Accelerating shrinkage of Patagonian glaciers from the Little Ice Age (∼AD 1870) to 2011

We used Little Ice Age (LIA) trimlines and moraines to assess changes in South American glaciers over the last similar to 140 years. We determined the extent and length of 640 glaciers during the LIA (similar to AD 1870) and 626 glaciers (the remainder having entirely disappeared) in 1986, 2001 and 2011. The calculated reduction in glacierized area between the LIA and 2011 is 4131 km(2) (15.4%), with 660 km(2) (14.2%) being lost from the Northern Patagonia Icefield (NPI), 1643 km(2) (11.4%) from the Southern Patagonia Icefield (SPI) and 306 km(2) (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 degrees S and the large icefields, with the NPI and SPI now shrinking at 9.4 km(2) a(-1) (0.23% a(-1)) and 20.5 km(2) a(-1) (0.15% a(-1)) respectively. The shrinkage of glaciers between 52 degrees S and 54 degrees S accelerated after 1986, and rates of shrinkage from 1986 to 2011 remained steady. Icefield outlet glaciers, isolated glaciers and ice caps south of 54 degrees S shrank faster from 1986 to 2001 than they did from 2001 to 2011.