Ice gives vital clues about past climate

With samples stretching back 800,000 years, core ice samples from Antarctica and Greenland are helping scientists reach conclusions on our current climate.

Ancient ice is helping researchers learn about earth's past climate, and a key stop on the scientific journey is a huge freezer in suburban Denver called the National Ice Core Laboratory.

The ice is extracted from Antarctica and Greenland and shipped to the Colorado lab.

There, workers conduct preliminary tests and then slice it up so it can be shipped to scientists across the country.

The ice provides a wealth of historical information, from air temperature to greenhouse gases to evidence of cosmic events.

The record reaches as far back as 800,000 years.

Researchers say it's remarkably precise, even reflecting seasonal changes.

Ice cores have led scientists to significant conclusions about climate, including that CO2 levels in the atmosphere today are higher than at any other time recorded in the ice.