Palaeo-glaciers archives in western Ireland as a vantage on abrupt shifts of the Last Glacial Termination

Numerical models simulating potential future climate schemes are tested against different proxy-based reconstruction of paleoclimate and must be finely tuned. In the north Atlantic region, records indicate that the Last Glacial Termination was interrupted by rapid, high-amplitude reversals (Heinrich Stadial 1, Younger Dryas) during which temperatures got back to nearly ice-age cold conditions.
These events are thought to be year-round cooling periods and could be close analogues for future climate change in the north Atlantic region. Terrestrial glacial deposits give a high resolution vantage on abrupt shifts but remain poorly investigated. Previous studies based on surface exposure dating on glacial landforms show that glaciers retreats occurred within HS1 and YD, contradicting the prevailing models. Thus mapping palaeo-mountain glaciers former extend, dating their retreat and reconstructing their successive palaeo-equilibrium lines altitude allow to determine whether this pattern is a consensus for the northern hemisphere palaeo-glaciers. This approach also provides information on the timing and magnitude of past climate change. This study is based on the west coast of Ireland directly impacted by westerlies, located downwind of the North Atlantic Ocean and which contains key sites where palaeo-mountain glaciers let the footprints of their passage. Here, we present the first results  from the Geologic Perspectives on Abrupt Climate Change (GeoPAC²) project: Strengthening Ireland’s capacity for projecting future change. The new beryllium-10-dated glacier records reveals phase of ice retreat occurring within HS1. It questions the rising seasonality hypothesis which suggests an increase of summer temperatures during melting season. The results of this work will provide useful quantitative data for investigate North Atlantic climate variability and improve both climate and glaciological models.