Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene

作者：Levy Richard^*; Harwood David; Florindo Fabio; Sangiorgi Francesca; Tripati Robert; von Eynatten Hilmar; Gasson Edward; Kuhn Gerhard; Tripati Aradhna; DeConto Robert; Fielding Christopher; Field Brad; Golledge Nicholas; McKay Robert; Naish Timothy; Olney Matthew; Pollard David; Schouten Stefan; Talarico Franco; Warny Sophie; Willmott Veronica; Acton Gary; Panter Kurt; Paulsen Timothy; Taviani Marco; Askin Rosemary; Atkins Clifford; Bassett Kari; Beu Alan; Brian Blackstone

来源：Proceedings of the National Academy of Sciences, 2016, 113(13): 3453-3458.

DOI：10.1073/pnas.1516030113

• Antarctica
• ice sheet
• Climate Optimum
• Ross Sea
• Miocene

Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23-14 Mya) is a compelling interval to study as global temperatures and atmospheric CO2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3-4 degrees C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major dis-conformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO2 concentrations were at or below preindustrial levels (similar to 280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (similar to 500 ppm) atmospheric CO2. These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene.

• 出版日期2016-3-29