Could Cleaner Air Actually Intensify Global Warming?
A smokestack - Is the solution to global warning more pollution? (Philippe Lopez / AFP/Getty Images)
As much of the world marked Earth Day this past week, the Environmental Protection Agency reported that air pollution has declined dramatically over the past 20 years. It sounds like good news, but science writer Eli Kintisch argues that there's a surprising downside: Cleaner air might actually intensify global warming.
"If we continue to cut back on smoke pouring forth from industrial smokestacks, the increase in global warming could be profound," Kintisch writes in an opinion piece for the Los Angeles Times.
Kintisch isn't talking about greenhouse gases like carbon dioxide; he's talking about another kind of pollutant we put in the sky -- "like aerosols from a spray can," he tells NPR's Guy Raz. "It turns out that those particles have a profound effect on maintaining the planet's temperature."
Greenhouse gases and aerosol pollutants work in opposing ways on the Earth's climate, Kintisch explains. "The greenhouse gases warm the planet when they're emitted, because they absorb heat reflected up from the ground -- the greenhouse effect. These aerosols, though, do the opposite. They block sunlight, they make clouds more reflective -- and by doing that, they actually cool the planet.
"The problem is that we're cutting the cooling pollution as we make our air cleaner," he says.
The Scope Of The Problem: Still A Mystery
Some scientists, he says, are confident that this is connected to global warming, but they don't know how large the effect is. "That's the frightening thing, because if it's a big cooling effect, it means that we've been actually warming the planet more than we know," Kintisch says. "As we take away that unexpectedly helpful cooling mask, we're going to be facing more global warming than we expected.
"If, however, the aerosol cooling is less than we fear, then it won't be such a big deal as we clean our air, though it will still be an effect."
The solution, of course, isn't to stop cutting air pollution. "We have to continue doing that, because these pollutants contribute to asthma, they contribute to respiratory diseases, they cause all sorts of health problems, and they make our environment dirty," he says. "But there's a variety of answers that are more sophisticated than simply continuing to pollute."
Gunk To The Rescue
One of those answers is pretty radical: injecting new pollutants into the stratosphere while we continue to clean up our emissions. It's one of the theories of "geoengineering" that Kintisch explores in his new book, Hack the Planet.
It sounds contradictory, but the idea is actually based on a natural polluter -- volcanoes. Kintisch points out that nearly 20 years before the eruption of Eyjafjallajokull in Iceland shut down air traffic across Europe, a much bigger volcano in the Philippines affected the climate over a much broader area.
"In 1991, when Mount Pinatubo erupted, it put tons of sulfur into the stratosphere," he says. "Those sulfur aerosols cooled the planet."
So if we found ourselves in a climate crisis where oceans were rising rapidly and coastal areas were flooding, some scientists think "we could mimic the cooling effect of natural volcanoes and make man-made volcanoes by putting our own gunk, essentially, up in the upper atmosphere," Kintisch says.
"It's unclear whether we would be able to respond and actually stop a disintegrating ice sheet situation," he cautions. "However, some scientists think we're getting near that worse-case scenario right now."
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GUY RAZ, host:
This past week, as much of the world marked Earth Day, the Environmental Protection Agency quietly released a report showing that over the past 20 years, air pollution has declined dramatically.
The EPA says much of that's because of tougher regulations on industry, and all that's good news, right? Well, not exactly, according to science writer Eli Kintisch. In a recent opinion piece in the Los Angeles Times, he writes: The world is running short on air pollution, and if we continue to cut back on pollutants, the increase in global warming could be profound.
Eli Kintisch is the author of new book on geo-engineering. It's called "Hack the Planet," and he joins me in the studio.
Welcome.
Mr. ELI KINTISCH (Author, "Hack the Planet"): Hey, Guy, how's it going?
RAZ: Okay, so explain how you think that cleaning up our air is going to speed up climate change.
Mr. KINTISCH: We put out two kinds of pollutants into the sky. The first kind are traditional air pollutants, the majority of which are called aerosols like aerosols from a spray can. The other kind are greenhouse gases, which warm the planet.
RAZ: Like CO2.
Mr. KINTISCH: Right, but scientists have recently learned the aerosols have a profound effect on maintaining the planet's temperature. In fact, scientists recently estimated that if we were to institute all the air pollution controls we have on the traditional pollutants, we could accelerate global warming by as much as a degree Fahrenheit.
RAZ: All right, let's be clear for a moment. We're not talking about carbon emissions, right? Virtually, all scientists agree that these emissions contribute to the warming of the Earth. So that's not what we're talking about.
Mr. KINTISCH: Right, the greenhouse gases have the opposite effect. The greenhouse gases warm the planet when they're emitted because they absorb heat reflected up from the ground, the greenhouse effect. These aerosols, though, do the opposite. They block sunlight, or they make clouds more reflective, and by doing that, they actually cool the planet. And the problem is that we're cutting the cooling pollution as we make our air cleaner.
RAZ: But I mean, is it really a problem because it's still pollution, right? I mean, we don't want our children and ourselves inhaling even these so-called good pollutants, right?
Mr. KINTISCH: Absolutely. The solution to this problem is not to stop cutting our traditional pollutants. We have to continue doing that, because these pollutants contribute to asthma, they contribute to respiratory diseases, they cause all sorts of health problems, and they make our environment dirty. But there's a variety of answers that are more sophisticated than simply continuing to pollute.
RAZ: So I mean, is there an iron-clad link between an increase in global warming and a decrease in sulfates, or is it coincidental?
Mr. KINTISCH: I think scientists know that there's a direct connection. What scientists don't know is how large it is, and that's the frightening thing because if it's a big cooling effect, it means that we've been actually warming the planet more than we know and that as we take away that unexpectedly helpful cooling mask, we're going to be facing more global warming than we expected.
If, however, the aerosol cooling is less than we fear, then it won't be such a big deal as we clean our air, although it still will be an effect. There's also the radical idea, as we clean our air, of putting new pollution up into the stratosphere.
RAZ: This is what's called geo-engineering. That's the topic of your book, "Hack the Planet." How would that work? You would literally take these sulfates and inject them into clouds?
Mr. KINTISCH: There's a natural air pollutant, and we're seeing it in Iceland right now, and that's volcanoes, and in 1991, when Mount Pinatubo erupted, it put tons of sulfur into the stratosphere this is the high atmosphere above the weather and those sulfur aerosols cooled the planet. And so what scientists have thought about is if we decide that we're in an emergency in the future, we could mimic the cooling effect of natural volcanoes and make man-made volcanoes by putting our own gunk, essentially, up in the upper atmosphere.
RAZ: So if climate change was happening so rapidly that the oceans were rising, and coastal areas were flooding, and you had this very dramatic crisis that was happening, unfolding before our eyes, scientists believe that there could be a possibility, in the future, where they could literally go up into the sky and put these chemicals into the stratosphere?
Mr. KINTISCH: It's unclear whether we would be able to respond and actually stop a kind of disintegrating ice sheet situation. However, some scientists think we're getting near that worst-case scenario right now and that maybe as we cut our greenhouse gas emissions, we also should think about making the planet more reflective by doing geo-engineering. It's a radical idea.
RAZ: Absolutely fascinating. That's Eli Kintisch. He is the author of the new book about geo-engineering. It's called "Hack the Planet."
Eli Kintisch, thanks for coming in.
Mr. KINTISCH: Thanks a lot, Guy. Transcript provided by NPR, Copyright National Public Radio.
