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Urban Heat Islands and U.S. Temperature Trends

Filed under: — group @ 13 February 2013

Guest Commentary by Zeke Hausfather and Matthew Menne (NOAA)

The impact of urban heat islands (UHI) on temperature trends has long been a contentious area, with some studies finding no effect of urbanization on large-scale temperature trend and others finding large effects in certain regions. The issue has reached particular prominence on the blogs, with some claiming that the majority of the warming in the U.S. (or even the world) over the past century can be attributed to urbanization. We therefore set out to undertake a thorough examination of UHI in the Conterminous United States (CONUS), examining multiple ‘urban’ proxies, different methods of analysis, and temperature series with differing degrees of homogenization and urban-specific corrections (e.g. the GISTEMP nightlight method; Hansen et al, 2010). The paper reporting our results has just been published in the Journal of Geophysical Research.
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  1. D.E. Parker, "Climate: Large-scale warming is not urban", Nature, vol. 432, pp. 290-290, 2004.
  2. X. Yang, Y. Hou, and B. Chen, "Observed surface warming induced by urbanization in east China", J. Geophys. Res., vol. 116, 2011.
  3. J. Hansen, R. Ruedy, M. Sato, and K. Lo, "GLOBAL SURFACE TEMPERATURE CHANGE", Rev. Geophys., vol. 48, 2010.

2012 Updates to model-observation comparisons

Time for the 2012 updates!

As has become a habit (2009, 2010, 2011), here is a brief overview and update of some of the most discussed model/observation comparisons, updated to include 2012. I include comparisons of surface temperatures, sea ice and ocean heat content to the CMIP3 and Hansen et al (1988) simulations.
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Unforced Variations: Feb 2013

Filed under: — group @ 4 February 2013

This month’s open thread on climate science…

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