Accelerating shrinkage of Patagonian glaciers from the "Little Ice Age" (c. AD 1870) to 2011 Seminar

Event details

We used "Little Ice Age" ("LIA") trimlines and moraines to assess changes in South American glaciers over the last ~140 years. We determined the extent and length of 640 glaciers during the "LIA" (c. AD 1870) and 626 glaciers (the remainder having entirely disappeared) in 1986, 2001 and 2011. The calculated loss of glacierised area between the "LIA" and 2011 is 4131 km2 (15.4%), with 660 km2 (14.2%) being lost from the Northern Patagonian Icefield (NPI), 1643 km2 (11.4%) from the Southern Patagonian Icefield (SPI), and 306 km2 (14.4%) from Cordillera Darwin. Latitude, size and terminal environment (calving or land-terminating) exert the greatest control on rates of shrinkage. Small, northerly, land-terminating glaciers shrank fastest. Annual rates of area loss increased dramatically after 2001 for mountain glaciers north of 52°S and the large ice fields, with the NPI and SPI now shrinking at 9.4 km2 a-1 (0.23% a-1) and 20.5 km2 a-1 (0.15% a-1) respectively. The shrinkage of glaciers between 52°S and 54°S accelerated after 1986, and rates of shrinkage from 1986-2011 remained steady. Icefield outlet glaciers, isolated glaciers and ice caps south of 54°S shrank faster from 1986-2001 than they did from 2001-2011. chaired by Professor Pete Langdon