GEORGE NEOKAK, a 48-year-old Inupiat Eskimo whale hunter, is getting worried. Where are the whales? He stands on the prow of the U.S. Coast Guard icebreaker Healy, three days out of Barrow, Alaska, cruising 30 miles offshore in the Beaufort Sea. It's early August, and at 11:30 P.M. the sun is low and the sky a glorious, tropical-looking array of pinks and lavenders. The Arctic water is as calm as an Everglades pond.

Bowhead whales are a food staple for George and his people back in Barrow. The Inupiat fall hunt normally starts soon, timed to the bowheads' migration, when the whales move west from summer feeding grounds off the coast of Canada. But so far, George hasn't seen any whales. The small, green leather-bound notebook he records them in is mostly empty.

The passenger list of the Healy is unusual on this trip, too. The first night, Secretary of Homeland Security Michael Chertoff coptered out to the icebreaker; he flew 3,500 miles from Washington, D.C., and spent 15 hours on the ship. Homeland Security runs the Coast Guard, but Chertoff had never spent a night aboard a cutter before. Rapid changes in the Arctic brought him north, he said.

And then there's the Coast Guard commandant, Admiral Thad Allen, who came with Chertoff and awarded the crew an unusual commendation—at least compared with standard military ones. The admiral and Chertoff, wearing crisp blue uniforms with their names stitched in white, stood proudly in the hangar as an officer read the citation. It was for work furthering U.S. economic and strategic interests in the face of climate change, "as the ice edge recedes further each spring."

The top of the earth is changing fast, and the ceremony is one indicator of the sudden political importance of the Healy. According to the Intergovernmental Panel on Climate Change, the 5.5 million square miles of sea and land above the Arctic Circle are warming twice as quickly as the rest of the planet. "We've never seen [ice melt] like this in history," said Canadian Ice Service forecaster Luc Desjardins.

First launched in 1999, the Healy has spent most of the past decade cruising Alaskan waters while loaded with scientists. This week's group will study sea conditions and marine life. But next week's mission involves mapping the 10,000-foot-deep sea bottom beyond the previously iced-over Chukchi Cap. The findings could increase the size of the U.S. and bring in billions of dollars in oil and natural-gas revenues. At the commendation ceremony, Secretary Chertoff was clear about one big role the Healy will be playing in the coming days and years. "We want to determine what our national boundary is," he said. Next week's mission is sensitive; no print journalists are being allowed on board.

Now, standing with George on the prow, I look out at ice that's vanilla white on top and candy blue below the waterline. George, in his blue sweatpants and hooded sweatshirt, tries searching for whales from the starboard side for a while. He tries the stern, where scientists scramble to prepare equipment. He tries the bridge, which is soothingly dark except for the glow of computer screens. He gazes at a sea he's hunted on since he was eight years old but which, in some ways, seems new to him in 2008.

"No whales," George says.