Material of the Month
August 2025
Arctic Warming has Detrimental Consequences for Permafrost Deposits

Figure: Reduction of the permafrost area in the Northern Hemisphere as
a function of an increase in mean annual air temperature at a 2°C interval.
20°C+ warming is likely to result in the complete disappearance of permafrost.

Arctic warming has detrimental consequences for permafrost deposits, a vast carbon store. We use cave carbonates (speleothems) from Siberia to determine when the Northern Hemisphere was last permafrost-free. These speleothems grew 8.6 million years ago, a time when regional tempera-tures were 6.6°C to 11.1°C higher than modern.
Our findings provide direct evidence that warming to such levels would leave most of the Northern Hemisphere permafrost-free, releasing large amounts of carbon and further acerbating global warming.

This work was carried out by a multidisciplinary team including Dr. Franziska Anna Lechleitner from LARA @DCBPunibern, who will take up a new position starting in September 2025 as group leader at the WSL (Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft / Swiss Federal Institute for Forest, Snow and Landscape Research) in Birmensdorf.

References:

  • A. Vaks, A. Mason, S. F. M. Breitenbach, A. Giesche, A. Osinzev, I. Adrian, A. Kononov, S. Umbo, F. A. Lechleitner, M. Rosensaft, G. M. Henderson;
    "Arctic speleothems reveal nearly permafrost-free Northern Hemisphere in the late Miocen"
    Nature Communications, 2025, 16, 5483/1-13; doi:10.1038/s41467-025-60381-5.