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Narrator: This is The Takeaway with MHP, from WNYC and PRX in collaboration with GBH News in Boston.

Melissa Harris-Perry: The UN's intergovernmental panel on climate change says that the Earth's temperature will rise by 2.7 degrees Fahrenheit by 2040 if we don't curb our greenhouse gas emissions. In July, UN Secretary-General António Guterres warned.

António Guterres: Greenhouse gas concentration, sea level rise, and ocean heat have broken new record. Half of humanity is in the danger zone from floods, droughts, extreme storms, and wildfires. No nation is immune. Yet we continue to feed our fossil fuel addiction.

Melissa Harris-Perry: Now, curbing our planet's fossil fuel addiction is sure to be a massive multi-decade effort, requiring unprecedented level of global cooperation, or we could just block out the sun.

Andre Layton: First, the weather changed, war made the Earth even hotter, her ice melted, and all the species crashed.

Melissa Harris-Perry: In the 2013 movie, Snowpiercer and the TV series of the same name, that's exactly what we humans did. In the story, the Earth heated up in the 20 teens, and authorities sprayed chemicals into the stratosphere to deflect some of the sun's heat.

Andre Layton: The men of science tried to cool the Earth to reverse the damage they had sown, but instead they froze her to the core.

Melissa Harris-Perry: It triggered a new ice age, and a few survivors took refuge on a high-speed train hurdling across the global Antarctica on a constant loop. Scientists have debated this idea of essentially dimming the sun for decades, but research into making it a reality has recently won some powerful financial backers, including Bill Gates and a range of venture capitalists and philanthropists. It's an example of what's called geoengineering.

Dr. Alan Robock: Geoengineering is a proposed scheme to have humanity actually control the world's climate. It comes in two flavors. One is to take the carbon dioxide out of the atmosphere, which is causing the warming and the other is to reflect some sunlight to cool the Earth.

Melissa Harris-Perry: That's Dr. Alan Robock.

Dr. Alan Robock: I'm a distinguished professor of climate science in the Department of Environmental Sciences at Rutgers University.

Melissa Harris-Perry: Is this just holding up like a big piece of aluminum foil up to the sun and pushing it back the other way?

Dr. Alan Robock: That's one of the proposed schemes. It's to put a reflector in outer space between the Earth and the sun. You could put a lot of little satellites or shiny frisbees up there, or you could make a big one farther from the Earth between the Earth and the sun. Most people think that idea is too expensive, too technologically questionable and nobody's proposing that. The proposal that most people are studying is to inject sulfuric acid into the stratosphere, which would then form tiny little droplets, a thin cloud, which would reflect sunlight, just like volcanic eruptions do occasionally.

Melissa Harris-Perry: Just hearing you make that sentence. [chuckles] This injection that creates a cloud a bit like a volcanic eruption, at my gut that feels like a bad idea.

Dr. Alan Robock: Well, me too, the first meeting I went to I had all these engineers and physicists talking about how cool it would be, and I started writing down reasons why it might be a bad idea, and I got up to 20 reasons. I published that 20 reasons why geoengineering might be a bad idea. I thought about it more since then, and now I'm up to 28 reasons, but I also have a few reasons why it could be beneficial. If you could do it, the number one reason is it could reduce global warming and reduce the impacts of global warming.

Melissa Harris-Perry: 28 why stratospheric geoengineering might be a bad idea. Maybe walk me through some of those 20, at least.

Dr. Alan Robock: [chuckles] I'll first talk about effects on the climate system. If you reflect sunlight, you cool land more than you do the ocean. It's the land-ocean contrast in the summer that drives the summer monsoon, and that rainfall in Asia and Africa is important for agriculture. The monsoons would be weaker and you get less rain there in the summer.

Melissa Harris-Perry: Monsoon sounds like a something one would want less of, but in fact, they're actually quite important, right?

Dr. Alan Robock: Yes. Monsoon just means seasonal rainfall. Here, where we live, I'm in New Jersey or on the east coast, we get about the same amount of rain all year long, but there it's dry in the winter. It's the winter monsoon, it's wet in the summer, the summer monsoon. They depend on that rainfall for agriculture in China and India and the [unintelligible 00:04:52] and Western Africa.

Melissa Harris-Perry: What would happen if, in fact, less rain fell?

Dr. Alan Robock: That's not the only thing that would happen, perhaps temperatures would be lower. There would be more carbon dioxide. We're using crop models to calculate what the response would be. Right now in India, for example, they're taking a lot of groundwater out for irrigation, which isn't going to last more than a couple more decades, but right now changes of rainfall might not be as important as it would be in a couple of decades when they actually are proposing to do this geoengineering.

Melissa Harris-Perry: Okay. Give me some of your other 28 reasons.

Dr. Alan Robock: Well, the particles in the stratosphere would deplete ozone, and that would be more ultraviolet radiation would reach the surface. That would be bad for humans, for natural ecosystems, and probably bad for agriculture. You can't do it today if you wanted to. The technology actually doesn't exist. People have designed on paper, airplanes that could fly that high and spray sulfuric acid or sulfur Dax, I guess, but they don't exist now. It might take a decade or more to develop them, and it's a question how well they might work, but let's assume you could do it, and you're doing it for a while and reducing global warming.

Meanwhile, we continue to put in the gases in the atmosphere that are causing the warming. It's like pulling back on a spring. If at some point you stop, there'd be rapid warming at a rate much faster than there would be if we didn't do anything. This is called the termination effect.

Melissa Harris-Perry: Maybe just one more before I become too terrified to go on. [chuckles]

Dr. Alan Robock: The question is how could the world agree on what temperature we want the planet to be? How to set the thermostat? What if Canada and Russia wanted a bit warmer? They don't mind it there, they can exploit the Arctic. They spend less on heating, whereas islands that are drowning now in the Pacific want it cooler, and so how could we even agree on this? You could say, "Well, okay, we know it's going to help most people, but some people aren't going to be as well off, and so we'll compensate them." There's not a good record of doing that in the past when you build a dam or do urban renewal.

Also, we couldn't tell which specific impacts were directly caused. There might be drought somewhere or flood somewhere. Geoengineers are doing it. You can say, "Well, that just might have happened by chance." "Yes, but I still want you to compensate me for it." Who's going to do that?

Melissa Harris-Perry: How would we decide and who would get to decide what temperature we're going to set the Earth to?

Dr. Alan Robock: It's a question of global governance. Global governance isn't working too well right now in mitigation, reducing the emission of greenhouse gases. There are huge economic interests at hand. To develop a global governance structure that would allow everybody to agree on this, hasn't been done, but people are working on how to do it.

Melissa Harris-Perry: That said, frequently in science and technology, when we are talking about advances, what is possible that aren't yet here, we will hear these doomsday scenarios. Thinking of everything from embryonic stem cell research to the notion of human cloning, and how it's all going to be, so troubling, and yet science and technology do in fact tend to march on. Is this being alarmist or are there important considerations to take into account, but we really should move forward towards this?

Dr. Alan Robock: No, let's take a step back. Global warming is real. It's being caused by humans. It's bad for most people. We're sure of that, and we know the solution. We don't even want to be working on this. The solution is to leave the fossil fuels, oil, coal, natural gas in the ground. Don't burn it and don't emit carbon dioxide. That's a solution. We could rapidly transition to an energy system based on the sun and the wind. We already have the technology to do that, but economic interests are preventing that, that's the problem. It's really a political problem. It's not a technical problem.

Melissa Harris-Perry: Talk a bit about why there might be more political will to do an interventionist geoengineering than to stop doing something like burning fossil fuels.

Dr. Alan Robock: I read recently that the fossil fuel industry makes about $2.8 billion a day and they have for the last 50 years around the world. That's a trillion dollars a year and that's enough money to pay every politician in the world to let them keep doing it. That's the problem. The question is who makes decisions? In some countries that don't have a lot of fossil fuels, they have a carbon tax. If you go to Europe and try to buy gasoline, it costs about three times what it costs the United States, that's the carbon tax, and they don't have huge SUVs, and they don't drive as much. They have small cars when they do drive.

In the US, per person, we emit a lot, and then China is burning coal which is much less efficient at generating energy and producing lots of CO2. What really we need to do is let China, India, and other developing countries raise their lifestyle to what we have without putting CO2 in. Can we provide the technology to them to do that? The price of solar panels is going down. The price of wind power is going down. Whether we can actually implement a carbon tax or a carbon fee and dividend as the government collects the money and gives it back to the people is a political decision, and we'll see how fast it goes.

Now, as the impacts of climate change become more and more visible, people are a lot more aware. It's really hot now. It's hotter than it would've been if we hadn't been putting these greenhouse gases in the atmosphere. There are forest fires, stronger storms, and as people see that and feel the impact, terrible flooding we had in [music] Kentucky just recently, people are worried about it. What can we do?

Melissa Harris-Perry: All right. Let's take a pause here. More on The Takeaway in just a moment.

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Melissa Harris-Perry: We've been hearing from Professor Alan Robock about solar geoengineering and some of his 28 reasons why he says it's a bad idea. He says it's still important to research all the possibilities.

Dr. Alan Robock: I think we should see if we can actually fly a plane up there and create a cloud that we would like, see whether it's possible, how easy it is. In the meantime, we have to work as hard as we can on mitigation because if we're not doing mitigation, if we're not actually trying to reduce the emissions, geoengineering will not be an answer. You have to do a huge amount of it, and there could be a lot of bad consequences. If we want to keep global warming to 2 degrees Celsius above pre-industrial temperatures, that's 3 1/2 degrees Fahrenheit. We can't do that just with mitigation because we're slowly reducing the emissions.

Maybe we want to shave off a little bit of the warming, keep it at 2 degrees rather than 3 degrees with geoengineering temporarily for a few decades. That's the scenario that people are looking at. Maybe we want to implement it like that, but the question is, would that be more dangerous to do that or dangerous not to do that? It's a risk-risk comparison, and we're doing climate modeling calculations to see what the potential impacts would be, so we can make an informed decision in the future.

Melissa Harris-Perry: If the plane that could fly up there, to make it the most simple, were in fact developed if the technology were possible. If we tried this, are we talking about in a best-case scenario, a total reversal of the warming of the Earth that we've caused? Are we talking about some degrees? I'm just wondering, in order to do a cost-benefit analysis, to understand what the potential benefit is.

Dr. Alan Robock: It depends how thick a cloud you create. How many fleets of airplanes you have doing it? It depends what temperature you want the planet to be. We know after a big volcanic eruption like the Pinatubo eruption in 1991, there was very quick cooling of Earth. The cloud formed in a couple of months and it reflected sunlight, and it was colder the next year. Big volcanic eruptions like Tambora in 1815 produced a year without a summer where it was a degree cooler for a year. We know that it could work. The question is, how much do we want to do? How much can we afford?

On my list of benefits, the sun wouldn't be quite as bright. It would be a thin haze and plants like that, but a beautiful red and yellow sunsets. On my list of risks or concerns is unexpected consequences. On my list of benefits is unexpected benefits. [chuckles] People say, "What do you work on geoengineering? What's that?" "We're going to fly an airplane over your daughter's school, and we're going to spray sulfuric acid in the air, and that's going to solve the global warming problem." They say, "What? You want to do something that crazy?" Well, maybe I should work much harder on mitigation, much harder on not producing CO2, so it might have this effect of scaring people into not doing it.

Melissa Harris-Perry: Is there a more moderate way though? Because I suppose what I'd say is, on the one hand, no, of course, I wouldn't trust that. Then, I do trust the only life that I personally, as far as I can tell, get to live to all kinds of technology every day in terms of how our world operates.

Dr. Alan Robock: Well, depends on the scale. When you drive your car, you wear a seat belt. God forbid you have an accident, it will help you, it'll save you, but it won't destroy the whole world. This is technology for the whole world. It's not just for much smaller skill activities. We have to reduce our emissions of carbon dioxide and other greenhouse gases as quickly as we can. We have to do that no matter what. There is technology to take the carbon dioxide out of the atmosphere, carbon dioxide removal, but it's very expensive and people are working to see if they can do it at scale more effectively.

Then the question is where do you put the carbon dioxide? We think there might be enough space underground to pump it, or you could make plastics out of it or something. People are working on that too and both of those things would reduce the warming. We have to do that as quickly as we can. I've got solar panels on my house. I've got an electric car, but it costs a lot of money. The law was just passed, the government will subsidize purchases of electric cars. There are things we can do to incentivize people to emit less so that we have to do that no matter what.

Melissa Harris-Perry: Dr. Alan Robock is distinguished professor of climate science in the Department of Environmental Sciences at Rutgers University. Thanks so much for taking the time with us.

Dr. Alan Robock: My pleasure. Thank you for having me.

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