沿岸氷河の後退は気候変動と関連している(Coastal Glacier Retreat Linked to Climate Change)

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2022-07-14 テキサス大学オースチン校(UT Austin)

世界の沿岸氷河の多くがこれまでになく急速に融解していますが、氷河を取り巻く環境の自然な変動により、大規模な後退を引き起こしている原因を正確に突き止めることは困難でした。このたび、テキサス大学地球物理学研究所(UTIG)とジョージア工科大学の研究者が、沿岸氷河の後退の理由と、それが人為的な気候変動によるものである可能性を解明するための方法を開発した。沿岸氷河は直接海に溶け出すため、人為的な影響を考慮することで、海面上昇をより正確に予測できるようになるかもしれません。

<関連情報>

海洋性末端氷河の後退における人為的気候変動の役割を定量化するための確率論的フレームワーク A probabilistic framework for quantifying the role of anthropogenic climate change in marine-terminating glacier retreats

John Erich Christian, Alexander A. Robel, and Ginny Catania
The Cryosphere  Published: 13 Jul 2022
DOI:https://doi.org/10.5194/tc-16-2725-2022

沿岸氷河の後退は気候変動と関連している(Coastal Glacier Retreat Linked to Climate Change)

Abstract

Many marine-terminating outlet glaciers have retreated rapidly in recent decades, but these changes have not been formally attributed to anthropogenic climate change. A key challenge for such an attribution assessment is that if glacier termini are sufficiently perturbed from bathymetric highs, ice-dynamic feedbacks can cause rapid retreat even without further climate forcing. In the presence of internal climate variability, attribution thus depends on understanding whether (or how frequently) these rapid retreats could be triggered by climatic noise alone. Our simulations with idealized glaciers show that in a noisy climate, rapid retreat is a stochastic phenomenon. We therefore propose a probabilistic approach to attribution and present a framework for analysis that uses ensembles of many simulations with independent realizations of random climate variability. Synthetic experiments show that century-scale climate trends substantially increase the likelihood of rapid glacier retreat. This effect depends on the timescales over which ice dynamics integrate forcing. For a population of synthetic glaciers with different topographies, we find that external trends increase the number of large retreats triggered within the population, offering a metric for regional attribution. Our analyses suggest that formal attribution studies are tractable and should be further pursued to clarify the human role in recent ice-sheet change. We emphasize that early-industrial-era constraints on glacier and climate state are likely to be crucial for such studies.

1702地球物理及び地球化学
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