Simple rule predicts when an ice age ends

A simple rule can accurately predict when Earth's climate warms out of an ice age, according to new research led by UCL. In a new study , researchers from UCL, University of Cambridge and University of Louvain have combined existing ideas to solve the problem of which solar energy peaks in the last 2.6 million years led to the melting of the ice sheets and the start of a warm period. During this interval, Earth's climate has alternated between cold (glacial) and warm (interglacial) periods. In the cold times, ice sheets advanced over large parts of North America and northern Europe. In the warm periods like today, the ice sheets retreated completely. It has long been realised that these cycles were paced by astronomical changes in the Earth's orbit around the Sun and in the tilt of its axis, which change the amount of solar energy available to melt ice at high northern latitudes in summer. However, of the 110 incoming solar energy peaks (about every 21,000 years) only 50 led to complete melting of the ice sheets.