北極の融解期は1980年代より1週間長くなった、新たな海氷研究で判明(Q&A: The Arctic melt season is a week longer now than it was in the 1980s, shows new UW research on sea ice trends)

2026-09-02 ワシントン大学(UW)

ワシントン大学の研究チームは、北極海の海氷を長期観測したデータを解析し、1980年代と比べて北極の融解期が約1週間長期化していることを明らかにした。衛星観測などを用いて1979~2024年の海氷の季節変動を調べた結果、北極全体で融解開始時期が早まり、凍結開始時期が遅くなる傾向が確認された。特に海氷が薄くなったことで、夏季の融解だけでなく、秋季の再凍結の遅れも顕著になっている。融解期の長期化は海氷面積の減少だけでなく、海氷の厚さや熱収支、太陽光の吸収などにも影響し、北極域の気候システムをさらに変化させる可能性がある。研究者らは、こうした海氷の季節サイクルの変化を継続的に監視することが、北極の将来予測や気候変動への理解に重要だとしている。

北極の融解期は1980年代より1週間長くなった、新たな海氷研究で判明(Q&A: The Arctic melt season is a week longer now than it was in the 1980s, shows new UW research on sea ice trends)
Researchers collecting measurements of algae and sea ice properties in the Chukchi Sea in July 2011, as part of NASA’s Impacts of Climate on the Eco-Systems and Chemistry of the Arctic Pacific Environment (ICESCAPE) mission. The changes of the Arctic sea ice cover have repercussions for the functioning of the polar marine ecosystem. Photo: Melinda Webster

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北極および南極の海氷の特性とプロセスの変化 Changes in Arctic and Antarctic sea-ice properties and processes

Melinda A. Webster,Stefanie Arndt,Angela Bliss,Sahra Kacimi,Ted Maksym,François Massonnet,Aku Riihelä & Takenobu Toyota
Nature Reviews Earth & Environment  Published:02 September 2026
DOI:https://doi.org/10.1038/s43017-026-00816-9

Abstract

Although sea ice covers only ~9% of the world’s oceans, its presence and absence greatly alter the energetic balance of Earth’s climate. Owing to geographic differences, Arctic and Antarctic sea ice have different dominant properties and processes, which in turn produce different responses to natural climate variability and anthropogenic climate change. This Review surveys the changes in sea-ice properties and processes of the Arctic and Antarctic environments. The Arctic melt season has lengthened by ~7.4 days per decade during 1979–2024, alongside decreases in winter sea-ice thickness (1.6 m mean total over 1980–2023), summer surface albedo (0.03 per decade over 1979–2020) and spring snow depth (2.5 cm per decade over 1954–2024). Changes in the Antarctic are smaller than those in the Arctic owing to contrasting regional and temporal trends. From a dynamic perspective, sea-ice motion in both hemispheres has increased, by 0.63 cm s–1 per decade in the Arctic (1978–2024) and 0.69 cm s–1 per decade in the Antarctic (1982–2024), whereas trends in polynya occurrence differ by region. This Review highlights major knowledge gaps and provides recommendations for joint model-observation efforts to improve understanding of sea ice and its role in Earth’s climate system.

1901環境保全計画
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