If you were looking for a motto or a moral imperative to live by here you go: Building bright green cities: that’s the great moral and political challenge of our day. So says Alex Steffen, editor and CEO of Worldchanging.com. He goes on to explain why:

That is our generation’s Abolition, our era’s World War Two. If we can achieve this, we’ll provide component innovations, new mental models and more time for billions of people around the world to blaze their own trails to their own new models of prosperity. We’ll address the major causes of planetary environmental destruction, relieve the suffering of hundreds of millions of people and protect the rights of future generations — all while improving our own lives and preparing our region for the economy of the 21st century. This isn’t just a win-win proposition, it’s the possibility of multi-dimensional, cascading, feedback-loops full of win.

Jargon aside, Steffen is right: building green cities isn’t just a progressive, you-should-do-this kind of thing — it’s absolutely necessary for the survival of the planet. It seems clearer now that religious, social and economic differences among people will no longer divide people as much as access to safe, desirable places to live. And I’m not just talking about the millions of environmental refugees predicted in the coming years, I’m talking about the potential for America’s green cities to become more and more popular while their suburbs and exurbs become increasingly untenable — what then?

Steffen takes a hard line that drastic action is necessary:

Our current way of living is toast in either case, and will vanish within the next few decades; the only question is, what will replace it? Will our way of living be followed by millennia of ecological impoverishment, increased human suffering and diminished cultural possibilities; or will it be followed by a better way of life, one that prevents catastrophic collisions with ecological reality, and leaves us (and billions of others) wealthier, healthier and happier? That’s the only real choice we have in front of us.

How do we get there?

We need (for really direct and documented reasons) bold, rapid action and the completion of goals on a strict timetable. If any particular action can’t make a case for itself as part of a bold and rapid shift, I increasingly suspect it’s a sparkly distraction, not a stepping stone.

Steffen’s blog post began because he attended a Town Hall meeting in Seattle and called on it to become a carbon-neutral city. What he hasn’t said is what it will take to get there — and understandably, there’s no easy answer. Changing “our current way of living” is bound to have some scary consequences, be they economic or social. But Seattle may be the best chance we get: according to Smarter Cities, which ranks cities according to their sustainability, Seattle is the greenest city in the country.

Like Steffen, I’m less troubled by the idea that we will need new technologies to make us carbon neutral — what’s hardest to find is the way of encouraging people to make drastic changes in their lifestyles to be more sustainable. How do we do that in a democratic society? I’m curious to hear your suggestions…

Diana Lind is the former executive director and editor in chief of Next City.