 the last glacial maximum (lgm) refers to a period in the earth's climate history when ice sheets were at their most recent maximum extension, between 26,500 and 19,000â20,000 years ago,{ marking the peak of the last glacial period. during this time, vast ice sheets covered much of north america, northern europe and asia. these ice sheets profoundly impacted earth's climate, causing drought, desertification, and a dramatic drop in sea levels. it was followed by the late glacial maximum. ==glacial climate== 400px|thumb|temperature proxies for the last 40,000 years 400px|thumb|map of vegetation patterns during the last glacial maximum the formation of an ice sheet or ice cap requires both prolonged cold and precipitation (snow). hence, despite having temperatures similar to those of glaciated areas in north america and europe, east asia remained unglaciated except at higher elevations. this difference was caused by the fact that the ice sheets in europe produced extensive anticyclones above them. these anticyclones generated air masses that were so dry on reaching siberia and manchuria that precipitation sufficient for the formation of glaciers could never occur (except in kamchatka where these westerly winds lifted moisture from the sea of japan). the relative warmth of the pacific ocean due to the shutting down of the oyashio current and the presence of large east-west mountain ranges were secondary factors preventing continental glaciation in asia. in warmer regions of the world, climates at the last glacial maximum were cooler and almost everywhere drier. in extreme cases, such as south australia and the sahel, rainfall could be diminished by up to ninety percent from present, with floras diminished to almost the same degree as in glaciated areas of europe and north america. even in less affe
Climate_history Glaciology Ice_ages Pleistocene