Multicentennial Climatic Changes In The Tere-Khol Basin, Southern Siberia, During The Late Holocene

摘要

Pollen analysis was carried out on an 80-cm sedimentary section on the shoreof Lake Tere-Khol (southeastern Tuva). The section consists of peat overlapping lake loamsand covers the last 2800 years. The alternation of dry-wet and cold-warm epochs has beenestablished, and changes in heat and moisture occurred non-simultaneously. The first halfof the studied interval, from 2.8 to 1.35 kyr BP was relatively arid and warmer on average.Against this background, temperature fluctuations occurred: relatively cold intervals 2.8–2.6 and 2.05–1.7 kyr BP and relatively warm 2.6-2.05 and 1.7-1.35 kyr BP. The next timeinterval 1.35-0.7 kyr BP was relatively humid. Against this background, the temperaturesvaried from cold 1.35-1.1 kyr BP to relatively warm 1.1–0.7 kyr BP. The last 700 years havebeen relatively cold with a short warming from 400 to 250 years ago. This period includeda relatively dry interval 700–400 years ago and more humid climate in the last 400 years.The established climate variability largely corresponds to other climate reconstructionsin the Altai-Sayan region. The general cooling trend corresponds to an astronomicallydetermined trend towards a decrease in solar radiation in temperate latitudes of theNorthern Hemisphere, and the centennial temperature fluctuations detected againstthis background correspond well to changes in solar activity reconstructed from 14Cproduction and the concentration of cosmogenic isotopes in Greenland ice. Againstthe general tendency towards aridization, alternating wet and dry phases correspondwell to changes in the activity of the Asian monsoon, established by the oxygen-isotopecomposition of speleothems in South China.