So, there’s this geoengineering idea that could stop global warming, right? The idea here is that snow is good at reflecting the sun’s heat back into the atmosphere, and water is bad at doing the same. Most other things that cover the earth’s surface fall on a continuum between those two. The technical word for this is albedo (read that link, very good starting place).
Ok, so what’s the effect size of this?
Earth’s average surface temperature due to its albedo and the greenhouse effect is currently about 15 °C. If Earth were frozen entirely (and hence be more reflective), the average temperature of the planet would drop below −40 °C. In contrast, if the entire Earth was covered by water – a so-called ocean planet – the average temperature on the planet would rise to almost 27 °C.https://en.wikipedia.org/wiki/Albedo
Ok, big effect size. From this, it follows that changing the albedo of a few percent of the earth’s surface would be enough to counteract the 2-3 degrees Celsius rise in global temperatures that’s expected in the next I-forget-how-long.
So, Marine Cloud Brightening is a particular implementation of this: “have a ship with a huge humidifier on it, that sprays water droplets into clouds to make them more reflective and raise their albedo”. If you do this over enough of the ocean you’ll get a global 2-3 C drop.
These people estimate it would cost about 1B USD/yr to maintain a cloud brightening program worldwide. Note that some of the other work on that site is shit, but this publication is basically fine.
Ok, so 1B/yr doesn’t sound bad to mostly counteract global warming. But can we do better?
Here’s a better solution I came up with.
Basically, we’re at the point where nobody has outfitted a ship and just tried doing it. Like, we don’t even know what exact design you’d use for the giant humidifiers.
So, my solution is basically: hire some engineers to design a few possible alternatives for the humidifier, put them on a few ships, and then test them all out.
My rough guess is that this would cost on the order of magnitude of 30m USD. Mainly depends on how big of a boat you need to use for it, and how many boats/humidifiers you’re testing at once. I see a number of 10 year old supply vessels at around 120ft and 40ft beam for about 3m USD, which may or may not be the right thing to use. I imagine the boat(s) would be the plurality of the cost.
Anyways, governments like sure things, so if you did this and then wrote up a report of, “here’s a strategy that worked reasonably well, well enough that it’d be a good use of resources to put it to use worldwide instead of doing more testing first, and here’s a neatly packaged writeup of how you can implement it at scale based on what we learned”, I’d say, given my sense of how governments work, that’d make at least one of them a hell of a lot more likely to fund the actual cost of doing the worldwide version of Marine Cloud Brightening.
I’ll probably fund this, or something very close to it, in maybe 4 years (2023), assuming my world domination/world saving/money making plans continue at their current rate.
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