"The carbon dioxide released into the atmosphere by industry's burning of coal and oil-—more than half of it during the last generation—may have changed the atmosphere's composition sufficiently to account for a general warming of the world by about one degree Fahrenheit." (Page 512 / 666 / 9)
“The ever accelerating progress of technology and changes in the mode of human life give the appearance of approaching some essential singularity in the history of the race beyond which human affairs, as we know them, could not continue.”
which some people worry about.
To me, his thoughts on the weather are some of his most interesting things to read just from the fact even someone with the brain power of Von Neuman could be utterly and completely wrong.
It is the ultimate lesson in the fallibility of what you believe to be true.