Scientists are to dig up ice dating back more than 100,000 years in an attempt to shed light on how global warming will change the world over the next century.
The ice, at the bottom of the Greenland ice sheet, was laid down at a time when temperatures were 3 top 5 degrees Celsius (5 to 9 degrees Fahrenheit) warmer than they are today.
With temperatures forecast to rise by up to 7 degrees Celsius in the next 100 years, the ice, more than 8,000 feet (2,400 meters) below the surface, is thought by researchers to hold valuable clues to how much of the ice sheet will melt.
Drilling will start in northern Greenland during the summer in an international project involving researchers from 18 countries to extract ice cores covering the Eemian interglacial stage.
The Eemian began 130,000 years ago, ending 15,000 years later, and is the most recent time in the Earth's past when temperatures resembled those that can be expected if greenhouse gas emissions are not brought under control.