Your brain on CO2
Our atmosphere's CO2 concentration was at about 300 parts per million in 1960, and it's at about 400ppm today, with 500ppm in urban environments. Indoors in poorly ventilated rooms, the concentration is around 1000ppm.
There has been research to study the effects of different levels of CO2 concentration in office employees and it found a 15% decrease in cognitive function at levels of 1000ppm.
In another study, the CO2 concentration was measured in different schools across the country, and in 50% of classrooms, the concentration was above 1000ppm. Concentrations about 1400ppm lead to a 50% decrease in cognitive function.
With rising CO2 levels, this means that by the end of the century, it is predicted that the CO2 will be high enough that humans as a species will have cognitive function reduced by around 15%.
This is a huge issue. People joke about the movie idiocracy becoming a reality, but with rising CO2 levels it's less of a joke and more of an inevitability. Humans are going to end up becoming more dumb than we already are because we just can't stop pumping CO2 into the atmosphere.
Besides decreasing cognitive function outright, a higher CO2 level has also been linked to reduced food nutrition. Besides vitamins and other micronutrients, there is a significant reduction in protein.
We need to reduce our CO2 emissions before useless food and stupid people become the least of our concerns.