I've had a similar thought related to CO2. The human race will become collectively dumber as CO2 levels rise. It might take a while for CO2 levels to double or

I've had a similar thought related to CO2. The human race will become collectively dumber as CO2 levels rise. It might take a while for CO2 levels to double or quadruple, but high indoor CO2 levels make people perform worse, and so increasing the base CO2 level will make everyone dumber. And as you say, the heat won't help either. This is an angle I've taken with people who don't believe human activity increases temperatures. A small intelligence hit applied to literally every single human is a big thing. And it's hard for people to deny we're increasing CO2 levels.