When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth
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Originally broadcast on: October 19, 2009 on PBS's The NewsHour with with Jim Lehrer.
Ice cores show us the Eemian Period
0:03
Heidi Cullen: Far in the north of Greenland, a team of climate scientists from 14 nations, including the US, has just completed its first season of drilling a 1.6-mile core of solid ice.
0:16
JP Steffensen : 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.
0:28
Heidi Cullen: JP 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.
0:42
Jeff Severinghaus: The beautiful thing about an ice core is that it's got all of these different indicators: atmosphere composition, temperature, mean ocean temperature, dust. All these kinds of indicators on exactly the same time scale.
0:56
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.
1:09
Heidi Cullen: 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.
1:19
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 analog of what our future looks like under global warming.
1:30
Heidi Cullen: During the Eemian, temperatures were somewhere between 5 and 9 degrees Farenheit warmer than today…a scenario that climate models suggest could happen again by the end of the century if present trends continue.
1:42
Jeff Severinghaus: It’s a very realistic scenario for what we may experience in the next hundred to two hundred years.
1:53
Simon Shupbach: We are getting older and older with every meter that we melt; we are getting back to the future.
1:58
Heidi Cullen: Thirty feet below the surface in the huge trench carved from snow is where the ice ore research begins.
2:05
JP Steffensen : The newest thing that we have right now at NEEM that nobody else has tried is the 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 the hot plate from one end and then as it melts you do the analysis, millimeter by millimeter.
2:29
Simon Shupbach: You can hear the bubbles coming out of the ice.
2:34
Heidi Cullen: The samples are also cut, bagged and boxed up, and then shipped to research centers around the world.
2:44
JP Steffensen : We call it the Post Office.
2:47
Heidi Cullen: The logistics of ice core drilling are far from simple.
2:51
JP Steffensen : It’s just complicated. And I hate complications. I like for things to run smoothly.
Life in Greenland
2:56
Heidi Cullen: The operation starts in the small town of Kangerlussuaq on Greenland’s west coast.
3:01
JP Steffensen : My first season was in 1980. So that’s 29 years ago. And that was a marriage for life.
3:10
Heidi Cullen: Keeping the operation running smoothly is his wife and fellow scientist, Dorthe Dahl-Jensen, NEEM’s project leader.
3:18
Dorthe Dahl-Jensen: I work mostly as coordinator of the project, and I need to get the drill teams, and the scientists, and the logistics people and the airplanes to come.
3:25
Heidi Cullen: The airplanes come courtesy of the 109th Airlift Wing of the New York Air Force National Guard…and pilots like George Alston.
3:35
George Alston: Well, we’re the only unit in the world that flies the specialized LC-130 aircraft, a C-130 on skis, which allows us to support the scientific efforts and take these large airplanes and land them on skis.
3:47
Heidi Cullen: But getting to the ice drilling camp is just part of the challenge.
3:52
Vasilii Petrenko: It's always light, so when you first get here it may be a little hard to sleep. It takes a couple of nights to get used to it, but then you get so tired from work and from not sleeping nights before, that it no longer becomes a problem.
4:04
Heidi Cullen: Vasilii Petrenko is a scientist at the University of Colorado.
4:08
Vasilii Petrenko: It’s a very simple life. It’s kind of like a frontier outpost. We sleep mostly in those red structures that you see behind me; they are called weather ports.
4:19
Heidi Cullen: While the NEEM field camp may look like a frontier outpost on the surface, Petrenko and others are engaged in very sophisticated scientific research underground.
What NEEM Is Teaching Us
4:28
Vasilii Petrenko: One of the things that we see in the ice cores is a strong correlation between carbon dioxide levels and temperatures. So at times of warm temperatures, carbon dioxide is high, at times of cold temperatures; carbon dioxide is low which reinforces what science has been showing recently, that carbon dioxide does cause warming.
4:48
Heidi Cullen: And that warming leads to melting. The Greenland ice sheet contains enough ice to raise global sea level by 23 feet - a worst-case scenario associated with global warming.
5:00
Heidi Cullen: Satellite data from the NASA Grace mission show that Greenland’s reservoir of ice has plummeted in recent years. About 340 billion tons of ice melt in 2007 alone – about the same as San Francisco Bay draining completely every week for a year.
5:17
Heidi Cullen: Scientists hope this new ice core will tell them how much of Greenland’s ice melted during the Eemian Period – when global sea level was 13 to 20 feet higher, a finding that could be crucial in determining how much and how quickly sea level could rise over the next several centuries.
5:33
Dorthe Dahl-Jensen: We know from all the other ice cores that we have drilled that we find ice from the Eemian period in the ice cores. Of course this immediately tells us that even though it was warmer in Greenland, it wasn’t warm enough for the whole Greenland ice sheet to disintegrate. And that’s something that is debated a lot; how much warming we would need in the future before the Greenland ice sheet would totally disappear, before we go beyond the tipping point.
5:56
Heidi Cullen: Now that this drilling season has come to an end, the scientists are heading home, working to unlock the climate history trapped inside those tiny, but telling, bubbles.
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