<P> 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 because the ice sheets in Europe produced extensive anticyclones above them . </P> <P> 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 . </P> <P> All over 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 90% from present, with florae diminished to almost the same degree as in glaciated areas of Europe and North America . Even in less affected regions, rainforest cover was greatly diminished, especially in West Africa where a few refugia were surrounded by tropical grasslands . </P> <P> The Amazon rainforest was split into two large blocks by extensive savanna, and the tropical rainforests of Southeast Asia probably were similarly affected, with deciduous forests expanding in their place except on the east and west extremities of the Sundaland shelf . Only in Central America and the Chocó region of Colombia did tropical rainforests remain substantially intact--probably due to the extraordinarily heavy rainfall of these regions . </P>

When did the last ice age reach its maximum