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Politics : The Environmentalist Thread -- Ignore unavailable to you. Want to Upgrade?

To: Brumar89 who wrote (20387)	2/15/2008 5:13:23 PM
From: maceng2	Read Replies (1) \| Respond to of 36921

#16 It's Urban Heat Island effect 2.6% skepticalscience.com skepticalscience.com It's Urban Heat Island effect The skeptic argument...There has been a great deal of controversy about the accuracy of the temperature data, mainly the bias of temperature data due to urban heat island effect. This controversy has lead many to focus on rural temperature stations. Rural stations are intended to represent the cool breezy countryside, small towns, farms, trees and grass. In recent weeks, researchers have been visiting these temperature stations. What they noticed was that there are serious problems with the quality of these temperature stations. They noticed that many of these temperature stations were located next to concrete buildings, near hot exhausts of air conditioning units, attached to metal towers and poles, surrounded by driveways and above gravel. What the science says... When compiling temperature records, NASA GISS go to great pains to remove any possible influence from Urban Heat Island Effect. They compare urban long term trends to nearby rural trends. They then adjust the urban trend so it matches the rural trend. The process is described in detail on the NASA website (Hansen 2001). They found in most cases, urban warming was small and fell within uncertainty ranges. Surprisingly, 42% of city trends are cooler relative to their country surroundings as weather stations are often sited in cool islands (eg - a park within the city). The point is they're aware of UHI and rigorously adjust for it when analysing temperature records. This confirms a peer review study by the NCDC (Peterson 2003) that did statistical analysis of urban and rural temperature anomalies and concluded "Contrary to generally accepted wisdom, no statistically significant impact of urbanization could be found in annual temperatures... Industrial sections of towns may well be significantly warmer than rural sites, but urban meteorological observations are more likely to be made within park cool islands than industrial regions." Another more recent study (Parker 2006) plotted 50 year records of temperatures observed on calm nights, the other on windy nights. He concluded "temperatures over land have risen as much on windy nights as on calm nights, indicating that the observed overall warming is not a consequence of urban development". Does temperature rise correlate with urban areas? Surfacestations.org are compiling photographs of US weather stations photographs to demonstrate the unreliability of surface temperature measurements. Photos are an anecdotal way to do science - the only way to quantify the impact of urban heat island is to analyse the data from these stations. This is what GISS have done, with their methodologies and data freely available online. Nevertheless, a picture is worth a thousand words (although not a thousand data points) so I'll indulge in some pretty pics also. Compare a map of surface temperature rise for 2005 (the redder areas show greatest temperature rise) to a satellite photo of earth at night. see link above