Urban farms as green infrastructure for urban heat mitigation

Abstract

Urban impervious surfaces are a significant contributor to the urban heat island (UHI). Efforts to mitigate the UHI often focus on reducing impervious surface area by adding green infrastructure, especially trees. Urban farms are another type of green infrastructure that provide green space in the form of pervious soils and actively transpiring crops. Using six years of hourly temperature measurements in and near an urban farm in St. Paul, Minnesota, USA, the goal of this study is to examine whether an urban farm, characterized by a high proportion of green space and a low proportion of tree-covered green space, can effectively contribute to urban heat mitigation. Results show that mean monthly temperatures at the farm do not differ significantly from nearby locations with a higher proportion of tree-covered green space. In contrast, mean monthly minimum temperatures at the farm in July and August are cooler by about 1 °C than the broader urbanized area, with no significant differences in mean monthly maximum temperatures. These results suggest that the urban farm potentially can reduce the nocturnal UHI without exacerbating the daytime UHI. Further research, including in other geographical/climatological contexts, will help elucidate the heat mitigation potential of urban agriculture as green infrastructure.