Background
Barrow, Alaska, which is situated on the Arctic Coastal Plain at the western edge of the Barrow Peninsula near the Chuckchi Sea at 71.3°N, 156.5°W, is described by the authors as "the northernmost settlement in the USA and the largest native community in the Arctic," the population of which "has grown from about 300 residents in 1900 to more than 4600 in 2000."

What was done
In mid-June of 2001, Hinkel et al. installed 54 temperature-recording instruments in and around Barrow, half of them within the urban area and the other half distributed across approximately 150 km² of surrounding land, all of which provided air temperature data at hourly intervals 1.8 meters above the surface of the ground. In this paper, they describe the results they obtained for the following winter (December 2001-March 2002).

What was learned
Based on urban-rural spatial averages for the entire winter period, the urban area was found to be 2.2°C warmer than the rural area. During this period, the mean daily urban-rural temperature difference increased with decreasing temperature, "reaching a peak value of around 6°C in January-February." It was also determined that the daily urban-rural temperature difference increased with decreasing wind speed, such that under calm conditions (< 4 knots or 2 m s^-1) the daily urban-rural temperature difference was 3.2°C in the winter. Last of all, under simultaneous calm and cold conditions, the urban-rural temperature difference was observed to achieve hourly magnitudes exceeding 9°C.

What it means
For a town of less than 5000 people, Barrow has an urban heat island effect that is huge. Perhaps that is why global warming is thought by some to be so strong in high northern latitudes: even small congregations of people in these regions can create a significantly elevated near-surface air temperature where they live and work.