Using past Irish mountain glaciation to improve our understanding of abrupt climate changes in the terrestrial North Atlantic during the last glacial termination

The last glacial termination (LGT; ~19.6-11.7 ka) was a period of rapid climate change. Global temperatures increased by ~6ºC, causing extensive ice mass loss, large shifts in atmospheric and ocean circulation, and approximately 120 m of sea level rise. However, records indicate that warming during the LGT was not uniform, with several abrupt, high-amplitude changes in temperature recorded in North Atlantic proxy records. Because climate models currently struggle to replicate these rapid climate events, it is crucial to produce additional climate proxy data, particularly from the underrepresented terrestrial realm, to better understand these changes and their potential to inform future climate models.

Mountain glaciers respond rapidly to climate forcing, and thus are sensitive indicators of changes in climate. Mapping and dating past glacier fluctuations provides important information about changes in past glacial mass balance, which can be used to understand the timing and magnitude of associated climate change. In Ireland, immediately downwind of the North Atlantic, there is extensive evidence that mountain glaciers occupied mountain ranges across the island as the British-Irish Ice Sheet receded during the LGT. Therefore, investigating past Irish mountain glacier fluctuations provides the opportunity to examine a terrestrial signal of abrupt climate change in the North Atlantic region.

Here we present an overview of the Abrupt Climate Change in Terrestrial Ireland (ACCTIR) project, which aims to use past Irish mountain glaciation to investigate palaeo-climate in the terrestrial North Atlantic during the LGT. ACCTIR pairs geomorphic mapping and cosmogenic surface-exposure dating of mountain glacier moraines with glaciological modelling to establish the timing and magnitude of glacial – and thus climatic – change in terrestrial Ireland during the LGT. We present new glacial-geomorphic mapping of target field areas in southern Ireland, as well as unpublished surface-exposure ages from the Wicklow Mountains. Once the dating is complete, we will combine our results with previously published ages to model potential climate scenarios compatible with past glacial fluctuations.  This work will provide a range of quantitative data that will be useful for improving climate and glaciological models and will help us to better understand North Atlantic climate variability.