Hi Hi Mate,
You would think that man made structures obviously have an effect. Cities create what is known as 'Urban Heat Islands', and have their own microclimates.
In towns and cities:
Sunshine duration 5 to 15% less
Annual mean temperature 1 to 2 degrees warmer
Temperatures on sunny days 2 to 6 degrees higher
Occurrence of frosts 2 to 3 weeks fewer
Relative humidity in winter 2% less
Relative humidity in summer 8 to 10% less
Total precipitation 5 to 30% more
Number of rain days 10% more
Number of days with snow 14% fewer
Cloud cover 5 to 10% more
Occurrence of fog in winter 100% more
Amount of condensation nuclei 10 times more
As well as the absorption you mention, heat release from industrial and domestic buildings
contributes to UHI's, as does the build up of hygroscopic pollutants from cars/industry which helps form smog/cloud which traps radiation - pollution domes.
Less surface water in urban areas means less evapotranspiration and more heat in lower atmosphere.
Also increased heat and activity leads to more air cooling systems = increased electricity use = release of more CO2.
However, UHI's contribution to global warming is negligible. The Northern Hemisphere contains the vast majority of UHI's and the surface air temperature and lower-tropospheric temperature is not significantly different from the Southern Hemisphere.
Even if UHI's had a greater effect on the ambient temperature, this planet would probably be able to deal with it by the reduction of CO2 allowing more heat to radiate out into space. This is the issue - mass deforestation and the continued CO2 release from human activity is preventing heat release. Whilst this planet attempts to balance things, we are still pumping crap into the atmosphere.
If you want to help, turn your computer off and plant a tree
Regards,
Blacknad.
