Perennial snow and ice features, including both perennial snowpatches and glaciers, play an important role in alpine hydrologic systems, with their melt providing streamflow in years when precipitation and seasonal snowmelt are scarce. Although much attention has been paid to the response of glaciers across the Western United States to a warming climate, relatively little research has been devoted to the status of perennial snowpatches under the same conditions. We use the Normalized Difference Snow Index to investigate spatial and temporal changes in perennial snowpatches and glaciers in Yosemite National Park, California, over thirty-four years (1988–2021), enhancing this remote sensing analysis with a field campaign focused on in situ observations and sampling of a subset of features for stable isotope analysis. We find that, over our study period, Yosemite’s perennial snowpatches decreased in number from 418 to 66 and decreased in area by 93 percent (from 2.33 to 0.17 km2), with a mean decrease of −0.065 km2/year, outpacing glacier area change. The decrease in perennial snowpatch area is primarily correlated with warming temperatures (p < .001) and fluctuating wintertime precipitation (p < .02), with periods of exceptionally high winter snowfall buffering summertime melt.
Hawkins et al. (Tue,) studied this question.