Recent changes in seasonal snow and alpine glaciers in the Columbia River Basin, Canada

Projected loss of seasonal snow and alpine glaciers in the decades ahead will affect many communities and ecosystems that rely on surface runoff from mountain environments. The Canadian portion of the Columbia River basin drains over 100,000 km² of mountainous terrain in British Columbia. This region hosts practically all of the alpine glaciers within the entire Columbia River basin, and it also represents one of the key areas for water storage as seasonal snow. We describe the results of an integrated five-year monitoring program of the Basin's alpine snow cover and alpine glaciers and how these frozen reservoirs have changed. Our methods include bi-annual airborne laser altimetry surveys that sample over 10% of the Basin's ice cover. To understand the meteorological drivers of recent change we use the Weather Research and Forecast (WRF 3.6) Model run at 1 km resolution to simulate accumulation and melt of the winter snowpack and alpine glaciers over the period 2010-2018. We evaluate these recent changes against historical records of seasonal snow (snow pillows and snow courses), and glacier area and mass change from satellite imagery. Finally, we evaluate climatic and non-climatic factors that explain changes in the basin's snow and ice over the period 1979-present.