Progressively smaller glacier lake outburst floods despite worldwide growth in lake area

This paper consists of a mapping exercise, where the authors mapped the areas of 1,686 glacier lakes, just before they drained, across 13 glaciated mountain regions across the world outside of polar regions. They further examined the trends in pre-glacier lake outburst flood (GLOF) lake areas between 1990 and 2023. 

The findings show that pre-GLOF lake areas showed little change, or even decreased, regionally through time - even as the total lake area, and thus hazard potential, grew overall. This counterintuitive finding reflects limits to growing GLOF magnitudes, such as:

• The decoupling of lakes and parent glaciers;
• The development of wide, low-gradient outlets;
• Human management.

Across all regions, pre-GLOF lake areas depend on a few ice-dammed lakes, which have produced ten times more reported outbursts and ten times larger outbursts than moraine- and bedrock-dammed lakes. The latter two dam types will continue to hold growing amounts of meltwater, thereby accounting for most of the overall GLOF hazard potential, while ice-dammed lakes will shrink with deglaciation.