can we stave off global warming by blocking out the sun?

In the Simpsons’ episode Who Shot Mr. Burns, the titular villain builds a device that blocks out the sun for the citizens of Springfield in a scheme to force them to buy more electricity from his nuclear power plant. But what if Mr. Burns actually had a valid plan to fix our current climate predicament? As world leaders do their best impression of Nero fiddling while Earth burns, a small but vocal group of engineers and scientists is wondering if we should resort of things like seeding clouds and launching mirrors or solar shades into space to deflect sunlight and buy us more time to elect better leaders and finally clean up our act once and for all.

At first glance, these seem like good ideas, albeit reminiscent of Futurama’s what-if-we-pushed-the-Earth-farther-from-the-sun way. If our politicians refuse to do anything about a crisis and seem hell bent on letting their donors and friends pollute all they want, why not come up with solutions that make an end run around them and blunt, if not negate the damage they’re letting happen? And while geoengineering that involves seeding clouds or reshaping the planet might have serious unforeseen consequences, collapsing entire ecosystems and doing more damage than just the warming itself, space-based approaches might actually be more attractive because they could be easily scrapped if they start doing damage, quickly undoing their effects.

But those ideas come with a massive drawback of their own. We need to put enough stuff into space to deflect or absorb the vast amount of energy coming towards us and launching a lot of stuff into space means having to shell out a lot of cash. We’re talking about anywhere between thousands and millions of rocket launches, vast factories devoted to making mirrors and shades and robots, some not even on Earth, and resources of entire nations and vast economic trading blocs being rerouted to make these projects a reality. Oh, and don’t forget that all this effort will have to be undertaken under the plan that if these ideas backfire, we quickly scrap them, effectively flushing all that cash down the drain.

so, how much does it cost to block sunlight?

Initial plans considered blocking one percent of incoming sunlight by putting up a sunshade at the L1 point, a stable, parking spot orbit 1.5 million kilometers from Earth right between us and our home star created by a fluke of gravitational interactions in the solar system. But to block one percent of all light we get from the Sun would require the shade to be 1.2 million square kilometers, which means that the desired structure would measure somewhere between the land areas of Columbia and South Africa, and push the total bill for just putting it into space well north of $800 trillion, nearly eight times all the money and assets on Earth. Obviously, that’s not going to work unless we decide to completely discard our entire monetary system.

Other, more cost-effective ideas are being floated by ambitious engineers who want to launch vast clouds of moon dust and swarms of 16 trillion robots arranging themselves into a 97,000 kilometer wide permeable solar sail controlled by lasers and ion engines to avoid crashing into each other and being pushed back by the pressure of the sunlight they’re deflecting. The latter plan doesn’t involve a price tag of all the money in the world eight times over, but even the most optimistic launch costs based on SpaceX’s reusable spacecraft and economies of scale would put the costs of research, development, manufacture, and launch somewhere around $14.5 trillion, or essentially the GDP of China.

And even then, after anywhere between 16,000 and 30,000 launches of tiny robots at the cost of the world’s second largest economy’s annual output, all we’d accomplish is maybe a couple of decades of stable temperatures, after which the mercury would start climbing once again. On top of that, since the project would obviously take a serious amount of time to accomplish while we keep emitting greenhouse gases, it would have to deflect more and more light and grow in scope and cost as it’s being built and launched. It’s the equivalent of trying to outrun a treadmill that’s slowly picking up pace under your feet.

why geoengineering won’t solve climate change

So, if we consider that it’s absurd to spend tens of trillions to kick the can down the road, it’s just as absurd to pay $5.2 trillion in subsidies for the fossil fuels causing the problem in the first place every year. If we really wanted to pay for a high-tech robot swarm to delay the brunt of global warming for 20 or 30 years, we could pay for them by slashing those subsidies to the bone or eliminating them altogether. But if we went that far, the price of renewables would plummet in contrast to the price of gas, oil, and coal, and we’d have more than enough cash to make permanent changes to our infrastructure, replant forests to create new carbon sinks, and keep our emissions down for good.

Basically, the choices we have are tackling the actual problem or giving us a bit more time to pretend we can get a handle on things before they get too bad, and it’s telling that politicians are pushing us towards the second option because they don’t want to participate in the hard work to try to deal with the consequences of doing things right. We can’t simply keep stalling for time because as we do, even if all those toxic emissions aren’t raising the temperature and triggering climate change, they’re building up pollutants in the environment, killing crops and sickening millions. The more we pretend we can do business as usual, the more people will be dealing with respiratory diseases, cancers, and birth defects.

One of the most underreported stories of the past decade has been an explosion in various green projects as people regardless of political affiliation are making the choice to invest in cleaner air and water, which is why it’s so absurd to see so many those who could supercharge the efforts in question wallow in poisonous and whine about reallocating money we already have to change things for the better. Certainly, one can be forgiven for thinking that the only way to fix our climate problems is to buy us more time to eject the retrograde man-children blocking progress regardless of popular support for it, but the best case scenario will still deal catastrophic damage to the environment, and the worst enables said retrograde man-children to pretend that they’re right and nothing needs to be done, which is the exact outcome we’re trying to avoid.