Siberian Federal University: More details of the climate of Siberia over the past 9000 years

Scientists from the School of Ecology and Geography of Siberian Federal University have studied how the vegetation cover and climatic conditions in the south of Eastern Siberia have changed over the past 9000 years in order to trace the response of natural communities to global and regional climate changes at different stages of the Holocene.

On the basis of an integrated approach including more than 10 different methods, the team retrieved indicators of changes in the natural environment (fungal spores, plant pollen, invertebrate remains) from bog sediments layer by layer, determined the age of peat, and analyzed mineral particles. All this made it possible to reveal the intervals of concentration of palaeosignals mutually indicating special climatic conditions in the past. So, the interval of 8150–7400 cal. BP. (calibrated years before present) turned out to be a temperature maximum — obviously, during this period in the south of Eastern Siberia there was sharp warming of the climate combined with high humidity, then the proportion of fir in the forests increased. Period 7400-5100 is marked by an arid climate, which led to an increase in the number of fires, and in the period 4500–3000 cal. BP., the scientists noted high moisture and received evidence of river floods.

“The international team of authors obtained unique materials thanks to a complex of paleoecological methods. For the first time for the territory of the Yenisei River basin, they applied a method to study non-pollen palynomorphs (spores of fungi, algae, invertebrate remains), which helped to supplement the results of spore-pollen analysis. I would note that the method of spore-pollen analysis and analysis of non-pollen palynomorphs were studied in the framework of my scientific internship at the University of Göttingen under the guidance of Lyudmila Shumlovskikh, Doctor of Biology, researcher at the University of Göttingen (Germany), senior researcher at P.N. Krylov Herbarium, Tomsk State University,” said Alexandra Mikhailova, senior lecturer at the Department of Ecology and Environmental Management at the School of Ecology and Geography, Siberian Federal University.

The scientist noted that the morphology and elemental composition of mineral particles were studied at the R&D Centre of Siberian Federal University using the method of electron probe microanalysis. A detailed analysis of the mineral layers made it possible to figure out the conditions of sedimentation, including the flow rate, which ranged from 0.08 to 0.16 m/s.

According to the researchers, in the Late Holocene, numerous pieces of evidence of a short-term drought of 1400–1300 cal. BP, the humid and warm Middle Ages (1300–650 cal BP), the Little Ice Age (450–300 cal. BP), for which an increase in the number of shell amoebas (indicators of increased moisture) and a short-term increase in the share of spruce in forests. The last 300 years have been characterized as moderately humid. The obtained results are consistent with previously published reconstructions of the paleoecological environment for the steppe and forest-steppe of the south of Eastern and Western Siberia and, in aggregate, indicate the presence of conditions with maximum humidity between 4500 and 3000 cal. BP.

“We believe that it is precisely the use of various paleoecological methods (multi-proxy approach), both classical (analysis of spores and pollen of plants, identification of macro-remains of plants and shells of mollusks, analysis of mineral particles), and innovative ones that are only gaining momentum in our country (analysis non-pollen palynomorphs, shell amoebas, charcoal counting micro- and macrocoals) made it possible to assess the natural conditions of the Holocene at a qualitatively new level. The use of this approach became possible, among other things, thanks to the participation of SibFU scientists in the DIMA British-Russian research group (Developing Innovative Multiproxy Approaches for Siberia and the Russian Far East),” explained Anna Grenadyorova, assistant professor of the Department of Ecology and Environmental Management, School of Ecology and Geography.

The comparison of obtained paleoecological results and already published reconstructions for peatlands and lacustrine sediments of the boreal zone of Siberia, the Altai-Sayan Mountains, Transbaikalia, southern Mongolia, Kazakhstan, as well as with data on the change in the surface temperature of the North Atlantic in the Holocene and calculated values of solar insolation, helped trace the influence of atmospheric air circulation at different stages of the Holocene on regional changes in the paleoclimate in Siberia and in nearby regions.

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