Seeing the city for the trees : public space, climate adaptation, and environmental justice in LA and New York's "Million Trees" campaigns

Abstract

Urban heat waves are becoming more frequent and severe as climate change magnifies the "urban heat island" effect. While trees significantly reduce ambient temperatures through shading and evapotranspiration, their effect is highly localized. Consequently, more people die from heat waves in neighborhoods with fewer trees. Moreover, low-income minority neighborhoods typically lack tree cover. Expanding the urban forest is therefore a critical climate adaptation measure, as well as an issue of environmental justice. To address these disparities, the City of Los Angeles and New York City each formed a public-private partnership to plant a million trees. Previous research has demonstrated that over-reliance on private capital may bias public-private partnerships towards profitable investment. Social justice goals are therefore harder to achieve where there is a lack of public funds. This research goes a step further by examining whether social justice is also harder to achieve where there is a lack of public space. New York and Los Angeles are often considered extreme examples of public and private space, making these cities ideal case studies. Moreover, in both cities, investment in public space, particularly green space, has historically been concentrated in affluent neighborhoods. This analysis reveals that while MillionTreesNYC planted far more trees, it did not prioritize low-income minority communities to a measurable degree. In contrast, MillionTreesLA planted fewer trees overall, yet concentrated them in low-canopy areas with higher poverty rates and a higher proportion of non-white residents. These outcomes were shaped by differences in program funding, which produced differences in each program's degree of centralized efficiency versus decentralized responsiveness to local contexts within underserved areas. However, the most critical factor in shaping environmental justice outcomes was the distribution of different types of public space across each city and among socioeconomic groups. These spatial inequalities directed the flow of trees differently in New York versus Los Angeles, with the result that the latter was better able to target low-income minority neighborhoods with low tree canopy. Remediating these socio-spatial inequalities will require cities to rethink public administration of public space as a tool for redistributing environmental resources to achieve greater environmental justice and climate justice. Such strategies will be critical to adapting vulnerable neighborhoods to the effects of climate change. These findings can inform on-going efforts to advance environmental justice and climate adaptation via public-private partnerships, particularly in an era when privatization of urban space and the need for urban climate adaptation are both increasing.