New paper finds another non-hockey-stick in Russian sub-Arctic, cooling over 4,500 years

A paper published today in Global and Planetary Change finds another non-hockey-stick in the Russian sub-Arctic with reconstructed temperatures showing a cooling trend over the past 4,500 years since the Holocene Climate Optimum. The paper adds to over 1,000 other worldwide non-hockey-sticks published in the scientific literature.

Proxy temperatures [2nd graph from left] show a decreasing trend from 4,500 years before the present [BP] to the end of the record in the 20th century

Proxy temperatures [2nd graph from bottom] show a decreasing trend from 4,500 years before the present [BP] to the end of the record in the 20th century

Oxygen isotope composition of diatoms as Late Holocene climate proxy at Two-Yurts-Lake, Central Kamchatka, Russia

• Hanno Meyer^a, , , 
• Bernhard Chapligin^a, 
• Ulrike Hoff^a, b, 
• Larisa Nazarova^a, c, 
• Bernhard Diekmann

Abstract

Especially in combination with other proxies, the oxygen isotope composition of diatom silica (δ¹⁸O_diatom) from lake sediments is useful for interpreting past climate conditions. This paper presents the first oxygen isotope data of fossil diatoms from Kamchatka, Russia, derived from sediment cores from Two-Yurts Lake (TYL). For reconstructing late Holocene climate change, palaeolimnological investigations also included diatom, pollen and chironomid analysis.

The most recent diatom sample (δ¹⁸O_diatom = + 23.3‰) corresponds well with the present day isotopic composition of the TYL water (mean δ¹⁸O = -14.8‰) displaying a reasonable isotope fractionation in the system silica-water. Nonetheless, the TYL δ¹⁸O_diatom record is mainly controlled by changes in the isotopic composition of the lake water. TYL is considered as a dynamic system triggered by differential environmental changes closely linked with lake-internal hydrological factors.

The diatom silica isotope record displays large variations in δ¹⁸O_diatom from + 27.3‰ to + 23.3‰ from about ~ 4.5 kyrs BP until today. A continuous depletion in δ¹⁸O_diatom of 4.0‰ is observed in the past 4.5 kyrs, which is good accordance with other hemispheric environmental changes (i.e. a summer insolation-driven Mid- to Late Holocene cooling). The overall cooling trend is superimposed by regional hydrological and atmospheric-oceanic changes. These are related to the interplay between Siberian High and Aleutian Low as well as to the ice dynamics in the Sea of Okhotsk. Additionally, combined δ¹⁸O_diatom and chironomid interpretations provide new information on changes related to meltwater input to lakes. Hence, this diatom isotope study provides further insight into hydrology and climate dynamics of this remote, rarely investigated area.