Compared to freshwater from rain or melted snow, meltwater from glaciers is physically and chemically unique, and serves an important role in high latitude coastal hydrology and ecology. Today, as glaciers worldwide are shrinking, the amount and timing of glacier meltwater delivery into streams are both changing, with potential impacts for infrastructure and ecosystems. However, those changes may be difficult to identify in coastal areas due to large differences in year-to-year precipitation. Here, we use computer modeling to examine freshwater changes for the western Juneau Icefield in Southeast Alaska between 1980 and 2016. We detect several changes, including increases in the amount of glacier meltwater occurring annually and in spring (+10% and +16% per decade), and in total basin freshwater (+1.4% and +3% per decade). This suggests the area is still in a period of increasing glacier meltwater before the glaciers shrink to the extent that the amount diminishes. We also find that the peak amount of glacier meltwater is occurring earlier (2.5 days per decade), meaning that the type of freshwater arriving downstream at that time of year is changing. Our findings highlight that high latitude coastal watersheds are experiencing observable changes in freshwater as glaciers continue to shrink.
Young, J. C., Pettit, E., Arendt, A., Hood, E., Liston, G. E., & Beamer, J.. 2021. A Changing Hydrological Regime: Trends in Magnitude and Timing of Glacier Ice Melt and Glacier Runoff in a High Latitude Coastal Watershed. Water Resources Research. 57,7: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020WR027404. DOI: https://doi.org/10.1029/2020WR027404.