Abstract

Atmospheric mineral dust loading was around 2-4 times greater than present day during the last glacial maximum and the flux reconstructed over Greenland was several orders of magnitude higher. The glacial climate was also characterised by rapid transitions from cold to warm (stadial to interstadial states) during which the Greenland dust flux varied by a factor of around 20. Over Europe, loess profiles accumulated during the cold phases and these show a one-to-one correspondence with Greenland ice-core dust peaks. Size-resolved geochemical analyses have recently shown two distinct sources of this European loess, whilst the provenance of glacial dust in Greenland is subject to ongoing debate. In this talk I’ll introduce a set of Earth System model simulations using the HadGEM2-ES model designed to simulate coupled climate-dust changes during the Last Glacial Maximum and in response to abrupt cooling events. These simulations show that the circum-Atlantic sector (primarily the Sahel with smaller contributions from central America and Alaska) could have made substantial contributions to dust over the Atlantic region. This is primarily because the modelled cooling weakens the hydrological cycle over the northern tropics and increases emissions and weakens in-transport deposition. I’ll look at how well these model results fit available records and discuss potential implications of changes in dust radiative forcing. I’ll conclude with possible avenues for further refining our understanding of these large palaeo-dust variations.