Too bad it's over.

While it lasted, the global-warming debate was an entertaining free-for-all. Then this month the U.N. Intergovernmental Panel on Climate Change came out with its latest report. It was if someone had pounded a gavel. No more discussion, please. This case is closed.

Those of you still skeptical that human activity is the prime cause of global warming — well, we've put up with your annoying behavior long enough. Go to your room. Be quiet. What's the matter with you anyway?

People began comparing misguided skeptics to Holocaust deniers. Al Gore was a bit less direct. His choice of words: "global warming deniers."

A San Diego Union-Tribune media columnist, Carol Goodhue, said the controversy no longer deserved balanced coverage in the newspaper. "Sometimes the facts are so overwhelming on one side that it's unfair and inaccurate to give equal weight to both sides," she wrote last week. "This is one of those times."

Heidi Cullen of the Weather Channel said TV weathercasters who displayed disbelief in human-caused warming should have their professional certification yanked.

I'm no scientist, and I'll acknowledge human activity may have played a role in the one-degree increase in global temperatures measured over the last century. But how significant was that role? And are other factors, such as solar activity, more dominant?

I doubt that climate scientists, for all their professed certainty, know either, at least with enough certainty to justify demands that the activity causing the warming — economic growth — be squashed flat. Severe limits on greenhouse gas emissions, which many propose, would undermine the economic future for millions of people.

Nor is the global-warming consensus as rock solid as some would have us believe. Last April, 60 Canadian scientists sent a letter to Prime Minister Stephen Harper, urging a fresh look at the science backing up the Kyoto global-warming treaty.

"Observational evidence does not support today's computer climate models," the scientists wrote, "so there is little reason to trust model predictions of the future. Yet this is precisely what the United Nations did in creating and promoting Kyoto and still does in the alarmist forecasts on which Canada's climate policies are based."

Even the U.N. intergovernmental panel backed away from earlier predictions that the sea level would rise by 3 feet by the end of the century. The new prediction: 17 inches.

Like manias in financial markets, there are manias in environmental fears.

In the late 1960s, the great fear was overpopulation. "The battle to feed all humanity is over," declared the ecologist Paul Ehrlich, author of "The Population Bomb." "In the 1970s the world will undergo famines — hundreds of millions of people will starve to death."

A few years later, the reigning fear was global cooling. Many became concerned about a disturbing trend in falling temperatures, beginning around 1940.

That trend reversed, obviously. But environmentalists have been predicting disasters of one sort or another — often in a bullying tone of closed-minded finality — for more than a generation. They see their attitude as "progressive" in some way, and science-based.

But the scientific mind is not incurious in the manner of, say, Heidi Cullen. The scientific impulse is to see settled beliefs as potential targets of opportunity.

For centuries, global temperature trends have ebbed and flowed in cycles some scientists now link to solar activity. From 200 B.C. to A.D. 600, temperatures trended upward. From 600 to 900, the trend was down, then up again until 1300. What became known as the Little Ice Age ran from 1300 to 1850. These shifts had little to do with greenhouse gases.

Oops, sorry. I forgot the debate's over.

E. Thomas McClanahan is a member of the Kansas City Star editorial board.