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The timing and magnitude of Holocene glacial oscillations in most currently ice‐free areas of Antarctica remain unknown. This work focuses on the recent deglaciation in the northern sector of the Fildes Peninsula, King George Island, northern Antarctic Peninsula. The ice cap covering ca. 90% of the island has receded since the Last Glacial Maximum and exposed ca. 29 km2 of ice‐free land. We reconstruct its glacial history based on a dataset of 12 36Cl exposure ages obtained through cosmic‐ray exposure (CRE) dating of moraine boulders, polished surfaces and erratic boulders surrounding the peninsula's northern plateau. Results reveal that the deglaciation of the northern Fildes Peninsula took place during the Holocene Thermal Maximum at 7–6 ka, when warm conditions promoted a massive glacial retreat. The present arrangement of ice‐free areas was in place by 6 ka. Small cirque moraines suggest the subsequent occurrence of favourable climate conditions for glacial expansion fed by intense snow deflation at 4.6 and 1 ka at the foot of the northern plateau. The deglaciation pattern of the Fildes Peninsula resulted from the combined shrinkage of different ice masses, rather than of the long‐term retreat of the King George Ice Cap. No evidence of glacier expansion during more recent cold periods (i.e. the Little Ice Age) was found. These results fit well with regional deglacial histories inferred from lacustrine sediments and raised beaches and complement the existing chronological framework to help better understand the peninsula's Holocene geoecological dynamics. [ABSTRACT FROM AUTHOR]

We analyzed the single‐grain mineralogical composition of aeolian dust transported to central East Antarctica for provenance purposes. Comparison with data from the last glacial period shows for the first time disappearance of carbonates during the Holocene related to sea level rise and suppressed deflation from the Argentinean continental shelf, exposed during Marine Isotope Stage 2. Zeolites, related to alteration of volcanic glass in the subglacial/periglacial environment of Patagonia, show a similar behavior. The remaining minerals, remarkably similar between the two climatic periods, are compatible with a Pampean and Patagonian provenance, but Holocene data show a more pronounced volcanic and metamorphic imprint and presence of minerals related to warm climate weathering environments compatible with an additional contribution from subtropical latitudes of South America. These results do not imply a major large‐scale reorganization of atmospheric circulation after the last climatic transition. Plain Language Summary: Aeolian mineral dust particles transported through the atmosphere from the austral continents to the Antarctic ice sheet represent a tracer of atmospheric circulation and transport, as well as being a source of information about environmental conditions within dust source regions. Many lines of evidence suggest that central East Antarctic dust is sourced from South America during the last glacial period, whereas there is not a general consensus about dust provenance during the Holocene. A major limitation to this problem is represented by the extremely low dust concentration in Antarctic ice during interglacials. In this study, we analyzed the single‐grain mineralogy of more than 2,300 mineral dust particles transported by winds to Dome C during four different time windows within the Holocene, the current interglacial. Comparing results with those obtained from dust deposited during the last glacial period, we observe that some minerals that are typically associated to glacial climate conditions in Patagonia almost disappear during Holocene, while the remaining minerals are compatible with a South American provenance in both climate periods. Data thus suggest that the dominant atmospheric circulation patterns did not experience a significant change with climate. However, data suggest an additional contribution from subtropical South American latitudes during Holocene. Key Points: The mineralogy of more than 2,300 aeolian dust particles windblown to central East Antarctica (Dome C) during the Holocene was identifiedDisappearance of carbonate dust during the Holocene relates to sea level rise and suppressed deflation from the Argentinean shelfAeolian dust suggests Pampean and Patagonian provenance in the Holocene and a lower latitude contribution, without major circulation changes [ABSTRACT FROM AUTHOR]

Abstract: A long-standing debate concerning Neogene Antarctic climate in the McMurdo Dry Valleys relies largely on evidence from landscape evolution, glacial modeling and stratigraphy. We provide new evidence from meteoric 10Be for the onset of frozen, hyper-arid conditions on a high elevation (1840m) interfluve at Table Mountain. A simple decay model for the co-occurrence of meteoric 10Be and illuviated clay in cores of ice-cemented glacial sediments indicates that the clays were actively migrating down from the surface in a warm climate until the system froze between 6 and 9Ma. Although this age range may be sensitive to possible interference by in situ produced 10Be, the implied minimum age of 6Ma for the Sirius Group indicates that the Dry Valleys were permanently frozen down to this elevation at this time. The model also suggests denudation rates of 1–6cmMyr−1 since freezing. These data provide an independent test of glacial-stratigraphic evidence used to determine Antarctic paleoclimate. [Copyright &y& Elsevier]

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]

Mineral dust aerosols represent an active component of the Earth's climate system, by interacting with radiation directly, and by modifying clouds and biogeochemistry. Mineral dust from polar ice cores over the last million years can be used as paleoclimate proxy, and provide unique information about climate variability, as changes in dust deposition at the core sites can be due to changes in sources, transport and/or deposition locally. Here we present results from a study based on climate model simulations using the Community Climate System Model. The focus of this work is to analyze simulated differences in the dust concentration, size distribution and sources in current climate conditions and during the Last Glacial Maximum at specific ice core locations in Antarctica, and compare with available paleodata. Model results suggest that South America is the most important source for dust deposited in Antarctica in current climate, but Australia is also a major contributor and there is spatial variability in the relative importance of the major dust sources. During the Last Glacial Maximum the dominant source in the model was South America, because of the increased activity of glaciogenic dust sources in Southern Patagonia-Tierra del Fuego and the Southernmost Pampas regions, as well as an increase in transport efficiency southward. Dust emitted from the Southern Hemisphere dust source areas usually follow zonal patterns, but southward flow towards Antarctica is located in specific areas characterized by southward displacement of air masses. Observations and model results consistently suggest a spatially variable shift in dust particle sizes. This is due to a combination of relatively reduced en route wet removal favouring a generalized shift towards smaller particles, and on the other hand to an enhanced relative contribution of dry coarse particle deposition in the Last Glacial Maximum. [ABSTRACT FROM AUTHOR]

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: We present a new reconstruction of the Antarctic Ice Sheets between 20 ka BP and the present day. Our reconstruction is derived using a numerical model to generate a physically-consistent ice surface across the whole of the continent. We define the extent of the ice sheet at five time slices; 20, 15, 10, 5 and 0 ka BP, assuming an equilibrium state for the 20 ka BP time slice, and a transient state for the deglacial time slices. The evolution of the ice sheet within the numerical model is driven by variations in temperature, accumulation rate, and relative sea level. In order to reconstruct the concave profile of the ice sheet in marine-grounded regions, such as the Ross and Weddell Seas, we force our model to develop channels of faster flow by defining greater basal sliding along the trajectory of former ice streams. We find a strong dependence upon the basal sliding parameters, and also the position of the grounding line. We use an extensive data base of geological and glaciological data to constrain our ice-sheet reconstruction. Grounding-line extent is prescribed from marine geological data and we test ice-sheet thickness against onshore geological data at 62 sites. Of the five time slices considered, our 20 ka BP reconstruction is the best constrained by data and has an RMS misfit of 147.6 m when compared to observations of ice thickness change between 20 ka BP and the present day. Across all time slices there are large regions of the ice-sheet which are poorly constrained, especially after 20 ka BP. We estimate the spatial distribution of uncertainty in our ice-sheet reconstruction, and note that the solutions are least reliable in regions of complex topography. We predict that the Antarctic Ice Sheets contributed 9 ± 1.5 m of eustatic sea level to the global ocean between 20 ka BP and the present, and our reconstruction with minimum misfit contributes ∼8 m eustatic sea level during this period. These values, which we argue are an upper bound, are lower than many previous estimates. The reconstructed pattern of ice unloading can serve as a new input for glacial isostatic models. [Copyright &y& Elsevier]

Abstract: New diatom-biostratigraphic age data derived from piston core were used to constrain the chronology for a seismic-based interpretation of West Antarctic Ice Sheet (WAIS) advance and retreat from the North Basin outer shelf in western Ross Sea. The data demonstrates that grounded ice occupied the outer shelf on at least ten occasions during the last 2.0Ma of the Pleistocene. Although the biostratigraphic resolution is low, the constraints permit correlations to coeval section recently drilled in South McMurdo Sound at the AND-1B drill site. Our interpretation of regional-scale correlations suggests that the Pleistocene dynamics of the WAIS involved grounding-line translations in excess of 600km. However, the data also suggests that only two major advances of grounded ice occurred since ~0.71Ma. In other words, several of the late Pleistocene sediment cycles at AND-1B must represent only minor advance and retreat of grounded ice to and from South McMurdo Sound. The results prove false the long-standing tacit assumption that the WAIS experienced major advances in association with peak glacials and eustatic lowstands during the last 700ka of the Pleistocene. These results show that piston cores can be used to constrain the timing of pre-Holocene grounding events. These data also highlight the need for regional-scale correlations to distinguish between major versus minor grounding-line translations of grounded ice in the marine setting. [Copyright &y& Elsevier]

Abstract: The question of whether Pliocene climate was warm enough to support a substantial vegetation cover on Antarctica is of great significance to the ongoing and controversial debate on the stability or dynamism of Antarctic ice sheets during warm periods with high atmospheric greenhouse gas concentrations. Here we present a systematic palynological comparison of pollen and dinoflagellate cyst assemblages from Early Pliocene diamictites and underlying late Cretaceous sediments collected from James Ross Island, northern Antarctic Peninsula. The diamictites are dated using a combination of 40Ar/39Ar and 87Sr/86Sr isotope ages on interbedded lavas and pristine bivalves. Well preserved pectinid shells and cheilostome bryozoans suggest that the palynomorph-bearing sediments were probably deposited during warmer Pliocene interglacials and later amalgamated into a diamictite formed by a major ice advance during cold glacial cycle. The palynological analyses presented herein do not identify any in-situ pollen and spores which indicate the presence of a substantial vegetation cover. Our study suggests a local (i.e. James Ross Island) provenance for most of the diamictites, whilst sediments from the western coast might have been delivered by ice sheets from the Antarctic Peninsula. Whilst the acritarch Leiosphaeridia might imply the presence of sea-ice and near-modern climate conditions during the Late Neogene, the presence of the dinoflagellate cyst Bitectatodinium tepikiense at one location suggests that sea surface temperatures might have been substantially warmer during some interglacials. The absence of in-situ pollen and spores in the James Ross Island diamictites cannot be taken as proof of non-existence of vegetation. However, the combined palynological and geological evidence presented in this paper makes the presence of a substantial Pliocene vegetation cover on James Ross Island unlikely and supports previous reconstructions of a permanent ice sheet on the Antarctic Peninsula throughout the Late Neogene. [Copyright &y& Elsevier]

Abstract: The Little Ice Age (LIA) is one of the most prominent climate shifts in the past 5000yrs. It has been suggested that the LIA might be the most recent of the Dansgaard–Oeschger events, which are better known as abrupt, large scale climate oscillations during the last glacial period. If the case, then according to Broecker (2000a, 2000b) Antarctica should have warmed during the LIA, when the Northern Hemisphere was cold. Here we present new data from the Ross Sea, Antarctica, that indicates surface temperatures were ~2°C colder during the LIA, with colder sea surface temperatures in the Southern Ocean and/or increased sea-ice extent, stronger katabatic winds, and decreased snow accumulation. Whilst we find there was large spatial and temporal variability, overall Antarctica was cooler and stormier during the LIA. Although temperatures have warmed since the termination of the LIA, atmospheric circulation strength has remained at the same, elevated level. We conclude, that the LIA was either caused by alternative forcings, or that the sea-saw mechanism operates differently during warm periods. [Copyright &y& Elsevier]

Abstract: Present understanding of Antarctic climate change during the Early to Mid-Miocene, including major cycles of glacial expansion and contraction, relies in large part on stable isotope proxies from deep sea core drilling. Here, we summarize the lithostratigraphy of the ANDRILL Southern McMurdo Sound Project drillcore AND-2A. This core offers a hitherto unavailable ice-proximal stratigraphic archive from a high-accommodation continental margin setting, and provides clear evidence of repeated fluctuations in climate, ice expansion/contraction and attendant sea-level change over the period c. 20.2–14.2Ma, with a more fragmentary record of Late Miocene and Pliocene time. The core is divided into seventy-four high-frequency (fourth- or fifth-order) glacimarine sequences recording repeated advances and retreats of glaciers into and out of the Victoria Land Basin. The section can be resolved into thirteen longer-term, composite (third-order) sequences, which comprise packages of higher frequency sequences that show a consistent stratigraphic stacking pattern (Stratigraphic Motif). The distribution of the six recognized motifs indicates intervals of less and more ice-proximal, and temperate to subpolar/polar climate, through the Miocene period. The core demonstrates a dynamic climate regime throughout the Early to Mid-Miocene that may be correlated to some previously-recognized events such as the Mid-Miocene Climatic Optimum, and provides a detailed reference point from which to evaluate stable isotope proxy records from the deep-sea. [Copyright &y& Elsevier]

Abstract: We review the post-glacial climate variability along the East Antarctic coastline using terrestrial and shallow marine geological records and compare these reconstructions with data from elsewhere. Nearly all East Antarctic records show a near-synchronous Early Holocene climate optimum (11.5–9ka BP), coinciding with the deglaciation of currently ice-free regions and the optimum recorded in Antarctic ice and marine sediment cores. Shallow marine and coastal terrestrial climate anomalies appear to be out of phase after the Early Holocene warm period, and show complex regional patterns, but an overall trend of cooling in the terrestrial records. A Mid to Late Holocene warm period is present in many East Antarctic lake and shallow coastal marine records. Although there are some differences in the regional timing of this warm period, it typically occurs somewhere between 4.7 and 1ka BP, which overlaps with a similar optimum found in Antarctic Peninsula terrestrial records. The differences in the timing of these sometimes abrupt warm events in different records and regions points to a number of mechanisms that we have yet to identify. Nearly all records show a neoglacial cooling from 2ka BP onwards. There is no evidence along the East Antarctic coastline for an equivalent to the Northern Hemisphere Medieval Warm Period and there is only weak circumstantial evidence in a few places for a cool event crudely equivalent in time to the Northern Hemisphere''s Little Ice Age. There is a need for well-dated, high resolution climate records in coastal East Antarctica and particularly in Terre Adélie, Dronning Maud Land and Enderby Land to fully understand the regional climate anomalies, the disparity between marine and terrestrial records, and to determine the significance of the heterogeneous temperature trends being measured in the Antarctic today. [Copyright &y& Elsevier]

Abstract: The aim is to investigate the evolution of the subglacial landscape of Antarctica using an ice sheet and erosion model. We identify different stages of continental glaciation and model the erosion processes associated with each stage. The model links erosion to the basal thermal regime and indicates that much of the Antarctic interior may have been subject to less than 200m of erosion. The depth of erosion reflects the presence or absence of warm-based ice and the consistency of ice flow direction. This information, linked with knowledge about landscapes of glaciation in the northern hemisphere and some simple but robust assumptions about initial topography, is used to generate a map of the subglacial Antarctic landscape in which much of the lowland interior resembles the landscapes of areal scouring typical of the Laurentian and Scandinavian shields. Near the continental margins selective linear erosion has overdeepened pre-existing river valleys by as much as 2.8km. High elevation plateaus adjacent to such drainage systems have survived largely unmodified under cold-based ice. High erosion rates result from steep thermal gradients in basal ice. Mountain regions such as the Gamburtsev Mountains, uplands in Dronning Maud Land and massifs in West Antarctica are likely to bear features of local alpine glaciation. Such landscapes may have been protected under cold-based ice for the last 34Myrs or possibly longer. [Copyright &y& Elsevier]

A new species of rotifer, Rhinoglena kutikovae n.sp. (Monogononta: Epiphanidae), is described from a freshwater lake in the Bunger Hills, East Antarctica. The new taxon is characterized by the following combination of characters: body conical to vase-shaped; a single toe; distal foot pseudosegment bulged; tail prominent, semi-circular; two small spherical pedal glands with common duct, forming a complex with caudal ganglion; trophi with seven major teeth with offset head and two smaller teeth without offset head. The new species is compared with R. fertoeensis, R. frontalis and R. tokioensis, of which scanning electron microscopic information is presented of the trophi. R. kutikovae n.sp. is probably a relict species that survived Quaternary glaciations in glacial lacustrine refugia on the Antarctic continent. [ABSTRACT FROM AUTHOR]