Pattern, style and timing of British–Irish Ice Sheet advance and retreat over the last 45 000 years: evidence from NW Scotland and the adjacent continental shelf

• Published in: Journal of Quaternary Science
• Main Authors: Bradwell, Tom, Fabel, Derek, Clark, Chris D., Chiverrell, Richard C., Small, David, Smedley, Rachel K., Saher, Margot H., Moreton, Steven G., Dove, Dayton, Callard, S. Louise, Duller, Geoff A. T., Medialdea, Alicia, Bateman, Mark D., Burke, Matthew J., McDonald, Neil, Gilgannon, Sean, Morgan, Sally, Roberts, David H., Cofaigh, Colm ó
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: Greenland; Ice Sheet; Ice Shelves
• Online Access: http://nora.nerc.ac.uk/id/eprint/530254/; https://nora.nerc.ac.uk/id/eprint/530254/1/jqs.3296.pdf; https://doi.org/10.1002/jqs.3296

Predicting the future response of ice sheets to climate warming and rising global sea level is important but difficult. This is especially so when fast‐flowing glaciers or ice streams, buffered by ice shelves, are grounded on beds below sea level. What happens when these ice shelves are removed? And how do the ice stream and the surrounding ice sheet respond to the abruptly altered boundary conditions? To address these questions and others we present new geological, geomorphological, geophysical and geochronological data from the ice‐stream‐dominated NW sector of the last British–Irish Ice Sheet (BIIS). The study area covers around 45 000 km2 of NW Scotland and the surrounding continental shelf. Alongside seabed geomorphological mapping and Quaternary sediment analysis, we use a suite of over 100 new absolute ages (including cosmogenic‐nuclide exposure ages, optically stimulated luminescence ages and radiocarbon dates) collected from onshore and offshore, to build a sector‐wide ice‐sheet reconstruction combining all available evidence with Bayesian chronosequence modelling. Using this information we present a detailed assessment of ice‐sheet advance/retreat history, and the glaciological connections between different areas of the NW BIIS sector, at different times during the last glacial cycle. The results show a highly dynamic, partly marine, partly terrestrial, ice‐sheet sector undergoing large size variations in response to sub‐millennial‐scale climatic (Dansgaard–Oeschger) cycles over the last 45 000 years. Superimposed on these trends we identify internally driven instabilities, operating at higher frequency, conditioned by local topographic factors, tidewater dynamics and glaciological feedbacks during deglaciation. Specifically, our new evidence indicates extensive marine‐terminating ice‐sheet glaciation of the NW BIIS sector during Greenland Stadials 12 to 9 – prior to the main ‘Late Weichselian’ ice‐sheet glaciation. After a period of restricted glaciation, in Greenland Interstadials 8 to 6, we find ...