How large a scale and with how many countries participating would cloud seeding be able to reverse these effects? Last I remember it was only a few countries in Asia that were attempting anything of the sort.
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https://en.wikipedia.org/wiki/Marine_cloud_brightening
A disadvantage of solar radiation management like this is that it does nothing for ocean acidification. But it could buy us time by heading off feedback effects that cause the planet to emit a lot more greenhouse gas of its own, due to melting permafrost, forest fires, etc.
We've just got a taste of it, when we realized the sulfur contamination by crude oil burning cargo ships was unknowingly off-setting climate effects by solar shielding, because cleaning up emissions apparently accelerated climate change. So there we have a horrible scenario: Pollute the environment or suffer rapid global warming.
Imagine the fun, if we engineered and employ a shielding "solution", intentionally. Comfortably sitting around 1.5°C, at some point, me may notice out there is some horrible chemistry happening in the upper atmosphere due to our "inert" shielding agents, where the fallout increasingly sterilizes every mammal on the planet, but we also kinda, uppsie-doopsie now additionally have 4°C worth of CO2 in the atmosphere waiting for prime time, so... stopping with the shielding emission would cause extremely rapid warming acceleration collapsing every ecosystem on the planet.
Caught between a rock and a hot plate.
When we've gone carbon neutral, we may think about these measures to reduce the temperature a bit again, but it's just a recipe for disaster, if used to "buy some time".
The reason we need this to buy some time is that those climate feedbacks aren't far away. We've seen in the geological record that really doesn't take much excess heat (usually from orbital variations) to kick off a warming cycle that would take things entirely out of our hands.
Simply eliminating emissions would have been a great plan, but we're beyond that now. A lot of climate scientists say the safe CO2 level is 350ppm. I remember when we blew past that and they said "ok, but seriously don't go past 400ppm." Now we're at 425ppm with emissions going strong. Solar power, electric cars, all this stuff gives me hope for the future if we can do it in time, but we're in a race and we're losing.
And it's not like this sort of cloud seeding would deploy all at once. We'd ramp up gradually and see how it goes. At the very least, we could replace the cloud cover that the article says we've eliminated over the past twenty years.