Every generation has its great cause. In the 1940s they stopped worrying about the economy for a while and voted for the guy who’d lick Hitler. After 20 years of looking the other way, we have to back the people who’ll finally take on carbon.

On any given day, in any given month, there is always something more important going on. Gas prices are going though the roof; you’re worried that your health care might disappear; the war drags on endlessly, or the next one beckons. On any given day, these make the front page of your paper, and the frontal cortex of your brain. That’s how we work – we’re geared for novelty; we recognize change and go on alert.

And yet, in any given year or any given decade, there’s nothing that approaches the significance of the ongoing destruction of the environment. Think only about global warming: The temperature really started to climb only a quarter century ago, and already we’ve managed to thaw open the Northwest Passage. If you look at Earth from space, it looks markedly different than it did when you were born – way less white stuff up on top. We’ve managed to melt the permafrost of the north enough that methane, once trapped below the ice, is beginning to seep out. We’ve changed the size of the deserts. We’ve opened tens of millions of acres of forest to heat-loving pests and to the devastating fires that followed in their wake. We’ve melted away most of the tropical and subtropical glaciers that provide drinking water to hundreds of millions of people. We’ve spread the aedes aegyptii mosquito well beyond its former range and managed in the process to infect tens of millions with dengue fever. Simply by warming the air we’ve raised the amount of water vapor it can hold, thus triggering drought in arid areas and deluge in wet ones.

And all that’s with only one degree of temperature rise. Scientists say we can expect five degrees more this century unless we get our act together fast. We are, in other words, a Geological Force.

You’d never know it from the voting booth, though. We still cast our ballots with the old priorities in mind; if the pollsters manage to even include “the environment” on the list of possible factors, it usually comes in near the bottom. We’ve been taught to think that “the economy” and “war and peace” are real issues and the environment is a kind of luxury item you might get to when times are good and we are at peace. Except how are you going to make the economy work when the planet doesn’t? How are you ever going to have anything that looks like peace when people start running out of water and the sea level forces them from their homes? The short answer to both questions is, You’re not. A year ago, a British government panel reported that climate change would cost more than both World Wars and the Great Depression combined. A few months later, a U.N. panel reported that there were already millions of environmental refugees; indeed, one team of researchers said the underlying cause of the horror in Darfur may have much to do with shifts in monsoonal rains in a warming world.

Elections – politics of all kinds – therefore become key. Rajendra Pachauri, who accepted the Nobel Prize on behalf of the Intergovernmental Panel on Climate Change last year, said recently that we have until 2012 to begin making substantial changes in energy policy, or the window to do something about global warming will close. Let’s see, 2012, that’s, hmmm – kinda close. The next president after this one will take office in 2013. I guess this election counts.

Counts more, in fact, than the new lightbulb in your kitchen. If you figure there are 10 percent of Americans who care enough about global warming to do all the right things, that gets you – essentially nowhere in the fight to slow carbon emissions into the atmosphere. On the other hand, 10 percent of Americans voting for the environment is enough to tip almost any election. Changing the lightbulb above your kitchen table only matters a little tiny bit; we’re not going to fix this crisis one lightbulb at a time. But changing the guy in the Oval Office – that might matter a lot.

Especially if you let it be known that you’re voting for the environment. There are lots of ways to do that: You can write an email. You can make a donation, with a little note on the email form saying: “I care most about climate change.” You can go to 350.org and join us in our campaign to invite the presidential victor to the big international climate conference in Poland in December. You can show up at the polling place with your face painted green.

It’s possible to break through the apathy: Last year in this country our 350.org organized 2,000 demonstrations in all 50 states, with essentially no money – just people who wanted to make a difference. They knew that every single second, minute, hour, day the world is getting less like the one we were born into and more like the one we fear.