"China’s a country of 1.4 billion that very soon is going to have a child population you’d expect in a country of 700 million". Noah Smith notes that it's likely the birth rate fall has actually been gradual, but they were trying to avoid reporting it until now. Yglesias says that his book 1 Billion Americans can now be scaled back to 700 Million Americans.
As a reminder, the iron-air batteries are really big and heavy, so they're useless for cars, but for grid storage, none of that matters.
Believe it or not, housing is the thing to focus on in terms of having the most impact we can on people's lives. A 'kitchen table issue' as M. Nolan Gray puts it.
He points to a study indicating we could have prototype vaccines ready for all 26 of the known viral families for about 24 billion dollars. A steal at twice the price!