Permafrost occurrence at Mt. Sashirui, Shiretoko mountain range, eastern Hokkaido, Japan

Researchers have confirmed the first occurrence of permafrost in the Shiretoko mountain range, specifically at Mt. Sashirui in eastern Hokkaido, Japan. Through 5.5-meter borehole temperature measurements near the summit, a wind-swept site covered by alpine dwarf shrubs, the study identified conditions close to the threshold for permafrost formation. The persistence of permafrost here is attributed to thermal insulation provided by bryophyte and lichen cover during summer and efficient heat transfer through frozen shrub branches and thin snow layers in cold spells. This discovery highlights the vulnerability of mountain permafrost to climate change, emphasizing the need for continuous long-term monitoring to track shifts in ground temperatures in this UNESCO World Heritage Site.

OHNO, H., NAKAMURA, S., TERAYAMA, G., KUMAGAI, Y., HASHIMOTO, K., WATANABE, T., HACHIKUBO, A., TATEYAMA, K., ADACHI, H., ADACHI, R., TSUKAYA, K., SATO, K., HATA, K., KOMAMIYA, S., SATO, K., & MINAMI, H. (2025). Permafrost occurrence at Mt. Sashirui, Shiretoko mountain range, eastern Hokkaido, Japan（知床連山，サシルイ岳における永久凍土の発見）. Bulletin of Glaciological Research, 43(0), 1–7. https://doi.org/10.5331/bgr.24r05