LATE GLACIAL AND HOLOCENE DEGLACIATION IN THE PERUVIAN ANDES: A REVIEW OF TIMING, RATES AND CLIMATIC CONDITIONS

Glacial moraine chronology provides a basis for evaluating the timing and rates of deglaciation for late glacial and Holocene paleoglaciers in the Peruvian Andes. Paleoglacier volumes provide a constraint on climate conditions when viewed with other proxy records. Rates of deglaciation were calculated for paleoglacier volumes on both the western side of the Quelccaya Ice Cap and the northwest side of the Cordillera Vilcanota, Perú. The late glacial episode of deglaciation on the west side of Quelccaya is coincident with rapid deglaciation in the Cordillera Blanca of north central Perú that occurred during the Younger Dryas interval, out of phase with glaciation in the North Atlantic region (Rodbell and Seltzer, 2000). The fastest rates of deglaciation were calculated for the youngest paleoglaciers, corresponding to the last few centuries. These rates fall within the range of modern rates measured on the Quelccaya Ice Cap, interpreted as evidence of enhanced atmospheric temperatures (Brecher and Thompson, 1993; Thompson, 2000). Applying the maximum modern deglacial rates to the late glacial ice volumes results in deglaciation over a few centuries, consistent with lake-core evidence. These results imply that rates of deglaciation may fluctuate significantly over time, and that high rates of deglaciation may not be exclusive to the late 20th century.

Brecher, H. and Thompson, L. G. (1993). Measurement of the retreat of Qori Kalis glacier in the tropical Andes of Peru by terrestrial photogrammetry. Photogrammetric Engineering & Remote Sensing 59(6), 1017-1022.

Rodbell, D. T. and Seltzer, G. O. (2000). Rapid Ice Margin Fluctuations during the Younger Dryas in the Tropical Andes. Quaternary Research 54, 328-338.

Thompson, L. G. (2000). Ice core evidence for climate change in the Tropics: implications for our future. Quaternary Science Reviews 19, 19-35.