Further to my point in the above post about the urgent need to lower the world's population, I've just come across a HN story titled “Mathematics in the 21st century” by mathematical physicist John Baez†, HN story: https://news.ycombinator.com/item?id=27014683.

The HN item links to a lecture given by Baez on YouTube here: https://www.youtube.com/watch?v=lUqqQXFTHUY.

He discusses issues that mathematics faces in the 21st Century and as part of that he discusses what both mathematics and mathematicians can do in the new Anthropocene epoch (human era) and he raises the subject of the greatest challenges humankind is now facing such as the high level of atmospheric carbon dioxide, dangerous changes to the biosphere and global warming (even veganism gets a mention).

At 33:24 into the lecture, he quotes the following point on a slide:

"Consider having fewer children or adopting. In the US each extra child adds 9,400 tonnes of carbon dioxide to the air" [over his/her lifetime of 80 yrs].

He goes on to say the statement is controversial and gets people annoyed, and they get extremely emotional about it.

You can download Baez's lecture slides here: https://topos.site/topos-colloquium/assets/slides-2021-03-25...

And the source of his reference comes from here: https://terra.oregonstate.edu/2011/05/one-less-child/ Quote:

" The Oregon State University professor of statistics and OSU colleague Michael Schlax published a paper in the journal Global Environmental Change describing an individual’s “carbon legacy” — the amount of carbon likely to be emitted in the future by one’s descendants. Parents, they reasoned, could be held accountable for one half of their children’s emissions, one quarter of their grandchildren’s and declining portions down through the generations."

I was unaware of these new statistics until now but I'm not the least surprised at what they show. As I've already mentioned in my earlier post, the Green/Environmental movement has deliberately played down these stats for decades as the subject is so sensitive. Baez also makes the point to the effect that if no one mentions the issue then it remains in the background and it won't go away.

As I've discussed earlier, the biggest elephant in the room is population growth. The fact that many people find the subject very confronting and too unpalatable to discuss is a great problem for the human race. As we've seen before, this issue is almost too 'hot' to handle and it's a game person who mentions it—as it's a case of 'shooting the messenger' for anyone who does.

For example, Stanford Professor Paul R. Ehrlich (https://en.wikipedia.org/wiki/Paul_R._Ehrlich) and his wife Anne received considerable criticism for their widely read 1968 book The Population Bomb https://en.wikipedia.org/wiki/The_Population_Bomb. That said, the Ehrlichs published that book 53 years ago and I'd suggest that now, given the huge amounts of newly-measured environmental data and much more sophisticated models of climate change, it will be much harder to dispute these claims.

Given the subject's very controversial and emotional nature, I doubt that the passage of time will have made its acceptance any easier to swallow.

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† Baez's Wiki bio: https://en.wikipedia.org/wiki/John_C._Baez