Quantifying the 2015 Glacier Decline in Olympic National Park, Washington, USA

In the Olympic Mountains of Washington, USA, the winter of 2015 was over 2°C warmer than average, and the snowpack was the lowest ever recorded (~4% of average). The summer of 2015 between June 15th and September 1st was 2.6°C warmer than average, and this, combined with the lack of seasonal snow, led to record losses (~10 m in many locations) of glacial ice. Here, we combine manual snow and ice measurements with repeat lidar flights from the Airborne Snow Observatory (ASO) and digital elevation models reconstructed from high-resolution World View imagery to quantify losses on ten glaciers in Olympic National Park. Quantifying this loss is critical to determining how much new snow fell on the glaciers during the 2016 OLYMPEX field experiment. We compare our numbers with streamflow records and reported long-term rates of glacier change to put 2015 in perspective.