It's not the biggest of gaffes, but as a politician working yo tackle climate change would've said something along the lines of "reproductive rights are good, but the link to climate change you suggest in your question is tenuous". Coz you know.. the emissions growth hasn't been coming from the areas with exploding populations. Eventually they will catch up, but I don't think central america, middle east, africa, india and south east asia would start emitting as much as china (proportionally) anytime soon. India for example has to increase its percapita emissions 8-10times before they reach the percapita emissions of the US. If we ignore per capita and look at the absolute numbers, the US is still 3x the emissions level. That sort of boom in emissions isn't gonna happen in the 10-15 years timespan that most of these leaders are talking about when fighting climate change.

Again, not per capita, but as an absolute figure, the top 10% produce as much pollution as the bottom 50% of the world. At that rate they are developing, the climate catastrophe will already have come to pass by the time they "catch up".

And more importantly, the person's question was also pretty weird for another reason. IIRC outside of africa, there aren't many countries having kids at wildly higher than replacement rates. In India for example, the youngest "slice" of the population pyramid is smaller than the previous generation, but their population will continue to grow because imrpoving medical facilities will result in the population pyramid getting "thicker" up top as more people live longer... So you can see why that last part makes this a touchy subject.

No expert really thinks population are gonna "explode" anywhere really, its expected to settle at around 11billion by 2100.