Berkeley Lab

Climate Readiness Institute – Climate Science for Low-Carbon Communities (LBL LDRD)

PI: William Collins

William CollinsThe purpose of this project is to develop the scientific basis for understanding trade-offs in climate adaptation and mitigation that affect urban physical microclimates. Using the San Francisco Bay Area as a testbed, we will conduct ultra-high resolution climate simulations that examine interactions among existing microclimates, modifications to the built environment, and global climate change. The simulations are designed to fill a near-term information gap that stymies effective climate change preparedness efforts, namely a lack of understanding regarding how global climate change will affect the risk of extreme heat events and how modifications to the built environment could ameliorate or enhance such risks at the neighborhood and regional scales. Urban modifications to be examined include the widespread adoption of white roofs, infrared reflective coatings, rooftop photovoltaics, and diminished water use for landscape irrigation. More broadly, this project will enhance basic scientific understanding of land-atmosphere interactions in urban environments and develop a standing capacity for addressing other climate-related risks to urban environments such as extreme precipitation and flooding.

The model system we will use to construct simulations of adaptation and mitigation options for the Bay Area consists of three components, each of which is described in greater detail below: (A. Meteorological boundary conditions projected for 2050 under business-as-usual scenarios using Earth system models, together with meteorological reanalyses for 2010; (B. The Weather Research and Forecasting Model (WRF), combined with a detailed urban canopy model; (C. Detailed descriptions of the San Francisco and Bay Area built landscape; and (D. Our hypothetical modifications to the urban infrastructure for adaptation to climate change and likely resulting water shortages. The numerical experiments will focus on the year 2050 for two reasons: (1. the thermal and hydrological impacts on the Bay Area from global climate change under a business-as-usual scenario will be significant and distinguishable from unforced variability in the climate system; and (2. widespread deployment of the hypothetical alterations to the regional urban infrastructure will likely take a decade or more from now. The goal of the experiments is to quantify the effects of these alterations on the Bay Area urban climate (e.g., surface air temperatures). The outer experimental domain will consist of Alameda, Contra Costa, Marin and San Francisco counties, which cover 1910, 1870, 1350, and 120 km2 for a total of 5250 km2. The inner experimental domain will cover San Francisco at 100-200 meter resolution.