National Geographic : 2010 Jun
is composed of less than 5 percent soot," he says, "it is the soot that causes it to turn black." e darkness decreases the albedo, or re ectivity, 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 sub- stance 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 e ect. In just a week, melting ice has turned our camp into a slushy quagmire. Somewhere in the distance, the melt- water lake has drained into the moulin we had searched for. It's been like witnessing the cre- ation of an ice analogue for Utah's canyonlands, the geologic clock ridiculously sped up. Balog's time-lapse cameras have captured it all. " ey're recording the heartbeat of the planet," he says. Before the expedition departs, Balog per- suades 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 can- not 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 sha , walls of blue ice surround me, and I am soaked with frigid spray. e blue Arctic sky above is framed by jagged three-story icicles. Below, vanishing into the abyss, is the thundering waterfall that bored this sha . Scientists have dumped yellow rubber duck- ies, sensored spheres, and huge quantities of dye into moulins, hoping to track their jour- neys 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. A er 20 minutes hanging by my rope, I climb back out. j Summer meltwater collects in a lake (le ). Days later the water has drained through a snow-covered channel a er a moulin opened under the ice several miles away.