First part boils down to the classic catholic strategy of "outbreed the enemy" with handwavy reasoning along the lines "worst things are not going to be happen to first world peoples". Some cherry picked factoids sprinkled here and there like sea level rise in SF and NYC. Total red herring.
In Europe we already saw the migration crisis from Syria and how it was a great polarizing tool. There is no border wall that can be built (let alone be moral in any shape or form) to keep out billions of starving and misplaced from the global south and keep us in the first world nice any cozy.
Then the part about the carbon cost of raising children goes to the tehcno-utopian realm of carbon capture with some really optimistic dollar numbers.
I'm 40 and probably going to have kids, but if I were young I'd totally hold older generations feet to the fire and tell governments: "fuck you, if you don't get your shit together and start doing something meaningful about the climate catastrophe, I'm not going to have kids".