WARNING: the following contains arithmetic and big numbers.
PROFESSOR Shine and his fellow alumni of the Royal Society omitted to provide any costings for their proposed Solar Radiation Modification (SRM) that I reported on last week. Actually that’s not quite true, for they airily suggest costs of ‘a few billion’.
No doubt distinguished professors of the climate regard internet search engines as infra dig and pocket calculators as redolent of grubby commerce. So I, as a pleb, hereby offer my services.
Recall that that Mt Pinatubo eruption injected an estimated 20million tons of sulphur dioxide (SO2) into the upper atmosphere, leading to global cooling of half to one degree centigrade for a year or two. The scientists want to reduce global heat by 1.5 degrees, which might require 60million tons, if the effect is linear, which it probably isn’t. So for simplicity let’s stick with 20million tons. How much would it cost to launch this amount into the upper atmosphere?
There are two ways of doing it: by rocket or modified air freighters. Since the proposal was embargoed until November 5 I guess they prefer rockets, so we’ll consider that option first.
Currently the most cost-effective launch mechanism is the Superheavy from SpaceX, Elon Musk’s outfit. The Superheavy has a payload of 100 tons. (Brings out calculator . . .) That’s 200,000 launches. SpaceX plans about 50 in 2026, by the way. Prices start at a bit over $1,000 (£760) per kilogram, so the cost would be about $20trillion (£15.3trillion), roughly the entire GDP of the European Union plus the UK. Don’t expect a discount: Elon Musk is the guy the Royal Society tried to cancel. We will need to pay this every year (the SO2 doesn’t last long) so forget about that hip replacement or pothole repairs.
In fact the cost might be worse. High pressure gas requires strong containment and pressure vessels can be anything from three to five times as heavy as the gas they contain. So, nearly the entire global GDP, every year. Forget eating, for ever. Happily, SO2 is quite easily liquified so the containment vessels could be significantly lighter, but not negligible. Maybe we could get away with only spending the GDP of the EU plus China (as if!)
So if the rocket is a damp squib, what about repurposed air freight? On the face of it the economics look more attractive because prices are only about $1,785 (£1,361) per ton, so the base calculation would be about $37billion (£28billion) per year. But there are also disadvantages. There are humans on board so containment vessels would have to be more robust, apparatus to aerosolise the SO2 would have to be carried, and there is a further difficulty. Jets can’t fly at the required altitude and so the SO2 would be squirted into air containing lots of water vapour. The SO2 and H2O would react to form sulphurous acid (H2SO3) and later sulphuric acid (H2SO4). The production of sulphuric acid is highly exothermic, which is a bit of a problem when you are trying to cool, not heat, the atmosphere. The effect of the SO2 shielding us from the sun’s deadly rays would be shorter lived, so we would have to spray at more regular intervals. The fallout of sulphuric acid is probably dilute enough not to make holes in your umbrella, but better check just to make sure.
The cost of adding to or repurposing the air freight fleet would be significant. The industry turnover is about $120billion (£92billion) so adding another $30-70billion will inevitably push up prices. The supply / demand curves in aviation are quite inelastic, so the price increases will be extreme.
Oh, I nearly forgot. This SO2 stuff: you have to buy it. Sulphur isn’t very expensive as commodities go and the price fluctuates wildly but usually you can buy it for around $100 (£76) a ton. So only $2billion (£1.53billion) a year, eh? Not really, because there are competitive clients in a market producing only 80million tons a year. The boffins want to blow millions of tons into the stratosphere where, by definition, it doesn’t get recycled. Industrial sulphur, used in food preservation, tyres, fertiliser, pesticides, pharmaceuticals etc is often recycled. Sulphuric acid is one of the most widely used industrial chemicals with applications too numerous to list, and because it’s a corrosive and potentially dangerous acid its use and reformulation is tightly regulated. Raining acid while making everything else more expensive would not make the Royal Society popular.
Not all the sulphur can be economically recycled, so where do we get the new stuff? Oh dear. Here’s the clue to why it’s cheap. Sulphur is present in crude oil (see the price difference between Texas Sweet and Canadian tar sands), natural gas and coal (typically 2 per cent). Regarded as a contaminant, refiners and coke plants are happy to sell it to the highest bidder even if the price is low. Ironically. If we save the planet from fossil fuels / global boiling / carbon we won’t have any SO2 to save the world from . . .
Boffins. The whole manifesto is utterly mad. Until we have invented a sort of brain defibrillator to jolt these people out of their idée fixe we will have to section them. Nurse!
