HR: 09:30h
AN: PP51A-07 INVITED     [PDF]
TI: The Little Ice Age in the tropical Andes
AU: * Jomelli, V
EM: jomelli@cnrs-bellevue.fr
AF: CNRS Laboratory of Physical Geography, UMR 8591 1, Place A. Briand, Meudon-Bellevue, 92195 France
AU: Cooley, D
EM: cooleyd@colorado.edu
AF: Department of Applied Mathematics, University of Colorado ECOT 231, Boulder, CO 80309-0526 United States
AU: Naveau, P
EM: naveau@colorado.edu
AF: Department of Applied Mathematics, University of Colorado ECOT 231, Boulder, CO 80309-0526 United States
AU: Rabatel, A
EM: rabatelantoine@yahoo.fr
AF: CNRS Laboratory of Physical Geography, UMR 8591 1, Place A. Briand, Meudon-Bellevue, 92195 France
AB: The period known as the Little Ice Age, from the 17th to the 19th century, brought a cooling of around 0.5 degrees Celsius as well as varyingly humid episodes Eurasia and North America. Because of a lack of long paleoclimatic time series in the tropical Andes, it is still unclear if similar cooling occurred over these tropical and Southern Hemisphere regions. Furthermore, if changes did take place, it is currently not well established if they were temporally synchronous or shifted with respect of the variations in the Northern Hemisphere or the globe. To look into this important climatic question and for advancing our understanding of the past climate links between the tropics and higher latitudes, 25 glaciers located in Bolivia and in Peru were carefully selected. Glacial activity and environmental changes were analyzed using lichenometry. Largest lichen diameters were measured in the different glacial basins. To better analyze these maximum diameters and to more appropriately represent uncertainty and the character of this collected data, age estimates of the different moraine systems were derived using extreme value theory rather than the traditional averaging. The results reveal two particular phases of glacier growth, 1550-1600 and 1800-1850. These two phases have also been identified in other proxy records, such as ice-cores and documentary data (particularly from church chronicles). In order to understand the climatic changes that could have contributed to the glacial variations, a simple model based on both precipitations and temperatures is applied to estimate mass balance questions in the basins. A cooling of the order of 0.5 C seems to be the most consistent with the data. Finally, these findings are compared with the better-known histories of Northern Hemisphere mid-latitude glaciers.
DE: 1625 Geomorphology and weathering (1824, 1886)
DE: 1827 Glaciology (1863)
DE: 1833 Hydroclimatology
DE: 3344 Paleoclimatology
DE: 3374 Tropical meteorology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting