John Baez: “Mathematics in the 21st century”

At 33:24 into the video John Baez quotes a research article about the environmental implications of having children. That topic was also covered by me earlier in Ask HN: Why Aren't You Vegan? https://news.ycombinator.com/item?id=27005062 and I've since referred a post there to this one.

Unfortunately, that topic is now flagged. It seems that that it's still too 'hot' to handle (even for HN) as Paul Ehrlich found out decades ago. Given that fact, I'm surprised that Baez is brave enough to mention it here (of course he's correct to do so).