

Why would one assume that every civilization is going to have access to fossil fuels in the first place? Earth has coal and oil because of a specific sequence of events that don’t necessarily follow.
Also, the severity of climate change that we’re facing is in no plausible way “end of the line” for humans. It could be disruptive to our current civilization but it’s not going to end us. One could even easily hypothesize alien planets where induced global warming would be an enormous benefit to a civilization living on it. Just a few tens of thousands of years ago major regions of Earth were covered with ice caps, if our civilization had arisen back then a case could be made that accelerating their melting would be beneficial in the long run.
This isn’t really Great Filter material.



Even the higher orbits aren’t as big a problem as might be assumed. There are still mechanisms other than aerodynamic drag that clear debris from those orbits, they’re just slower. And the combination of fewer high-altitude satellites and much bigger orbital volume make it harder to get a dangerous density of debris going in the first place.