Urban Heat Projections in a Changing Climate: Washington, DC, Case Study

Abstract

Climate change has been shown to elevate urban temperatures, intensify extreme heat events, and raise heat exposure risks in cities. Characterizing the future trends and levels of heat-related problems is important in order for cities to plan and initiate appropriate climate adaptations. This paper proposes a method to project the urban heat island (UHI) effect and heat waves using an asynchronous regional regression model (ARRM) that statistically downscales Coupled Model Intercomparison Project Phase 5 (CIMP5) simulations into local observations. A case study illustrates the application of the proposed method using Washington, DC, data. Projections based on the highest greenhouse gas concentration scenario, representative concentration pathway (RCP) 8.5, indicate a continually increasing trend of heat waves in Washington, DC, in the 21st century. The lowest concentration scenario, RCP 2.6, leads to a slight decay of heat waves after a half-century of increase. The UHI effect projected by RCP 8.5 will be stronger at hot temperatures but weaker at low temperatures, whereas the UHI effect projected by RCP 2.6 will stay the same as the present.