Urban Warming vs. Global Warming in East China
Yang, X., Hou, Y. and Chen, B. 2011. Observed surface warming induced by urbanization in east China. Journal of Geophysical Research 116: 10.1029/2010JD015452.
As their contribution to the subject, Yang et al. used monthly mean surface air temperature data from 463 meteorological stations, including those from the 1981-2007 ordinary and national basic reference surface stations in east China and from the National Centers for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, in order to investigate the effect of rapid urbanization on temperature change for six different categories of population size/density -- metropolis, large city, medium-sized city, small city, suburban and rural -- as determined from satellite-measured nighttime light imagery and census data.
The three researchers say their findings indicate that "rapid urbanization has a significant influence on surface warming over east China," noting that "overall, UHI effects contribute 24.2% to regional average warming trends," and that "the strongest effect of urbanization on annual mean surface air temperature trends occurs over the metropolis and large city stations, with corresponding contributions of about 44% and 35% to total warming, respectively," with UHI trends of 0.398°C and 0.26°C per decade. And they say that due to other considerations, the UHI warming trends and their contributions to the overall warming over east China provided in their paper "can still be regarded as conservative."
The Chinese scientists conclude that if such UHI trends continue, "certain metropolitan areas may experience a rate of warming well beyond the range projected by the global climate change scenarios of the IPCC," referencing Stone (2007), while adding that "the increasing divergence between urban and rural surface temperature trends highlights the limitations of the response policy to climate change [that] focus only on greenhouse gas reduction," citing Stone (2009). And, of course, their findings call into serious question some of the basic conclusions of the IPPC, such as the organization's claim that UHI effects "have a negligible influence on global warming trends."
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