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Comment by tobr | Hacker News Reader

This was discussed in the latest episode of The Ezra Klein Show[1]. Apparently aerosols artificially held down temperatures roughly 1940–1980, after which they started to be reduced (from my memory of what they discussed). So it might be that the contribution of the greenhouse effect is masked in that period of the temperature graph.

1: https://www.nytimes.com/2023/09/05/opinion/ezra-klein-podcas...

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A good review paper on "global dimming" and changes in surface shortwave radiation is by Wild [0].

[0] https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...

Were the aerosols from above-ground nuclear bomb detonations? I remember seeing a graph years and years ago that showed the temperatures really starting to rise was above-ground nuclear bomb testing was banned.

Crazy spur-of-the-moment idea - should we pursue dumping some sort of aerosol into the upper atmosphere to reduce the amount of heat Earth receives from the sun? Obviously this shouldn't be pursued in lieu of curtailing our pumping C02 into the atmosphere, but it could alleviate some of the damaging effects from what we've already done.

YC backed: https://makesunsets.com/

Aerosols were probably sulfuric acid. Unfortunately this has negative side-effects. Aerosol can also be produced by monoterpenes, e.g. pinene, but there is disagreement about whether this can be helpful.

The crazy part about this is that doing something like that is within reach of a number of wealthy individuals. All it takes is one delusional billionaire to throw caution, and a metric buttload of aerosols to the wind and we will find out whether it was a good idea or not.

Putting up a geosynchronous mirrored-foil tarp that shadows the entirety of one of earth's larger deserts would take about the same amount of effort — and be much easier to reverse if it turns out to be a bad idea.

I think the important part here is you could do the aerosol injection secretly. It's pretty much impossible to launch a rocket to geosync orbit without a major government getting involved in your business.

This has been studied in pretty extensive detail & what I remember is that it’d require a custom plane design to get to efficiencies where this is worth pursuing. And the number of flights required would be hard to hide from a motivated government adversary. Still worth pursuing. Any takers on here?

Sulphur oxides have been proven to reduce global warming - when the ocean freighters cleaned up their emissions in a bid to stop pollution we saw increases in temperature. I hear people suggesting that we dump a ton of that in the upper atmosphere, but adding more crap to the air to try and stop the previous crap reminds me of how the old lady who swallowed the fly ended up with horse-sized problems.

It'd be just a giant game of whack-a-mole, not too dissimilar to what humans tried to do after destroying some ecosystems: travel to a new place in boats carrying rats, the rats get to a new land and multiply quickly, bring cats to control the rat population, the cats kill a lot more than rats and multiply quickly, rinse and repeat.

Complex systems that feedback into each other get very, very tricky to manage. We can't even do that with stupid software, it's a massive human hubris to believe we can do to systems we don't even comprehend...

Except we don't need to replace those sulfur dioxide emissions with more sulfur dioxide; Salt water misted into the air has the same effect, while being pretty unlikely to harm anything.

Even that will produce halogens and has the potential to change rain patterns.

That's why you do it on offshore platforms, such that the water and salt and anything else simply return to the ocean.

The spraying platform would constantly be growing salt all over it, and that's not a fun thing to maintain though.

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