New paper finds another non-hockey-stick in Siberia

A new paper published in Quaternary International reconstructs temperatures in Eastern Siberia over the past 10,500 years and finds "Reconstructed mean July temperatures were equal or up to 1.5 °C higher than today between [6,000 and 5,000 years before the present]" during the Holocene Climate Optimum. 

Temperature reconstruction shown in first graph at left shows temperatures were up to 1.5C higher than today between 6,000 to 5,000 years ago. Dotted vertical line shows present temperature.

Prior posts on non-hockey sticks

Holocene climate conditions in central Yakutia (Eastern Siberia) inferred from sediment composition and fossil chironomids of Lake Temje

• Larisa Nazarova^a, b, , , 
• Herman Lüpfert^a, 
• Dmitry Subetto^c, 
• Ludmila Pestryakova^d, 
• Bernhard Diekmann^a

• ^a Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, Telegrafenberg A43, 14473 Potsdam, Germany
• ^b Kazan Federal University, Kremlyovskaya Street 18, 420018 Kazan, Russia
• ^c St. Petersburg Gerzen Pedagogical University, Moika 48, 191186 St. Petersburg, Russia
• ^d North-Eastern Federal University, 58 Belinsky Street, Yakutsk 677891, Russia

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Abstract

A 380 cm long sediment core from Lake Temje (central Yakutia, Eastern Siberia) was studied to infer Holocene palaeoenvironmental change in the extreme periglacial setting of eastern Siberia during the last 10,000 years. Data on sediment composition were used to characterize changes in the depositional environment during the ontogenetic development of the Lake Temje. The analysis of fossil chironomid remains and statistical treatment of chironomid data by the application of a newly developed regional Russian transfer functions provided inferences of mean July air temperatures (T_July) and water depths (WD). Reconstructed WDs show minor changes throughout the core and range between 80 and 120 cm. All the fluctuations in reconstructed water depth lie within the mean error of prediction of the inference model (RMSEP = 0.35) so it is not possible to draw conclusions from the reconstructions. A qualitative and quantitative reconstruction of Holocene climate in central Yakutia recognized three stages of palaeoenvironmental changes. The early Holocene between 10 and 8 ka BP was characterized by colder-than-today and moist summer conditions. Cryotextures in the lake sediments document full freezing of the lake water during the winter time. A general warming trend started around [8,000 years before the present] in concert with enhanced biological productivity. Reconstructed mean T_July were equal or up to 1.5 °C higher than today between [6,000 and 5,000 years before the present] 6.0 ka and 5.0 ka BP. During the entire late Holocene after 4.8 ka BP, reconstructed mean T_July remained below modern value. Limnological conditions did not change significantly. The inference of a mid-Holocene climate optimum supports scenarios of Holocene climatic changes in the subpolar part of eastern Siberia and indicates climate teleconnections to the North Atlantic realm.