The other way of solving the problem is to let people kill each other fighting over dwindling resources as the planet dies and becomes sterile, because we're not smart enough as a species to find and maintain a sustainable state of equilibrium with our environment. This scenario is apparently the one we're choosing, by default.

Human industrial/economic activity is what's killing the planet. The planet cannot sustain the side effects of an economy of 7 billion people. It doesn't matter what you think, it doesn't matter what you say, it doesn't matter if you recycle, or drink out of paper straws, or vote for the green party, or switch to hydrogen cars, or bury your head in the sand. If you want to solve the problem, but don't want to have less children, then figure out another way to reduce the population by billions of people. I can't wait to hear it.