Let me begin with a book recommendation: The Planet Remade: How Geoengineering Could Change The World by Oliver Morton.
I would change the title of this book to “The Planet Remade: How Geoengineering Has Changed The World And Will Continue To Change It As Long As Humans Are Monkeying On It, In It, and Around It.” But I understand that might be a less catchy title.
Look, I accept the distinction Morton makes between ‘willful change’ and not, and he needs to establish some boundaries for the discussion. It’s pretty clear we’ve already created massive changes in the planet’s systems. We have altered its features, most obviously by redirecting rivers, creating dams, digging giant tunnels into mountains, covering hundreds of thousands of square miles with concrete, cement, asphalt and all kinds of other crazy stuff (like, say… putting golf courses in the middle of deserts), and (mostly for bad reasons) blowing up lots and lots of different places. We have pumped and continue to pump trillions of tons of gases and chemicals into the biosphere. Geoengineering is already happening, so how about we do it for something other than manufacturing complicated barbeque grills, phone cases and christmas tree decorations?
The book’s discussion on the transformation of the nitrogen cycle is particularly interesting, since this was a key factor in making Norman Borlaug’s high-yield dwarf “superwheat” a feasible crop at large scale (dwarf wheat consumes more nitrogen). Much is frequently said of Borlaug’s work and the Nobel prize he got for it (and with good reason) but less is known about the massive geoengineering activity that started before that work and made it possible.
Geoengineering will be a key element in reversing some of the effects of climate change, since it is pretty clear that “just” reducing emissions won’t cut it.
Just sulfate it.
If I had to bet on a method for climate engineering that’s going to be used in the next few decades, I’d go for stratospheric sulfate aerosols — which the book covers well. Why? As The Joker in TDK said of gasoline and dynamite: “They’re cheap!” If none of the world powers is going to do it, any one of a number of other countries will eventually decide that it’s time to stop the ocean from erasing their coast sooner rather than later. The consequences of this could lead to (surprise!) war, perhaps even nuclear war, which Morton discusses as well. Nothing like some optimism about saving the planet sprinkled with apocalyptic thinking. Just kidding, that’s something important to discuss too. (Nuclear winter is also discussed in terms of its climate impact).
Near the end the book spends a good amount of time talking about asteroids, but not in the way I thought would be … kind of obvious. It focuses on asteroids as an Extinction Level Event. Dino-killer, etc. The point he makes is that the various ideas discussed around how to stop an asteroid from crashing to earth are in a way similar to the idea of using geoengineering to save us from a different kind of cataclysm.
This is an interesting argument but….
Asteroid Mining + Stratospheric Aerosols = Profit!
Fine… maybe not profit, just saving the world. My point is, what the book doesn’t discuss is the use of asteroids for geoengineering… and not as an argument. It mentions “asteroid wrangling” but all hope is dashed when we see that it’s talking about moving an asteroid off-course to prevent it from hitting earth. Ridiculous. We have Bruce Willis for that!
One of my personal obsessions is the topic of asteroid mining. Yes, within the next few decades we will begin mining asteroids, there’s no doubt in my mind about that. And it seems inevitable to me that we’ll also be using some of the results of that for climate engineering via the stratosphere (and later to create massive structures in orbit around the planet).
Why? because the biggest cost in seeding the stratosphere is energy, specifically, the kinetic energy you need to spend to move millions of tons of what essentially is dust from the ground (where it is manufactured cheaply) to its stratospheric destination over 8-10 kilometers above the surface of the earth, depending on latitude. This “cost” is more of a logistical cost rather than a pure energy cost. How so?
Option A: Airplane!
(Not the movie). Let’s say we are going to seed a million tons of sulfate aerosols into the stratosphere.
The energy required to lift a mass of a million tons of material to a height of 10,000 meters would be ~98.1 terajoules (give or take a Joule, E = m x g x h) = ~27 GWh (gigawatt-hour) = 27,000,000 kWh. In the US (with average energy cost of 12c/kWh) just lifting the dust would cost at minimum 2.7 million dollars. Add to that the necessary costs for stamps, copy paper, printing receipts and office parties, copies of Microsoft Windows, safety goggles, and such, and the cost would rise by several million more. So round it up to 10. 10 MM USD = 1 million tons of material at stratospheric height.
Now, the Mount Pinatubo eruption in 1991 is estimated to have injected 20 million tons of sulfates and resulted in an estimated 0.5 C cooldown across the planet within a year. This cooldown dissipated as quickly as it arrived (at least in geological terms) so a long term geoengineering operation would require adding sulfates for several years, perhaps decades.
With this we could derive a “baseline cost” of 200 million dollars to make global temperatures drop half a degree centigrade within a year. Sounds cheap! We could have a 2×1 offer and make it an even degree cooler.
The energy transfer, sadly, is not “pure”, and so, therefore, neither is the cost. If you are spreading the material from, say, a plane, the weight of the plane, the fuel, transport to airfield form the factory and so forth also comes into play. The logistics chain and equipment required becomes really complicated, really fast. Not impossible by any means, just complicated and much more costly, running into billions. For a less hand-wavy (and more systematic but way longer) analysis, see Geoengineering Cost Analysis and Costs and economics of geoengineering.
Here’s where asteroids come into play.
Option B: Asteroids!
(Not the game). Using asteroids for this purpose seems to me like a perfect match. Any nasty by-products of the mining and manufacture remain in space, where hazardous chemical waste is not a problem since a lot of the stuff out there is already hazardous chemicals, plus no one can hear you scream.
Asteroids contain enough material to either obtain what you need directly or by synthesizing what you need using micro factories landed/built (by other micro-factories landed on the asteroid) for that purpose.
The energy required for the deployment of the material will be far lower (you’ll always need some amount of energy expenditure in the form of thrusters and the dispersion device), but you would be able to rely on gravity to do most of the work (if the asteroid in question has been captured and placed in orbit around the earth, even better). Instead of fighting gravity, we’d use it to our advantage.
Most of the maneuvers involved in transferring material would rely on gravity assist rather than rockets (plus aerobraking for atmospheric reentry when needed) which makes them cheaper, and, something that is hardly ever mentioned, less prone to failure simply because there are fewer components in the system, particularly components of the very large, very explosive kind, like the Saturn V’s S-IC of the Space Shuttle’s SRBs.
Now that people are excitedly talking about the possibility that we may have found a Dyson Sphere in our own neighborhood (KIC 8462852 FTW – only 1,480 light years away!) talking about these types of projects could sound to people more like science and less than science fiction. As a bonus, this gets us closer to a Type II civilization. We’ll definitely need to throw a party when that happens.
TL;DR go read this book. It’s very likely that stratospheric sulfate aerosols will be used for climate engineering within the next few decades. But why wouldn’t we use asteroid capture and mining for that? Can this possibly be a new idea? Also: Dyson Spheres!
PS: I haven’t found discussion of this type of sourcing of material for geoengineering, so should this be a new idea I fully expect my fair share of the massive profits. Just let me know and I’ll send my bank information. Can’t send funds myself though, most of my money is in the hands of a nigerian prince who is using it to process an inheritance.