the Arctic Circle.