Summer-time climate impacts of projected megapolitan expansion in Arizona

• Published in: Nature climate change 2013-01, Vol.3 (1), p.37-41
• Main Authors: Georgescu, M., Moustaoui, M., Mahalov, A., Dudhia, J.
• Format: Article
• Language: English
• Subjects: 704/844/2739; 704/844/685; 704/844/841; Built environment; Climate Change; Climate Change/Climate Change Impacts; Climate effects; Convection, turbulence, diffusion. Boundary layer structure and dynamics; Earth and Environmental Science; Earth, ocean, space; Environment; Environmental Law/Policy/Ecojustice; Evapotranspiration; Exact sciences and technology; External geophysics; Greenhouse gases; Indexing in process; letter; Meteorology; Sustainable development; Urban environments; Urban sprawl
• ISSN: 1758-678X; 1758-6798
• DOI: 10.1038/nclimate1656

Regional climates can be modified by urban development affecting the radiation and hydrological balances. This study looks at the expanding megapolitan area in the Sun Corridor, Arizona, USA, and models local climate change in line with urban development. Efforts characterizing the changing climate of southwestern North America by focusing exclusively on the impacts of increasing levels of long-lived greenhouse gases omit fundamental elements with similar order-of-magnitude impacts as those owing to large-scale climate change 1 , 2 . Using a suite of ensemble-based, multiyear simulations, here we show the intensification of observationally based urban-induced phenomena and demonstrate that the direct summer-time climate effects of the most rapidly expanding megapolitan region in the USA—Arizona’s Sun Corridor—are considerable. Although urban-induced warming approaches 4 °C locally for the maximum expansion scenario, impacts depend on the particular trajectory of development. Cool-roof implementation reduces simulated warming by about 50%, yet decreases in summer-time evapotranspiration remain at least as large as those from urban expansion without this mode of adaptation. The contribution of urban-induced warming relative to mid- and end-of-century climate change illustrates strong dependence on built environment expansion scenarios and emissions pathways. Our results highlight the direct climate impacts that result from newly emerging megapolitan regions and their significance for overcoming present challenges concerning sustainable development 3 , 4 .