How far are humans pushing up Earth's thermostat? Andrew Revkin, the prize-winning New York Times science writer, has spent more than 20 years exploring this question.

Revkin's lecture at UVM, "Making Sense of Climate Change, from the North Pole to the White House," sponsored by the Burack President's Distinguished Lecture Series, was attended by a capacity crowd at Billings Lecture Hall on March 18, 2008.

UVM science writer Joshua Brown spoke with Revkin to learn more about views about what it means to live on a warming planet.

UVM: As a reporter, you talk to a lot of experts and researchers. What do you see as the most important unanswered questions about the science of climate change?
Revkin: The big one remains the sensitivity of the climate system to greenhouse gas build-up. We still don't know if doubling carbon dioxide and other greenhouse gases will lead to a one-and-a-half-degree or four-and-half-degree warming. That's a huge range with hugely different consequences.

And it's about the same range it was thirty years ago. There are many uncertainties, like what clouds do and what vapor does. It's not game over in terms of the science by any means.

I saw papers in Science, one in 2005, one in 2006, and then one recently in Nature Geosciences, that seemed to be pointing in all sorts of directions about the Antarctic ice sheet. Is it growing or shrinking?
In a warming world, Greenland and Antarctica will lose ice. In Greenland, sea levels were four to six meters higher 130,000 years ago during the last warm interval between ice ages, so we know warmer times had less ice and higher seas, but we don't know how quickly that will happen. And that's where, again, you get into very high levels of uncertainty in the science.

There's been some attempt by some activists out there to portray everything as a closed case: "we're in a disaster zone and it's unfolding a clear way." That really doesn't hold up to the data. But climate change is real.

So what other big questions are you exploring?
Can we innovate our way toward nine billion people? There is this ongoing debate between those who say we'll just keep getting smarter and richer for the next fifty years—and that will make us able to both limit our environmental impacts and sustain the world's resources—even as we head toward nine billion people. Others say we're already over the cliff like Wiley Coyote, that we're in what's called "overshoot."

History points toward the libertarians. Our history, so far, is that we've gotten richer, wealthier, and live longer and better lives—by far—than we did 100 years ago. And 100 years ago was far better than 100 years before, and on and on. If you just look at history you'd say: we'll grow and prosper and get smarter and do things better.

And yet for decades you've had this drumbeat of people saying there are limits to growth and we're going to hit a wall. We're still in this weird situation where you can't see the wall. And it becomes almost a values judgment about how you look at the same data whether we're heading for a wall of whether we're going to climb over the wall.

Where are most scientist leaning right now? Is there any consensus around whether we can create a sustainable world with nine billion people?
Going with what I see on my blog and the people I talk to, I'd say there is no consensus. There's still a wide range of views.

James Lovelock would say the world's carrying capacity of human beings is more like one billion. He's probably an outlier, but there are also people who are highly confident: Jesse Ausubel at Rockefeller University, who I highly regard and has an amazing intellect and grasp of history and data, sees us reforesting the world and having agricultural advances that will make the path toward nine billion do-able—and probably still having us have better lives. So I see a deep divide.

At the Society of Environmental Journalists conference here at UVM in October 2006, I heard a lot of reporters doing public soul searching about climate change, saying that they were failing in their professional duty to calibrate the importance of the climate story to the amount of coverage.
We've certainly had a big up-tick in journalism coverage of climate change. Matthew Nesbit, communications professor at American University, just did a paper on the recent burst of coverage. But he also did some polling to show that it hasn't really mattered, that opinions haven't really changed; they've become more polarized.

I was struck by an article by Beth Daley in the Boston Globe recently about the social psychology of change: even people who care about climate change won't stop idling their cars. Do you consider how difficult it is, even once people start to make changes in their behavior, to get them to stick with it?
The sociology of climate is the big unspoken, unreported story. I've done some blogging on this that started with a piece I wrote in the paper, "Are Words Worthless in the Climate Fight?" Some of the research I referenced is incredibly depressing: we have a limited basket of worries and it mainly gets filled up with, "what's for dinner?" and "how am I going to pay the bills?" and a little bit about who is going to be the next president—and that's about it. There's no room for long-term issues.

Following on from that thought, I've been surprised that I haven't heard much discussion of the implications of climate change for democracy. Are these issues so difficult that we'll have no ability, politically, to react until it's so late that extreme measures start to look reasonable? Do you wonder about the capacity for democracy to persist in light of environmental threat?
I've seen it portrayed the other way. John McCain, when I interviewed him, said democracies don't do well with these kinds of problems.

I guess if we ended up in worst case global turmoil—water wars, energy wars, refugee flows—you could see that pushing everyone toward authoritarianism, but that scenario…well, we'll just see how things play out!

I think democracy, or at least the kind of democracy we have here, is limiting our ability, particularly with congressional issues, to be effective with the climate problem. And I think that's more of a real-time problem to grapple with than the inverse.

Probably the most dangerous thing most people do is drive around in their cars, and the reasonable risk approach, therefore, would be to wear a motorcycle helmet anytime you get behind the wheel. And yet we'd be considered social freaks driving around in our neighborhoods with helmets on. Is the same social pressure at work in environmental issues?
Yes, we tend to ignore the looming risk: some bowel issue that makes you think you'd better get a colonoscopy, but, man, colonoscopies suck! We're not good at managing personal risk. So if we're not good at that scale, when you take it to the global scale, where you're hedging against a risk that mainly is posed for someone living in Bangladesh much more than Boston, then it makes it that much more difficult.

I think it was John McPhee who said that one of the basic tragedies of the human condition is that we can't imagine more than one or two generations ahead.
You might call that a tragedy, but the libertarians say history shows us that the lack of recognition of what will come two generations ahead is usually because of progress: life will be better or cheaper or simply more amazing.

This limit of imagination is not tragedy. But there is a fundamental question: will the tradition of progress and innovation get us through? Allow us to thread the needle of heading toward nine billion people, all aspiring to a quality of life, without really big losses?

You've written a book for kids, you have small children. What do you say to children about climate change?
I say this is your challenge and your opportunity, much more than mine. I'm of the fossil generation! What's unique about young people right now is that they can shape their career, their lifestyle, their education, around some facet of this great question, particularly around the energy question. Be a teacher or communicator, an artist or investor. There are things you can do in your life to shift the balance toward new energy options or toward alleviating poverty. So they have every opportunity right now to make this their quest—and also to make a lot of money in the process. It's a great time to be a kid.