New paper finds urban heat islands can account for up to 2°C warming

A paper published today in Theoretical and Applied Climatology finds "The impact of urbanization on annual mean surface air temperature has been found to be more than 1 °C in urban areas, and the maximum difference is almost 2 °C." While climate alarmists claim this urban heat island [UHI] effect has had an insignificant effect on observed temperatures, this paper and many others show that the UHI effect is significantly greater than the 0.7C global warming observed since 1850. The majority of weather stations are located near areas of urbanization or have other siting issues that can exaggerate warming. 

Theoretical and Applied Climatology

November 2012

Modeling the climatic effects of urbanization in the Beijing–Tianjin–Hebei metropolitan area

• Mingna Wang, 
• Xuezhen Zhang, 
• Xiaodong Yan

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Abstract

In this analysis, the weather research and forecasting model coupled with a single-layer urban canopy model is used to simulate the climatic impacts of urbanization in the Beijing–Tianjin–Hebei metropolitan area, which has experienced significant expansion in its urban areas. Two cases examining current landscapes and the sensitivity test of urban areas replaced by cropland have been carried out to explore the changes in the surface air and atmospheric boundary structure. The impact of urbanization on annual mean surface air temperature has been found to be more than 1 °C in urban areas, and the maximum difference is almost 2 °C. The change in near-surface level temperature is most pronounced in winter, but the area influenced by urbanization is slightly larger in summer. The annual mean water vapor mixing ratio and wind speed are both reduced in the urban area. The effect of urbanization can only heat the temperature inside the urban boundary layer, below 850 hPa. The modeling results also indicate that the underlying surface thermal forces induced by the “urban heat island” effect enhance vertical air movement and engenders a convergence zone over urban areas. The convergence at low level together with the moisture increases in the layer between 850 and 700 hPa triggered the increase of convective precipitation.