Warm fossils under ice: clues to Antarctica’s Cenozoic ice sheet history

Abstract for the Paleontological Society Distinguished Lecture Series
 

David M. Harwood, Stout Chair of Stratigraphy, Dept. of Geosciences, University of Nebraska-Lincoln
Lincoln, NE 68588-0340

 Knowledge of past ice volume variation in Antarctica will enable us to assess the potential for future changes due to global warming.  However, the stratigraphic record of Cenozoic Antarctic life and paleoclimate is largely hidden by the thick ice cover. Fossil evidence obtained from beneath the ice sheets, or transported from subglacial sources to deposits at the ice sheet margin, provides a means to reconstruct fluctuating ice volume, paleogeography of marine basins, and past climate change.  This approach of ‘reconstructive biostratigraphy’, involving fossils in the Sirius and Pagodroma groups suggest pre-Pleistocene climate warmer than present, ice volume reduction, repeated marine flooding of Antarctic basins, and survival of higher plant-supported terrestrial communities until the Pliocene.  These results fuel an ongoing debate concerning the character and stability of Neogene ice sheets.  When did the present cold-polar conditions begin?  How did Antarctic life adapt to progressive isolation and cooling?  How many glacial/deglacial cycles occurred during the Neogene?  Was Antarctica immune or actively linked to global warming during Pliocene time?  Did Plio-Pleistocene uplift of the southern and central Transantarctic Mountains lead to regional cooling, sea-ice development and onset of the present cold-polar conditions?  Fossil evidence provides the basis to raise these questions and to start outlining some possible answers.