The penultimate temperate period, 127-110 ka before present (BP), bracketed by abrupt shifts of the global climate system initiating and terminating it, is considered as an analogue of the Holocene because of a similar low global ice-volume. Ice core records as well as continental and marine records exhibit conflicting evidence concerning the climate variability within this period, the Last Interglacial. We present, for the first time, a high-resolution record of oxygen isotopes in diatom opal of the Last Interglacial obtained from the Ribains Maar in France (44¿ 50'09″ N 3¿ 49'16″E). Our results indicate that the Last Interglacial in southwestern Europe was generally a period of climatic stability. The record shows that the temperate period was initiated by an abrupt warm event followed midway by a minor climatic transition to a colder climate. An abrupt isotopic depletion that occurs simultaneously with abrupt changes in pollen and diatom assemblages marks the end of the temperate period, and is correlative with the Melisey I stadial. Variations in the isotopic composition of lake-water related to the isotopic composition of precipitation and evaporation dominate the biogenic opal oxygen isotope record. ¿ 2001 American Geophysical Union