Anthropogenic heat island at Barrow, Alaska, during winter: 2001–2005

The village of Barrow (71°N latitude) is the largest native community in the Arctic, with a population of approximately 4500 people. Situated on the coast of the Arctic Ocean in northernmost Alaska, the area is entirely underlain by permafrost. Although most supplies must be imported, Barrow relies on local natural gas fields to meet all energy requirements for building heat and electrical power generation. This energy eventually dissipates into the atmosphere, and can be detected as a pronounced urban heat island (UHI) in winter. Since 2001, a 150 km 2 area in and around Barrow has been monitored using ∼70 data loggers recording air temperature at hourly intervals. The mean daily temperature of the urban and rural areas is calculated using a representative sample of core sites, and the UHI magnitude (MUHI) is calculated as the difference in the group averages. The MUHI is most pronounced in winter months (December–March), with temperatures in the urban area averaging 2°C warmer than in the surrounding tundra and occasionally exceeding 6°C. The MUHI is maximized under cold and calm conditions, and decreases with wind speed and warmer temperatures. It is strongly and directly correlated to natural gas utilization on a monthly basis. Integrated over the home heating season, there is an 8% reduction in freezing degree days in the village. It is unlikely that anthropogenic heat contributes to the forward shift in the snow meltout date that has been observed near Barrow over the past 60 years.