Arctic Urban Heat Islands – Natural Laboratories of the Climate Change
Urban climate may significantly differ from the corresponding regional climate. Urban climate is warmer. Urban temperature raise considerably reduces severity of the cold northern climate, and hence, supports multitude of local environmental changes ranging from thawing of frozen soils to advancement of invasive species. We investigated the climate impact of long-term persistent urban warm anomalies through several observational field campaigns and analysis of the satellite remote sensing data for all 118 Arctic urban settlements. We used almost two decades of the Earth’s observations by the Moderate Resolution Imaging Spectro- radiometer MODIS instrument onboard of the polar orbiting Terra/Aqua NASA satellites to document urban land surface temperature and biological productivity anomalies. We found strong and persistent urban heat islands in all cities. On average, urban temperatures were higher by 1.5 to 2.5 K both in winter and summer. Further, we studied dependence between the observed urban warming and endogenous (e.g., population density) and exogenous (e.g., surrounding land cover type) factors. The field campaigns documented massive impact of the local climate anomalies. Urban ecosystems favor more productive and diverse plant species. Urban soils are warming and drying. The study emphasizes the need to account for inevitable and large local climate change following the urbanization of the Arctic. We argue that the urban heat island is an essential factor of the environmental quality and sustainable development in the region and more generally in the northern boreal areas. Many cities reveal the temperature anomalies that correspond to regional climate change by the mid- and end-21st century.