Response of the marginal marine environment to post-glacial warming in the Ross Sea, Antarctica
Christina R Riesselman1, Rebecca L Parker2, Greer Gilmer3, Jae IL Lee4, Kyu-Cheul Yoo4, Min Kyung Lee4, Cristina Subt5, Robert M Mckay6, Brad E Rosenheim5, Richard H Levy7, Christian Ohneiser8 and Robert B Dunbar9, (1)University of Otago, Departments of Geology and Marine Science, Dunedin, New Zealand, (2)University of Exeter, Exeter, United Kingdom, (3)University of Otago, Dunedin, New Zealand, (4)Korea Polar Research Institute, Incheon, Korea, Republic of (South), (5)University of South Florida, St Petersburg, FL, United States, (6)Victoria University of Wellington, Wellington, New Zealand, (7)GNS Science, Lower Hutt, New Zealand, (8)University of Otago, Departement of Geology, Dunedin, New Zealand, (9)Stanford University, Stanford, CA, United States
Abstract:
The Holocene represents our most recent and accessible window into the forcings and feedbacks that drive global climate, and is characterized by episodes of abrupt change superimposed upon long-term trends. However these intervals of rapid change are not globally synchronous, highlighting the influence of regional climate processes that may operate on societally significant time scales. Around Antarctica, ice core and marine sediment paleoclimate records indicate heterogeneity in the timing and geographic locus of warming associated with deglaciation and Holocene climatic events. Regional variability in the extent of Antarctic warming throughout the Holocene is mirrored in recent observations, where overlapping modern instrumental records reveal dramatic regional differences in the extent and magnitude of polar warming and ice mass balance. In order to understand the processes by which the Antarctic cryosphere responds to – and impacts – a changing climate, it is therefore essential to develop regionally representative records from geographically dispersed locations around the continent and margin.
Here, we summarize initial results from a suite of marine sediment cores collected in the Southern Ocean and western Ross Sea by the R/V Araon during the 2015 ANA05B expedition. This expedition recovered 35 cores on a latitudinal transect from 69-77° S. In 18 of these, ice retreat is recognized in whole-core measurements of magnetic susceptibility and bulk density, and in a lithologic transition from terrigenous to diatomaceous sediments. To examine the evolution of the marginal marine environment following deglaciation, we focus specifically on cores collected from the Robertson Bay, Moubray Bay, Mawson Glacier, and Ross Island regions. In many of these cores, the recovery of seasonally laminated diatom oozes enables us to develop high-resolution snapshot reconstructions of Holocene sea surface conditions, based on diatom micropaleontology and stable isotope geochemistry. Placing these snapshots in a continental context requires robust chronostratigraphic constraint, which will enable us to examine linkages between marginal marine conditions and terrestrial processes by correlating our new Ross Sea records to high-resolution ice and sediment core reconstructions across East Antarctica.
