On the day that the latest report on global warming was released, I went out and bought a light bulb. OK, an environmentally friendly, compact fluorescent light bulb.

No, I do not think that if everyone lit just one little compact fluorescent light bulb, what a bright world this would be. Even the Prius in our driveway doesn't do a whole lot to reduce my carbon footprint, which is roughly the size of the Yeti lurking in the (melting) Himalayas.

But it was either buying a light bulb or pulling the covers over my head.

By every measure, the U.N.'s Intergovernmental Panel on Climate Change raises the level of alarm. The fact of global warming is "unequivocal." The certainty of the human role is now somewhere over 90 percent. Which is about as certain as scientists ever get.

I would like to say we're at a point where global warming is impossible to deny. Let's just say that global warming deniers are now on a par with Holocaust deniers, though one denies the past and the other denies the present and future.

But light bulbs aside — I now have three and counting — I don't expect that this report will set off some vast political uprising. The sorry fact is that the rising world thermometer hasn't translated into political climate change in America.

The folks at the Pew Research Center clocking public attitudes show that global warming remains 20th on the annual list of 23 policy priorities. Below terrorism, of course, but also below tax cuts, crime, morality and illegal immigration.

One reason is that while poles are melting and polar bears are swimming between ice floes, American politics has remained polarized. There are astonishing gaps between Republican science and Democratic science. Try these numbers: Only 23 percent of college-educated Republicans believe the warming is due to humans, while 75 percent of college-educated Democrats believe it.

This divide comes from the science-be-damned attitude of the Bush administration and its favorite media outlets. The day of the report, Big Oil Sen. James Inhofe of Oklahoma described it as "a shining example of the corruption of science for political gain." Speaking of corruption of science, the American Enterprise Institute, which has gotten $1.6 million over the years from Exxon Mobil, offered $10,000 last summer to scientists who would counter the IPCC report.

But there are also psychological reasons why global warming remains in the cool basement of priorities. It may be, paradoxically, that framing this issue in catastrophic terms ends up paralyzing instead of motivating us. Remember the Time magazine cover story: "Be Worried. Be Very Worried." The essential environmental narrative is a hair-raising consciousness-raising: This is your Earth. This is your Earth on carbon emissions.

This works for some. But a lot of social science research tells us something else. As Ross Gelbspan, author of "The Heat is On," says, "when people are confronted with an overwhelming threat and don't see a solution, it makes them feel impotent. So they shrug it off or go into deliberate denial."

Michael Shellenberger, co-author of "The Death of Environmentalism," adds, "The dominant narrative of global warming has been that we're responsible and have to make changes or we're all going to die. It's tailor-made to ensure inaction."

So how many scientists does it take to change a light bulb?

American University's Matthew Nisbet is among those who see the importance of expanding the story beyond scientists. He is charting the gradual reframing of climate change into a moral and religious issue — see the greening of the evangelicals — and into a corruption-of-science issue — see big oil — and an economic issue — see the newer, greener technologies.

In addition, maybe we can turn denial into planning. "If the weatherman says there's a 75 percent chance of rain, you take your umbrella," Shellenberger tells groups. Even people who clutched denial as their last, best hope can prepare, he says, for the next Katrina. Global warming preparation is both his antidote for helplessness and goad to collective action.

The report is grim stuff. Whatever we do today, we face long-range global problems with a short-term local attention span. We're no happier looking at this global thermostat than we are looking at the nuclear doomsday clock.

Can we change from debating global warming to preparing? Can we define the issue in ways that turn denial into action? In America what matters now isn't environmental science, but political science.

We are still waiting for the time when an election hinges on a candidate's plans for a changing climate. That's when the light bulb goes on.

Ellen Goodman is a columnist for The Boston Globe. Reach her at ellengoodman@globe.com.