I would imaging the massive amounts of concrete buildings and kilometres of black tar roads would absorb a tremendous amount of the sun's infra-red radiation during the day, and release it back to the atmosphere at night causing a significant rising average in temperatures - has anyone bothered to investigate this - the cigarettes are a non-issue - normal human breathing is exhaling from 30 000 to 50 000ppm CO2. Climate activists are generally not scientists, so I would not bother trying to discuss anything meaningful with them. Neo
