A professor of biological sciences at Stanford University, he has been arguing the dangers of human-induced climate change for over two decades. In this interview, he outlines the 'best guess' global warming scenario which has been arrived at by the bulk of scientists. He also explains how the challenge of finding new carbon free energy sources can be met, and why the 1997 Kyoto Protocol on reducing greenhouse gas emissions was a crucial event for the world, even if it is not ratified by the United States.

Several people have said: 'Well, isn't it a good thing that our industrial progress has produced not just carbon dioxide but sulfur aerosols, which cool us back down?' And I've always said I didn't like the idea of using acid rain to solve global warming, because those aerosols are not only bad for ecosystems when they rain acids into the lakes and streams and soils, but they're also part of the air pollutants which, when we breathe, we know from statistical tests, leads to increased lung and respiratory disease and what we call excess deaths, which sounds very clinical unless somebody in your family happens to be susceptible to that kind of air pollution.

Some people want to shove it in the stratosphere--what we call geo-engineering. That at least wouldn't have health effects. But the aerosol offset is only partial. And even if it would offset the global warming almost completely, it's not going to leave the world's climate unchanged, because there'll be pockets in the world that'll actually be cooler, then other pockets much warmer, so you'll have blobs of warming and blobs of cooling. And that's a change, because our water supplies, our agriculture, and our ecosystems, they live locally, not globally. They don't care about 2 degree global mean change. They care about what happens in their region. And having regional aerosols offsetting some of the global effects is not going to prevent regions from still being disturbed. And we're still going to have climate disturbance if we try to solve global warming by regional air pollution, to say nothing of the health effects and the environmental effects of that air pollution.

The other uncertainty concerning the magnitude of the global warming change has to do with the feedbacks that operate. Some people have argued that maybe the climate isn't as sensitive as all that, in which case you'd get a smaller change rather than a bigger one.

Scientists don't have a Hippocratic oath, but we have to tell the truth. Everybody's truth is relative. But our truth means a wide range of possibilities that we can imagine. And I can imagine so-called feedback processes, where if you warm up the earth, you melt snow and ice, which adds further warming. If you do that, it makes the clouds taller, which makes them trap more heat, instead of wider. And if I conjure up these feedbacks, I can end up expecting that we could have climate change that's catastrophic in the next century.

I can also conjure up another set of feedbacks: The clouds get wider; it gets drier in between the clouds. There are a number of feedbacks we can conjure up, which makes it warm up only a degree or so, at the relatively mild end of the spectrum. Well, most scientists would argue that these very mild and very catastrophic outcomes are plausible, maybe even a 10 percent chance of each of them. But the bulk of the likelihood is somewhere between the end of the world and the "good for you" scenarios that you see all the time in the newspapers and in the Congressional debates.

The bulk of scientists are pretty straight about saying this is a probability distribution. And right now our best guess is that we're expecting warming on the order of a few degrees in the next century. It's our best guess. We do not rule out the catastrophic 5 degrees or the mild half or one degree. And the special interests, ..... from deep ecology groups grabbing the 5 degrees as if it's the truth, or the coal industry grabbing the half degree and saying, "Oh, we're going to end up with negligible change and CO₂'s a fertilizer," and then spinning that as if that's the whole story--that's the difference between what goes on in the scientific community and what goes on in the public debate.

Let's say you've convinced everybody that the probable climate change for doubling would be on the order of a few degrees, in the middle. Then the question will be asked: Why should that matter to me? Why should I bother about that?

Well, for many years, when we talk about a few degrees warming, most people say, "A few degrees? So what? If I change my thermostat a few degrees, I'll live fine. The trees over there on the north side of the slope are already 5 degrees cooler than the trees on the south side of the slope." Of course, if you look carefully, you find they have different trees on the north side and the south side. So the point is that one or two degrees is about the experience that we have had in the last 10,000 years, the era of human civilization. There haven't been--globally averaged, we're talking--fluctuations of more than a degree or so. So we're actually getting into uncharted territory from the point of view of the relatively benign climate of the last 10,000 years, if we warm up more than a degree or two.

So you're saying that globally averaged, there is a significant difference in this shift in degrees upward?

Globally averaged, more than a few degrees is significant. After all, when ice sheets came down to Manhattan Island (you can find the scratches from the ice still in Central Park on the rocks), that was 20,000 years ago. It took about 10,000 years for nature--not us--to warm the earth up. Well, it warmed up 5 to 7 degrees Celsius, something like 10 Fahrenheit. It did that in 5,000 to 10,000 years. The average rate of change is one degree or so per thousand years. Now, what happened? The trees that are now in Canada (the spruce trees and the arboreal forest) and the oaks that we now have in the middle Atlantic states, for example, they were all compressed far to the south, in-in the current US southeast, 20,000 years ago. They moved over the 10,000 year transition to where they now are. In their process of moving, giant species like the saber tooth cats and the mammoths went extinct, not just due to climate change, but that was a piece of the story.

Today, we're talking about humans modifying the climate so that if we're lucky, we only get another degree in the next century. That's one degree per century, not one degree per millennium, which is the natural average rates. It could be several degrees per century, is our best guess. Compare that to this, to the degree per millennium of history, and now ask one more factor: How are the species of trees, for example, and birds and so forth, how are they going to migrate? In history, they just migrated. Now they have to cross factories, farms, freeways, and urban settlements. So if you have the combination of fragmented habitats with nature getting into smaller and smaller patches, now you change the climate ten times faster than the history for which they have experience, this seems to me an absolute prescription for an extinction crisis where we lose a large fraction of the species now on earth. The real question is: Does anybody care?

Let's say you've convinced me and I do care. Now we turn to the notion of mitigation. I say: Yes, I'd like to do something about it, but I've just realized that most of our energy in the world comes from fossil fuels. What makes you think this is even a feasible problem to solve?

It's certainly not feasible that we're going to solve the underlying cause of greenhouse gas buildup in the atmosphere in a decade, or even two. How did we in the western countries get rich? We had a Victorian Industrial Revolution. We had sweatshop, polluted cities, coal-burning power plants, and industry and so forth. Then we got tired of the loss of quality of life associated with that kind of crowding, social inequity, and pollution. And through sets of rules and through inventive technology, we invented a better system. We're still hooked on it, but we're more efficient than we were. Now we talk to China and India and other developing countries. And we're talking about global warming. They're saying, "Wait a minute. You guys used the Victorian Industrial Revolution to get rich. Now you're telling us there's a reason we can't do the same thing."

So it's very difficult to expect that the world is going to automatically overnight turn off its addiction to carbon-based energy. We're going to be on it for a while. But that doesn't mean that we can't begin right now (in fact, we should have begun three decades ago) developing the kinds of technologies that we need over the next several decades to replace the more polluting Victorian industrial technologies. I mean, after all, what is the internal combustion engine that we all love to drive around in? It's a Victorian technology. The next phase up is what we call hybrid cars, with a mix of electric batteries and so forth. And the phase after that is fuel cells. They're three or four times more efficient. They don't produce nearly as many pollutants. They don't require a large balance of payments deficit for oil-importing countries. Well, they're coming. The question is: Are we going to let them come at the slow rate that they'll happen naturally? Or should we say we can protect the climate at the same time that we can have industrial development?

What we really need is a global technology policy to try to accelerate the rate of development of clean technologies, and to help especially the developed world not just develop by old technologies, but to literally leapfrog over the Victorian Industrial Revolution right to high tech, saving themselves air polluted cities at the same time that they move to more efficient systems. But it won't happen automatically in less than a half a century. We need planetary-scale policy if we're going to accelerate it so that it happens in decades, not in a century, and if we're going to prevent doubling or tripling of CO₂ along the way.

But these technologies, even though they're more efficient, they still basically use fossil fuels. A fuel cell will still use methanol as the feed stock for hydrogen. You still have the problem that even if everything is more efficient by quite a big factor, and you have a growing population in India and China with a growing standard of living, a vastly increased energy resource, that that's fighting against any efficiencies you make. Do you have to basically attack the issue of where your energy comes from?

Those of us who argue that we should have at least an initial technology strategy to try to go to more efficient technologies (fuel cells, switching from coal to gas), we recognize that those still produce CO₂. But I'd much rather see CO₂ double in 2150 than in 2050. Because the rate at which climate changes is dramatically important for how much damage it does, because it affects our capacity to adapt, and it especially affects nature's capacity to adapt.

At the same time, if we had a price on carbon, if we weren't all allowed to use the atmosphere as a free sewer, then the inventive genius of our industrial folks (and they're really quite clever; they just need incentives) to invent non-carbon-based alternatives would be stimulated. As long as the price of energy remains so that a bottle of mineral water in the store costs three times more per gallon than gasoline at the pump, we haven't got incentives for that kind of development.

So I think that yes, in the short run, we go toward efficiency. In the long run, we have to deal with the overall size and scale of the human population. It has to start to stabilize. And we have to begin to develop those technologies that have much less impact. But in the end, we can't keep growing indefinitely, because we will run out of room and we'll run out of atmospheric capacity to continuously absorb our wastes.

There are U.S. Congressmen who would say that it's not fair because it only involves developed countries and not the developing countries; and since these countries will become the major emitters in the next 20 years, it doesn't make sense.

The criticism I've heard of Kyoto is, "It's not fair to countries like the U.S. or Japan because the developing world is left out." But there are two big facts to remember. Number one, if you look at all the carbon dioxide that's been emitted into the atmosphere in the last 100 years, 80 percent of it came from the rich countries, only 20 percent from those poor countries. And we have a factor of 10 or more per capita use of those fossil fuels. So how dare us ask those groups, which have had a minority share in the problem, to all of a sudden have an equal share in the solution when they're relatively impoverished, and we use that very pollution to get rich? We obviously have to take the first steps--in any world, in any ethics, at least that I personally share.

On the other hand, that having been said, we can't leave the developing world out very long, because if only the rich countries participate, then we can't make a very big difference. Because the big numbers in terms of how much junk we're going to throw in the air column, when the now developing countries with large population start emitting at anywheres near per capita rates that we have, we can't let that happen unless we're looking at a quadrupling of CO₂ over the next century or two, which to me is unacceptable.

So what that means is, we have to begin allowing the developing world to leapfrog past the Victorian Industrial Revolution to new technologies. And that's going to involve having them in the game. But they're not even going to listen unless we have ten years to show them that we're serious, by taking the first step. And how can somebody who created 80 percent of the problem not be responsible for taking the first step?

So the developed world has to pay for this, you're saying, initially?

The developed world (a) created the bulk of the problem, and (b) has the bulk of the resources to fix it. Obviously, it has to pay for it initially. And we're going to be inheriting the pollution that comes from China and India and Indonesia and so forth, over the next century. So it's in our interests to help them pick a development path that's different than the one that we used 100 years ago to get to our status, and namely that's switching toward more high technology and less polluting energy systems as they develop.

The other argument you hear from industry is that the U.S. economy is the economy which drives the world. It's one third of the world economy. It's the main reason everything's working. And if you put a tax on energy or you try and transfer wealth from the US to developing countries, you threaten this.

Well, there's been a lot of specious nonsense in the climate change debate. And one of the worst exaggerations are those people who say that Kyoto protocol and any climate policy is going to bankrupt the western countries. I actually saw somebody have the nerve in a Detroit newspaper to say they were going to lose 68,500 jobs, which is below the noise level of how many jobs will be created the next few decades. This is pseudo-precision if ever there was any. We haven't got a clue that that's going to happen at all. They completely neglected the fact that in the process of increasing the price of conventional energy, this sends signals, market signals, to whole new industries which spring up to deal with efficiency.

So what we're really talking about is not a threat to the economy at all. We're talking about a threat to certain industries and interests. And that's real. If I were a coal miner, I'd be very worried about climate policy. And that's legitimate. And I think we as a decent society have to think about transitions to help people in those positions. But that doesn't mean that the overall economy is going to be damaged.

The other factor is: This stuff cited all the time about how expensive it is, forgets the fact that we're not going to have to solve the problem alone in the U.S. or Japan; that we can look around the world and find the cheapest place to abate carbon, and do that; or we don't have to abate carbon by just dropping fossil fuel injected CO₂. We can reduce methane or nitrous oxide, which we can do through agriculture. And a lot of the initial steps can be done for free. In fact, we can make money doing it.

And our own economies are not perfectly efficient. This is what's called the "no regrets market failure". That's the fancy lingo, which basically says we don't all have the best motors, the best lightbulbs, the most efficient cars and industrial processes. We're not perfect. That the industry standard is way ahead of the industry practice. And therefore, if climate policy forced us to be more efficient, we actually would be replacing inefficient technologies with more efficient ones that would cost us less money to buy them than the money we're saving in fuels.

So therefore it's utter nonsense to argue that there's some bankruptcy from the western economies from the Kyoto policies, because it makes unrealistic assumptions that special interests just keep pushing, because they don't want to see their individual clients hurt. And there will be individual clients that will be hurt.

The other thing they say is that it wouldn't make any difference anyway. It's such a trivial contribution to the carbon problem that it would be offset in a few years.

If Kyoto is the only thing that happens, it only makes a 5 or a 10 percent difference on the time frame of a century. Nobody rational is arguing that Kyoto's the only thing that should happen. It's step one. Now, what happens is, the developed countries that created the problem take step one and show that they're serious and they're willing to do something about what they've created, and that they're sending the right signal to the developing world. Now step two involves getting the developing world in and helping to set up an international set of partnerships for technology transfer and development. That's very important. And step three is, in the process of developing these alternative technologies, what you then do is, you make the future cheaper.

How does that work? We're expecting to run out of oil eventually. Right? We've been going up, up, up. The U.S. has already gone over the top and imports a good fraction of its oil. Well, the same thing's going to happen in the world. We're going to go to the maximum production some time shortly after the turn of the century. In that case, prices are going to go up. We'll have to switch to alternatives. So if climate policy pushes us in that direction anyway, it means those alternatives, when they come online 10-20-30 years down the line, will come online cheaper than if we wait till then to need them, because we'll have put the research effort now. So what that means is that we make the future cheaper in the long run and have less disruption then, by these kinds of policies.

So what we are doing is, we're spending a little bit of a premium up front in order to have environmental pollution reduced and in order to have a safer, more viable and sustainable set of technologies in the future. The question is: Is this generation willing to make an investment in the future? And I think the answer is yes, but only when people aren't confused by that baffling debate where the "end of the world" and the "good for you" types are constantly getting attention on and off in the political and the media debate.

You talk about specious nonsense from industry. On the green side, I've interviewed people from environmental groups who've said they don't like coal, they don't much like gas, they don't like oil, they don't like nuclear, they don't like hydro. And with a straight face, they'll say the world's energy can be supplied from solar and wind and biomass.

The world's energy system is going to have to be mixed. We can't just have one kind. There was a report a long time ago called A Time To Choose. Well, we don't want to choose one. We want to choose a lot. There's a concept in economics called the marginal dollar. Where do I invest my next marginal dollar? Well, the first thing I do is, I split it into small change and I invest in a lot of things, because it's not clear what the price of all these alternatives are going to be until we start inventing them. What was the price of computers and their ability when we first started distributing them widely, 20 years ago? Prices were high. Capability was low. Now the prices are infinitesimal in terms of the capability, relative to what we had before.

The same kind of thing could be expected to happen in energy and in other kinds of industries. But you have to have experience. The economists call it learning by doing. Now, how do you learn by doing? You got to do. And you're not going to do if there's not an incentive to start. So that's the role of government: to help provide those incentives, to get these fledgling and alternative technologies the practice and experience so that we can begin to get the prices down, get the bugs worked out, rather than to wait till we have an absolute certain crisis, and then we go into crisis mode and we have terrible dislocation.

Best analogy I have is: When OPEC (for political reasons, not for environmental reasons) dramatically raised the price of oil in 1973, well, this was very disruptive to the world economy. People literally died in India and Pakistan because it coincided with the drought, and the price of fertilizer skyrocketed at the same time the droughts occurred. What we learned in that was two things. One is, you can't have radical price rises in a short period of time. That really does hurt the economy. It's the steepness. The second thing we learned is that over the next ten years the rate of energy efficiency improvement, instead of creeping along at 1 percent efficiency improvement per year, took a dramatic jump, went up a factor of several above that, because the price was high and people had an incentive to invent more efficient technologies.

So if we continue to have an artificially depressed price of energy (which is especially true in China, it's true in the U.S. and in other places where they don't charge the full price for the damages that our current energy create), then we don't have the incentives to develop the alternatives. And without incentives, how can we expect industries to get the "learning by doing" experience that we need in order to have these technologies come online cheaper and more efficiently over the next few decades?

Clearly, new technologies are bounded by the laws of physics. Many energy people I've spoken to can never imagine the so-called new renewables being a big players. As we go forward, we have the situation where it seems to get less likely that Kyoto is ratified. And some things are happening, like the shutting down of nuclear plants and large hydro plants, which seem to indicate going backwards. What are your views on this?

The first major thing to do is to get efficiency improved. We are not anywheres near as efficient as we could be. The engineering capabilities are way ahead of the state of the art. That's step one. Step two is to see to it that the developing world doesn't pick the wrong branch point. China doesn't have to pick the coal branch. It can go gas. And the efficiency in China, India, places like that, are vastly lower than it is here, and we're already a factor of two lower than Japan.

But China would have to import gas if it used gas, and so would India, which would be expensive for them. It would cut back their chance of developing.

Part of the problem we have is geopolitics. There's more than enough gas in Russia to deal with lots of needs for China. But if I were Chinese, would I trust the Russians with my industrial jugular, having the gas pipeline? Probably only if there were international guarantees in the pipeline. So now we're looking at a situation where we end up, because of historical animosities and distrusts, picking sub-optimal strategies for energy because we haven't got a good global geopolitical strategy. And what that means is that we need to set up international guarantees, just like we have peacekeeping forces.

President Carter once said that energy was the moral equivalent of war. Well, he was proved right in the Persian Gulf War many years later. And I think that we'll again be seeing that. And one of the things that we could do is, we can set up international guarantees for trade, so that Russia, who could sure use the foreign exchange, could sell gas to China, who would certainly like to cut the air pollution in Beijing. And there's a perfect bargain waiting to made, if only somebody could watch the pipeline and have everybody assured that it would be a viable alternative.

So while the technologies that we're going to see in the foreseeable future are not going to stop us from probably doubling CO₂, why not delay it till at least the end of the next century? And let's hold it to a doubling and not go to the quadrupling that we're going to see by the middle of the century after that, with business as usual. We can't prevent some climate change, some damages, but we sure can slow the amount and the rate. And that's very important. But in the end, if we don't control the number of people in the world and start becoming satisfied with standard of living that will be higher than now but not growing very rapidly, then we will not be able to go on indefinitely without having climatic or other consequences to deal with in the long-term future.

What happens if Kyoto isn't ratified? Are you still optimistic?

Kyoto had two critical elements, which will be true in any agreement, whether Kyoto is ratified or not. Element A: You can't solve a problem [of the global commons] by yourself. Individuals, firms, and countries can't do it. It takes countries working together. It takes an international rule. That's not a trivial accomplishment.

The second accomplishment is that the people who did most of the damage and have most of the wealth have to take the initial steps. So we're dealing with a combination. For effectiveness, you need to have a planetary scale operation. And for equity and fairness, you need to have differentiated (as they call it) responsibilities as to who pays. I think those are going to be the principles of any agreement that takes place in the future.

And if Kyoto doesn't happen now, several years from now as the climate continues to drift up, as the super-hurricanes happen, as people's politics changes, as species extinctions become more and more in the news and people become aware of them, there will again be demands for international regimes, and we won't have to re-invent them. We'll be able to build from Kyoto. So even if it goes down, it's done its job of getting two important principles out in front of the global community and accepted by the vast bulk of the nations of the world.

Why aren't Congressmen more receptive to this now?

Congress operates on the basis of short-term interests. They worry about constituents back home. And there's a mythology in America that we're entitled to absolutely cheap energy for the indefinite future. And that's gotten us in a lot of problems: air pollution, acid rain, balance of payments deficits, and now climate change. And in order to get unhooked from our addiction to this kind of cheap energy, will involve transitions. And those transitions can have some pain. Now, what politician ever wants pain now, if that pain can get stalled until the next elected person in the future? And there are some politicians like that, but there aren't too many. And as a result of that, it's very easy and convenient to say, "Oh, well, no new taxes."

But when you read the polls in the US, most people believe that they want to have educated populace, they believe they want to have a clean environment, and they're willing to pay for it. I think the politicians are over-estimating the backlash they think they're going to get from people. I think the backlash is going to be bigger when the problems descend on us in the future and they say, "Why didn't you fix it when you knew you had time?"