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

Abstract

Pollen analysis was carried out on an 80-cm sedimentary section on the shore of Lake Tere-Khol (southeastern Tuva). The section consists of peat overlapping lake loams and covers the last 2800 years. The alternation of dry-wet and cold-warm epochs has been established, and changes in heat and moisture occurred non-simultaneously. The first half of 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 time interval 1.35-0.7 kyr BP was relatively humid. Against this background, the temperatures varied from cold 1.35-1.1 kyr BP to relatively warm 1.1–0.7 kyr BP. The last 700 years have been relatively cold with a short warming from 400 to 250 years ago. This period included a 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 reconstructions in the Altai-Sayan region. The general cooling trend corresponds to an astronomically determined trend towards a decrease in solar radiation in temperate latitudes of the Northern Hemisphere, and the centennial temperature fluctuations detected against this background correspond well to changes in solar activity reconstructed from 14C production and the concentration of cosmogenic isotopes in Greenland ice. Against the general tendency towards aridization, alternating wet and dry phases correspond well to changes in the activity of the Asian monsoon, established by the oxygen-isotope composition of speleothems in South China.

Keywords

• late holocene
• short-term climate changes
• little ice age
• medieval warm period
• pollen analysis
• south-eastern tuva