You might imagine that natural climate changes come only slowly. But ice cores reveal that Earth's climate has changed suddenly in the past. Find out what they tell us about abrupt climate change.
Ice cores drilled from the Greenland ice sheet contain a record of climate change.
They show that, in the past, Earth's global climate has been given to abrupt changes. Dr. Richard Alley of Penn State University is an expert on Greenland ice cores. Even small climate shifts during the recent stable period came during times of change in human history. For example, the Vikings settled Greenland during a slight warming a millennium ago. They used Greenland as a stepping stone to North America.