Glacier Equilibrium-Line Altitude Change Across Alaska and Adjacent Canada Indicates a Cold, Dry Little Ice Age and Weaker Aleutian Low

As Arctic warming accelerates, understanding hydroclimate shifts is key to projecting glacier melt and sea-level rise. We assess the climatic signature of the Little Ice Age (LIA; ∼1250 to 1900) by quantifying changes in equilibrium-line altitude (ΔELA) for 215 Alaskan glaciers from the LIA maximum to present (2016–2024), using remote sensing and geographic information system methods. ELAs have risen by 170 ± 8 m, equivalent to 1.6 ± 0.3°C summer warming (assuming constant precipitation) or 248 ± 89 mm w.e. annual precipitation increase (assuming 2.3°C warming). The latter is ∼4X the precipitation change observed since 1950. Glacier morphology and topographic setting explain 32% of ΔELA variance, likely reflecting differing sensitivities to climatic shifts and elevation-dependent warming. Spatially interpolated ΔELA residuals are most strongly correlated to winter precipitation (r = −0.67). Results suggest the LIA was characterized by (a) colder, drier conditions and (b) a weak, westward-displaced Aleutian Low that has since strengthened and shifted eastward.