Recovery from the last ice age About 15,000 years ago, the earth began to warm and the huge ice sheets covering much of North America and Eurasia began to melt.  This had a number of impacts: (1) lake formation in regions left behind by glaciers (2) sea level rise. (3) colonization of formerly glaciated regions by vegetation, and huge changes in the ecology of other regions due to the overall global-scale warming. The period since the great ice sheets melted is known as the Holocene