Sidney R. Hemming
Sidney R Hemming is a Professor in the Department of Earth and Environmental Sciences at Columbia University and a member of the senior staff at Lamont-Doherty Earth Observatory. She was trained as a geologist and isotope geochemist at Stony Brook University where she studied tectonics and sedimentation of the Paleoproterozoic Animikie Basin for her Ph.D., and she used similar analytical approaches to study the provenance of North Atlantic “Heinrich” layers as a post doc at Lamont. Since joining Columbia she has established Lamont’s AGES (Argon Geochronology for the Earth Sciences) lab. Her current research interests are geochronology, paleoceanography and paleoclimate. Her research themes include understanding provenance and processes in marine sediments, with specific emphasis on the archives collected from IODP Expeditions 361 (Agulhas Current System), 382 (Iceberg Alley, Antarctica) and 395 (Reykjanes Ridge).
The State of the Antarctic Ice Sheets Across the Plio-Pleistocene Transition
Antarctica’s ice sheets currently hold approximately 57 meters of sea level equivalent, and a societal concern of global warming is that excess loss of ice would lead to flooding of global coastline communities. The accumulated marine geological and geophysical evidence along with sparse exposures around Antarctica have allowed scientists to piece together a history of glaciation including that major inception of continental scale glaciation began about 34 million years ago, with periodic waxing and waning due to Earth’s orbital variations. The details of how the ice sheets have changed through time around Antarctic remain incompletely understood, but research on materials recovered in International Ocean Discovery Program (IODP) expeditions 374, 379, 382 and 383, along with previous ocean and ice shelf drilling archives, and emerging information from old ice exploration are adding important improvements in our understanding. Collectively these archives provide a framework for understanding Antartica’s role in climate history, and also inform our selection of future drilling expeditions. I consider the interval between 2.58 and 1.8 to be particularly interesting as the new and old formally defined boundaries between the Pliocene and Pleistocene. This perspective will be centered on the discoveries across the Plio-Pleistocene transition, the interval between 3.3 and 1.8 Ma, from IODP Expedition 382, and will emphasize the integrated observations that are emerging as well as the overall importance of scientific ocean drilling and the amazing legacy of the JOIDES Resolution.
