A FEW YEARS AGO Al Gore, then dressed in his natural-hued attire, would have been out of place among the Hollywood elite, but last Sunday he was one of them and thrice hailed at the 79th Academy Awards dinner for his apocalyptic documentary on global warming, An Inconvenient Truth.

Unsurprisingly, Jimmy Carter called Gore "my favorite Democrat," adding that Gore could do "infinitely more" to prevent global warming by being "the incumbent in the White House" than by "making movies that get Oscars." Perhaps so.

At any rate, Hollywood, or at least its politically-correct precincts, went ga-ga over Gore with his boyish smile and his single-issue conviction.

Of course, there are three certainties, or near certainties, about the earth's climate and its impact on humans:

* The temperature surrounding the planet does alternate between colder and warmer periods and has done so for millions of years. There have been harsh "ice ages" and warmer periods. Since humans appeared on the planet, these changes have had an impact on civilization, from the medieval warm period which saw improved agricultural conditions in Europe to the "Little Ice Age" that followed, pushing settlers from Greenland and causing the rapid advance of glaciers in the Alps.

* In recent years, the retreat of sea ice in the arctic during the summer months has been accelerating, and the earth's climate is about one degree centigrade warmer than it was several hundred years ago.

* It is possible that human efforts to meet increasing energy demands have had a marginal impact

Moving to uncertainty, it has not been convincingly proved that human activity has had any significant impact on the alternate periods of global warming and global cooling. Competent climate scientists are divided on this crucial issue.

Fortunately, this complex debate yields some certainties that virtually all scientists agree upon and about which we Americans and others living in industrial societies can respond constructively.

Taking pot shots at the hypocrisy of global warming zealots may be amusing, but it doesn't advance rational debate or rational behavior. When House Speaker Nancy Pelosi, for example, requested a larger plane than her predecessor for nonstop trips to her home in San Francisco, Republican Rep. Patrick T. McHenry accused her of contributing to global warming because her spacious jet would produce "10,000 pounds of carbon dioxide and hour," far more than the smaller one used by previous speaker Dennis Hastert.

Then there is British billionaire entrepreneur Richard Branson, who with Al Gore at his side, offered a $25 million prize to anyone who can come up with a way to blunt global climate change by removing at least a billion tons of carbon dioxide a year from the Earth's atmosphere." The Wall Street Journal noted that his judges to determine the winner all "hail from the Apocalypse Now crowd."

Of course, prudent efforts to reduce concentrations of greenhouse gases and to eliminate noxious gases form the air we breath deserve support, starting with measures to produce cleaner fuel for millions of vehicles on American roads, which are a main source of pollution. Building cleaner coal-burning plants and even wind power should also be encouraged, when economically feasible.