Surface Pond Energy Absorption Across Four Himalayan Glaciers Accounts for 1/8 of Total Catchment Ice Loss

Glaciers in High Mountain Asia, many of which exhibit surface debris, contain the largestvolume of ice outside of the polar regions. Many contain supraglacial pond networks that enhance meltrates locally, but no large-scale assessment of their impact on melt rates exists. Here we use surfaceenergy balance modeling forced using locally measured meteorological data and monthly satellite-derivedpond distributions to estimate the total melt enhancement for the four main glaciers within the 400-km2Langtang catchment, Nepal, for a 6-month period in 2014. Ponds account for0.20±0.03m/year of surfacemelt, representing a local melt enhancement of a factor of14±3compared with the debris-covered area,and equivalent to12.5±2.0% of total catchment ice loss. Given the prevalence of supraglacial ponds acrossthe region, our results suggest that effective incorporation of melt enhancement by ponds is essential foraccurate predictions of future mass balance change in the region.