Evolution of glacial lakes from the Northern Patagonia Icefield and terrestrial water storage in a sea-level rise context

Abstract An increase of glacial lake area of 66.0 km 2 has been measured at the periphery of the Northern Patagonia Icefield (NPI) between 1945 and 2011. Results have been obtained by digitizing the glacial lakes from Lliboutry's topographic map and from various multitemporal Landsat satellite scenes (1976, 1987, 2001 and 2011). This first complete glacial lake inventory of the NPI indicates a total lake area of 167.5 ± 8.4 km 2 for 2011, which represents an increase of 64.9% with respect to the total glacial lake area of the NPI in 1945 (101.6 ± 19.1 km 2 ). The highest area increase was experienced by the San Quintin Lake with an expansion of 18.0 km 2 in the 1945–2011 period. Using a volume–area scaling model, a total volume increase of 4.8 km 3 is estimated for the entire glacial lake population in the 66-year period. Based on the volumetric increase of the glacial lakes we compute a terrestrial water storage factor of 10% of the contribution of NPI to sea-level rise for the last decade (2001–2011), which is considered as a lower bound since lakes that have lost contact with the ice are not considered in the inventory. The increasing risk of Glacial Lake Outburst Floods (GLOF's) due to the glacial lake enlargement is also discussed.