KEITH: But what revolution? How? We could really screw up. The fact is we’re in the early days of this, and many responsible people put forward plans for what to do without an adequate understanding of the risks and costs.
CLAUSSEN: I don’t think the things I suggested are meaningless.
KEITH: I didn’t say they were meaningless. Switch to natural gas and some efficiency—great, no argument. They’re the right things to do to start. But that only addresses about a third of the problem; it doesn’t give you the meat. Sorry to push you, but if we’re going to solve the climate problem, we really have to find a way to provide primary energy—something like 5 or 10 terawatts in the next 50 years—without emitting CO2.
CLAUSSEN: Do you agree that we have to do away with the internal combustion engine?
KEITH: No. Internal combustion engines are irrelevant because they’re only a prime mover. A prime mover turns a fuel into the mechanical energy used to drive a product; changing prime movers does close to zero to solve the problem. The question of whether we switch to fuel cells is high profile right now. But the crucial issue is how you generate the fuel you use and what emissions and environmental destruction that causes.
SARMIENTO: I don’t think about how to solve the problem per se—how to get industry to change, how to reduce greenhouse gas emissions, et cetera. What I think about is: At what level of CO2 is the problem a really serious one? When is it dangerous? What is dangerous? And at what level of CO2 do we consider the problem solved? Is 550 parts per million a safe scenario? And if we choose that scenario, will an 80 percent reduction in emissions today get you there by 2100? No matter how you look at it, I think there’s only one long-term solution: to stop using carbon as a source of energy, to switch away from using fossil fuels.
KEITH: That’s a nonsolution. How are you going to get primary energy? The problem is how to produce primary energy with low environmental insult. I agree that in the very long run, the solution is to get away from fossil fuels. But that doesn’t have to be for a couple hundred years. If you ask me when the right time is, I’d say toward 100 years. But I think we really do need to talk about where we might be in 50 years. How are we going to produce the extraordinary amount of energy we require without emitting carbon dioxide, which we must do?
FREY: And your answer?
KEITH: We need to put enormous effort into thinking about how to make truly environmentally clean or cleaner energy systems. In the meantime, capturing carbon out of the air and sequestering it is the most direct way we know how to provide energy without CO2 emissions and without building another infrastructure. My colleagues and I believe we can suck CO2 out of the air and put it into stable carbonate rocks at prices of a few hundred dollars a ton, and we think we can probably go lower. Many people think we’re crazy. But they’re wrong. We’re right.
CLAUSSEN: In your modest opinion.
KEITH: It’s a radical idea. While it might not be a good idea, and by no means do we understand all the risks and costs, it’s pretty clear you could do it. It’s an option. You could keep burning fossil fuels for 200 years and stop adding CO2 to the atmosphere.
SARMIENTO: You have to be careful how you say that. You may be able to strip the CO2 out, although I don’t know how well established that technology is yet. But then can you safely sequester it? That remains far from proven.
KEITH: Can you make hydrogen and capture CO2? We already do. There’s nothing magical about it. You can build a power plant at full scale. And you can put the CO2 down a hole, two, three kilometers in the ground. The only questions, which are very big questions, are about deep geochemistry and reservoir geology: how long it stays, what happens to it, what the risks are. People will be knocking on doors of government to permit these projects in the next decade.
CLAUSSEN: But what about the disposal of the CO2?
KEITH: That’s the big question: What happens when you put the carbon down a hole? Let’s start with the reason to be most terrified. The total leakage of natural CO2 from the ground through volcanoes is a couple of hundred megatons a year. That doesn’t scare me. What scares me are the places where CO2 seeps slowly out of the ground. Since CO2 is denser than air, it clings to the ground. Somebody was killed in the Sierras a couple of years ago when he walked into a low bowl in the ground that had a hot spring and, unknown to him, a little bit of CO2 coming out. The amount of CO2 currently leaking out that way is trivial compared with the amount we’re talking about sequestering in the ground. So that’s a reason to be scared.
FREY: So if we just bury carbon dioxide when we’re not sure how or if it’s going to leak, doesn’t that just push the problem on to another generation?
KEITH: Of course it does. But everything we do does. This is a game about balancing risks and costs between generations. If you’re expecting the CO2 to stay underground for only 100 years, it’s not worth doing. We’ve got to be confident that it will stay there more than a century.
SARMIENTO: Thousands of years, I’d say. I mean, this sounds too glib to me. If we start thinking, “Oh well, we’ll just burn through all our carbon reservoirs, and we’ll form carbonate rocks,” we’re going to end up with trace metal contamination and all kinds of unpleasant issues to deal with. There are some extremely bright, very capable scientists with tremendous enthusiasm and excitement for fertilizing the ocean with iron and sequestering CO2 in the deep sea. When I looked at what these projects would imply, I came to a totally different conclusion. I’m uncomfortable letting strong statements about this stuff go unchallenged without saying, “Wait a minute.”
KEITH: Let’s be frank about carbon sequestration. It’s a kludge; it’s ugly. It has risks and costs that we don’t understand well. And it avoids what seems to be a fundamental solution.
SARMIENTO: Thank you.
KEITH: But it is incorrect to imagine that the only way to solve the global warming problem is to remove consumption. Like it or not, there are technological fixes.
FREY: That gets us into the whole business of geoengineering the planet, doesn’t it?
KEITH: Well, we are already geoengineering the environment; it’s just that we’re not doing it consciously. We’ve modified the whole landscape; we’ve played a central role in extinguishing many species. Like it or not, we are already in the gardening business with this planet, and we need to decide what kind of garden we want. The climate problem results in part from the fact that we’re slowly growing an ability to both unintentionally and intentionally manipulate the planet at the largest scales.
The following day, the skies darkened, the temperature dropped, and beneath a steady rain, we floated for miles and miles—out of the foothills and along the coastal plain. As the river widened and the land opened up, we passed bear, musk oxen, and a drowned caribou, its huge rack of antlers still high above the waterline, like the limbs of a half-submerged tree. By midday, we had our first sightings of industry: Off to the west, distant oil trucks skimmed the horizon, and the stanchions of the Trans-Alaska Pipeline heaved into view. When we stopped for lunch on a small hillock to the west, we could hear the sound of diesel engines carried on the wind.
SARMIENTO: God, would you look at that! After days in the wilderness, it really stands out. Frankly, I’m still struggling to see the connections between the climate problem and this, but maybe it’s all one and the same thing. I mean, it’s all about the ways we humans have modified the planet. Twenty percent of Earth’s surface has been impacted by deforestation and such. We’ve increased the CO2 content by more than 30 percent. We’ve increased the methane content by, what, 150 percent?
Now let me ask a question. Say we forget about solving the climate problem and just continue to burn all this carbon: We change the pH and carbonate, we have four times the preindustrial CO2 level, we live in that world. Why do we think that’s bad? I mean, I don’t want to do that, but why not? This whole area we’re in now, it would develop into a forested area.