LAUSR

Global glacier retreat driven by climate change will have major impacts on regional water availability, as many communities rely on glacier runoff for water supply during warm and dry seasons. A community whose water resources are potentially vulnerable is one that sources water from a glacier-fed river where that river is expected to substantially change if glacier contributions become negligible. However, regional assessments identifying which communities’ water resources are most vulnerable to such changes are lacking. Here we use observed streamflow measurements, gridded climate data and a database of municipal water sources for communities in Alberta, Canada, to identify the relative importance of glacier runoff at the local scale. In a scenario of negligible glacier runoff, we predict unprecedented streamflow lows at several communities. This approach provides a methodology to identify communities whose water resources may be vulnerable to glacier retreat and would benefit from more-focused research. Climate warming over Canada drives glacier retreat and threatens water resources in regions that rely on downstream meltwater. Streamflow and climate data are combined with a municipal water source database to identify Alberta communities whose water supply would be most impacted by glacier retreat.