This is mostly a rhetorical post intended to convince people who are planning not to have kids because of climate change. I think these people trust the IPCC and so it's fair to use the IPCC's conclusions when talking to them without backing them up. If I were writing to try to convince global warming skeptics, I would be more careful about explaining why they should trust IPCC. I personally do trust IPCC but agree that it would be important to justify that if I was talking to people who might not.