Exploring urban agriculture as a climate change mitigation strategy at the neighborhood scale
Habeeb, Dana M.
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Extreme heat events are responsible for more annual fatalities in the United States than any other form of extreme weather. Urban centers are particularly vulnerable to the threats of excessive heat as most cities are home to large populations of lower income individuals who often lack access to air conditioning or adequate healthcare facilities. Urban populations are also more likely to be exposed to extreme heat due to the urban heat island (UHI) phenomenon. As the global population continues to urbanize, the number of vulnerable individuals will continue to increase making urban heat island mitigation strategies all the more important. In this research, I explore urban agriculture as an urban heat island mitigation strategy. I conduct a land cover analysis to investigate the climate effect of urban agriculture on local temperatures. I use satellite temperature data, land cover data, and urban form metrics to estimate how the percent change in urban agriculture impacts local temperatures. My research shows that urban agriculture decreases high nighttime temperatures during summer months, which is an important public health finding as nighttime temperatures are a better metric for capturing negative health effects from extreme heat than daytime temperatures. At the local level, an increase of 10-acres per km2 in agricultural land cover can reduce nighttime temperatures by approximately 0.65°F accounting for approximately 10% of Atlanta's UHI effect. Agricultural lands outperformed forested land cover as a nighttime cooling mechanism across the Atlanta MSA. I investigated whether the urban form of a neighborhood impacts the relationship between urban agriculture and local climate and found an interaction effect between urban agriculture and urban form when a heat wave is present. Agricultural implementations in dense urban neighborhoods decrease temperatures more than in the residential areas. Additionally, I found that a minimum of seven acres of agricultural lands must be implemented before cooling effects will occur in urban areas. Though agricultural lands can act as a successful heat mitigation strategy by lowering nighttime temperatures, during heat waves the magnitude of the cooling effect is diminished. As such, I argue for an active management strategy to ensure that urban agriculture maintains its cooling potential during extreme heat conditions. In addition, I argue that urban agriculture should not only be placed in cities but that the morphology of the built environment should be taken into consideration when selecting locations for urban agriculture. When designing heat mitigation strategies, it is important for planners and policy makers to quantify the difference between vegetative approaches in order to understand the tradeoffs they are making climatically, environmentally, and socially. As such the results of my research can help guide planners when selecting between vegetative UHI mitigation strategies and may further support the burgeoning urban agriculture movement.