120,000 Years of Climate Data

Each summer for the past seven years, scientists have been drilling a core through the Greenland ice sheet to learn about the earth's climate. On July 17, the scientists finally hit bedrock, ending the drilling. The ice core that they removed should tell scientists various aspects about the climate over the past 120,000 years. Most interesting is what the ice will tell us about past ice ages -- was the onset sudden or gradual? In the past, ice ages have occurred about every 10,000 years and it has been about 12,000 years since the last one, so we really want to know this information.