Drilling down in an Antarctic glacier

Robb Kulin drops ice cores back into the holes that were just drilled. (Photo: Eric Niiler)

Audio clip: Adobe Flash Player (version 9 or above) is required to play this audio clip. Download the latest version here. You also need to have JavaScript enabled in your browser.

Download MP3

The summer research season is winding down on Taylor Glacier, so researchers have gathered for a bit of fun before they break camp and head home. In this case, fun means dropping giant blocks of ice down holes that have been drilled in the glacier.

The big ice cylinders make a loud rumble and an eerie ping as they barrel down the bore holes. After an especially big and loud chunk, the group roars with laughter.

“That’s it, that’s Saturday night on the Taylor!” laughs site supervisor Paul Rose, a jovial Englishman.

Not that there’s not much else to do but work on this frozen ribbon of ice slowly scouring a barren Antarctic valley about 70 miles from the US research base on Antarctica’s McMurdo Sound. The ice-diggers have been camped out on top of the 1,800-foot thick glacier for two months during the Antarctic summer, drilling holes into its crusty surface in a quest to better understand the climate of ages past and perhaps help make better predictions about the future.

Most of the drilling holes here are a few hundred yards from camp. Rose walks over a layer of thin, crunchy snow to meet lead driller Tanner Kuhl standing by an upside-down plastic bucket. Kuhl, a drilling engineer from the University of Wisconsin, moves the bucket and peers down a blue hole about a foot in diameter that disappears almost 70-feet down into the ice.

It’s Kuhl’s job to run the gas-powered drilling rigs and then figure out how to get each thick plug of ice out of its hole. Kuhl says the standard approach is with sharpened teeth call coredogs, but the team has developed other tools of its own for when they have to improvise.

Once the ice cores are hauled to the surface, they’re cut into sections and flown by helicopter back to McMurdo and eventually to labs in the U.S., where researchers will examine air bubbles trapped inside.

“If we melt the sample and you inhale it, you’re breathing 50,000 year old air,” says Vasilii Petrenko, a climate scientist at the University of Colorado at Boulder.

Petrenko is interested in that ancient air because like today’s air, it contains greenhouse gasses like carbon dioxide and methane. And the levels of those gases tell scientists a lot about the ancient climate. With these ice cores, Kuhl and the other researchers are peering back in time.

In most parts of Antarctica, researchers have to drill deep to go farther back in time because the older ice lies farther down. But Petrenko says that here on the Taylor Glacier, there’s old ice right near the top.

In some places the ice at just 20-meters (about 21.8 yards) is 50,000 years old.

Petrenko says the Taylor Glacier is a special site because as it moves down from the center of Antarctica like a slow-moving river, newer ice from more recent snowfalls is eroded away by melting or strong winds, leaving older ice near the surface.

Even more unusual is that several different currents of ice are squeezed in next to each other. Petrenko points to a small depression in the ice about 100 meters (about 109.3) away, where he says the ice is only about 20,000 years old.

“In the span of 100 meters that we walk to there, we would cross 30,000 years,” Petrenko says.

This makes it easier and cheaper for Petrenko and his colleagues to do their work. Instead of several miles down, they have to drill only 70 or so feet to get the old ice they need.

Methane hydrates

Lately, the team of scientists has been looking for ice from about 15,000 years ago, a time like today when the earth’s climate was warming. In particular, they’re hunting for a specific variety of the trace gas methane, hoping to find out whether frozen methane hydrates, which form under the seafloor, were released as the oceans warmed after the last ice age.

Petrenko says the results could tell us a lot about what might happen in the future, because as the world warms, the bottom of the seafloor warms as well.

That means some of the methane hydrates might be destabilized and released into the atmosphere. And that’s important because methane is itself a potent greenhouse gas. More methane in the atmosphere leads to more warming, which could in turn lead to the release of more methane.

Petrenko and his team have already done some work on this question by drilling in Greenland. But the ice cores there had bits of soil and other organic matter that made it hard to get a good sample. They think these Antarctic glaciers will have a cleaner record of the past.

So far, Petrenko believes the undersea hydrates may not pose a threat, which would be good news.

“It’s good news in the sense that we’re not going to perish from a massive methane release from the oceans,” Petrenko says. “But it’s bad news in the sense that we’re still seeing methane rise in the atmosphere during times of global warming, and that methane has to come from somewhere.”

That “somewhere,” Petrenko says, is the world’s wetlands, which he suggests are definitely releasing more methane as the atmosphere warms.

The rate at which that’s happening is a subject for other researchers. Meanwhile, Petrenko and the rest of the crew will return next year to continue exploring the ancient methane of Antarctica’s glaciers, have some fun with ice chunks, and appreciate the raw beauty of this remote world.

“Even when it’s been foul weather, it’s beautiful up here,” site supervisor Rose says.

“It’s just untouched. The rocks up there are the same rocks that Scott’s party walked past. There are the times that the light up there has been so perfect you could be looking at an Edward Wilson watercolor. So it’s just magic.”