Rural air temperatures show significant urban heat island effects

Abstract

Abstract While the urban heat island (UHI) impact on air temperature is largest in densely populated cities, it also substantial at low population densities. A novel method for quantifying UHI warming as a function of population density using thousands of weather stations in the Northern Hemisphere shows that rural locations have average urbanization-related warming effects equivalent to twenty years of observed global warming. This is important because previous comparisons of warming at urban locations to presumed unaffected rural locations have likely underestimated the UHI warming of both. It also suggests that adaptation to, and mitigation of, increasing urbanization is more important for smaller towns and cities than for densely populated urban centers, the latter having already experienced saturation of UHI warming.