The Latest Geoengineering Scheme Is A Real Moon Shot
At its core, geoengineering is often about putting things into the atmosphere or into space that block some of the light emitted by the sun from reaching the earth’s surface. With humans seemingly unable to reduce their use of fossil fuels, another way must be found to reduce the amount of energy the planet receives from the sun every second of every day.
If we could find a way to reduce the power of sunlight by about 2%, we could theoretically burn every lump of coal, barrel of oil, or cubic foot of methane we could wrest from the earth forever, which corporate executives would do for fossil fuels and their shareholders delight. The concept is like a cosmic dimmer that would allow us to dim the intensity of sunlight just a tiny bit. It sounds simple, but it will cost trillions of dollars, has no guarantee of success, and could do unimaginable damage to life on our little blue planet in a small galaxy at the very edge of the universe.
Geoengineering 101
There are two ways geoengineering could work – theoretically. First, we could inject tiny particles of sulfur dioxide or water vapor or sea salt high into the atmosphere. Second, we could create a mirror system at the Legrange point L1, the point between the Earth and the Sun where the gravitational forces of both cancel. The exact position of L1 was postulated by Josephy-Louis Lagrange in an award-winning paper he wrote in 1772.
A team of researchers led by Ben Bromley, a theoretical astrophysicist at the University of Utah, has published a study suggesting dust particles located at L1 could do the trick well. The required amount of dust is calculated as 109 Kilograms, that’s about a hundred times more mass than people have ever sent into space.
According to the study, “Here we consider the reduction in sunlight received by Earth resulting from the placement of dust at or near the inner Lagrange point L1, which lies directly between Earth and the Sun, including gravitational perturbations from the Moon and others planets. Although unstable, these co-rotating orbits allow for the possibility of temporarily shadowing Earth. We start by evaluating the shadows cast by different types of dust; then we numerically determine orbits that persist near L1, including the effects of radiation pressure and solar wind. Our main results are a correlation between the quantity and quality of dust and the attenuation of sunlight on Earth in reachable orbits near L1. Compared to previous work, we are targeting a 1.8% reduction in solar irradiance, or 6 attenuation days per year.”
Getting millions of tons of dust from Earth’s surface into space would be a Herculean task (and would add countless greenhouse gas emissions to the atmosphere from all the rockets needed to get the job done). But Bromley and his team think they have a solution. Instead of sending materials from Earth into space, why not mine the materials you need from the Moon and launch them into space with magnetic railguns? The moon’s lower gravity would make the task much easier.
“A really exciting part of our study was finding that the natural lunar dust grains are just the right size and composition to efficiently scatter sunlight away from Earth,” says Bromley The guard“Since it takes much less energy to launch these grains from the lunar surface compared to an Earth launch, the ‘moon shot’ idea really appealed to us.” For an analysis of the composition and shape of the particles the researchers looked at, see the two graphics below.
Image credit: Bromley et al., via Plos.
The geoengineering details are the hard part
Taking the mining and railgun equipment to the moon would be a “significant project,” admits Bromley. It may be necessary to position a new space station near the L1 Lagrange point to “redirect dust packets to orbits that could provide shade for as long as possible.” Such an approach would act as a “finely tuned dimmer switch that leaves our planet untouched,” Bromley said, an advantage over other solar geoengineering proposals that have raised concerns about the environmental impact of spraying reflective particles into Earth’s atmosphere.
However, the lunar dust would have to be continuously hurled into space to mitigate global warming, or risk a so-called “termination shock” that would follow the temporary cooling if stopped abruptly and left the world too quickly to heat up again. Bromley insisted that the sci-fi idea of the research is no substitute for the primary task of reducing the planet’s warming emissions in the first place. “Nothing should stop us from reducing greenhouse gas emissions here on Earth,” he said. “Our strategy may be just a moonshot, but we should explore all options in case we need more time to get the work done here at home.”
That’s all well and good to say of him, but perhaps quite naïve when it comes to commercial and political realities. Chances are the fossil fuel industry would use this prospect as yet another excuse to just move on when it comes to extracting, transporting and incinerating their climate-killing products.
Ted Parson, an environmental law expert at UCLA, said the lunar dust proposal is a “fun, scientifically interesting speculation” that is unlikely to be put into practice, in part due to the higher cost and lack of control compared to Earth-based geoengineering Options . “Interest in space-based geoengineering schemes appears to be growing somewhat more broadly,” Parson said The guard. “They have long been dismissed as completely impractical for technical and cost reasons, but I get the impression that the continued reduction in startup costs is piqued by people’s interest and strange ideas are bubbling up.”
Opponents of solar geoengineering, whether on Earth or in space, argue that it is an unhelpful and potentially dangerous distraction from the urgent need to move away from burning fossil fuels. “The idea of mining the moon or near-Earth asteroids to artificially block parts of the sunlight is not a solution to the ongoing and deepening climate crisis,” said Frank Biermann, professor of global sustainability governance at Utrecht University. “What we need are massive savings in greenhouse gas emissions, which will require rapid technological advances and socio-economic transitions. Mining on the moon is not the answer we need.”
take that away
Geoengineering is like hydrogen fuel cell cars – an idea that refuses to go away. It is welcomed by those who blithely claim that just when humanity is on the brink of extinction, we will magically find a way through science to emerge from inevitable catastrophe. It’s a tender and touching fantasy, but it won’t help us when we need it most.
The hard work to decarbonize the global economy is the only thing that has any chance of succeeding. The only sensible thing to do is to keep going.