Think back to the last time you had to wait for a bus. How miserable were you? If you were in Boston, your experience might have included punishing wind and icy sleet — or, more recently, a punch of pollen straight to the sinuses. But in Florida’s Miami-Dade County, where the effects of climate change are both drastic and intensifying, commuters have to contend with an entirely different set of challenges: blistering temperatures and scorching humidity, making long stints waiting in the sun nearly unbearable. One of Miami’s most urgent…