Ancient Ocean Currents Linked To Longer And More Intense Ice-Age Cycles

A new study of deep ocean sediments has helped scientists determine why ice-age cycles became longer -- switching from 41,000-year cycles to 100,000-year cycles -- and more intense nearly 900,000 years ago. According to the study results published in the journal Science, the deep ocean currents responsible for the movement of heat around the globe may have stalled at that time because of increasing ice cover in the Northern Hemisphere, which might have contributed to longer ice-age cycles.