Phoenix warmed 10 degrees in the last 50 years, while the less urbanized surrounding areas have warmed much less. It must be the CO2.
The effects of the UHI are most pronounced during the summer (June-July-August) months. In a simple comparison, average high and low temperatures from Maricopa, AZ and Phoenix Sky Harbor International Airport were compared (Figures 2 and 3). Little difference exists between the high temperatures from 1961 through 2007; however, low temperatures have trended warmer at Sky Harbor as compared to Maricopa, indicative of the existence of a strengthening UHI.
Why would billions of cars, buildings, air conditioners, heaters, parking lots, asphalt roads, etc. cause surface temperatures to be affected?