Siberia’s current warming is greatest in 7,000 years

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North West Siberia experiences hottest summers in the last 7,000 years. While for several millennia the temperature of the region maintained a general cooling, there was a sharp change in the 19th century with a rapid rise in temperature, reaching its highest value in recent decades. These findings were published this week. Nature Communication.

Dendrochronologists from the Institute of Animal and Plant Ecology, the Ural Branch of the Russian Academy of Sciences (RAS) and the Ural Federal University (UrFU), thanks to multiple field trips to collect subfossil wood over the last 40 years, They were able to establish a unique and extraordinarily long chronology of tree ring widths of the Yamal region.

This chronology makes it possible to monitor the course of summer temperatures over the last 7,638 years. With the support of colleagues from the University of East Anglia, the Swiss Federal Institute for Forest, Snow and Landscape Research, and the Climate Research Unit at the University of Geneva, they were able to conduct analyzes to reconstruct and characterize trust. temperatures during this time and with an annual resolution.

Working area and thermal anomalies Nature

“Due to changes in Earth’s orbit, we would expect a continuous, slow and gradual decrease in summer solar energy and hence temperature in the subpolar latitudes of the Northern Hemisphere in the last 8-9 thousand years. Near the trees growing in Yamal, this cooling trend was interrupted in the middle of the 19th century when the temperature began to rise very rapidly. and reached the highest values ​​in the last decades,” says lead researcher Rashit Hantemirov.

Whatever the duration of the period under consideration (from 30 to 170 years), the closest period was the warmest period. Not only has the temperature reached unprecedented levels, but the rate of temperature rise has never been as rapid as it was after the mid-19th century.

“Extraordinary modern warming is supported by the confirmation that the last century was characterized by the complete absence of extreme cold. 27 years of extreme heat, 19 of which were in the last 40 years‘ indicates Rashit Hantemirov.

The authors of this study believe that human activities have not only affected climate change, but have become its main cause, at least for north-west Siberia.

Climate reconstruction research based on tree rings will continue into the future. Indeed, there is potential to extend the tree-ring chronology by another 2,000 years over time, the researchers say.

Research team members

“Thanks to the international collaboration, it will be possible to use parameters other than tree rings to further refine climate reconstructions. Together with our colleagues from Switzerland, we are working on the analysis of the cellular structures of tree rings.” and with the Institute. We aim to perform a climate reconstruction based on the analysis of the oxygen-18 isotope in the annual rings,” adds Rashit Hantemirov from the Department of Geology and Geophysics of the Chinese Academy of Sciences.

Stepan Shiyatov, the pioneer of dendrochronology in Russia, was the first to realize the value of ancient trees found on the Yamal Peninsula. Together with our colleagues from the Institute of Animal and Plant Ecology, It started 40 years ago with systematic collections of sub-fossil woods. Since then, more than two dozen expeditions have been undertaken; The tree ring widths have been measured and it has a current collection of more than 5,000 specimens currently archived at the Institute of Plant and Animal Ecology.

Tree trunk sections during operation Nature

About 2,000 larch and spruce subfossil specimens have also been dated (using the cross-dating method). This allowed the year of formation of each annual ring to be assigned with absolute precision for the last 8,800 years, now the longest tree ring chronology in the polar regions.

Tree rings are one of the best natural archives of natural conditions that existed in the past. (including air temperature). Trees grown in sub-polar regions and at high altitudes are generally most sensitive to temperature changes. Tree remains that lived thousands of years ago, such as the Yamal Peninsula, provide access to an understanding of the past, which is the best basis for assessing the future.

Reference work: https://www.nature.com/articles/s41467-022-32629-x

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