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 depo sition rates are used in conjunction with existing paleoclimate data to inf er likely characteristics of the mineral dust conditions at that time and i dentify contributions to the pattern of enhanced "dustiness" of the LGM rel ative to the present, indicated by ice core and loess data. Maximal consist ency between the GCM, the Climate: Long Range Investigation, Mapping and Pr ediction (CLIMAP) data set, and the ice core data, requires approximately a 15- to 30-fold increase in dust production globally during the last glacia l maximum relative to the preindustrial Holocene. In particular, regional 1 0- to 50-fold and 20-fold LGM increases are indicated in eastern Asia and S outh America, respectively. These implied source enhancements are quite ins ensitive to the details of the dust model. Analysis of the contributing fac tors suggests an increase in fine-particle availability in the source regio ns.