A binational social vulnerability index (BSVI) for the San Diego-Tijuana region: mapping trans-boundary exposure to climate change for just and equitable adaptation planning

To pursue just, inclusive, and participatory climate adaptation planning and policy, it is important to understand both regional climate trends and the ecological services that reduce vulnerability and exposure to climate risks at the community level. Rapidly growing cities like Tijuana and San Diego are doubly exposed to climate change because they have fewer resources to confront them and yet responsible for basic services that support everyday life of their residents, challenges that are complicated by the divided institutional and social context of an international border region. In the binational context, the regional community is fragmented by institutional, academic, and cultural factors, leading to adaptation planning that stops at the border despite the shared ecological setting of human settlements. This fragmentation is particularly dangerous for climate adaptation planning because it obscures inequalities as well as opportunities contained in the binational region. To address this deficit, we have synthesized information from a variety of regional spatial datasets to construct a continuous binational social vulnerability index (BSVI) at the census tract level across the San Diego-Tijuana border region. This paper details the datasets and methodology used to create the BSVI and explores some of the preliminary results of the analysis by juxtaposing this score with spatially explicit information on vegetation cover and climate projections of heat and rainfall extremes across the region. We close with a discussion on use of this research as a tool for local environmental justice and regional adaptation.