Name: What is Solar Geoengineering and Why is it Controversial?
Uploaded: undefined
Duration: undefined

NOVA

Scientists propose putting reflective aerosols into the stratosphere to reflect the sun's rays. But will this have unintended consequences?

Solar geoengineering is like drawing a curtain over the face of the Earth.

What is Solar Geoengineering and Why is it Controversial?

Carlisle Companies

Viking

NOVA Science Trust Logo

Scientists propose putting reflective aerosols into the stratosphere to reflect the sun's rays. But will this have unintended consequences?

Solar geoengineering is like drawing a curtain over the face of the Earth.

Planet Earth

What is Solar Geoengineering and Why is it Controversial?Published: November 20, 2020Frank Keutsch: Putting particles in the stratosphere could reflect back some sunlight to space, reducing the amount of sunlight that hits the surface and cooling down the planet..Narrator: The effect would be immediate.Steve Pacala: We know this works because every time a big volcano goes off and it injects aerosols into the stratosphere, the planet cools down.Sheila Jasanoff: That's the idea behind solar geoengineering. It's like drawing a curtain over the face of the earth. Frank Keutsch: The first time you hear about this and you think, “Well, that sounds like a really bad idea. How could that not go wrong?” But what we're doing to climate as humans, that really, to me, starts seeming also quite scary and crazy and really worrying.David Keith: The fact is the CO2 is in the atmosphere. Without a time machine, we can't make it go away. We want to, in the long run, do carbon removal. But during the time that concentrations are high, we might want to do solar geoengineering to reduce the climate risk.David Keith: All that is hard mounted to us.Frank Keutsch: That is exactly what I was thinking.David Keith: And then there is the balloon up there.Narrator: Frank and David's team is designing a first-of-its-kind experiment called SCOPEX to investigate the impacts of solar geoengineering.John Dykema: The only place I see that conversation getting sticky is where we do risk assessment on it.Frank Keutsch: If you put these particles out, what happens when these come back down? What happens when it gets into the environment? Are we endangering people?David Keith: There are lots of things that we might need to know where the existing experimental background is bad. You actually have to go out and make measurements.Narrator: The plan is to launch a 100 foot balloon into the stratosphere and release a plume of reflective aerosols.Frank Keutsch: We want to put out the particles of calcium carbonate, for example, and then go back through this plume and see whether the evolution of the air is the way we predicted based on our laboratory results. Frank Keutsch: This is an experiment on a very small scale. And in fact, the amount of material we’re putting out is less than a normal airplane flight puts out. Narrator: SCOPEX may be small, but many fear a large-scale manipulation of Earth’s atmosphere could trigger a cascade of dangerous, unintended consequences that ripple across the planet. Sheila Jasanoff: Nothing in our scientific capability actually enables us to understand the complexity of the interactions that would be set loose.Jane Long: It’s not just that it lowers the temperature, but what are some of the other effects on the hydrologic cycle, or on heat waves and droughts?Sheila Jasanoff: This is a manipulation of the Earth’s atmosphere on a huge scale. What happens if things go wrong?Narrator: SCOPEX is designed to start answering those questions. But there may be effects, beyond the physical, that no experiment can predict.Sheila Jasanoff: If we think that there's this solution out there then people may think it doesn't matter if you're polluting the planet. David Keith: The root of the concern is that solar geoengineering research, however well-intentioned, will be used as an excuse for big fossil fuels to fight emissions cuts. Scott Denning: It's just like a sci-fi dystopian novel or something where we continue to just belch all this CO2 into the atmosphere, but, “Hey, it's OK because we've got these little umbrellas that are, you know, hiding us from the sun.”David Keith: Solar geoengineering does not get us out of the ethical and physical requirement to cut emissions.

United States

Northern Mariana Islands

Puerto Rico

American Samoa

Guam

U.S. Virgin Islands

U.S. Minor Outlying Islands

US & Territories

Colossal explosions shake a remote corner of the Siberian tundra, leaving behind massive craters. In Alaska, a huge lake erupts with bubbles of inflammable gas. Scientists are discovering that these mystifying phenomena add up to a ticking time bomb, as long-frozen permafrost melts and releases vast amounts of methane, a potent greenhouse gas. What are the implications of these dramatic developments in the Arctic? Scientists and local communities alike are struggling to grasp the scale of the methane threat and what it means for our climate future. (Premiered February 2, 2022)

In the Arctic, enormous releases of methane, a potent greenhouse gas, threaten the climate.

Arctic Sinkholes

The top half of Jupiter in blue and green against a night sky

A composite image of Jupiter using images captured by the James Webb Space Telescope. Image Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Judy Schmidt.

Explore the cosmos, delve into ancient history, and follow an extreme rescue with NOVA’s most-watched documentaries released in 2022.

NOVA’s most popular science documentaries of 2022

Four bright orange loops brand off of a dark blue blob

A transmission electron micrograph of HIV-1 virus particles (orange) replicating from the plasma membrane of an infected H9 T cell. Credit: NIAID, Flickr

Scientists have cured a handful of people of HIV by piggybacking on treatments they received for blood cancer. But does that bring a widespread cure any closer?

What is Solar Geoengineering and Why is it Controversial?

Support Provided By

Explore More

Can We Cool the Planet?

Can Geoengineering “Undo” Climate Change?

How Much Coal Do People Burn Each Year?

Transcript

Credits

Support Provided By

Explore More

Can We Cool the Planet?

Can Geoengineering “Undo” Climate Change?

How Much Coal Do People Burn Each Year?