The Alaskan village of Shishmaref sits on an island known as Sarichef, five miles off the coast of the Seward Peninsula. Sarichef is a small island—no more than a quarter of a mile across and two and a half miles long—and Shishmaref is basically the only thing on it. To the north is the Chukchi Sea, and in every other direction lies the Bering Land Bridge National Preserve, which probably ranks as one of the least visited national parks in the country. During the last ice age, the land bridge—exposed by a drop in sea levels of more than three hundred feet—grew to be nearly a thousand miles wide. The preserve occupies that part of it which, after more than ten thousand years of warmth, still remains above water.

Shishmaref (pop. 591) is an Inupiat village, and it has been inhabited, at least on a seasonal basis, for several centuries. As in many native villages in Alaska, life there combines—often disconcertingly—the very ancient and the totally modern. Almost everyone in Shishmaref still lives off subsistence hunting, primarily for bearded seals but also for walrus, moose, rabbit, and migrating birds. When I visited the village one day last April, the spring thaw was under way, and the seal-hunting season was about to begin. (Wandering around, I almost tripped over the remnants of the previous year’s catch emerging from storage under the snow.) At noon, the village’s transportation planner, Tony Weyiouanna, invited me to his house for lunch. In the living room, an enormous television set tuned to the local public-access station was playing a rock soundtrack. Messages like “Happy Birthday to the following elders . . .” kept scrolling across the screen.

Traditionally, the men in Shishmaref hunted for seals by driving out over the sea ice with dogsleds or, more recently, on snowmobiles. After they hauled the seals back to the village, the women would skin and cure them, a process that takes several weeks. In the early nineteen-nineties, the hunters began to notice that the sea ice was changing. (Although the claim that the Eskimos have hundreds of words for snow is an exaggeration, the Inupiat make distinctions among many different types of ice, including sikuliaq, “young ice,” sarri, “pack ice,” and tuvaq, “landlocked ice.”) The ice was starting to form later in the fall, and also to break up earlier in the spring. Once, it had been possible to drive out twenty miles; now, by the time the seals arrived, the ice was mushy half that distance from shore. Weyiouanna described it as having the consistency of a “slush puppy.” When you encounter it, he said, “your hair starts sticking up. Your eyes are wide open. You can’t even blink.” It became too dangerous to hunt using snowmobiles, and the men switched to boats.

Soon, the changes in the sea ice brought other problems. At its highest point, Shishmaref is only twenty-two feet above sea level, and the houses, many built by the U.S. government, are small, boxy, and not particularly sturdy-looking. When the Chukchi Sea froze early, the layer of ice protected the village, the way a tarp prevents a swimming pool from getting roiled by the wind. When the sea started to freeze later, Shishmaref became more vulnerable to storm surges. A storm in October, 1997, scoured away a hundred-and-twenty-five-foot-wide strip from the town’s northern edge; several houses were destroyed, and more than a dozen had to be relocated. During another storm, in October, 2001, the village was threatened by twelve-foot waves. In the summer of 2002, residents of Shishmaref voted, a hundred and sixty-one to twenty, to move the entire village to the mainland. Last year, the federal government completed a survey of possible sites for a new village. Most of the spots that are being considered are in areas nearly as remote as Sarichef, with no roads or nearby cities, or even settlements. It is estimated that a full relocation will cost at least a hundred and eighty million dollars.

People I spoke to in Shishmaref expressed divided emotions about the proposed move. Some worried that, by leaving the tiny island, they would give up their connection to the sea and become lost. “It makes me feel lonely,” one woman said. Others seemed excited by the prospect of gaining certain conveniences, like running water, that Shishmaref lacks. Everyone seemed to agree, though, that the village’s situation, already dire, was likely only to get worse.

Morris Kiyutelluk, who is sixty-five, has lived in Shishmaref almost all his life. (His last name, he told me, means “without a wooden spoon.”) I spoke to him while I was hanging around the basement of the village church, which also serves as the unofficial headquarters for a group called the Shishmaref Erosion and Relocation Coalition. “The first time I heard about global warming, I thought, I don’t believe those Japanese,” Kiyutelluk told me. “Well, they had some good scientists, and it’s become true.”

The National Academy of Sciences undertook its first rigorous study of global warming in 1979. At that point, climate modelling was still in its infancy, and only a few groups, one led by Syukuro Manabe, at the National Oceanic and Atmospheric Administration, and another by James Hansen, at nasa’s Goddard Institute for Space Studies, had considered in any detail the effects of adding carbon dioxide to the atmosphere. Still, the results of their work were alarming enough that President Jimmy Carter called on the academy to investigate. A nine-member panel was appointed, led by the distinguished meteorologist Jule Charney, of M.I.T.

The Ad Hoc Study Group on Carbon Dioxide and Climate, or the Charney panel, as it became known, met for five days at the National Academy of Sciences’ summer study center, in Woods Hole, Massachusetts. Its conclusions were unequivocal. Panel members had looked for flaws in the modellers’ work but had been unable to find any. “If carbon dioxide continues to increase, the study group finds no reason to doubt that climate changes will result and no reason to believe that these changes will be negligible,” the scientists wrote. For a doubling of CO2 from pre-industrial levels, they put the likely global temperature rise at between two and a half and eight degrees Fahrenheit. The panel members weren’t sure how long it would take for changes already set in motion to become manifest, mainly because the climate system has a built-in time delay. It could take “several decades,” they noted. For this reason, what might seem like the most conservative approach—waiting for evidence of warming in order to assess the models’ accuracy—actually amounted to the riskiest possible strategy: “We may not be given a warning until the CO2 loading is such that an appreciable climate change is inevitable.”

It is now twenty-five years since the Charney panel issued its report, and, in that period, Americans have been alerted to the dangers of global warming so many times that volumes have been written just on the history of efforts to draw attention to the problem. (The National Academy of Sciences alone has issued nearly two hundred reports on global warming; the most recent, “Radiative Forcing of Climate Change,” was published just last month.) During this same period, worldwide carbon-dioxide emissions have continued to increase, from five billion metric tons a year to seven billion, and the earth’s temperature, much as predicted by Manabe’s and Hansen’s models, has steadily risen. The year 1990 was the warmest year on record until 1991, which was equally hot. Almost every subsequent year has been warmer still. The year 1998 ranks as the hottest year since the instrumental temperature record began, but it is closely followed by 2002 and 2003, which are tied for second; 2001, which is third; and 2004, which is fourth. Since climate is innately changeable, it’s difficult to say when, exactly, in this sequence natural variation could be ruled out as the sole cause. The American Geophysical Union, one of the nation’s largest and most respected scientific organizations, decided in 2003 that the matter had been settled. At the group’s annual meeting that year, it issued a consensus statement declaring, “Natural influences cannot explain the rapid increase in global near-surface temperatures.” As best as can be determined, the world is now warmer than it has been at any point in the last two millennia, and, if current trends continue, by the end of the century it will likely be hotter than at any point in the last two million years.