Any answers shouldn't consist of "well it's a fraction of what the aviation industry emits" because _the entire point_ of Starship is to scale-up to aviation-like operations.
You want more specifics, I take it?
* It's been well known for decades that high-altitude supersonic flight damages the ozone layer significantly faster than conventional aircraft. New Scientist, 1997 [1]
* More recently, concerning reentries of spacecraft: Atmospheric impacts of the space industry require oversight, Nature, 2022 [2]
Our upper atmosphere is fragile and contains the bulk of the ozone layer that protects us all from skin cancer and being bathed in brutal ultraviolet radiation. You willing to risk it because "space is cool"?
[1]: https://www.newscientist.com/article/mg15320692-500-science-...
If you are an engineer or even have half a brain nothing prevents you from doing a more in depth analysis, make a blog and post it here.
Right now not only are you a naysayer but you are even putting on hacker news commenter the burden of defending your point.
For the first study, you have conveniently focused on "supersonic flight" as the issue which is not the fundamental issue cited in the article (link isn't working for me, btw, I had to google it find it myself). The fundamental issue is in aircraft fuel and the sulphur based impurities it carries. Starship burns Methane and LOX. In general, these fuels (fuel and oxidizer) are typically kept as pure as possible and are unlikely to contain much more than trace sulphur impurities as there removal is a standard and well followed practice.
So for full clarity, your argument as presented here is completely without merit and it looks like your first study was intentionally presented in a way to obfuscate its extremely tenuous link to the issue at hand.
As an aside, you're also quite focused on your mood affiliation with the topic, doing things like asserting the motivation of those you reply to without any evidence (eg 'You willing to risk it because "space is cool"?'). This won't help you think clearly about a topic.
Your asteroid mining for profit is arguably meaningless if we have no ozone layer.
Now high-altidude effects would increase the greenhouse effect of these emissions by some factor I don't know. At the same time a large amount of fuel is actually burned by the booster at below airliner altitudes. Another mitigating effect is that some of this methane could be produced renewably.
I haven't heard about Ozone depletion from spaceflight except for the case of reentering Aluminum burning up. Well this wouldn't be an issue with Starship flights.
So you know overall, let's just give it a lot of conservative margin and imagine we are looking at about 10% of the US airline or 0.2% of total US greenhouse impact. That is on the scale of a whole new industry, yes, but if you can imagine a world which has attained a sustainable rquilibirum surely you can also imagine one which has a bit of margin left? And this is only for the US!
What do you gain? Three of the points I mentioned have potential direct benefit for people.on earth: asteroid mining, L1 solar shield and brilliant pebbles.
Asteroid mining "for profit" also means that the economy profits, unless you believe that capitalism doesn't work. I read that less than 200t platinum are produced annually. Say your asteroid mining crashes that economy. I found some figure of 20kt of CO2 for each ton, so 4mt in total. That is more than your 1000 launches emit! Now my calculations are of course wrong but it seems plausible that the orders of magnitude could match. So you should definetly consider that your asteroid mining operations might stop other mining operations from happening which reduces your greenhouse impact.
Then you have the solar shield. It is certainly possible, although of course difficult and has some risk. But it's good to have a backup plan, no?
Mentioning theoretical solutions doesn't help if they will never be used practically.