He noticed a few of the protesters toting, or rather wearing, odd getups that in retrospect were the early prototypes of earthsuits: garments that looked much too heavy for such a hot day, because underneath they consisted of networks of cooling tubes against the skin. Those were connected to backpack units with lithium battery packs driving a refrigeration system. Heat had to be got rid of eventually, so the backpack had a chimney projecting straight up above the wearer’s head, shooting hot air that was visible from the heat waves coming off it. Those who wore them tended to be heavyset nerds.