Proglacial lake expansion and glacier retreat in Arctic Sweden

Proglacial lakes have increased in number and extent in Arctic Sweden since the 1950s/1960s as glaciers have retreated dramatically. Interrogation of Rapid Eye imagery highlights that some lake terminating glaciers had substantial (>100 m) rates of retreat between 2010 and 2018, with one other land terminating glacier also retreating at a similar rate. However, analysis of a regional remote sensing time series suggests that proglacial lake formation in this period across the area has not been uniform. Despite glacier accumulation areas having similar maximum elevations (∼2,000 m) and similar alpine topography, proglacial lakes in the southern area (Sarek) were found to be significantly smaller than proglacial lakes in the northern area (Kebnekaise), which had smaller glaciers within corries and more prominent terminal moraines. Therefore, it cannot be assumed that proglacial lake formation will occur as glaciers retreat in response to elevated air temperature, particularly as only 33% of glaciers had proglacial lakes in their forefield. Thus, whilst it cannot be assumed that proglacial lakes will accommodate water currently held in glaciers, the 108 lakes mapped here present a substantial area (4.767 ± 0.377 km2) of fresh water that has not previously been included in the Global Lakes and Wetlands Database (GLWD). This inventory therefore provides an important dataset that can be used to underpin our understanding of the role of proglacial lakes within the hydrological system in this area of the Arctic.