WASHINGTON -- A preventive war worked out so well in Iraq that Washington last week launched another. The new preventive war -- the government responding forcefully against a postulated future threat -- has been declared on behalf of polar bears, the first species whose supposed jeopardy has been ascribed to global warming.

The Interior Department, bound by the Endangered Species Act, has declared polar bears a "threatened" species because they might be endangered "in the foreseeable future," meaning 45 years. (Note: 45 years ago, the now-long-forgotten global cooling menace of 35 years ago was not yet foreseen.) The bears will be threatened if the current episode of warming, if there really is one, is, unlike all the previous episodes, irreversible, and if it intensifies, and if it continues to melt sea ice vital to the bears, and if the bears, unlike in many previous warming episodes, cannot adapt.

Because of restrictions on hunting, polar bears might be more numerous today than ever and might be twice as numerous as they were three decades ago -- when the media were fanning frenzy about global cooling. (Science magazine, March 1975, reported "the approach of a full-blown 10,000-year ice age.") As Nigel Lawson, a former British Cabinet member, writes in his new book "An Appeal to Reason: A Cool Look at Global Warming":

"Over the past two-and-a-half-million years, a period during which the planet's climate fluctuated substantially, remarkably few of the earth's millions of plant and animal species became extinct. This applies not least, incidentally, to polar bears, which have been around for millennia, during which there is ample evidence that polar temperatures have varied considerably."

But Interior Secretary Dirk Kempthorne says the "threatened" label is mandatory because sea ice has been melting and computer models postulate future melting caused by human activity. So, now that human activity is assumed to be the primary cause, or even a measurable cause, of warming, the decision to classify the bears as threatened has become a mighty lever.

Now that polar bears are wards of the government, and now that it is a legal doctrine that humans are responsible for global warming, the Endangered Species Act has acquired unlimited application. Anything that can be said to increase global warming can -- must -- be said to threaten bears already designated as threatened.

Want to build a power plant in Arizona? A building in Florida? Do you want to drive an SUV? Or leave your cell phone charger plugged in overnight? Some judge might construe federal policy as proscribing these activities. Kempthorne says such uses of the act, unintended by those who wrote it in 1973, would be "wholly inappropriate." But in 1973, climate Cassandras were saying that "the world's climatologists are agreed" that we must "prepare for the next ice age" (Science Digest, February 1973). And no authors of the Constitution or the Fourteenth Amendment intended to create a "fundamental" right to abortion, but there it is.

No one can anticipate or control the implications that judges might discover in the polar bear designation. Give litigious environmentalists a compliant judge and the Endangered Species Act might become what New Dealers wanted the National Industrial Recovery Act of 1933 to be -- authority to regulate almost everything.

What Friedrich Hayek called the "fatal conceit" -- the idea that government can know the future's possibilities and can and should control the future's unfolding -- is the left's agenda. The left exists to enlarge the state's supervision of life, narrowing individual choices in the name of collective goods. Hence the left's hostility to markets. And to automobiles -- people going wherever they want whenever they want.

Today's "green left" is the old "red left" revised. Marx, a short-term pessimist but a long-term optimist, prophesied deepening class conflict, but thought that history's violent dialectic would culminate in a revolution that would usher in material abundance and such spontaneous cooperation that the state would wither away.

The green left preaches pessimism: Ineluctable scarcities (of energy, food, animal habitats, humans' living space) will require a perpetual regime of comprehensive rationing. The green left understands that the direct route to government control of almost everything is to stigmatize, as a planetary menace, something involved in almost everything -- carbon.

Environmentalism is, as Lawson writes, an unlimited "license to intrude." "Eco-fundamentalism," which is "the quasi-religion of green alarmism," promises "global salvationism." Onward, green soldiers, into preventive war on behalf of some bears who are simultaneously flourishing and "threatened."