About 34 million years ago, Earth's climate cooled and an ice sheet formed on Antarctica as atmospheric carbon dioxide (CO2) fell below ∼750 parts per million (ppm). Sedimentary cycles from a drill core in the western Ross Sea provide direct evidence of orbitally controlled glacial cycles between 34 million and 31 million years ago. Initially, under atmospheric CO2 levels of >600 ppm, a smaller Antarctic Ice Sheet (AIS), restricted to the terrestrial continent, was highly responsive to local insolation forcing. A more stable, continental-scale ice sheet calving at the coastline did not form until ∼32.8 million years ago, coincident with the earliest time that atmospheric CO2 levels fell below ∼600 ppm. Our results provide insight into the potential of the AIS for threshold behavior and have implications for its sensitivity to atmospheric CO2 concentrations above present-day levels.
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|Titolo:||Antarctic Ice Sheet variability across the Eocene-Oligocene boundary climate transition|
|Citazione:||Antarctic Ice Sheet variability across the Eocene-Oligocene boundary climate transition / Galeotti, Simone; Deconto, Robert; Naish, Timothy; Stocchi, Paolo; Florindo, Fabio; Pagani, Mark; Barrett, Peter; Bohaty, Steven M.; Lanci, Luca; Pollard, David; Sandroni, Sonia; Talarico, FRANCO MARIA; Zachos, James C.. - STAMPA. - 352:6281(2016), pp. 76-80.|
|Appare nelle tipologie:||1.1 Articolo in rivista|