I don’t think you should be downvoted. People really don’t like it because it is clearly not the optimal way to solve the problem, but we should take the possibility seriously instead of down voting anyone who brings it up as something that might happen.

We are letting anthropogenic global warming happen because it’s cheaper in the very near term. But climate change is a real thing and will have real, life-threatening effects especially for some geographic regions.

If we accept the reality that: 1) humans often just do what is cheapest and easiest even if the long-term consequences are bad AND 2) global warming will start killing massive numbers of people from things like heat stroke, putting enormous political pressure on governments to do something,

…then The logical conclusion (combined with how insanely cheap SO2 is to deploy, we’re talking maybe $50 billion a year, maybe less) is that there is an extremely high probability that some nation will just unilaterally do sulfur dioxide. Think of a Nation like India, with a large population that will be vulnerable to heat stroke and a big enough budget and military to just unilaterally do something like this to stop the political unrest of hundreds of thousands of heat stroke deaths per yearz

And on top of that I don't think it'd even be possible to know who deployed the SO2.

The stuff isn't uranium and not much is needed. Any nation with an airplane should be able to get away with it.

You need quite a bit, and it needs to be continually deployed. It wouldn’t be hard to tell who is launching like 25,000 tons of sulfur dioxide into the stratosphere every year. It would leave effects clearly visible by satellite: https://earthdata.nasa.gov/esds/competitive-programs/measure...

But I said $50 billion per year. That’s what probably way too high. Other estimates mention $18 billion per year, I found one that mentioned $2 billion per year, and just doing the calculation by hand based on fuel and per hour operating costs, I get only like $100 million, although that depends on altitude (I think 20km is usually ideal, although most cargo jets can’t go much above 13km).

I even wonder what the effect would be of just using sulfur-rich jet fuel on regular commercial long-haul flights. The cost would be minimal or even negative (as sulfur-rich crude is cheaper). I guess in this way any nation could just decide to do sulfur-rich fuel in their long haul fleet and few would immediately notice.

It’s such a crappy solution to the problem, though, and will doubtless cause a bunch more problems. But it’d be insanely cheap to do.

Because I think you’d be the person to ask: what is the feasibility of putting up a space sunshade to block some incoming solar radiation, using starship/super heavy?

Let’s say you need to reflect 1% of the light reaching the earth’s disc. If you’re using solar sail like devices with an average areal density of 10 g/m² and you have launch cost of $10 per kilogram (using LEO figures because devices made really lightweight can actually move themselves around with pressure from sunlight)… about $150 billion in launch costs. Material/spacecraft costs are a big question mark and can vary by 5-6 orders of magnitude, so let’s say it’s $10/kg, for a total of $300 billion.

Still sub optimal compared to other solutions but it’s possible we may need to try something like that.

Thanks for the breakdown. I like the idea of something we can remove more easily down the line, even if it’s more expensive. I suppose we probably won’t have the luxury, though.

Calcium carbonate is a better fit - see Gates’s experiments. Likely to still be disastrous, but better than sulfur dioxide

Grammar tip, if someone name ends in s, you can just write Gates’ experiment.

Interesting thanks.

Why disasterous?

Particulate matter in the air causes precipitation. Spraying large amounts of particulate matter into the sky is likely to drastically change global rainfall patterns - so you might get a ton of rain in the Sahara, where it’s useless, and none at all in the American Midwest. The result could be drastic food shortages and famines. Major volcanic eruptions have been associated with droughts and famines. I think geoengineering on this scale may be necessary, but it is a terrible option and an absolute last resort

When you say rain in the Sahara would be useless, are you saying it's already a carbon sink or something? After all it seems that rain in the Sahara would eventually cause forests to grow, given a few years.

Top soil takes a long time to form. I imagine most of the water would go into the aquifer.

Isn't the upside of this kind of geoengineering the reversibility? If we inject SO2, and we don't like the effect, we stop. IIRC it doesn't hang around that long.

There's likely a decade+ tail after the end of active particulate injection. If there is too much to begin with, you piss off all the electorates with years of chaotic weather, threatening food production, financial markets, and ecologies all over the world. Get it just right, you wreak less havoc, piss off fewer electorates, and lower global average temperatures. Get too small an effect, you risk overcorrection or the project failing before it has a chance to really work.

There's also the fact that you're altering a chaotic system, with fundamentally unpredictable side effects, some of which could last longer than a human lifespan. Wanna make California get monthly hurricanes? How about weekly tornados in Colorado? Bury New York city in ice?

It's not that any of those things are probable just that they're possible, and chaotic systems can drastically, catastrophically, and exponentially change configuration, and no matter how good your supercomputer simulations are, you fundamentally cannot predict the consequences.

All of human civilization teeters on the current climate configuration - geoengineering has terrifying potential. Humans have a horrible track record in attempts to predictably alter chaotic systems and ecologies. We damn well better know what we're doing before we use globally acting tools.

What is country A likes it but B does not? Seems like a source of conflict.

Similar to the GERD but in the sky.

Can somebody please explain the SO2 thing? Im googling to no avail...