With Jeff Goodall, of Yale Environment 360:
Geoengineering the Planet: The Possibilities and the Pitfalls: Caldeira argues that sharply reducing greenhouse gas emissions is by far the most prudent course. Still, given the huge volume of carbon dioxide that humanity continues to pour into the atmosphere, Caldeira says it would be folly not to undertake research into geoengineering. With the prospect that the world could reach a level of dangerous warming this century, Caldeira maintains it’s necessary to determine which projects — such as putting particles in the stratosphere to reflect sunlight into space — might work and which will not. He likens geoengineering schemes to seatbelts — a technology that might reduce the chance of injury in case of a climate crash. But, warned Caldeira, “Thinking of geoengineering as a substitute for emissions reduction is analogous to saying, ‘Now that I’ve got the seatbelts on, I can just take my hands off the wheel and turn around and talk to people in the back seat.’ It’s crazy.”
Yale Environment 360: I want to start with this little dust-up over SuperFreakonomics. In the book, you are quoted as saying, when it comes to global warming, “Carbon dioxide is not the right villain.” Is that accurate?
Ken Caldeira: That is not accurate. I don’t believe I said anything remotely like that because I believe that we should be outlawing the production of devices that emit carbon dioxide, and I don’t think we can solve this carbon climate problem unless we drastically reduce our carbon dioxide emissions very soon.
e360: They also write that you are convinced that human activity is responsible for “some” global warming. What does that mean?
Caldeira: I don’t think we can say with certainty whether we’re responsible for 90 percent of it or we might be responsible for 110 percent of it...
e360: Another thing that plays in to the same kind of sensibility is the idea that the doubling of CO2 traps less than 2 percent of the outgoing radiation emitted by the Earth. When that’s phrased like that, it makes it sound like it’s not really much of a problem.
*Caldeira: *You should think of the whole global warming problem as a 1 percent problem, at least for doubling of CO2. In absolute temperature Kelvin — scientists like to use the Kelvin scale — the current Earth temperature is around 288 degrees Kelvin, and a 3-degree warming on top of that is basically a one-percent additional warming. And so this whole issue of climate change, when viewed from an Earth-system perspective, is a story about 1 percents and 2 percents...
e360: The authors also cite you as saying that a doubling of CO2 yields a 70-percent increase in plant growth, suggesting it would be a boon to agricultural activity. It sounds like one of those old CO2-is-good-for-you ads. Can you explain that?
Caldeira: Yes... the 70-percent increase in plant growth... came out of a paper that we produced, I believe, in 2005. We took a model... which has a very low climate sensitivity, and what I would consider a hyperactive land biosphere--produced 9-degree Centigrade warming globally and 20 degrees around East Antarctica. Now that’s 16 degrees Fahrenheit globally, and something like 36 degrees around Antarctica.... So we were showing, look, even if CO2 fertilization is at the high end of anybody’s imagination, we still produce rather frightening temperatures. But I do believe the basic sign is correct, that with more CO2, plants can use water more efficiently... agricultural productivity will increase in the mid and high latitudes, where warmer weather will help the plants grow, but will decrease productivity in the poor equatorial nations where heat is already stressing crop yield.
e360: Overall, do you feel like your work has been accurately and fairly represented in this book?
Caldeira: The main misrepresentation is the quote that says that CO2 is not “the right villain”... but if you say what’s the primary gas responsible for the planetary warming, I would say it’s carbon dioxide.... [T]he other statements that are attributed to me... based in fact and based on studies.... [P]ull back to the case of the biosphere taking up 70 percent of CO2--well, yes, we have a published study that said that. It also presented results saying that we might warm up the planet enough to risk melting Antarctica.... [T]here is a selective use of quotes. If you spend several hours talking to somebody and they take a half-dozen things and put it in a book, then it’s going to be in the context and framing of arguments that the authors are trying to make... the contexts and the framing of those issues are very different from the context and framing that I would put those same facts in... So I think that the casual reader can... come up with a misimpression of what I believe and what I feel about things.
e360: Let’s talk a little bit more broadly about geoengineering. I was struck by something one of the authors said on NPR the other day — that he got interested in geoengineering when he realized that the problem with global warming is not that there is too much carbon in the air; it’s that it is too hot. Do you agree with that?
Caldeira: The reason it is too hot is that there is too much carbon dioxide in the air. Now the carbon dioxide itself, of course, has big negative implications for ocean acidification and ecosystems, including coral reefs. So there are direct CO2 effects.... [I]f we had some magic thing that would reverse all effects of CO2 perfectly, then you could say, “Well the problem is not CO2.” But nobody really expects that we are going to have some magic, perfect CO2 nullifier.... [T]o present it as if, “Well, it not’s really CO2, but the effects of CO2,” it’s like if you got shot by a bullet and you said, “Well, it wasn’t really the bullet that was the problem, it was just that I happened to have this hole through my body...”
e360: Right. Well, a lot of people think of geoengineering as a quick and cheap fix for global warming. Is it?
Caldeira: Let’s pretend for a moment that putting dust in the stratosphere is easy to do and works reasonably well... and that China or India then went into a decade or two of deep drought. Whether the system caused that drought or not, I think the Chinese or the Indians would rightly suspect that the reason they have this drought and ensuing famines might be due to this system that was put up by these other countries. And you could easily imagine that there would be a great amount of political tension.... Then, of course, the system is not going to work perfectly... not going to address... ocean acidification... not going to perfectly offset global warming.... [G]eoengineering options [are] something we would only want to consider if our backs were really up against the wall... because the alternatives look so frightening.
e360: I know that some scientists have suggested that there should be some kind of taboo on geoengineering research. But I know that you’ve been outspoken in the need for a federally-funded geoengineering research program. Can you explain that?
Caldeira: Yes, I think we don’t know right now whether these kinds of approaches have the potential to reduce risk or not. In our climate models, the amount of climate change can be reduced by these kinds of approaches, but the climate models are an imperfect reflection of reality.... Let’s say geoengineering doesn’t work, and that it would add to risk. It seems to me it would be worth having a research program to demonstrate that beyond a reasonable doubt so we can all forget about this and move on. On the other hand, if these options do have the potential to reduce risk, then it seems to me that we would like to have the option to reduce that risk should a time come where that would seem necessary. I kind of think of these geoengineering options as seeing, “Well, can we invent some kind of seatbelts for our climate system?” We need to drive the climate system carefully, we need to greatly reduce emissions. But even if we’re driving carefully we still run the risk of getting into an accident. And seatbelts can potentially reduce the damage when we’re in an accident.... I’m much in favor of a very broad-spectrum approach.... [T]hinking of geoengineering as a substitute for emissions reduction is analogous to saying, “Now that I’ve got the seatbelts on, I can’t just take my hands off the wheel and turn around and talk to people in the back seat.” It’s crazy.
e360: Can you sketch briefly what a geoengineering research program might look like?
Caldeira: The first thing I would do is use the plural, and say “programs.” Because many different things are lumped into the same category.... David Keith and Klaus Lackner have been looking at capture of carbon dioxide from the air.... [T]hat’s very different from, say, putting sulfur dust in the stratosphere.... [T]wo new programs — one looking at what are the scalable, fast-acting things we could do in the event of an emergency. What could we do fast that would start the earth cooling within a couple of years if we really wanted to? And then I think we need another research program in saying how can we backpedal out of our high greenhouse gas concentrations....
e360: Do you think it’s inevitable that we’re going to try to engineer the Earth’s climate?
Caldeira: First of all, nobody can really see the future.... I think that there are pathways that we might start regionally and slowly ramp up to something more global. I think that’s a possibility. The other possibility is a real emergency situation where there’s a phase change in public opinion, [where] it becomes conventional wisdom that we can’t tolerate this climate change any more, that we have to do something.... I would wager that we would never deploy any geoengineering system, and that we’re more likely just to try our best to adapt to it. But I think there’s enough of a risk that it’s worth investigating whether there are options to reduce risk and damage....
[W]e’re talking here about people’s lives... I don’t think we’re going to deploy these systems to save polar bears... [but] to help people from dying of famines, or something dramatic like that. And I think that these techniques have a potential to save lives and reduce suffering, and we should explore whether that’s true or not.... [W]e’re obviously interfering with the climate system wholesale now, and it’s possible that more intelligent interference could reduce the damage from the first interference. But it could make it worse. I don’t think we know, which is why we need the research program.