Combined climate-land change driven impacts from co-produced land cover scenarios in San Juan, PR

Cities interact with local and large-scale weather phenomena in a variety of ways, fundamentally modifying the local surface energy and water balance. These interactions often lead to an intensification of extreme heat, flooding, and other weather hazards. As cities prepare to contend with the impacts of global climate change, stakeholders have begun to envision scenarios that not only address coming challenges but also increase urban services and livability.

A series of workshops attended by representatives of municipal and federal government, as well as community organizations and academia led to the development of three positive visions of the future for the coastal, Caribbean city of San Juan, PR. Workshop outcomes were quantified and used to modify pixel transition rules in a series of cellular automata (CA) simulations trained on historical land cover imagery, producing spatially explicit land cover projections up to the year 2080. CA results are then used as input to high-resolution (1 km) Weather Research and Forecasting (WRF) model simulations to study how these changes impact urban temperatures and other local processes (e.g., sea breeze and heat fluxes). Simulations of the three envisioned scenarios, using bias-corrected Community Earth System Model (CESM1) RCP 8.5 data, are compared against results from a “business as usual” land cover scenario, highlighting modification of the urban heat island and sea breeze.