Mountain glacier extents at the Last Glacial Maximum

Mountain regions experienced repeated glacial expansions and retreats during the Quaternary, shaping landscapes, ecosystems, and regional climates. While numerous reconstructions exist for individual mountain glaciers, global geodatabases remain scarce and rarely updated to reflect the latest observations. Here, we present GLACIMONTIS, a global geodatabase of maximum recorded areal extents of mountain glaciers at local Last Glacial Maximum, spanning 57-14 kyr BP. Our synthesis integrates reconstructions from 209 studies across 271 mountain ranges worldwide, compiling 15,014 individual glacier reconstructions, including 8,809 reconstructions compiled for the first time in a global geodatabase. Our work updates knowledge in 135 mountain ranges and highlights research gaps in 71 others. GLACIMONTIS represents the most comprehensive and up-to-date synthesis of mountain glacier areal extent at the global and local Last Glacial Maximum, providing spatial boundaries for refining climate-glacier modeling and delineating paleoecological reconstructions, and a framework for identifying regional research gaps. GLACIMONTIS advances Quaternary science by enhancing access to paleoglacier reconstructions and fostering interdisciplinary research in and across mountains worldwide.