the mousterian pluvial was caused by large-scale climatic changes during the last ice age. by 50 kybp (thousand years before present), the wisconsin glaciation ("würm glaciation" in europe) was well-advanced; growing ice sheets in north america and europe displaced the standard climatic zones of the northern hemisphere southward. the temperate zones of europe and north america acquired an arctic or tundra climate, and the rain bands typical of the temperate zones dropped to the latitudes of northern africa.