Researchers are working to find effective methods for slowing the impacts of the warming climate.
Urban expansion can raise surface temperatures up to six degrees Fahrenheit in megapolitan areas, an Arizona State University news release reported. Researchers are looking at how methods such as "cool roofs, green roofs and hybrids of the two" could affect the warming world.
"This is the first time all of these approaches have been examined across various climates and geographies," Matei Georgescu, an assistant professor in Arizona State University's School of Geographical Sciences and Urban Planning and a senior sustainability scientist in the Global Institute of Sustainability said in the news release. "We looked at each adaptation strategy and their impacts across all seasons, and we quantified consequences that extend to hydrology (rainfall), climate and energy. We found geography matters."
Cool roofs may work California's Central Valley, but that may not be the case in other regions.
Cool roofs "reflect incoming solar radiation" which cools down buildings in the summer and helps reduce energy demand; this can be accomplished by painting the roof white.
The problem with cool roofs is that they continue to cool the building in the wintertime, which can end up increasing energy demand during those months.
Green roofs do not cool the building as much in the summer, but they also do not increase energy demand as much during the winter.
"The energy savings gained during the summer season, for some regions, is nearly entirely lost during the winter season," Georgescu said.
"In Florida, our simulations indicate a significant reduction in precipitation," he said. "The deployment of cool roofs results in a [two to four] millimeter per day reduction in rainfall, a considerable amount (nearly 50 percent) that will have implications for water availability, reduced stream flow and negative consequences for ecosystems. For Florida, cool roofs may not be the optimal way to battle the urban heat island because of these unintended consequences."
The team hopes to gain insight into the advantages or disadvantages of different urban adaption technologies.
"We simply wanted to get all of the technologies on a level playing field and draw out the issues associated with each one, across place and across time," Georgescu said.
"Urban-induced climate change depends on specific geographic factors that must be assessed when choosing optimal approaches, as opposed to one-size-fits-all solutions," the researchers said in the news release.
