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Here we present the first compilation of sediment volumes, sedimentation rates, and chronology of Quaternary sediment packages along the entire marine margin of the Eurasian ice sheets (EurIS; British-Irish, Kara-Barents Sea-Svalbard, and Fennoscandian). This compilation allows for a subdivision of the EurIS development into three phases (2.6-1.5 Ma, 1.5-0.78 Ma, and 0.78-0 Ma). At the start of the Quaternary, sedimentation rates increased, relative to pre-Quaternary rates, by an order of magnitude. This abruptness in rate change excludes tectonic raising of landmasses as the main factor, but more likely reflects climate change through increased glacial erosion. The sediment distribution data suggest that the Kara-Barents Sea-Svalbard Ice Sheet (KBSIS) already was quite large at the beginning of the Quaternary, and well before 1.5 Ma it extended to the shelf edge and coalesced with the Fennoscandian Ice Sheet (FIS), which prior to 1.5 Ma most likely was located near the coast. Large ice streams and intense glacial erosion characterized the KBSIS in the 1.5-0.78 Ma time period, whereas the FIS at that time extended farther out on the continental shelf. After 0.78 Ma, a north-south change in EurIS development occurred. In the FIS and the British-Irish Ice Sheet (BIIS), large ice streams developed and shelf-edge glaciations occurred nearly 1 m.y. later compared to the KBSIS. The FIS and BIIS also repetitively coalesced in the North Sea. A significant drop in sediment input along the KBSIS marine margin, to the lowest Quaternary level, suggests a less erosive KBSIS. [ABSTRACT FROM AUTHOR]

We describe a revised understanding of the extent and dynamics of the Cordilleran Ice Sheet on the continental shelf of northern British Columbia, Canada. During the Local Last Glacial Maximum ice streams occupied two of the three shelf‐crossing troughs in Queen Charlotte Sound (Goose Island Trough and Mitchell's Trough). A 25‐km‐wide outlet glacier – the Hecate Glacier – flowed south in Hecate Strait, parallel to the modern coast. It reached a grounding line at the head of Moresby Trough, beyond which an ice shelf may have extended to the edge of the continental shelf. The southern part of the independent Haida Gwaii Ice Cap formed piedmont lobes dissected by tunnel valleys. An emergent area east of the ice cap corresponds with the 'Hecate Refugium'. Subsequently grounded ice retreated from the shelf troughs. The Hecate Glacier retreated incrementally towards the north. Mainland ice then stabilized along a north–south margin near modern coasts, marked by submarine moraines in the Chatham Sound region and elsewhere. This margin was probably contemporaneous with the margin at Mt. Buxton in the south of the study area, dated at c. 17.6 to 16.6 ka (Darvill et al. 2018). Off southern Haida Gwaii, following a retreat, a glacier margin was established east of Juan Perez Sound, proximal to a sandur plain graded to a water level of −150 m. Proglacial lakes to the north of here were the likely source for an outburst flood that created gravel bedforms and an area of sea‐floor scour. In a final phase, diminished mainland ice was confined to fjords, and retreat inland is marked by a succession of submarine moraines, beginning with a moraine at the Douglas Channel sill. The study has implications for the migration pathways for human migration into the Americas following deglaciation. [ABSTRACT FROM AUTHOR]

The last glacial period (LGP; ca. 110–10 kyr BP) was marked by the existence of two types of abrupt climatic changes, Dansgaard–Oeschger (DO) and Heinrich (H) events. Although the mechanisms behind these are not fully understood, it is generally accepted that the presence of ice sheets played an important role in their occurrence. While an important effort has been made to investigate the dynamics and evolution of the Laurentide ice sheet (LIS) during this period, the Eurasian ice sheet (EIS) has not received much attention, in particular from a modeling perspective. However, meltwater discharge from this and other ice sheets surrounding the Nordic seas is often implied as a potential cause of ocean instabilities that lead to glacial abrupt climate changes. Thus, a better comprehension of the evolution of the EIS during the LGP is important to understand its role in glacial abrupt climate changes. Here we investigate the response of the EIS to millennial-scale climate variability during the LGP. We use a hybrid, three-dimensional, thermomechanical ice-sheet model that includes ice shelves and ice streams. The model is forced off-line via a novel perturbative approach that, as opposed to conventional methods, clearly differentiates between the spatial patterns of millennial-scale and orbital-scale climate variability. Thus, it provides a more realistic treatment of the forcing at millennial timescales. The effect of both atmospheric and oceanic variations are included. Our results show that the EIS responds with enhanced ice discharge in phase with interstadial warming in the North Atlantic when forced with surface ocean temperatures. Conversely, when subsurface ocean temperatures are used, enhanced ice discharge occurs both during stadials and at the beginning of the interstadials. Separating the atmospheric and oceanic effects demonstrates the major role of the ocean in controlling the dynamics of the EIS on millennial timescales. While the atmospheric forcing alone is only able to produce modest iceberg discharges, warming of the ocean leads to higher rates of iceberg discharges as a result of relatively strong basal melting at the margins of the ice sheet. Our results clearly show the capability of the EIS to react to glacial abrupt climate changes, and highlight the need for stronger constraints on the ice sheet's glacial dynamics and climate–ocean interactions. [ABSTRACT FROM AUTHOR]

Considerable uncertainty surrounds the extent and timing of the advance and retreat of the Greenland Ice Sheet (GIS) on the continental shelf bordering Baffin Bay during the last glacial cycle. Here we use marine geophysical and geological data to show that fast-flowing ice sheet outlets, including the ancestral Jakobshavn Isbræ, expanded several hundred kilometers to the shelf edge during the last glaciation ca. 20 ka. Retreat of these outlets was asynchronous. Initial retreat from the shelf edge was underway by 14,880 calibrated (cal) yr B.P. in Uummannaq trough. Radiocarbon dates from the adjacent Disko trough and adjoining trough-mouth fan imply later deglaciation of Jakobshavn Isbræ, and, significantly, an extensive readvance and rapid retreat of this outlet during the Younger Dryas stadial (YD). This is notable because it is the first evidence of a major advance of the GIS during the YD on the West Greenland shelf, although the short duration suggests that it may have been out of phase with YD temperatures. [ABSTRACT FROM AUTHOR]

Cryospheric events in the Arctic Ocean have been largely studied through the imprints of ice sheets, ice shelves and icebergs in the seafloor morphology and sediment stratigraphy. Subglacial morphologies have been identified in the shallowest regions of the Arctic Ocean, up to 1200 m water depth, revealing the extent and dynamics of Arctic ice sheets during the last glacial periods. However, less attention has been given to sedimentary features imaged in the vicinity of the ice-grounded areas. Detailed interpretation of the sparse available swath bathymetry and sub-bottom profiles from the Lomonosov Ridge and the Amundsen Basin shows the occurrence of mass transport deposits (MTDs) and sediment waves in the central Arctic Ocean. The waxing and waning ice sheets and shelves in the Arctic Ocean have influenced the distribution of MTDs in the vicinity of grounding-ice areas, i.e. along the crest of Lomonosov Ridge. Due to the potential of Arctic sediments to hold gas hydrates, their destabilization should not be ruled out as trigger for sediment instability. Sediment waves formed by the interaction of internal waves that propagate along water mass interfaces with the bathymetric barrier of Lomonosov Ridge. This work describes the distribution and formation mechanisms of MTDs and sediment waves in the central Arctic Ocean in relation to grounding ice and internal waves between water masses, respectively. The distribution of these features provides new insight into past cryospheric and oceanographic conditions of the central Arctic Ocean. • Ice sheet oscillation may trigger formation of Mass Transport Deposits (MTDs). • MTDs in the Arctic Ocean reveal past locations of the ice sheet edge. • Distinct location of the ice sheet edge during Marine Isotope Stages 6 and 2 • Internal waves between water masses form sediment waves (SW) in the Arctic Ocean • MTDs and SW are related to grounding ice and oceanic flows in the Arctic Ocean. [ABSTRACT FROM AUTHOR]

During the last glacial cycle, the Antarctic Ice Sheet (AIS) has passed from an interglacial state, warmer than present day (PD), slowly into a glacial state, known as the Last Glacial Maximum (LGM) and then deglaciated on a faster timescale into the Holocene and PD conditions. Although we have proxy data of the size and extent of the ice sheet for the LGM, neither the oceanic temperatures of the Southern Ocean, nor the precipitation fields are well constrained. Also the time evolution of the ice volume during the glacial cycle is not fully clear. It is well assumed that it follows a sawtooth pattern, but from a modelling perspective different combinations of parameters and boundary conditions can give rise to plausible Antarctic configurations. Here we aim to study the uncertainty in AIS evolution resulting from ice-sheet model parameters, as well as the imposed climatic fields used as forcing. For this purpose we use the three-dimensional thermomechanical hybrid ice-sheet-shelf model Yelmo, which treats ice dynamics via the shallow-ce and shallow-shelf approximations, and accounts for basal melt below ice shelves and a subgrid parameterisation for treatment of the grounding line. We will focus on the effect of different climatic fields, such as precipitation and oceanic temperatures, as well as the effect of different enhancement factors and basal drag choices for reproducing consistent Antarctic configurations in the LGM and the PD. Improving our understanding of the effect of different ice-dynamics configurations in various climatic scenarios will help to better understand the past evolution of the AIS and potentially constrain its future evolution as well. [ABSTRACT FROM AUTHOR]

Improved understanding of the dynamics, extent and palaeogeography of retreating ice sheets can be accomplished by combining ice sheet modelling with the wealth of evidence they leave behind. Large volumes of constraining data exist and numerical models which can simulate entire glaciations are readily available. However, attempts to directly compare and connect empirically-based reconstructions with model-based simulations have been surprisingly rare, perhaps due to the complexity of combining the two fields and the abundance of approaches that could be taken. Here, we focus on a new method of directing ice sheet model simulations to match empirically reconstructed ice extents through time. Empirical evidence recording the behaviour of the last British-Irish Ice Sheet has been enhanced by the BRITICE-CHRONO consortium of researchers. This has been a six-year project to constrain the timing of retreat by a systematic dating programme focused on the marine-to-terrestrial transition. From two research cruises (18,000 km of geophysical data and 377 vibro- and piston cores), along with numerous investigations of stratigraphic sections on land we collected samples for dating from 914 sites from which 639 new geochronometric ages have been derived (336 radiocarbon, 156 luminescence and 157 cosmogenic). Organised into eight key transects from the shelf break to tens of kilometers onshore the pattern and pace of retreat has been compiled into an ice sheet wide reconstruction of ice extent at one thousand year times steps. We then used numerical models either forced or nudged to comply with these ice extents to yield simulations of ice sheet change thereby incorporating ice sheet physics, grounding lines, ice shelves, ice streams, and glacio isostatic adjustment and sea level. This empirically-constrained model simulation of the last British-Irish Ice Sheet will be presented. [ABSTRACT FROM AUTHOR]

The last glacial period (LGP; ca.110-10 ka BP) was marked by the existence of abrupt climatic changes on millennial time scales. Ice sheets are thought to play an important role in their occurrence or, at least, to have responded to these climate changes. While a considerable effort has been made to investigate the dynamics and evolution of the Laurentide Ice Sheet (LIS) during this period, the Eurasian Ice Sheet (EIS) has received less attention, particularly from a modeling perspective. Here we focus on the response of the EIS by using a hybrid, three-dimensional, thermomechanical ice-sheet model that includes ice shelves and ice streams. The model is forced offline including the effects of both atmospheric and oceanic variations. Our results show that the EIS responds with enhanced ice discharge in phase with interstadial warming in the North Atlantic when forced with surface ocean temperatures. Conversely, when subsurface ocean temperatures are used, an increase in ice discharge is found both during stadials and at the beginning of the interstadials. Separating the atmospheric and oceanic effects demonstrates the major role of the ocean in controlling the dynamics of the EIS on millennial time scales. While the atmospheric forcing alone is only able to produce modest iceberg discharges, warming of the ocean leads to higher rates of iceberg discharges and major grounding line reorganizations. Our results highlight the need for stronger constraints on the local North Atlantic behavior in order to improve our understanding of the ice sheet's glacial dynamics and its implication in the occurrence of millennial-scale climate variability. [ABSTRACT FROM AUTHOR]