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Abstract: Understanding of Neogene climate in Antarctica has been an intractable problem for over 20 years. Competing models of the effect of Pliocene climatic warmth have not yet been reconciled. New sedimentological and paleontological data from Dry Valley Drilling Project core (DVDP-10) demonstrate a dynamic climate regime for the early and mid-Pliocene record preserved in the floor of Taylor Valley. This succession of interbedded mudrocks, sandstones, conglomerates and diamictites includes evidence for times when the coastal plain landscape of Taylor Valley may have been vegetated by higher land plants. Biostratigraphic data from DVDP-10 are utilized to correlate to the more detailed and finely resolved record in the AND-1B core in southern McMurdo Sound. Accordingly, the interval in DVDP-10 that records dynamic environmental fluctuations with a possible vegetated coastal plain land system is bracketed at 4.92–4.25Ma. These data suggest that low altitude terrains of the Dry Valleys during the Early Pliocene were subjected to glacial-interglacial cycles in which some interglacials were largely ice-free. [Copyright &y& Elsevier]

Abstract: Marine Isotope Stage 31 (MIS-31) is one of the major interglacials of the early Pleistocene ~1.08 to 1.06Ma. Data from proximal sediment cores around several sectors of Antarctica indicate strong sea surface warming and ice shelf and sea ice retreat. Benthic deep-sea-core δ18O values at this time are some of the lowest of the Pleistocene, indicating both deep sea warming and reduced global ice volume. A coeval alignment of orbital parameters produces one of the strongest high-latitude summer insolation anomalies of the last several million years. Here we use a 3-D ice sheet-shelf model to simulate the evolution of Antarctic ice sheets through the event, and a global climate model to simulate temperatures and sea ice during peak Antarctic warmth. The ice model predicts nearly complete collapse and subsequent recovery of marine ice in West Antarctica, and the ice and climate model results agree well with proximal sediment core data in the Ross Embayment recovered by the ANDRILL and Cape Roberts drilling projects. The dominant forcing is found to be variations in sub-ice-shelf oceanic melting, with insignificant surface melting of terrestrial ice flanks even during peak warmth. Implications are noted in light of other observations and theories of Pliocene–Pleistocene Antarctic ice sheet variability that do involve surface melt. [Copyright &y& Elsevier]

Abstract: The Antarctic Peninsula has been identified as a region of rapid on-going climate change with impacts on the cryosphere. The knowledge of glacial changes and freshwater budgets resulting from intensified glacier melt is an important boundary condition for many biological and integrated earth system science approaches. We provide a case study on glacier and mass balance changes for the ice cap of King George Island. The area loss between 2000 and 2008 amounted to about 20km2 (about 1.6% of the island area) and compares to glacier retreat rates observed in previous years. Measured net accumulation rates for two years (2007 and 2008) show a strong interannual variability with maximum net accumulation rates of 4950mm w.e. a−1 and 3184mm w.e. a−1, respectively. These net accumulation rates are at least 4 times higher than reported mean values (1926–95) from an ice core. An elevation dependent precipitation rate of 343mm w.e. a−1 (2007) and 432mm w.e. a−1 (2008) per 100m elevation increase was observed. Despite these rather high net accumulation rates on the main ice cap, consistent surface lowering was observed at elevations below 270m above ellipsoid over an 11-year period. These DGPS records reveal a linear dependence of surface lowering with altitude with a maximum annual surface lowering rate of 1.44ma−1 at 40m and −0.20ma−1 at 270m above ellipsoid. These results fit well to observations by other authors and surface lowering rates derived from the ICESat laser altimeter. Assuming that climate conditions of the past 11years continue, the small ice cap of Bellingshausen Dome will disappear in about 285years. [Copyright &y& Elsevier]