Late Holocene fluctuations of Qori Kalis outlet glacier, Quelccaya Ice Cap, Peruvian Andes.

The temporal and spatial patterns of late Holocene climate conditions provide valuable information for testing hypothesized mechanisms of recent climate changes. As a proxy for late Holocene climate in the southern tropics, we present a 10Be chronology of moraines deposited by Qori Kalis, an outlet glacier of Quelccaya Ice Cap in Peru. The Qori Kalis moraines are located downflow from the Quelccaya ice cores and provide the first glacial extent record that can be compared directly to annually resolved tropical ice core records. Qori Kalis advanced to its late Holocene maximum extent prior to 520 ± 60 yr before CE 2009, when Quelccaya ice core net accumulation values were at or below their late Holocene average. Subsequent glacial retreat between ~520 and 330 yr before CE 2009 coincides with the highest net accumulation values of the ~1800-yr-long ice core record. Therefore, we suggest that temperature, rather than net accumulation, was the primary driver of these glacial fluctuations. Comparison of the late Holocene fluctuations of Qori Kalis glacier with glaciers in the southern tropical Andes, Patagonian Andes, Switzerland, Alaska and New Zealand suggests globally synchronous, centennial-scale cold events. [ABSTRACT FROM AUTHOR]