In case you haven’t noticed, things are getting a little bit desperate when it comes to climate change. We need global solutions and meaningful action as of yesterday, but our political leaders and corporate overlords alike are mostly doubling down on the status quo. Enter: Theoretical physicists.
A group of researchers from the University of Utah and Harvard believe they’ve hit on a possible fix for the ongoing, human-caused warming of Earth. And—buckle up for this one—their cutting-edge proposed solution is to shoot millions of metric tons of moon dust into Earth’s orbit every year to partially block out the Sun’s rays, thus cooling the planet.
We’re officially at the point in environmental collapse where scientists think it’s worth exploring lunar mines and a space-based dust distribution system to buy time. Meanwhile, down on Earth, fossil fuel companies are achieving record profits, abandoning even their weak emissions reductions promises, and actively working to increase their oil and gas production. This... says a lot about society.
But let’s at least hear the scientists out. What did they do?
“We looked at a variety of dust types and orbit solutions to see how much dust would be needed to make an impact on Earth’s climate,” explained lead study researcher and University of Utah theoretical astrophysicist Benjamin Bromley in an email to Earther. “We settled on a favorite concept, involving lots of moondust in a jet-like stream that can shade the Earth.”
The seed of the idea came from Bromley and his co-authors’ previous work on planet formations and space collisions, wherein a small amount of dust “intercepts a lot of starlight.”
In their study, published Wednesday in the journal PLOS Climate, Bromley and his co-researchers used mathematical modeling to determine the ideal type of particle, particle distribution, and necessary particle mass for shading Earth from the Sun. In their tests, they were aiming for a 1.8% attenuation of the Sun’s heat—equal to about six days per year of “an obscured Sun,” according to the study.
They found that, materials-wise, lunar dust would be about as good as any other option for dispersing sunlight. The ideal Sun-blocking particle is “high-porosity,” with “fluffy grains to increase the extinction efficiency per unit mass,” according to the research, and moon dirt fits the bill pretty well (fun fact: apparently so does coal dust). Their volume estimates revealed that about 54 million metric tons of lunar dust per year, strategically targeted at the point where that dust would be most likely to persist in orbit the longest, would do enough to offset warming.
More dust would have to be added every few days to keep it going. Notably, the study authors didn’t include any sort of cost analysis in the publication.
But Bromley and team did compare different theoretical approaches to dust delivery. Ultimately, they determined that, relative to the option of having a platform hovering in orbit at Earth-Sun L1 Lagrange point that shoots off dust clouds, “a simpler approach is to ballistically eject dust grains from the Moon’s surface.” Ah yes, a Moon cannon. True simplicity.
As to why lunar dust seems like a good option for addressing climate change, the astrophysicist explained that launching material from the Moon is more energy efficient than from Earth, because of gravity. Also, “the raw material is plentiful,” he added.
Asked if he plans to keep going down this research path, Bromley was unambiguously enthusiastic. “Yes! there are more details to fill in, especially now that we focus on the moondust jet idea!” he said.
I can’t fault scientists for thinking creatively and trying to apply their expertise to the biggest challenge currently facing humanity. And they’re hardly the ones who got us into this mess. But the fact is, we already know how to stop climate change without risking further environmental havoc. Number one: Drastically reduce our fossil fuel use.
To be fair, Bromley did acknowledge that lunar dust isn’t the one and only answer to climate change. “The hard work here at home—climate change mitigation measures like leaving the fossil fuels in the ground, carbon recapture and other strategies [are] essential and must remain the primary focus for addressing climate change,” he said.
But in his earnest view, this sort of geoengineering project can be part of a multifaceted approach. “Our goal was to explore possibilities if we need more time, by assessing the potential of using dust as a space shield. Our findings are that there may be advantages to it as compared with other astro/geo-engineering solutions, but it would be an enormous endeavor.”
This is far from the first seemingly outlandish, space-based geoengineering proposal. There are ideas out there ranging from space bubbles to putting a literal physical shade between Earth and Sun. Then, there’s a whole suite of suggestions for things we could do down on the surface. Scientists have looked into building a wall around Antarctica to prevent ice sheet collapse. Lots of research out there explores dumping iron into the oceans to make our seas absorb more CO2. At least one Harvard scientist has built a whole career around the idea of injecting sulfur particles into the upper atmosphere to reflect the Sun’s heat.
Actually enacting some of those more “grounded” geoengineering proposals is becoming more and more likely. Last year, the Biden Administration announced a multi-million dollar geoengineering research plan. Last month, Mexico had to enact a new nationwide ban on geoengineering after a startup company apparently went rogue. As climate change progresses, more scientists are hopping on board with the idea that we might need to take drastic action.
But at this point in human history, it should be obvious that all efforts (intentional or otherwise) to change Earth’s atmosphere, oceans, or climate on any grand scale come with a boatload of unintended consequences. From destroying the field of astronomy to potentially trashing agriculture, geoengineering is incredibly risky.
When it comes to addressing climate change, we’ve got options. We could build a network of dust cannons on the Moon, yes—or we could build a comprehensive, electrified mass transit system. We could send 54 million metric tons of lunar dirt into orbit every year, or we could expand our offshore wind capacity over offshore drilling. We could do what’s guaranteed to work, or we could make a perilous bid for a sci-fi future. Which is more likely to end well? It probably doesn’t take a rocket scientist (or a theoretical physicist) to figure out those odds.