Could the Urban Heat Island effect account for some of this reported rise in temperature? The Intergovernmental Panel on Climate
No. The effects of expanding cities and changes in land-use on global temperatures are not significant as far as the average values over whole continents, or even Earth’s hemispheres, are concerned. More ….
The Urban Heat Island effect refers to the fact that cities are usually warmer than the countryside. This is partly because heat from the Sun is stored during the day by the large areas of concrete and tarmac found in cities and is released at night; other factors in cities include higher levels of fine particles (aerosols) and less sunlight being reflected by roofs, car parks etc. This phenomenon also affects rainfall, cloudiness and the daily temperature difference between night and day. Some temperature recording locations, once in the open countryside, have been absorbed into an urban area as the adjacent city grew so that the temperature measurements could have been skewed towards warmer values. However it is relatively simple to check such suspect data for quality and consistency to avoid the Urban Heat Island effect. The IPCC (2007) stated that ‘…. effects of urbanisation and land use change on the global temperature record are negligible … as far as hemispheric- and continental-scale averages are concerned.’