Inception, growth and decay of the British Irish Ice Sheet - Dec 21

Understanding the growth and decay of marine-based ice sheets and ice sheet sectors is of fundamental importance due to the potential inherent instability of these ice masses and their impact on sea level. The utility of numerical ice sheet models that seek to predict the future behaviour of marine-based ice sheets and, in particular, how they destabilise and retreat in response to climate change, are often limited by the short time period over which modern observations extend. The BIIS was a relatively small and dynamic ice sheet (ca. 840,000 km2 at the last glacial maximum (LGM)) and ca. 300,000 km2 was marine-based; Clark et al., 2012). This makes it a good analogue for how marine-based ice sheets deglaciate. Furthermore, the dynamics and apparent climatic sensitivity of the BIIS reflects its maritime position, bordering the Northeast Atlantic. This was an area known to have experienced large-scale climatic and oceanographic changes, including polar front migration, during the last cold stage, and likely during earlier periods (cf. Scourse et al., 2009). The last two decades have seen major advances in the reconstruction of the BIIS through the application of improvements in dating techniques (e.g., terrestrial cosmogenic nuclides), glacial geomorphological mapping from remote sensing datasets both marine and terrestrial, an increasing focus on offshore sedimentary and geophysical records, as well as a number of large-scale international research programmes focused on BIIS reconstruction (e.g., Britice-Chrono, GLANAM, GLAMAR). Whilst very recently the Britice-Chrono project resulted in a series of publications on BIIS last glacial advance and retreat (JQS special issue – ref to transect papers), much of the effort has focused on the last glacial cycle and, with few exceptions (Stoker 1997; Thierens et al., 2011), our knowledge of earlier BIIS glaciations prior to Marine Isotope Stage 5e and in particular BIIS inception, remains poor (Lee et al., 2012). The aim of the proposed project is to identify drilling sites for an IODP proposal in order reconstruct the growth and decay of the British-Irish Ice Sheet (BIIS) during the Cenozoic from inception to final disappearance and to assess the associated atmospheric and oceanographic drivers and feedbacks. Although there have been a number of IODP/ODP/DSDP drilling legs along the NE Atlantic margin (e.g., IODP 307 to Porcupine Seabight) these previously drilled sites are not suitably located to address the above research questions. Furthermore, there is now a wealth of seismic data, including 3D seismic, collected from national programmes such as the Irish National Seabed Survey (NSS) and its successor programme INFOMAR (INtegrated Mapping FOr the Sustainable Development of Ireland's MArine Resource) which is available for pre-site survey and site selection.