San Francisco and Berkeley Lab Team Up on Pioneering Climate Study

The City and County of San Francisco, in partnership with Lawrence Berkeley National Laboratory (Berkeley Lab), have released a pioneering new climate study that will provide more detailed information to help San Francisco adapt to our changing climate and the extreme storms it will bring.

The peer-reviewed study, commissioned by the City and led by scientists at Berkeley Lab with support from Pathways Climate Institute, Urban Waterworks, and City staff, was published in the journal Weather and Climate Extremes. Using supercomputing resources at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC), the research team found that the effect of climate change on future storms will be significant, leading to more powerful storms unleashing substantially more water. In addition, storm-total precipitation associated with the most common type of storm in the Bay Area – an atmospheric river with an extratropical cyclone – may increase by up to 26% to 37% by the end of this century.

“We simulated how historically impactful storm events could change if similar events occurred in future climates,” said lead author Christina Patricola, who holds an affiliate faculty position in Berkeley Lab’s Climate and Ecosystem Sciences Division and is an assistant professor at Iowa State University. Patricola ran a weather research and forecasting model on the Cori supercomputer at NERSC to complete the simulations.

“This collaboration is one of the first of its kind to apply the climate modeling expertise at Berkeley Lab to inform local decision-makers, and Cori allowed us to complete the simulations with exceptional expediency,” said Michael Wehner, a senior scientist in Berkeley Lab’s Applied Mathematics and Computational Research Division and a co-author on the study. “By tailoring our models to the City’s specific questions, we are able to provide more confident answers in the amount of heavy rainfall that can be expected in a future warmer world.”

The study also provides a much more localized look at the effects of these projected storms. Prior to this, many climate models had a resolution of 200 kilometers, or 124 miles. One square on the model grid represented the entire Bay Area. Even what had been considered state-of-the-art climate models have resolutions of about 25 kilometers, or roughly 5.5 miles. Those models can broadly represent West Coast atmospheric rivers but cannot adequately address the complex topography of the Bay Area, which leads to highly variable precipitation rates from one city to the next. This new study has a much more detailed resolution of 3 kilometers, or less than 2 miles, which can provide very local projections for how much rain is expected to fall.

“Having this level of detail is a game-changer,” said Dennis Herrera, general manager of the San Francisco Public Utilities Commission (SFPUC), which was the lead City agency on the study. “The SFPUC has been at the forefront when it comes to studying climate change and using that data to guide our decisions. This study will help us stay out front on this issue. This groundbreaking data will help us develop tools to allow our port, airport, utilities, and the City as a whole to adapt to our changing climate and increasingly extreme storms.”

Additional analysis is still underway to develop data products and tools that will support the City’s ongoing climate resilience efforts. As part of this work, Pathways Climate Institute, with support from Berkeley Lab, is developing a guidebook to help planners, modelers, engineers, and decision-makers use the incredible wealth of information that this study provides to better prepare San Francisco for future storms. The guidebook is slated for completion in late 2022. 

This state-of-the-art modeling effort was funded by the SFPUC, San Francisco Office of Resilience and Capital Planning, San Francisco International Airport, and the Port of San Francisco.

An allocation of computing time at NERSC was provided by the U.S. Department of Energy (DOE) Office of Biological and Environmental Research, Earth and Environmental Systems Sciences Division. NERSC is a DOE Office of Science user facility operated by the DOE Office of Advanced Scientific Computing Research.

This article is adapted from a news release originally published by the San Francisco Public Utilities Commission.