Eight years ago, Denis Hayes—the founder of Earth Day and arguably America's pre-eminent environmentalist—visited WW as part of "The Race to Stop Global Warming" tour.

Back in 2001, the then-fresh Bush administration, as we suspected, had no interest in joining that race.

With an Obama administration in office, Hayes dropped in again recently to discuss what America can do to regain the ground we've lost on global warming since 2001. Hayes, president of the Seattle-based Bullitt Foundation, had lots on his mind: Obama, cap and trade, "passive houses." And even the proposed new bridge over the Columbia River.

All right, we'll bite. What's your read on the Columbia River Crossing?

Don't build the damn bridge. The elementary truth—which Oregon more than any other state and Portland more than any other city has subscribed to—is that the more transportation of any kind you have in a community, the more dysfunctional the organization of that community is. What that comes down to is, you have a whole lot of people coming here from Washington who ought to be staying in Washington. People going in the other direction ought to be staying here. And we ought to be thinking of other ways to move freight.

What do you say to the mom and dad in Vancouver with two kids who've got a mortgage they're struggling with and they've got jobs they need to get to in Portland when unemployment is 12 percent?

Whether we build a bridge or not, they're going to have to get to work someplace for as long as it takes to build a bridge. Their kids are going to be in college. And if they're an average American, they're going to have shifted jobs twice during that period of time. But there will be painful consequences always for people who have a car that gets 15 mph and a house with five bedrooms. That's not what the future is going to look like.

Why should Portland take the lead in accepting the painful consequences?

It's to avoid painful consequences that you have a little bit of pain now to avoid more pain in the future. I grew up next to Portland and I know it's not utopia. But Portland has built something better. Why should you do it? Because you can.

Let's talk about cap and trade, and carbon taxes. Is that of any value in combatting global warming?

I'd take the both of best worlds. You put a cap on all the carbon as it enters the economy, not where it comes out of smokestacks and exhaust pipes. And you say you cannot bring carbon into the national economy unless you have a permit and the number of permits is capped. You then auction those permits.

What you're proposing is a cap and no trade? So how do we get China to agree to cap?

I don't think there's any particularly easy way to force countries to do it. But once you have a carbon cap on the American economy, even the most free-trade economist would say if China doesn't play along, at that point on behalf of the planet, protectionism makes sense…. Beginning to swiftly ratchet down the amount of carbon emitted into the atmosphere and ultimately to reduce the amount of carbon in the atmosphere—if you've got to do one thing in the Obama administration, that would be the thing. All of life evolved when, give or take, we had 280 parts per million of carbon dioxide in the atmosphere. We're now up to about 380 parts and growing about 2 parts per year. The critical threshold that is unacceptable is about 350. When you're at 380, that's pretty scary.

Why can't Obama and a Democratically controlled Congress do more?

My great advantage is being on the West Coast talking to smart people in a non-adrenaline-filled atmosphere. I'm talking about designing a system that will work. Back in Washington, D.C., they're trying to design a system that will pass. You can't get anything through without coal-state Democrats. It has nothing to do with science. It has nothing to do with economics. It has to do with the interest of political folks who want to get re-elected. If you're president, you've got a chance to do two or three things. You decided health care is going to be one. The other one can be climate, and you ought to be as bold on climate as you are on health care.

Do you think the market for green energy will always require a government subsidy on the premise that it's a common good, or will it ultimately survive on its own in the marketplace?

You look at the kinds of tax incentives for the oil industry, coal industry and nuclear industry over time. They absolutely dwarf what you're talking about. If you could get rid of all that, I'd be happy to fight it out in the marketplace. But I don't see a way to do that.

We're writing about passive houses this week. Why don't more people do them?

Most of the home builders are guys that took wood shop in high school and were carpenters for a while or plumbers for a while and finally scraped together enough money to take that huge risk and build a house on spec and get some banker to support them. They can build three or four or five houses a year. It's a decent living but not a whole lot of margin in it. So they are naturally the most conservative elements out there. You've got something you know how to build and nothing goes wrong. And you're able to sell the damn things, why would you tweak it? To change that, you can do a little bit with codes and ordinances and what have you. But passive design, if done well, is brilliant. If done poorly, it's counterproductive. You have to know what you're doing, and people who build three houses a year are not going to be very adventurous.

Tell us about your lifestyle and how it jibes with being America's pre-eminent environmentalist.

The car I drive is a Prius. We replaced our [oil] furnace with a [natural gas] furnace that is 96 percent efficient. We replaced all of our lights with compact fluorescents. We replaced all our windows. I've come to fairly routinely resole all the soles of my shoes. I'm not pure vegetarian but tending increasingly toward it. I have one kid. If we were to aspire to have a Swedish standard of living, that's about 2 billion people with current technologies. Since we're now at about 6 and a half billion people, you could make a decent argument that zero population growth is not at all a radical philosophy.

What are your guilty pleasures?

It's not at all a pleasure, but it's a source of guilt—jet travel, although I buy offsets. With the 40th anniversary of Earth Day coming up, I'll be traveling to about 20 countries. The irony is not lost on me.