What do we do if SETI is successful?

Time is a factor here. How close in time and space would be them?

If we get something coming from more than 100 light years away we might not have the technology to respond, and if we do it may not matter anyway if we are at risk of not having a technological civilization anymore 100-200 years forward. So the meaningful actions on those cases may not include answering back.

Then it will be the actual use of that message. Lets assume that we will decide that is a signal from a civilization that is out there. It will be a signal meant for us and for any other civilization that doesn't have the knowledge/culture level as them, meant for giving us a common ground for communicating back, or it will be something that just will tell us that someone intelligent is out there, but no mean to understand it?

So the options are that we find apparently benevolent aliens willing to contact us, or that we find out that someone is out there but no way to communicate/reach them. I think the second scenario is the most probable one, and how our civilization will react if widely enough will change with time, novelty at first and indifference a few years later.

I cannot imagine any scenario where we're just 100-200 years away from "no more tech" that isn't purely total nuclear destruction. Even then, we'd probably be so close to getting back to a technological civilization that it'd be a blip in the radar at best if we're talking about a society that far away.

We lost 150 years of progress? That's okay, we had 800 more years to advance before the aliens showed up or whatever.

It's such a weird thing I see so many people assuming. We were down to like 16,000 humans on Earth at one point, and that was before we'd developed things that you could theoretically scavenge and jumpstart your tech.

People need to stop doomscrolling; I'm certain this is depression projected.

With all due respect, I don't think you understand what the "worst case" scenario looks like for global warming, and how close we are to that scenario. For reference, check out figure 1 in this nature article [1].

That has warming by 2300 as 8C in an "emissions continue current trends" path.

Here's chatgpt giving a picture of what 8C warming looks like. Speculative, hallucinations, caveat emptor, etc...but to give a sense of proportion this, last time the earth was 8C *cooler* than now, ice covered 25% of the planet:

> At +8°C, Earth is fundamentally transformed. Large parts of today’s populated zones—South Asia, the Middle East, Africa, southern Europe, the southern U.S.—are functionally uninhabitable for humans outdoors. Wet-bulb temperatures regularly exceed survivable limits. Agriculture collapses across the subtropics; even mechanized, climate-controlled farming is marginal. Most of the world’s food comes from high-latitude regions: a narrow band across northern Canada, Scandinavia, and Siberia. Sea levels are dozens of meters higher, drowning coastal megacities; Miami, New York, Shanghai, and London are gone. Phoenix is lifeless desert. Seattle is coastal tundra, wetter but still survivable.

> Civilization persists only in fragments. Mass migration and resource wars have rewritten borders. Population is a fraction of 21st-century levels. Global trade, universities, and modern governance are mostly memories. Local, self-sufficient polities dominate. The United States as an institution likely dissolves or transforms beyond recognition—2 out of 10 chance of recognizable survival. Harvard or MIT survive, if at all, as digital archives or autonomous AI-driven knowledge systems—3 out of 10. The world would still have people and culture, but not civilization as we know it.

Edit: I would appreciate knowing why I'm getting downvoted when I added citations for *possible* warming paths (from nature!). Yes, the chatgpt explanation is speculative but I mean, look at the thread we're discussing.

[1]: https://www.nature.com/articles/s41612-020-0121-5