Impact of luminescence dating on geomorphological and palaeoclimate research in drylands

Luminescence dating has truly transformed the science of deserts and drylands and has necessitated a revision of conventional interpretation of sedimentary records and stratigraphic correlations. This contribution discusses key questions in palaeoclimatology of global deserts, the meaning of a luminescence age on desert sand and presents a review of luminescence-dated aeolian sand records from the deserts in the two hemispheres. Luminescence dating has in fact transformed dryland palaeoclimatology from a qualitative science into a quantitative one. Processes ranging from past sedimentation rates to dune migration rates and the changes in surface winds can now be quantified. A key inference is that, during the past, aeolian sedimentation occurred episodically and for limited time durations. Accentuated aeolian aggradations occurred during specific climatic regimes, the timing of which was determined by an optimal combination of sediment supply, transport and preservation or erosion. This fact has important implications for global climatology and aspects such as albedo changes through time. The absence of an aeolian record documents climate or erosion and should be interpreted as such. Loess on the fringes of drylands is a still untapped resource for palaeoclimate studies. The review also outlines new developments made using luminescence methods for desert palaeoclimatology.