The mineral dust aerosol cycle during the Last Glacial Maximum

The Canadian Centre for Climate Modelling and Analysis general circulation model (GCM) is used to investigate the factors influencing the mineral dust distribution at the time of the last glacial maximum (LGM). Simulated deposition rates are used in conjunction with existing paleoclimate data to infer likely characteristics of the mineral dust conditions at that time and identify contributions to the pattern of enhanced "dustiness" of the LGM relative to the present, indicated by ice core and loess data. Maximal consistency between the GCM, the Climate: Long Range Investigation, Mapping and Prediction (CLIMAP) data set, and the ice core data, requires approximately a 15- to 30-fold increase in dust production globally during the last glacial maximum relative to the preindustrial Holocene. In particular, regional 10- to 50-fold and 20-fold LGM increases are indicated in eastern Asia and South America, respectively. These implied source enhancements are quite insensitive to the details of the dust model. Analysis of the contributing factors suggests an increase in fine-particle availability in the source regions.