Research press release


Nature Geoscience

Climate science: Melting glaciers might contain less ice than previously thought

氷河の氷の厚さに関するコンピューター解析から、世界中の氷河が全て融解した場合の海水準上昇の全量は、これまでの推定よりも20%少ない可能性があることが示唆された。この知見を報告する論文が、Nature Geoscience に掲載される。


今回、Romain Millanたちは、数千の人工衛星画像を用いて氷河の氷の動きの高分解能全球分布図を作製した。このデータに基づいて、Millanたちは氷の厚さを計算することが可能となり、世界中の氷河に蓄えられた氷の全量を見積もった。その結果、氷河は257ミリメートルの海水準上昇に寄与する可能性があることが明らかになった。これは、これまでの見積もりよりも20%少ない。これまでの評価との注目すべき違いは地域的にも見られ、ヒマラヤ山脈にはより多くの氷があるが、熱帯の南米アンデス山脈などの他の地域では氷の量は少なく、その地域の住民の水の利用可能性に影響を与える。



The total rise in sea levels that would occur if all of the world’s glaciers melted may be 20% less than previously estimated, suggests computational analysis of glacier ice thickness published in Nature Geoscience.

Sea level is on the rise due to melting glaciers, shrinking ice sheets and the thermal expansion of the oceans. Melting glaciers contribute around 25–30% of current sea level rise, but the total amount of water in glaciers remains unclear due to a lack of ice thickness observations.

Romain Millan and colleagues used thousands of satellite images to construct a high-resolution global map of glacier ice motion. Based on this data, the authors were able to compute ice thickness and provide an estimate of the total volume of ice stored in glaciers worldwide. They found that glaciers have a potential to contribute 257mm to sea level rise, which is 20% less than previously estimated. Notable differences to previous assessments were also found regionally, with the results suggesting there is more ice in the Himalayas, but less ice in other regions, such as the tropical Andes of South America, which impact the water availability for local population.

The authors conclude that their results may affect the prediction of glacier evolution worldwide, given the importance of accurate glacier geometry and dynamics for glacier modelling.

Additional, on-site observations of ice thickness that form the foundation of these analyses, are, however, needed. The impact of melting glaciers should also not be mistaken for overall sea level rise projections, which are influenced by other phenomena such as thermal expansion and shrinking ice sheets.

doi: 10.1038/s41561-021-00885-z


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