The Upper Pleistocene period spans the time from the last (Eemian, Ipswichian) interglacial period, 120 ka, to the termination of the last (Weichselian, Devensian) glaciation 11.5 ka. It was characterized by a complex sequence of climatic oscillations that ranged from glacial episodes, when ice sheets covered much of the Northern Hemisphere, to interglacial and interstadial intervals when the climate was often as warm as, or warmer than, that of the present day. Each of these events disrupted the biological systems so that many species had to alter their geographical ranges in order to track acceptable climates from one place to another across the continent. These movements of species enable estimates to be made of the terrestrial climatic history of the period. Among the most valuable of climatic indicators are the Coleoptera (beetles) whose robust exoskeletons are readily preserved in waterlogged sediments. Using the well-known mutual climatic range method on species from fossil beetle assemblages, it has been possible to make quantified estimates of the thermal climatic conditions during various phases of the Quaternary in western Europe. These show that, during warmer intervals, mean July temperatures were at least 3° C warmer than now, and winter figures were not much different from those of the present day. During the colder episodes, the mean July temperatures were at least 7° C colder than the present and winter temperatures were very much colder and of Siberian intensity. Rates of change from one climatic regime to another were often very rapid and may have involved a rise in summer temperature of 1° C per decade.