You at least have to admit that they are a massive financial drain on people who do it just because it's 'normal' or some weird societal expectation. Even when you ignore the environmental considerations, having children is simply not a good idea for many people that do it.
Climate change is not going to be literally the end of the world, or even human civilization. At the worst we'll see mass immigration to the global north and the centre equatorial band become more difficult to inhabit.
Farm yields will probably drop to some extent, and we might see a few wars, but we are fairly well equipped to survive.