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Should We Change the Climate … On Purpose?

A climate change solution that involves … blocking out the Sun?

March 2024


Click to reveal bonus content (fun facts and additional insights) within script.


What would you be willing to do in order to protect the planet?

As fears about climate change have grown, we’ve heard a wide variety of by-now-familiar proposals:

Maybe we should shift over to renewable energy sources.

Maybe we should tax carbon.

Maybe we should stop eating meat.

Maybe we should use balloons to fill the stratosphere with chemicals to block out the sun.

Maybe we should … wait, what was that last one?


In recent decades, the world has been on a crusade to reduce carbon emissions.

And here’s the most important thing to know about that crusade: It hasn’t worked.

Despite the international treaties, the annual conferences, and the trillions of dollars invested in clean energy … global CO2 emissions have continued a largely uninterrupted rise. In 2021, humans put over 37 billion metric tons of CO2 into the atmosphere, 65 percent more than we did 30 years earlier.i

And look, by now, we all pretty much know the reactions this will generate.

Some people will say this just shows we have to redouble our efforts on things like renewable energy.

Some people will say “Who cares? Climate change isn’t a real problem anyway.”

Some people will say that we need to start focusing more on adapting to a changing climate.

But also — and this one you probably haven’t heard before — some people will say “forget about changing the environment by accident, let’s start changing it on purpose.” And, despite how that may sound, some of these people are serious enough that it’s probably worth understanding exactly what they’re talking about.

This, for instance, is Paul Crutzen — with his fellow Nobel Prize winners.

Crutzen — who won the Nobel in Chemistry for his work on the Ozone Layer — was one of the people most responsible for mainstreaming a concept known as geoengineering — the idea that humans can intentionally change the weather in order to mitigate the worst potential effects of climate change.

Now, if you think this sounds crazy … you should know that Professor Crutzen, who died in 2021, kind of agreed. Even he didn’t think it was an ideal solution. And he acknowledged that there could be plenty of potential risks.ii His argument, though, was that — since nothing else is making a difference — there might not be any better alternative.

In practice, there are two primary forms of geoengineering.

The first method is called “carbon capture”: literally pulling some of the extra carbon dioxide back out of the atmosphere.

There are lots of ways this might work, from direct air capture machines that filter the air,iii to genetically modifying plants to suck up more carbon.iv

Perhaps the most movie villain version is that if you fertilize the ocean with enough iron, you can spur algae blooms so massive that they’ll suck enough carbon out of the atmosphere to cool the planet.v

Now, we know what you’re saying: This all sounds good, but we need something weirder.

Well, you’re in luck because the other flavor of geoengineering is … blocking out the sun — just a little bit!

It’s called “geosolar engineering,” and the idea is to slightly brighten the atmosphere to reflect more of the Sun’s energy back into space. That means less heat trapped below … which means less It’s not intended as a cure so much as a way to stabilize things until we find a better alternative.

And here’s the thing: This is all surprisingly plausible.

The chemicals involved are cheap and incredibly efficient. There are several potential delivery mechanisms, from ships pumping out mist to brighten clouds, to bursting thousands of weather balloons filled with sulfur dioxide in the stratosphere, to jumbo jets pumping it out the back.vii

And perhaps most surprisingly, none of this costs that much … at least by the standards of, you know, altering the planet. The total expense would be about the same as what it takes to run an airline.viii

OK, maybe not Spirit.

But here’s the catch about geoengineering: While the science might be slightly easier than it sounds … all the other issues are likely to be way harder.

After all, who gets to make these decisions for the entire planet? And what happens if not everyone agrees?

What if the U.S. and Europe launched a carbon capture program? A major carbon emitter like China might just decide that gives them permission to emit even more.

What if we engaged in geosolar engineering? Even if it worked, the effects wouldn’t be evenly distributed around the globe. Who’s responsible, if, say, we accidentally push India, the world’s most populous nation, into a massive drought — which is a scenario that experts say could really happen?ix

But here’s the trickiest part about geoengineering. Even if every country got on the same page regarding this technology, the science is so straightforward that even rogue individuals could start fiddling with the climate. In fact, that’s already happened.

In 2012, a businessman working with a small town on Canada’s West Coast dumped 100 metric tons of iron sulfate into the Pacific in the hopes that it would trigger an algae bloom and help increase the region’s salmon population.x That got him condemnation from environmental groups around the world … but it also led to a plankton boom that covered 10,000 square kilometers.xi

So, what does the future look like? Actually, it may be more straightforward than it seems. Amongst experts there’s a pretty universal consensus on two points: (1) There are way too many unknowns for us to seriously consider geoengineering at this point and (2) It’s vital that we do more research so that we can understand geoengineering’s potential — and its limits. That’s why everyone from the federal government to Harvard to Bill Gates is now supporting more and better studies. xii

Will it work? Who knows. But remember: Many great ideas start out sounding crazy because they’re so revolutionary.

And lots of others sound that way because they’re actually insane.


  1. "CO2 Emissions" (Hannah Ritchie and Max Roser) — Our World in Data
  2. Professor Paul Crutzen: Nobel Winner and Advocate of a Climate “Escape Route” — European Parliament
  3. Direct Air Capture — International Energy Agency
  4. “Genetically Modified Trees Are Taking Root To Capture Carbon” (Margaret Osborne) — Smithsonian Magazine
  5. “John Martin” (John Weier) — NASA Earth Observatory
  6. “Reversing Climate Change With Geoengineering” (Sanjana Kulkarni) — Harvard University
  7. The Planet Remade: How Geoengineering Could Change the World — Oliver Morton
  8. Ibid.
  9. “What Happens if We Start Solar Geo-Engineering—and Then Suddenly Stop?” (Robinson Meyer) — The Atlantic
  10. B.C. Village’s Ocean Fertilization Experiment Probed — CBC News 
  11. "World’s Biggest Geoengineering Experiment ‘Violates’ UN Rules" (Martin Lukacs) — The Guardian
  12. "The US Government Is Developing a Solar Geoengineering Research Plan" (James Temple) — MIT Technology Review


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  1. Our World in Data
    "CO2 Emissions" (Hannah Ritchie and Max Roser)
  2. European Parliament
    Professor Paul Crutzen: Nobel Winner and Advocate of a Climate “Escape Route”
  3. International Energy Agency
    Direct Air Capture
  4. Smithsonian Magazine
    “Genetically Modified Trees Are Taking Root To Capture Carbon” (Margaret Osborne)
  5. NASA Earth Observatory
    “John Martin” (John Weier)
  6. Harvard University
    “Reversing Climate Change With Geoengineering” (Sanjana Kulkarni)
  7. The Planet Remade: How Geoengineering Could Change the World
    Book by Oliver Morton
  8. The Atlantic
    “What Happens if We Start Solar Geo-Engineering—and Then Suddenly Stop?” (Robinson Meyer)
  9. CBC News 
    B.C. Village’s Ocean Fertilization Experiment Probed
  10. The Guardian
    "World’s Biggest Geoengineering Experiment ‘Violates’ UN Rules" (Martin Lukacs)
  11. MIT Technology Review
    Geoengineering Research Plan" (James Temple)

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