Using up fossil fuels is simply not sustainable. Taking steps to adjust humanity’s behavior to that simple fact is resulting in less suffering the earlier it is started, and much more the longer we wait.
And that is only even without recognizing that the coastal cities will actually have to fight, among other issues, with raised water levels. If you are old enough, you won’t see it, but your children will.
That’s the major problem, the size of the problem will be obvious only once there’s no chance for fixing the problem.
That’s the risk that has to be addressed.