Nuance can be elusive when explaining whether extreme weather was “caused” by climate change, especially before the attribution studies come in. 

The atmospheric river that recently pummeled California is no exception, but “the severity of this storm is entirely what we would expect from climate change,” says Alex Hall, an atmospheric physicist and climate scientist at UCLA: 

  • “In our warming world, we are starting to see events like this most recent storm. These bigger events are entirely consistent with climate change.”
  • “We can’t say without more data that this one storm’s intensity is the result of climate change, but it goes both ways. We can’t say that this wasn’t climate change’s influence either.” 
  • “One way to detect the role of climate change is to measure events around the world and not just one storm. When we expand the scope globally, we do detect an increase in extreme precipitation due to climate change.” (See the 2021 study.)
  • “Given the amount of warming we’ve seen so far, we expect that big precipitation events should be about 10% more intense than they were before greenhouse gases were added to the atmosphere.” 
  • “The scary thing is that if you look into the future to the point where we have twice as much warming as today, you have events that are 20% more intense and entirely new classes of events that don’t even exist now.”

Hall can also comment on topics such as the role of El Niño in the Feb. 4–7 storms, how two wet years in California set the stage for wildfires this summer and fall, and the ongoing snow drought. Hall is a professor of atmospheric and oceanic sciences, director of the UCLA Sustainable LA Grand Challenge and a member of UCLA’s Institute of the Environment and Sustainability.

Media are encouraged to reach out for additional commentary, research and analysis from Hall or UCLA’s other climate experts.

Alison Hewitt
Senior Media Relations Officer

UCLA Strategic Communications | Office of Media Relations
| @ashewitt | @ahewitt.bsky