Remember The Twilight Zone? Back in 1961, Rod Serling wrote an episode that was set in New York City amid rampant global warming. Somehow the Earth's orbit had shifted, and the planet was moving inexorably toward the sun. "This is the eve of the end," Serling intoned in his introduction. "Because even at midnight it's high noon, the hottest day in history, and you're about to spend it -- in the Twilight Zone."

The story revolves around a few desperate New Yorkers struggling to survive the murderous heat. As the temperature climbs, social order crumbles. An intruder, crazed with thirst, breaks into an apartment to steal water. An elderly woman collapses and dies. Thermometers shatter, their mercury boiling over. Finally Norma, the main character, screams and passes out. Then comes the "Twilight Zone" twist: Norma wakes up to find that it's snowing outside. She'd been having a nightmare. The Earth isn't hurtling toward the sun, after all; it's spinning *away* from the sun. The world isn't going to end in searing heat, but in a dark and deathly deep-freeze. Fade to credits.

Well, that's climate change for you. Maybe Mother Earth is warming up, or maybe she's cooling down, but either way it's always bad news.

Here, for example, is former vice president Al Gore in 2006, on the threat posed by global warming: "Our ability to live is what is at stake." It doesn't get much more dire than that.

Yet here is climatologist Reid Bryson, in Fortune magazine's award-winning analysis of global *cooling* in 1974: "There is very important climatic change going on right now, and it’s not merely something of academic interest. . . . It is something that, if it continues, will affect the whole human occupation of the earth -- like a billion people starving." It doesn't get much more dire than that, either.

Bryson's article is quoted in "Fire and Ice," a richly documented report by the Business & Media Institute, an arm of the Media Research Center. Climate-change alarmism, the report shows, is at least a century old. A few examples:

"Geologists Think the World May Be Frozen Up Again," asserted a New York Times headline in February 1895. Worrisome if true, but just seven years later, the Los Angeles Times reported that the great glaciers were undergoing "their final annihilation" due to rising temperatures worldwide. By 1923, though, it was the ice that was doing the annihilating: "Scientist says Arctic ice will wipe out Canada," the Chicago Tribune declared on Page 1.

So it was curtains for the Canadians? Er, not quite. In 1953, The New York Times reported that "nearly all the great ice sheets are in retreat." Yet no sooner did our neighbors to the north breathe a sigh of relief than it turned out they weren't off the hook after all: "The rapid advance of some glaciers," wrote Lowell Ponte in The Cooling, his 1976 bestseller, "has threatened human settlements in Alaska, Iceland, Canada, China, and the Soviet Union." And now? "Arctic Ice Is Melting at Record Level, Scientists Say," the Times reported in 2002.

Over the years, the alarmists have veered from an obsession with lethal global cooling around the turn of the 20th century to lethal global warming a generation later, back to cooling in the 1970s and now to warming once again. You don't have to be a scientist to realize that all these competing narratives of doom can't be true. Or to wonder whether any of them are.

Perhaps that is why most Americans discount the climate-change fear-mongering that is so fashionable among journalists and politicians. Last spring, as Time magazine was hyperventilating about global warming ("The debate is over. Global warming is upon us -- with a vengeance. From floods to fires, droughts to storms, the climate is crashing"), a Gallup poll was finding that only 36 percent of the public say they worry "a great deal" about it.

Still, there is always a market for apocalyptic forebodings. Paul Ehrlich grew rich writing jeremiads with such titles as The Population Explosion and The Population Bomb, which predicted the imminent deaths of hundreds of millions of human beings from starvation and epidemic disease. The Limits to Growth, the Club of Rome's 1972 bestseller, warned that humankind was going to experience "a rather sudden and uncontrollable decline" as the world's resources -- everything from gold to petroleum -- ran dry. Jonathan Schell and Carl Sagan forecast a devastating "nuclear winter" unless atomic arsenals were frozen, or better still, abolished. Those doomsday prophesies never came to pass. Neither have the climate-change catastrophes that have been bruited about for a century.

"The whole aim of practical politics," wrote H.L. Mencken, "is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary." Mencken was writing in 1920, but some things never change.