I got a mathematics degree in the early 80s, but I knew about this long before that, because you don't need a mathematics degree to do simple arithmetic.

I just thought we would do some thing about it long before now.

I tried: we have no kids, I have never owned a car, we have a plant-based diet, we haven't flown in years. Very few other people seemed interested in changing, and even if they had, it would not have made any real difference.

To be honest, this is the thing that consoles me, and it's pretty thin beer: I don't think we were ever getting past this, and I am skeptical that any intelligent technological species would get past this. One generation would've had to dramatically cut its standard of living and population so that two generations later, disaster would not occur, and all of this traumatic life change based on abstract mathematics.

It wasn't going to happen. In exactly the same way that each of us has a finite and fairly short lifespan, our technological society was never going to go on for more than a few centuries. We should be glad that we saw the most exciting and wealthy part.

I should add that this is no excuse for not trying to mitigate the catastrophe, no excuse for waste, no excuse for obsessive consumption. "Someone else would've done it", is not any sort of moral reasoning.