Beneath the ice sheets

It's rare that an academic researcher gets to experience the life of a stunt pilot, but we found ourselves in more or less that position this past May, as we flew over the ice covered fjords of southeast Greenland. It was exhilarating-and a little scary. We were riding in one of NASA's research aircraft, a P-3 Orion turboprop, on which we had installed a special kind of radar for probing glacial ice. Although our equipment can work at higher altitudes, other science instruments needed to be flown low, over terrain so rugged that at times we came within a mere 30 meters of the ridges-near misses that our downward looking radar measured for us while we peered out the window holding our breath. Crisscrossing over this vast expanse of whiteness by air, you can easily forget that Greenland's huge endowment of ice is slowly disappearing. The eight-times-larger Antarctic ice sheet appears to be shrinking, too, particularly around the periphery. These two areas hold 99 percent of the land-based ice on Earth, and as it melts, the water that runs off flows into the oceans, adding to their rising level. Meanwhile, most mountain glaciers, which contain the remaining 1 percent of the ice perched on land, are also retreating, further compounding an increasingly urgent problem. If sea level goes up by a meter over the next several decades, as many scientists suspect will happen, it will disrupt the lives of countless people around the world.