Home / News / Academics / Changing winds brought rapid thinning of Patagonia ice sheets

 

Key Points in this paper

• Reconstructing the timing and rate of decay of the Earth’s ice sheets since the Last Glacial Maximum (LGM) allows us to assess the mechanisms of climate change globally

• This provides crucial information for testing climate models, and helps us better predict the response of modern ice sheets to future climate change.

• This paper uses evidence from maps, aerial and satellite imagery, along with rock samples from mountains, to reconstruct the maximum extent of the LGM in Patagonia.

• It suggests that an important factor in past melting in the region was the changes in the airflow patterns across the Southern Hemisphere (SH)

C3W’s Neil Glasser recently co-published a paper that presents the first reconstruction of vertical ice-sheet profile changes from any of the Southern Hemisphere’s mid-latitude Pleistocene ice sheets. Using cosmogenic radio-nuclide (CRN) exposure analysis to record the decay of the former Patagonian Ice Sheet (PIS) from the Last Glacial Maximum (LGM) and into the late glacial.

Using samples, from mountains along an east-west transect to the east of the present North Patagonian Icefield (NPI), serve as ‘dipsticks’ that allow us to reconstruct past changes in ice-sheet thickness, and demonstrates that the former PIS remained extensive and close to its LGM extent in this region until ~19.0 ka. After this time rapid ice-sheet thinning, initiated at ~18.1 ka, saw ice at or near its present dimension by 15.5 ka. They argue that this rapid thinning was triggered by a combination of the rapid southward migration of the precipitation bearing Southern Hemisphere (SH) westerlies and regional warming.

The paper is available under Open Access licence:

“Rapid thinning of the late Pleistocene Patagonian Ice Sheet followed migration of the Southern Westerlies” J. Boex, C. Fogwill, S. Harrison, N. F. Glasser, A. Hein, C. Schnabel & S. Xu

Scientific Reports 3, Article number: 2118 doi:10.1038/srep02118

Published 02 July 2013

The white lines in the east (upper panel) show previously mapped outer limits, the Hatcher and Rio Blanco moraines. Pink dots show the location of cosmogenic exposure age samples, from mountains Cerro Tamango in the west to Cerro Oportus and Sierra Colorado in the east. The white dotted line shows the location of the transect shown in the cross section. The lower panel shows the transect generated from SRTM data with x15 vertical exaggeration. Sampled boulders are shown with exposure ages (circles show 10Be, triangles show both Be and Al exposure ages).