Engineering Earth's Climate Could Be Dangerous Presidential science adviser John Holdren said this year he wouldn't rule out engineering the Earth's climate as an option to slow global warming. Rob Jackson, director of Duke University's Center on Global Change, discusses the dangers of modifying Earth's climate.
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Engineering Earth's Climate Could Be Dangerous

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Engineering Earth's Climate Could Be Dangerous

Engineering Earth's Climate Could Be Dangerous

Engineering Earth's Climate Could Be Dangerous

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  • <iframe src="" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

Presidential science adviser John Holdren said this year he wouldn't rule out engineering the Earth's climate as an option to slow global warming. Rob Jackson, director of Duke University's Center on Global Change, discusses the dangers of modifying Earth's climate.


You're listening to SCIENCE FRIDAY from NPR News, I'm Ira Flatow.

FLATOW: We have global temperatures rising, oceans growing more acidic, ice sheets melting. The question is: what can we do about it? And while some scientists have suggested that renewable energy is a step in the right direction for cutting down carbon emissions, they believe that clean energy alone may be too little, too late to prevent some climate catastrophes, and they say we might have to do something more radical, like reengineering the planet to help cool the planet down. Other scientists warn of unintended consequences, the risk of messing up the planet even more if we do that.

At the Ecological Society of America's annual meeting in Albuquerque this week, scientists talked about the pros and cons of engineering the Earth's climate. And my next guest organized that session.

Rob Jackson is a professor of environmental sciences and biology at Duke University in Durham, North Carolina. He's also director of Duke's Center on Global Change. He joins us from KUNM in Albuquerque.

Welcome to SCIENCE FRIDAY, Dr. Jackson.

Dr. ROB JACKSON (Duke University): Hello, Ira.

FLATOW: Hey there. What do we mean by engineering the climate?

Dr. JACKSON: Well, geoengineering is intentionally modifying the Earth's climate at large scales. You can think of it as sort of two approaches or two flavors. You might try and block sunlight to cool the Earth, or you might remove carbon dioxide or other greenhouse gases from the atmosphere. But the key thing is intentionally modifying, and again, at very large scales. We're really talking about reengineering the planet's climate.

FLATOW: Mm-hmm. And what are some of the ways that you might do that?

Dr. JACKSON: Well, take blocking sunlight. A couple of the approaches that have been made include space mirrors or reflective objects in the atmosphere that block the sunlight…

FLATOW: Such as - such as?

Dr. JACKSON: Such as literally, screens - you know, thousands of miles wide suspended in space. Pretty far out things literally and figuratively.

FLATOW: Mm-hmm.

Dr. JACKSON: But there is a nearer approach to block sunlight that is much more feasible potentially, and that's injecting dust into the stratosphere, and we know this cools the Earth because of volcanic eruptions. The best example of that is the Pinatubo eruption that happened about 20 years ago now. It blasted millions of tons of sulfur dioxide into the stratosphere, the upper atmosphere. And the Earth cooled by about a degree for over a year.

FLATOW: Mm-hmm. There was that famous one - a hundred years or so ago -the year without a summer?

Dr. JACKSON: That's right, Krakatoa.

FLATOW: Krakatoa. And so that's - those are different ways we make an artificial volcano, so to speak.

Dr. JACKSON: That's absolutely right. You can think of, you know, blasting them into the atmosphere with canons and many other approaches. But the key is, is getting them high into the atmosphere so that they'll stay up there for, you know, at least a year or more (unintelligible).

FLATOW: What about stuff on the Earth? We've heard strategies such as fertilizing, putting fertilizer in the ocean so that the algae will grow, and suck up (unintelligible) that way.

Dr. JACKSON: Right. The other flavor is to suck the greenhouse gases back out of the atmosphere once they've been put there, and ocean fertilization is an example of that. There are other approaches too, manipulating albedo, how reflective surfaces are, everything from small scale, painting the roofs of houses white like Secretary Chu proposed recently. That's not truly geoengineering unless you're thinking about this at a very large regional scale.

You know, the ocean citification is probably the most practical and it's I think unlike - the stratospheric dusting is not one that's probably likely to work, for a couple of reasons.

I mean, it's cheap. It's relatively feasible. And iron limits the growth of phytoplankton in many locations around the world, particularly down near Antarctica.

So for about 20 years now, people have been conducting experiments that release iron from ships into the ocean water down there. And look at how much of a bloom or a burst in growth you get from the phytoplankton. And you do in fact, in almost all cases, get a bloom in phytoplankton. But what you don't get is the biomass to sink down to the deep ocean. And that's where it needs to go to be locked away from the atmosphere.

So that's just one example of something that's relatively cost-effective. But right now at least the research suggests that it doesn't work very well.

FLATOW: Do we have research that suggests any of these things would be practical?

Dr. JACKSON: Well, again, I mentioned the - I think the one that would work almost certainly is the stratospheric dust-seeding, again, because of the…

FLATOW: (Unintelligible)

Dr. JACKSON: …because of the - that's right. There are many, many volcanic experiments that have done this, so that's probably…

FLATOW: But when you put dust up there, don't you get more rain? I mean, isn't dust like a nucleus for rain to start raining?

Dr. JACKSON: Yeah. It's a really - yeah. A really good question. So let's talk about that a little bit.


Dr. JACKSON: Let's go back to the blocking sunlight options. Imagine you had a magic dial in your hand and you can tune this dial up and down.

FLATOW: Right.

Dr. JACKSON: And right now we want to tune the sunlight dial down to reduce the Earth's temperatures. And you don't need to tune that dial down very much to offset the greenhouse gas effects of warming. So for instance, you know, you dial sunlight down a couple of percents and you can offset the warming - from the doubling of atmospheric carbon dioxide.

Now that'd be really helpful, tremendously helpful in reducing the effects of climate change. But it wouldn't fix all of our problems. For instance, when you dial down that sunlight, you don't just change temperature you also change the water cycle. And you can't tune temperature and rainfall equally.

FLATOW: Mm-hmm.

Dr. JACKSON: So for instance, rainfall is more sensitive to sunlight than temperature is. So when you dial down sunlight, you dial down rainfall even more. So this approach would almost certainly result in a decrease in rainfall in a number of places around the world.

FLATOW: Mm-hmm.

Dr. JACKSON: Now also, depending on what you put up into the atmosphere, the initial proposals have been sulfide aerosols, for instance. Now, sulfide chemistry potentially reacts with the ozone in the atmosphere. And one of our speakers yesterday, Simone Tilmes from NCAR, the national climate group in Colorado, she does studies and modeling works, suggesting that blasting sulfur into the stratosphere would prolong the ozone hole 50 or 100 years, for instance. And if we do this long-term, it could have a dramatic effect, even a bigger effect on ozone hole over the - on ozone depletion over the Arctic.

So one of the things to keep in mind is that it's very difficult to tune here, for one thing, and not change a bunch of other things.


Dr. JACKSON: And finally, I guess another thing just to think about is when we talk about tuning temperature, we're not addressing key issues like ocean acidification, where we're acidifying the ocean with carbon dioxide, endangering the skeletons and growth of marine organisms and coral reefs.

FLATOW: I guess the best solution to all of this would be defined someway of just sucking the CO2 out, wouldn't it, and putting it some place?

Dr. JACKSON: Well, that's exactly right.

FLATOW: Is that possible to do that, geoengineer something like that?

Dr. JACKSON: It is entirely possible. Like everything, it comes down primarily to energy and money.

FLATOW: Mm-hmm.

Dr. JACKSON: Right now, it's not cost effective for us to do that. And we'd have to have somewhere to put that carbon dioxide, or there have been proposals to combine energy with that carbon dioxide that's removed from the atmosphere and to make, you know, to make fuel out of it, essentially a renewable fossil fuel or a renewable carbon fuel.

You know, it's all about the money and the approaches and energy balance on what it would cost to do that. And it would also require a relatively carbon-free source of energy, whether that's wind, solar, something else, in an extremely large scale. So right now, it's not feasible. But of all the things that we could do, this would be the best - would be to remove those gases from the atmosphere, to go carbon neutral, if you will.

FLATOW: Mm-hmm. Yeah. Because carbon capture and sequestration is just -take a lot of work, a lot of money, a lot of work. And we need to find a place. Well, you know, people have talked about putting it deep down under the oceans where the carbon would turn back into its solid form, so it would stay down there forever. Is that possible?

Dr. JACKSON: It is at least feasible. There are many, many places around the world to store carbon, potentially. Deep in the oceans is one. You know, sediments in underground, one of the areas that we've worked on a lot in our group at Duke is carbon storage and geologic formations.

Now, strictly speaking, that's not really geoengineering unless it coupled to something that scrubs carbon dioxide from the atmosphere. But in principle, those kinds of approaches could work. You know, natural gas, for instance, you know, stays under the ground for millions of years. So there's pretty good evidence that those approaches could work. Again, though, the key is assessing the risks, but fundamentally the economics of it.

Right now, it's too expensive to do it unless we have a carbon tax or a cap and trade system or something else.

FLATOW: I see you're saying that no matter what we do, unless we do that also, it's not going to work.

Dr. JACKSON: Well, we could mandate it from the - a governmental standpoint. We could require certain approaches. That's not really the free market approach that most people, myself included, think is the most efficient way to do it. We need some sort of cap and trade system, trading system for carbon dioxide as has been passed recently by the House, the Waxman-Markey bill.

Alternatively, we could have a carbon tax that's not likely, in this country, anytime soon. But, yes, without some kind of price on carbon dioxide, there's no economic incentive for companies to act on this.

FLATOW: Mm-hmm.

Dr. JACKSON: Right now, that pollution is free.

FLATOW: Mm-hmm. Is there going to be, though, a tipping point that will be obvious to everyone that, you know, we - the consequences are getting serious enough to warrant, sort of, an intervention somehow.

Dr. JACKSON: Well this is really the - I think the crux of the issue why geongineering is so complicated. If you see geoengineering as something that hinders us from acting on climate change substantively - and by acting, I mean renewables and energy efficiency, the kinds of things that you mentioned at the beginning of the story. If you see through the lens of anything that slows down action, then geoengineering is perceived negatively.

And also, there are risks of geoengineering. We don't understand the climate system perfectly. On the other hand, you could also look at this and say regardless of where we end up in terms of greenhouse gas concentrations - 500 parts per million, six, seven, 800 parts per million are possible this century - shouldn't we at least be thinking about reducing some of the effects of those greenhouse gases, of cooling the Earth, even if it's an imperfect fix, or not a complete fix? I mean, those two arguments are both pretty strong.

FLATOW: Mm-hmm.

Let's get a phone call or two in here. Let's go to Saul(ph) in Aurora, Colorado. Hi, Saul.

SAUL (Caller): Hi, Ira. I thank you very much for playing a role in taking geoengineering, stop treating it like the crazy aunt in the attic about it and we don't talk. That's been an issue that we've faced for a long time. Now, Rob Jackson's talk has been much more pleasant than the write-up that I saw. But are you aware, Rob, of the fact that the National Academy of Sciences has a program, America's Climate Choices, which has included a workshop on geoengineering, which I attended, and which is calling for - probably, I'm guessing - will call for significant funding. Whereas just - don't you think we should be studying a lot more instead of treating it, you know, not talking about it?

Dr. JACKSON: Yeah. So as the caller noted, there's a national academy process going on now about climate change here. There was a recent royal academy report from the UK. The American Meteorological Society recently proposed or advocated doing some basic research on geoengineering.

You know - so the short answer to that question is, yes, I support limited research on geoengineering. Let me talk about, you know, what frightens me about it. And then let me talk about why, I think, some limited research is probably warranted anyway.

I mean, first of all, planetary engineering frightens me, point blank, because once we start down that road, I'm afraid we won't come back. It frightens me because I don't want the false perception of a quick fix to keeping us from cutting greenhouse gas emissions. And maybe most fundamentally, it frightens me because of what we don't know. What if something goes terribly wrong? This is the only planet that we have.

I mean, on the other hand though, we're already changing the Earth's climate unintentionally. And these changes are going to last 50 or 100 generations of people, the effects of those changes - not years but generations. So it's our responsibility to do everything we can to reduce the effects of climate change for those people and for other species on Earth.

FLATOW: Mm-hmm.

Dr. JACKSON: So if careful geoengineering can help us do that in the short term, then it's at least worth doing some small scale research on.

FLATOW: Mm-hmm. You're listening to SCIENCE FRIDAY on NPR News.

I'm Ira Flatow, talking with Rob Jackson.

You're going to need some public consensus to do any of these things, it seems, right? Do you think there is enough of the public convinced that global warming is human-caused? We keep hearing the, you know, people saying - even on this program, some of the listeners call in and say, oh, come on, you know - where's the proof? We've had callers say that the world is cooling off, not warming up.

Dr. JACKSON: Yeah. They're - you know, I can't emphasize too much how strong a scientific consensus is on this issue. Yes, there are still scientists who aren't convinced that global warming or climate change is entirely human-caused. But, boy, the community really has moved beyond that. The evidence is so strong and the consensus is so strong that, you know, the world is changing around us. I mean, for heaven's sakes, we're melting the North Pole. And so, yes, I think the consensus is strong and we need to act on it.

The barriers to it, that you brought up, now that's a really interesting issue. Of course, there are scientific uncertainties, but we also need to think about social research and other things. So let's talk a little bit about some of those issues.

So how about governance? Who controls the climate? I mean, who's tuning that climate dial, for instance, if we're blocking sunlight? What if one country decides to act unilaterally? Do you stop them? You know, what mechanisms are in place?

Then there are legal issues. I mean, first of all, is it legal and under what circumstances is it legal? There are all kinds of national, international agreements that regulate different aspects of this and, you know, and are conflicting to be perfectly honest.

FLATOW: Mm-hmm.

Dr. JACKSON: There are public acceptance issues, so will the public even allow research, let alone the perceived hubris of engineering the planet (unintelligible).

FLATOW: I remember I follow - I once, 25 years ago, followed cloud seeding in Florida, an experiment, and they had to stop it right, you know, in the middle of the experiment. I was watching the plane seed clouds and they said, well, suddenly, the political pressure is too much. We don't know if we're going to make it worse, you know?

Dr. JACKSON: Yeah. I mean, that's an interesting example because, you know, another barrier is a geopolitical barrier. The militaries around the world, for decades, have talked about owning the weather. And, you know, weather is not climate, weather is short-term, you know, short-term rainfall and temperature and things like that. But weather at a large scale, and over long time scales is, in fact, climate.

And this is not pie in the sky, in the Vietnam War in the 1960s, the U.S. military actually had a project called Project Popeye. And this project seeded the clouds over Ho Chi Minh trail to try and block supply lines that came from north to south to bring supplies to the North Vietnamese. And it appeared to work - somewhat. I think the evidence for cloud seeding and rainfall is you might be able to get five or 10 percent more rainfall under some conditions, especially cold conditions. But this is real. I mean, this is what we actually did.

So another issue is will people see geoengineering just through the lens of science and climate change? I don't think so. And will it be perceived as a geopolitical issue as well? I think it might.

FLATOW: Mm hmm. All right. Thank you very much for taking time to be with us today, Rob.

Dr. JACKSON: Thank you.

FLATOW: Thanks. Rob Jackson is professor of environmental sciences and biology at Duke University in Durham, North Carolina.

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