“My theory is that the BEST folks must have eaten at a Hollywood Chinese restaurant. You can tell because when you eat there, an hour later you find you’re hungry for stardom,” says Willis Eschenbach.
From Eschenbach’s “What the BEST data actually says:
We still have not resolved the UHI issue, in any of the land datasets… I remind folks again that the hype about BEST showing skeptics are wrong is just that. Most folks knew already that the world has been generally warming for hundreds of years, and BEST’s results in that regard were no surprise. BEST showed nothing about whether humans are affecting the climate, nor could it have done so. There are still large unresolved issues in the land temperature record which BEST has not clarified or solved. The jury is out on the BEST results, and it is only in part because they haven’t even gone through peer review.
The different studies over the years have come up with differrent results to the point that we don’t know whether small towns have higher UHI TREND or large cities. A large city may have a measured difference between no city and the city of as much as 10c, BUT that difference may have SLOWLY grown for the last 100 years meaning the actual yearly trend would be about .1c.
A small town that has just started a growth spurt may only have a UHI of 2c, but, the TREND due to additions of asphalt, concrete, and additional waste heat could be 1c per year.
A large city may not have any changes happening, in the area of the thermometer so could also have a ZERO TREND, as could a small town, while still have its previously grown UHI. Which cities have a UHI WARMING TREND and how much the trends are are a complete unknown at this point without a massive effort to increase the collection of data such as companion stations as close to the current thermometers as possible but still outside of human influence. Another possibility would be for the satellite measurements to be extended to ground level to find out what the areas surrounding the thermometers are doing and comparing to the current thermometers.
Another issue is that two identical cities with the same population and growth rate could be on the coast and inland. The coastal city will have a lower effect from UHI as the winds will be taking more heat away than in the valley where the wind direction will have a lesser effect.
As UHI is also affected by energy use and the efficiency of motors, air conditioners, insulation… it is another variable that is not easily estimated.
We just don’t know how much the UHI has affected the temperature records and just as important, WHEN the largest effects were happening!!! The current lack of warming may be partially due to the lower economic growth caused by our insane leftard governments!!
During the 70’s, the high altitude/latitude and rural reporting stations were closed. We used to have a rural reporting station in our neighborhood and it was closed. Also many small towns stations were closed as well (Leadville CO, Big Piney WY and Cutbank MT) at the time I think it was for economic reasons, but it still affects accurate temperature reporting.
Muller says UHI is not a factor, but then admits this :-
“Urban areas are heavily overrepresented in the siting of temperature stations: less than 1% of the globe is urban but 27% of the Global Historical Climatology Network Monthly stations are located in cities with a population greater than 50000.”
http://notalotofpeopleknowthat.wordpress.com/2011/10/23/mullers-problem-with-uhi/