Patagonian Glacier Response During the Late Glacial–Holocene Transition
Robert P. Ackert, Jr.,1*
Richard A. Becker,2
Brad S. Singer,2
Mark D. Kurz,3
Marc W. Caffee,4
David M. Mickelson2
Whether cooling occurred in the Southern Hemisphere during the
Younger Dryas (YD) is key to understanding mechanisms of millennial
climate change. Although Southern Hemisphere records do not
reveal a distinct climate reversal during the late glacial period,
many mountain glaciers readvanced. We show that the Puerto Bandera
moraine (50°S), which records a readvance of the Southern
Patagonian Icefield (SPI), formed at, or shortly after, the
end of the YD. The exposure age (10.8 ± 0.5 thousand
years ago) is contemporaneous with the highest shoreline of
Lago Cardiel (49°S), which records peak precipitation east
of the Andes since 13 thousand years ago. Absent similar moraines
west of the Andes, these data indicate an SPI response to increased
amounts of easterly-sourced precipitation—reflecting changes
in the Southern Westerly circulation—rather than regional
cooling.
2 Department of Geology and Geophysics, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, WI 53706, USA.
3 Woods Hole Oceanographic Institution, Clark 419, MS #25, Woods Hole, MA 02543, USA.
4 Purdue Rare Isotope Measurement Laboratory, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907–2036, USA.
* To whom correspondence should be addressed. E-mail: rackert{at}fas.harvard.edu
