JIM LEHRER: Next tonight: boring deep into the Greenland to understand climate history.
The story comes from Heidi Cullen, a climatologist and correspondent for Climate Central, a nonpartisan research group for journalists and scientists.
HEIDI CULLEN: Far in the north of Greenland, a team of climate scientists from 14 nations, including the U.S., has just completed its first season of drilling a 1.6-mile core of solid ice.
J.P. STEFFENSEN, field operations manager, North Greenland Eemian Ice Drilling Project: What you see here is a piece of ice from the climate change between the last glacial and the present climate. It's about 11,000 years old. And it contains a lot of tiny little bubbles of the ancient atmosphere.
HEIDI CULLEN: J.P. Steffensen is the field operations manager for the North Greenland Eemian ice drilling project, or NEEM, the project's ultimate goal, to unlock the climate history trapped inside those tiny bubbles.
JEFF SEVERINGHAUS, professor of geosciences, Scripps Institution of Oceanography: The beautiful thing about an ice core is that it's got all of these different indicators, atmospheric composition, temperature, mean ocean temperature, dust. All these kinds of indicators are on exactly the same time scale.
HEIDI CULLEN: Jeff Severinghaus, a scientist at the Scripps Institution of Oceanography, is working with NEEM scientists to reconstruct all those indicators, in the hope of learning more about a period in climate history known as the Eemian.
The Eemian period started about 130,000 years ago, and we know it lasted about 15,000 years before the Earth plunged back into an ice age.
JEFF SEVERINGHAUS: NEEM is really trying to get a record of the last time that the Earth was warmer than today. So, it's an analogue for what our future looks like under global warming.
HEIDI CULLEN: During the Eemian, temperatures were somewhere between five and nine degrees Fahrenheit warmer than today, a scenario that climate models suggest could happen again by the end of the century if present trends continue.
JEFF SEVERINGHAUS: It's a very, very realistic scenario for what we may experience in the next 100 to 200 years.
MAN: We're getting older and older. With every meter we're melting, we're getting back to the future.
HEIDI CULLEN: Thirty feet below the surface in this huge trench carved from the snow is where this ice core research begins.
J.P. STEFFENSEN: The newest thing we have now at NEEM that nobody else has tried is a very sophisticated analytical system. It's called continuous flow analysis, where, actually, in the field, you cut a slab of the ice core, a thin rod of ice following the length of the ice. And you tilt that vertically. And you melt it on a hot plate from one end.
And then, as it melts, you do the analysis, millimeter by millimeter.
MAN: You can hear the bubbles coming out of the ice.
HEIDI CULLEN: The samples are also cut, bagged, and boxed up, and then shipped to research centers around the world.
J.P. STEFFENSEN: We call it the post office.