urban heat island

Most of the reported temperature measurements are taken in or near densely populated areas such as cities and airports. Due to buildings, pavement, traffic, etc, temperatures are higher than in other locations. Further, due to population growth and human activity such locations become increasingly warmer as time goes on. This results in what is known as the "urban heat island effect", thereby skewing the temperature data. Rural and remote areas, let alone oceans, contribute few data points.. Thus as urban areas have grown and continue to do so, temperature data becomes increasingly skewed. Balloon and satellite data show no warming beyond our0.6o C per century rise, as earth awakens from the glacial times. While recent measurements from satellites are considered more accurate, unfortunately the IPCC has not adopted their use. Rather, they apply an adjustment factor to land measurements, but many scientists disagree with the accuracy of this. 

 

To make matters worse, two prominent U.S. agencies, GISS and NOAA, who provide temperature data to the IPCC, obtained measurements from 6000 weather stations around the globe in the 1970's. By 1990 they discarded all but 1500. Most of the discarded stations were from colder climates. They discarded 565 of the 600 from Canada, mostly in northern areas. They retained only one above the Arctic Circle. The Canadian government operates 1400 surface weather stations across the country, with more than 100 above the Arctic Circle.  Other discards were a number of stations at high altitudes in South America in favor of beach locations.  As a result, do you suppose their "average" reported world temperatures increased? 

 

  Please read these interesting articles: 

     A New Analysis of the Urban Heat Island Effect 

     The Urban Heat Island Effect in Winnipeg 

     Urban Heat Islands - Hotter Cities

     The Urban Heat Island