This story appears in the June 2010 issue of National Geographic magazine.
At first glance Greenland is an expanse of blinding white. But as my chopper swings low over the island, color catches my eye. For miles on end, bands of blue meltwater fringe the ice sheet. Fields of white are threaded with rivers, etched with crevasses, and blotched with lakes. There is also ice that appears neither white nor blue but rather brown and even black—darkened by a substance called cryoconite. This muddy-looking grit is a key topic of investigation for my four companions: photographer James Balog with his assistant, Adam LeWinter, and geophysicist Marco Tedesco with Ph.D. student Nick Steiner, both from the City College of New York.
Balog photographs ice—and the absence of it. He founded the Extreme Ice Survey (EIS) in 2006 "to create a memory of things that are disappearing," he says. EIS has deployed more than 35 solar-powered, blizzard-proof, time-lapse cameras aimed at glaciers in Alaska, Montana, Iceland, and Greenland—all of them snapping away day in and day out. Programmed to take 4,000 to 12,000 frames a year, they're making a constant record, like "little surrogate eyes out there watching the world for us," Balog says.
We set up camp 45 miles inland from the west coast village of Ilulissat, in a portion of Greenland's melt zone where the weathering of the top layers of the ice sheet exposes what is known as blue ice. This ancient ice is compressed to the point where most air bubbles—which normally refract light to give ice a milky or white appearance—have been squeezed out. With fewer bubbles, the ice absorbs light from the red end of the spectrum, leaving the blue to be reflected. Depending on the tricks sunlight plays, blue ice can also appear white, as it does in many places around us.
The camp stands beside a vast meltwater lake. Tedesco and Steiner study its depth, planning to compare their information with satellite readings of the depths of Greenland's supraglacial lakes. Each morning they launch a small craft to collect data. The vessel is a bait boat retrofitted with remote control, sonar, a laptop-driven spectrometer, GPS, a thermometer, and an underwater camera.
Greenland's meltwater lakes are prone to draining unexpectedly and quickly (thus Tedesco's unmanned research vessel). Balog once watched a lake drain overnight. The bottom of a moulin—a vertical shaft in the ice—opened up and sucked the entire lake into oblivion. In 2006 a team led by glaciologists from Woods Hole Oceanographic Institution and the University of Washington documented the draining of a two-square-mile supraglacial lake: More than 11 billion gallons of water disappeared into a moulin in 84 minutes, flowing faster than Niagara Falls.
The meltwater lake Tedesco is studying has an outlet river that must lead to a gulping moulin. LeWinter and I are determined to find it. Armed with ice axes, ice screws, and ropes, we set out. We haven't gone a quarter mile before we're stymied by holes in the ice. At first we can thread our way between them, but farther along, the rims are all touching, and we're forced to bound the pools, one knife-edge to the next. It's like playing leapfrog on razor blades.
We try an alternate route, following a ridge of ice that parallels the river. This time we make good headway and march across the ice sheet for miles. We can't find the moulin on foot, but we make an intriguing observation: On the journey out, the holes we were jumping were separate, circular bowls, but on the way back, just half a day later, there's been enough melting so that the holes are connected by swift-running creeks.
At camp that night we find out what Tedesco and Steiner have confirmed about the bottom of the meltwater lake. It is mottled with cryoconite.
Cryoconite begins as airborne sediment spread over the ice by wind. It is composed of mineral dust sucked up from as far away as Central Asian deserts, particles from volcanic eruptions, and soot. The soot particles come from fires both natural and man-made, diesel engines, and coal-fired power plants. Cryoconite is not a new phenomenon: Arctic explorer Nils A. E. Nordenskiöld discovered and named the fine brown silt during his visit to the Greenland ice sheet in 1870. Human activities have increased the amount of black soot in cryoconite since Nordenskiöld's day, and global warming has given it new importance.
Carl Egede Bøggild is a native Greenlander and geophysicist who has spent the past 28 years studying the ice sheet. Recently Bøggild has focused on cryoconite. "Even though cryoconite is composed of less than 5 percent soot," he says, "it is the soot that causes it to turn black." The darkness decreases the albedo, or reflectivity, of the ice, which increases the absorption of heat; that in turn increases the amount of melting.
Snow falls each year on the ice sheet along with a dusting of cryoconite. As each year's snow cover hardens, it traps the dust. When summers are particularly warm, as they have been in recent years, multiple layers of ice melt, releasing extra amounts of trapped cryoconite, which creates a more concentrated, darker layer of the substance at the surface. "What we have is a vicious, constantly accelerating cycle," Bøggild says. "It's like pulling a black curtain over the ice."
Even during our short expedition, it seems as if we are seeing that effect. In just a week, melting ice has turned our camp into a slushy quagmire. Somewhere in the distance, the meltwater lake has drained into the moulin we had searched for. It's been like witnessing the creation of an ice analogue for Utah's canyonlands, the geologic clock ridiculously sped up. Balog's time-lapse cameras have captured it all. "They're recording the heartbeat of the planet," he says.
Before the expedition departs, Balog persuades me to descend into a moulin right next to camp—one of the largest the EIS team has discovered in its 11 expeditions to Greenland. It is big enough to swallow a freight train—certainly big enough to swallow me. Still, I cannot resist rappelling into the maw of this chasm that Balog has dubbed "the beast."
On rimed ropes, I drop in. A hundred feet down the shaft, walls of blue ice surround me, and I am soaked with frigid spray. The blue Arctic sky above is framed by jagged three-story icicles. Below, vanishing into the abyss, is the thundering waterfall that bored this shaft.
Scientists have dumped yellow rubber duckies, sensored spheres, and huge quantities of dye into moulins, hoping to track their journeys and discover where along Greenland's coast the moulins empty. Some of the spheres and dye have been spotted; all the duckies disappeared. I am tempted to drop deeper, investigate further, but I think again. After 20 minutes hanging by my rope, I climb back out.