Zooming in on L.A.’s Warming Climate

First-of-its-kind study breaks down predictions for 27 L.A. microclimates

Kimberly Ayers

Green roofs like this one at Vista Hermosa City Park are part of the solution for Los Angeles

Listen to the radio version of this story on The California Report.

The City and County of Los Angeles now have customized climate predictions, thanks to a new UCLA study that took global climate science and made it local. A UCLA supercomputer ran for eight months to downscale 22 different global climate models, distilling them into a surgically precise look at L.A. County and beyond. It’s a new kind of Hollywood close-up and it’s a sobering one: temperatures will rise in areas of Los Angeles County by an average of 4 to 5 degrees by mid-century.

Commissioned by the city of Los Angeles, funded by a U.S. Department of Energy grant and conducted by UCLA’s Department of Atmospheric and Oceanic Science, the study focused on forecasting for the metro area between 2041 and 2060. But instead of relying on the global climate model grids that use data from 100 kilometer-square cells of the earth’s surface, the UCLA team’s “quintillion-plus” calculations — yes, that’s with 18 zeros — zoom in to a resolution of 2 square kilometers, just over a square mile.  So instead of data and forecasting for the whole county, you can talk specifically about climate change for Corona, for example.

“It’s not anecdotal. It’s not instinct. It’s based on science and it’s very specific.”
The number of extremely hot days in downtown L.A. will triple, and they’ll quadruple in the valleys and the mountains. Lead UCLA scientist Alex Hall says that was a surprise: he didn’t expect the downscaled models to signal that kind of warming. Part of Hall’s regular work has him watching the Santa Ana winds and mountain habitats so this data gives him a new reason to double down. “We live in a region where fire is driven by climate and weather. And so we absolutely want to understand in detail the implications of all this work for fire and fire risk.”

Mitigating those risks is a whole lot easier to sell when the science has your town’s name on it. County supervisor Zev Yaroslavsky told me. “That’s what this study has done. It’s given us the science. It’s not anecdotal. It’s not instinct. It’s based on science and it’s very specific.”

And there’s a brand new website, c-change.LA, that includes a slew of suggestions for Angelenos looking to mitigate and adapt to climate change in their own neighborhoods. This new study also gives further momentum to the city’s existing program, Adapt LA, which was started five years ago to green up the city’s energy and landscapes and clean up its air, efforts the city’s mayor Antonio Villaraigosa wants to keep moving.

“This stuff isn’t a luxury. We gotta do it. We can target it smart, we can do it in a way that’s phased in, but we’re definitely going to have to move.”