Observations and downscaled predictions of effects of land use and urban heat island on climate

July minimum temperatures at the Reno, Nevada airport have increased nearly four times faster than 25 regional rural stations. The localized increase in temperatures is believed to be a strong urban heat island (UHI) signal due to the rapid population growth in the Reno-Sparks metropolitan area. Since 1937, July minimum temperatures in Reno have increased by a factor of three when compared to rural stations, and since 1980, this rate has increased to nearly a factor of 4. 13 summertime Landsat images have been analyzed to develop an understanding of patterns of land use change in relation to the development of the UHI. Because the development of the UHI exceeds that predicted by the classical method of Oke (1973), we hypothesize that recent conversion of land uses from historical marshlands and agricultural to urban has changed the regional Bowen ratio and represents a key role in the UHI signal. Two future urban growth scenarios have been derived for the Reno-Sparks area for 2050 and 2099 and future UHI influences are extrapolated to these scenarios for inclusion in statistically downscaled future climate predictions from two IPCC emissions scenarios and 3 global climate models (CCSM3, CSIROMk3.5, and ECHAM5) during the period 2009-2099 to better predict future climate in this region and examine implications for future air quality, public health, energy, and water demand for the Reno-Sparks area.