In 2050, the biomass of all humans will be greater than the biomass of all humans in 2002, and thus so should the average temperature of the air increase.
All we need is to test the idea. The number-crunching can then begin.
Is there a correlation between planting trees and grass in Phoenix and warmer nights?
Not to worry. The Aids epidemic will take care of that.
Ah, yes, the heat-island effect. Most of the older climactic data came from airports, which were (reasonably) located out away from the cities they served. However, as time went by, cities expanded and surrounded the airport with construction, concrete, people, etc. This raised the ambient temperature of the airport, without any climactic change whatsoever.