Siberian trees are telling the humans it’s too hot !

Increases in sea ice melt, permafrost melt and wildfires are observed whilst Siberian temperatures continue to escalate beyond previous records, for example 38°C last year inside the Arctic Circle. To understand the changes, researchers looked at proxy records. Historically in the Siberian Arctic they have mostly included low-resolution pollen records and laminated lake sediments. They don’t show climate variability for any period shorter than 300 years and most end in the mid-twentieth century. This makes it difficult to predict changes and level of changes for future Arctic warming.

To enhance the existing data, the scientists used tree rings from the Yamal Peninsula to reconstruct 7638 years of Siberian Arctic summer temperature variability. The tree rings indicate the growing seasons within the Siberian Arctic and provide clues to the environmental factors affecting the tree growth. They were able to reconstruct warming trends based on previous Holocene summar cooling at the end of the previous little Ice Age but have found that current warming and the variation in temperature anomalies is unprecedented for the Yamal region in Siberia.

The Yamal tree-ring chronology has been developed by collecting these subfossil trees over the past 40 yrs during extensive fieldwork, making it the longest and best replicated tree-ring width (TRW) record from the Arctic with more than 4800 collected samples. The dataset used in this study contains 1611 TRW series (i.e. 1425 subfossil logs and 186 increment cores from living trees) from L. sibirica trees collected along four south-flowing rivers at elevations

Hantemirov, et al., 2022

They also used existing sampling data including permafrost regions where seasonal melt can reach up to 2m with the Yamal region affected by warming of the Barents and Kara seas. Surface air temperature has increased between 1.32 °C and +2.33 °C, and +2.02 °C and +3.06 °C compared to data from 1961 – 1990. They consistently found across different time windows that the current mean temperature increase is exceptional compared to other periods. Although this is a data reconstruction, the increases are supported by existing observational environmental and climate changes on the ground and in the air. They expect that heatwaves, permafrost melt and wildfires will continue to increase across the Siberian Arctic and recommend that adaptation strategies need to be adopted.

Hantemirov, R.M., Corona, C., Guillet, S. et al. Current Siberian heating is unprecedented during the past seven millennia. Nat Commun 13, 4968 (2022).

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