If you tell me that the Earth is going to change for the worse, and there's nothing we can do to stop it, then my response is we shouldn't try. We should instead work on how to survive the change. No reason to waste resources trying to stop something that can't be, spend them on dealing with it instead.
Likewise if you tell me Earth is doomed, and there's nothing we can do to stop it, then my response is that we should just not worry about the future at all, and enjoy what time we have left because there isn't anything else to do.
However if you tell me that we are creating a problem, but we can fix that problem by changing what we are doing, then I'm interested in hearing what you propose we do, what it would cost, how it would mitigate the problem, etc, etc.
If a problem is solvable then it makes sense to talk about what it would take to solve it. If a problem is just something we can't do anything about then we shouldn't worry about trying.