How California can better adapt to extreme weather


  • Climate change is expected to make atmospheric rivers like the ones that struck California even more destructive.
  • A major atmospheric river event in the state could cost at least $200 billion, according to a model by USC Price School Professor Adam Rose.
  • Potential solutions include banning construction in certain areas, buying out at-risk homes, and increasing resilience to climate-related disasters.

A rapid succession of deadly winter storms deluged the parched state of California in recent weeks. Unrelenting downpours overflowed rivers, submerged vehicles, evacuated neighborhoods, cut power to households, toppled over trees and tragically killed at least 22 people.

That torrential rains could suddenly plunge the state underwater during a historic drought may seem highly unusual. But experts from the USC Sol Price School of Public Policy warn that the recent storms offer a glimpse of the Golden State’s climate future – and that California is still not prepared for the expected extreme weather.

“It is a large task in front of us to make sure that we get actionable things done because what we saw in this last storm event is giving us a taste of what we’re going to continue seeing in the future,” said Santina Contreras, an assistant professor and expert on environmental planning at the USC Price School.

The risk of a megaflood

This month’s destruction was brought by a series of atmospheric rivers, or streams of water vapor that move across the sky and dump rain and snow. They’re fairly common on the West Coast, but sometimes they park over a region for a longer period, like they did this month, causing floods and mudslides. Although these most recent storms were most likely not linked to climate change, scientists warn that atmospheric rivers are set to become stronger and bring worse floods.

USC Price School Professor Adam Rose examined the risk posed to California by modeling an especially extreme atmospheric river storm scenario. Such an event – the last of which occurred in the 1860s – would pummel buildings with flood waters and wind, destroy crops and livestock and practically turn the Central Valley into a lake.

The disaster could cost $200 billion in state GDP over a three-year period (in today’s dollars), worse than Hurricane Katrina, Rose and his colleagues concluded in their 2015 study. (Another study put the cost as high as $1 trillion.) They noted that the sheer size of California’s economy contributed to the huge economic impact, though the state would also recover faster than less wealthy and developed states, like Louisiana and Mississippi after Katrina.

But California’s current economic advantage could erode over time as climate change and natural disasters take an increasing toll.

“As these storms and wildfires continue, and we have … possibly some overdue sizable earthquakes, California’s economy will suffer significantly, and our economic advantage will decrease,” Rose said. “People will start leaving the state as it becomes perceived as an increasingly dangerous place to live.”

Adapting to our climate future

How can California – and other places facing extreme weather – better adapt?

Some relatively inexpensive solutions relate to land-use planning, Rose said. Those include remaking flood maps – including projecting into the future – so that floodplains are enlarged, then banning construction of major buildings and infrastructure in those areas. Rose also suggested buying out homes in floodplains and updating similar maps for mudslides.

These discussions are particularly important when considering the risks facing the most vulnerable communities, said Contreras, whose work focuses on ensuring equity in environmental planning.

“There are a lot of environmental justice wrongs that have to be corrected in terms of the placement of people in very dangerous places,” she said.

However, while addressing where people live is an important question, Contreras said, moving communities out of risk-prone areas is often not simple. Her recent research on the impacts of managed retreat on informal communities found that relocation may not fully mitigate all risks, and can inadvertently create new issues for communities, such as exposing people to different hazards in a new place. This is something of particular importance in California, where communities are exposed to a wide variety of risks.

“We might assume that everything is fixed once communities are moved, but it’s often much more complicated than that,” she said. This is why the vulnerable communities most affected by climate change must be engaged in these discussions, she added.

Building resilience to wildfires

Of course, many people won’t want to leave their homes, and many want to rebuild in the wake of climate-related disasters such as wildfires.

USC Price School alum Jennifer Gray Thompson, CEO of the disaster recovery nonprofit After the Fire USA, said tribes and ranchers have cultural connections to their land. She also noted that relocating people will be difficult given California’s chronic housing shortage.

“What we should do is go in there and build resiliency in their home,” she said.

To protect against wildfires, measures include installing thinner air vents to block the entry of embers, surrounding properties with rocks and metal fences and improving communications systems to better alert people of conflagrations, she said. Forest management is also important, she added.

Thompson, who earned a master’s degree in Public Administration, helps communities navigate wildfires across the American West, collaborating with public officials, private-sector firms and nonprofits. Her leadership in the field of megafire disasters earned her a spot on the 2022 Forbes “50 over 50” list of women recognized for historic achievements after age 50.

One major obstacle to recovery that she’s seen is the byzantine process to get approved for financial assistance, she said.

“We need to put tech to work to have one platform for all of the agencies involved,” Thompson said. “There’s a huge amount of fraud in a disaster, but in our zeal to prevent fraud, we also prevent access.”