The small makeup room off the main floor of KUSI’s studios, in a suburban canyon on the north end of San Diego, has seen better days. The carpet is stained; the couch sags. John Coleman, KUSI’s weatherman, pulls off the brown sweatshirt he has been wearing over his shirt and tie all day and appraises himself in the mirror, smoothing back his white hair and opening a makeup kit. “I kid that I have to use a trowel, to fill the crevasses of age,” he says, swiping powder under one eye and then the other. “People have tried to convince me to use more advanced makeup, but I don’t. I don’t try to fool anyone.”

Coleman is seventy-five years old, and looks it, which is refreshing in the Dorian Gray-like environs of television news. He refers to his position at KUSI, a modestly eccentric independent station in San Diego whose evening newscast usually runs fifth out of five in the local market, as his retirement job. When he steps in front of the green screen, it’s clear why he has chosen it over actual retirement; in front of the camera he moves, if not quite like a man half his age, then at least like a man three quarters of it. His eyes light up, and the slight stoop with which he otherwise carries himself disappears. His rumble of a voice evens out into a theatrical baritone, full of the practiced jocularity of someone who has spent all but the first nineteen years of his life on TV.

By his own rough estimate, John Coleman has performed more than a quarter million weathercasts. It is not a stretch to say that he is largely responsible for the shape of the modern weather report. As the first weatherman on ABC’s Good Morning America in the late 1970s and early ’80s, Coleman pioneered the use of the onscreen satellite technology and computer graphics that are now standard nearly everywhere. In 1982, chafing at the limitations of his daily slot on GMA, Coleman used his spare time—and media mogul Frank Batten’s money—to launch The Weather Channel. The idea seemed quixotic then, and his tenure as president ended a year later after an acrimonious split with Batten. But time proved Coleman to be something of a genius—the channel was turning a profit within four years, and by the time NBC-Universal bought it in 2008 it had 85 million viewers and a $3.5 billion price tag.

Those were the first two acts of Coleman’s career. On a Sunday night in early November 2007, Coleman sat down at his home computer and started to write the 967 words that would launch the third. “It is the greatest scam in history,” he began. “I am amazed, appalled and highly offended by it. Global Warming: It is a SCAM.”

What had set him off was a football game. The Eagles were playing the Cowboys in Philadelphia on Sunday Night Football, and as a gesture of environmental awareness—it was “Green is Universal” week at NBC-Universal—the studio lights were cut for portions of the pre-game and half-time shows. Coleman, who had been growing increasingly skeptical about global warming for more than a decade, finally snapped. “I couldn’t take it anymore,” he told me. “I did a Howard Beale.”

Skepticism is, of course, the core value of scientific inquiry. But the essay that Coleman published that week, on the Web site ICECAP, would have more properly been termed rejectionism. Coleman wasn’t arguing against the integrity of a particular conclusion based on careful original research—something that would have constituted useful scientific skepticism. Instead, he went after the motives of the scientists themselves. Climate researchers, he wrote, “look askance at the rest of us, certain of their superiority. They respect government and disrespect business, particularly big business. They are environmentalists above all else.”

Charles Homans is an editor at Foreign Policy.