4 research outputs found
Late Holocene climate and environmental changes in Kamchatka inferred from subfossil chironomid record.
This study presents a reconstruction of the Late Holocene climate in Kamchatka based on chironomid
remains from a 332 cm long composite sediment core recovered from Dvuyurtochnoe Lake (Two-Yurts
Lake, TYL) in central Kamchatka. The oldest recovered sediments date to about 4500 cal years BP. Chironomid
head capsules from TYL reflect a rich and diverse fauna. An unknown morphotype of Tanytarsini,
Tanytarsus type klein, was found in the lake sediments. Our analysis reveals four chironomid
assemblage zones reflecting four different climatic periods in the Late Holocene. Between 4500 and
4000 cal years BP, the chironomid composition indicates a high lake level, well-oxygenated lake water
conditions and close to modern temperatures (w13 �C). From 4000 to 1000 cal years BP, two consecutive
warm intervals were recorded, with the highest reconstructed temperature reaching 16.8 �C between
3700 and 2800 cal years BP. Cooling trend, started around 1100 cal years BP led to low temperatures
during the last stage of the Holocene. Comparison with other regional studies has shown that termination
of cooling at the beginning of late Holocene is relatively synchronous in central Kamchatka, South
Kurile, Bering and Japanese Islands and take place around 3700 cal years BP. From ca 3700 cal years BP to
the last millennium, a newly strengthened climate continentality accompanied by general warming
trend with minor cool excursions led to apparent spatial heterogeneity of climatic patterns in the region.
Some timing differences in climatic changes reconstructed from chironomid record of TYL sediments and
late Holocene events reconstructed from other sites and other proxies might be linked to differences in
local forcing mechanisms or caused by the different degree of dating precision, the different temporal
resolution, and the different sensitive responses of climate proxies to the climate variations. Further
high-resolution stratigraphic studies in this region are needed to understand the spatially complex
pattern of climate change in Holocene in Kamchatka and the surrounding region.