Prioritizing adaptation to urban-induced climate change

U.S. population forecasts for 2100 range from 380 (B1 scenario) to 690 million (A2 scenario) inhabitants. Based on these estimates, scenarios of housing density and impervious surface cover datasets consistent with greenhouse gas emissions storylines have been developed for the conterminous U.S. as part of the Integrated Climate and Land Use Scenarios (ICLUS) project. These data were input into and used as surface boundary conditions within the Weather Research and Forecasting (WRF) modeling system to examine hydroclimatic consequences owing to urban expansion across the conterminous U.S. by 2100.

Continuous, multi-year and multi-member continental scale numerical simulations, at 20-km resolution, were performed for a modern day urban representation (Control), a maximum urban expansion (A2 scenario), and a minimum urban expansion (B1 scenario). A trio of adaptation approaches were explored to examine the potential offset of urban-induced warming to growth of the built environment. These include widespread adoption of cool roofs, a simple representation of green roofs, and a hypothetical hybrid approach integrating properties of both cool and green roofs (i.e., reflective green roofs).

Impacts of urban expansion vary regionally, with urban-induced summertime warming greatest for the Central Valley of California (whose landscape undergoes transition from agricultural lands) and least for Florida. Widespread adoption of adaptation strategies exhibits hydroclimatic impacts that are regionally and seasonally dependant. To help prioritize region-specific adaptation strategies the potential to offset urban-induced warming by each of the trio of strategies will be examined and contrasted across the various hydrometeorological environments.