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Four Winters of Urban Heat Island Data from Barrow, Alaska (USA)
Reference
Hinkel, K.M. and Nelson, F.E. 2007. Anthropogenic heat island at Barrow, Alaska, during winter: 2001-2005. Journal of Geophysical Research 112: 10.1029/2006JD007837.

What was done
The authors report that since 2001 for the village of Barrow, Alaska (71.3N, 156.5W) - which has a population of approximately 4500 people - screen-level air temperatures have been recorded at hourly intervals by 68 data loggers that were distributed "to form an approximate grid pattern over the 150-km2 study area" in and around the village.

What was learned
On the basis of rural and urban group temperature averages for the period 1 December to 31 March of four consecutive winters, Hinkel and Nelson determined that the spatially-averaged temperature of the urban area was about 2C warmer than that of the rural area, and that it was not uncommon for the daily magnitude of the urban heat island to exceed 4C. In fact, they report that on some days the magnitude of the urban heat island exceeded 6C, and that values in excess of 8C were even recorded, while noting that the warmest individual site temperatures were "consistently observed in the urban core area."

What it means
When attempting to measure a background global temperature increase that is believed to have been less than 1C over the past century (which represents a warming on the order of 0.1C per decade), it has to be appreciated just how difficult that task is when the presence of a mere 4500 people can create a winter heat island that may be two orders of magnitude greater than the signal being sought. Clearly, there is no way that temperature measurements made within the range of influence of even a small village can be adjusted to the degree of accuracy that is needed to reveal the true magnitude of the pristine rural temperature change. The only data of any value to this endeavor must be obtained from areas upon which there has been no historical human encroachment.

Reviewed 20 June 2007