Institute of Environmental Science and Geography, University of Potsdam, Potsdam-Golm, Germany.
Institute of Geosciences, University of Potsdam, Potsdam-Golm, Germany.
Nature. 2023 Feb;614(7949):701-707. doi: 10.1038/s41586-022-05642-9. Epub 2023 Feb 15.
Episodic failures of ice-dammed lakes have produced some of the largest floods in history, with disastrous consequences for communities in high mountains. Yet, estimating changes in the activity of ice-dam failures through time remains controversial because of inconsistent regional flood databases. Here, by collating 1,569 ice-dam failures in six major mountain regions, we systematically assess trends in peak discharge, volume, annual timing and source elevation between 1900 and 2021. We show that extreme peak flows and volumes (10 per cent highest) have declined by about an order of magnitude over this period in five of the six regions, whereas median flood discharges have fallen less or have remained unchanged. Ice-dam floods worldwide today originate at higher elevations and happen about six weeks earlier in the year than in 1900. Individual ice-dammed lakes with repeated outbursts show similar negative trends in magnitude and earlier occurrence, although with only moderate correlation to glacier thinning. We anticipate that ice dams will continue to fail in the near future, even as glaciers thin and recede. Yet widespread deglaciation, projected for nearly all regions by the end of the twenty-first century, may bring most outburst activity to a halt.
间歇性冰坝湖溃决导致了一些历史上最大规模的洪水，给高海拔地区的社区带来了灾难性的后果。然而，由于区域洪水数据库不一致，冰坝溃决活动随时间变化的估计仍然存在争议。在这里，通过整理六个主要山区的 1569 个冰坝溃决事件，我们系统地评估了 1900 年至 2021 年期间峰值流量、体积、年时间和源海拔的变化趋势。结果表明，在六个地区中的五个地区，极端峰值流量和体积（10%最高）在这一时期下降了约一个数量级，而中值洪水流量下降较少或保持不变。当今全球的冰坝洪水起源于更高的海拔，并且比 1900 年提前大约六周发生。具有重复爆发的单个冰坝湖显示出相似的规模和更早发生的负向趋势，尽管与冰川变薄的相关性仅为中度。我们预计，即使冰川变薄和退缩，冰坝也将在不久的将来继续溃决。然而，到二十一世纪末，几乎所有地区都预计会出现冰川大范围融化，这可能会使大多数冰坝溃决活动停止。
