Sign In or Create an Account.

By continuing, you agree to the Terms of Service and acknowledge our Privacy Policy

Climate

The Flood-Filled Future of California

It does rain in Southern California after all.

The California flag, underwater.
Heatmap Illustration/Getty Images

More Californians have searched for news about “floods” in 2023 than “wildfires,” which seems in keeping with this summer’s series of out-of-left-field climate disasters. The worst smoke pollution hit … the East Coast. The deadliest wildfire in modern U.S. history leveled … a former wetland in Hawaii. Naturally a hurriquake in Los Angeles and catastrophic flooding in Palm Springs would come next?

But California’s reputation as the land of drought and fire has obscured the fact that extreme flooding is the other player in the state’s deadly climatological triumvirate. From the atmospheric rivers this winter, which caused some 500 mudslides and inflicted as much as $1 billion in damage, to Hurricane Hilary dumping record-breaking rains over the southwestern United States this weekend, floods are understandably top-of-mind (especially with a relatedly somewhat slow start to the state’s fire season).

Here’s what you need to know about the future of extreme floods in the Golden State:

Will California be hit by more hurricanes?

Former Hurricane Hilary was the first tropical storm to make landfall in California in 84 years, easily snapping the practically nonexistent late August daily rainfall records around L.A. In fact, hurricanes making landfall in the lower lefthand corner of the U.S. is so rare that there isn’t actually much of a data record for scientists to use as a point of comparison, Inside Climate News reports — which makes forming future projections and establishing links to climate change actually rather difficult.

What we do know is this: California has largely avoided hurricanes in the past due to the generally cold waters off its coast, which NBC News describes as acting as a sort of “shield” for the state. Hurricanes get their strength and moisture by forming over warm waters, and the eastern Pacific has historically been as much as 9 degrees cooler than the same latitude in the Gulf of Mexico.

But California’s shield has a crack. July was the hottest recorded month on planet Earth and the waters Hilary passed over on its journey north were 4 degrees warmer than usual, the Los Angeles Times explains. Sure enough, research shows that hurricane landfalls in the eastern Pacific could increase dramatically along with global and oceanic warming — bringing more rain and floods along with them.

There are certain conditions that made Hilary particularly unusual, however: A heat dome that formed over the central United States, for example, helped tug the storm directly over California, as opposed to a more typical path of a hurricane or tropical storm being pushed out to sea by easterly winds off the continent. So while hurricanes might be more intense and wet in the future, they won’t necessarily continue to make it over to California the way Hilary has.

Does El Niño have anything to do with floods in California?

Yes, to some extent. In addition to greenhouse gas emissions making the oceans warmer, the weather pattern called El Niño is likely responsible for some of the warming of the waters off of Baja California, which intensified Hurricane Hilary. But again, there were also unique conditions that contributed to Hilary’s unusual path over the southwestern United States, including the prevailing wind patterns. Strong El Niño years, as a result, don’t necessarily mean more hurricanes for Southern California.

El Niños have tended to bring higher winter rainfalls to Southern California, though that is also not necessarily a guarantee. NOAA’s outlook for the coming winter doesn’t currently show above-average precipitation expected for the state. Some El Niño years are actually drier than average, which goes to show that “El Niño is just one hand on the atmospheric steering wheel,” Weather Underground writes.

Why are we even talking about floods? Isn’t California in a drought?

California isn’t a land of droughts or floods — it’s a land of both. A better way to think about the future of weather in the state is as one of extremes.

That’s because, “[i]n a seeming paradox, drought and flooding are two sides of one coin,” Governing explains. “A warmer atmosphere can hold more water, and higher temperatures cause more water on the Earth’s surface to evaporate. This can result in bigger rainstorms.”

The good news is, most of California is now free of drought conditions and this year’s fire season has been quieter because of all the wet vegetation. But while Tropical Storm Hilary apparently only inflicted minor damage and no known deaths this weekend, floods have been a devastating fixture of life in the Golden State before and they will be again.

As Yale Climate Solutions warned earlier this year, “Given the increased risk [due to climate change], it is more likely than not that many of you reading this will see a California megaflood costing tens of billions in your lifetime.”

What is California’s worst-case flood scenario?

California doesn’t need 40 days and nights of rain to experience its worst-case flood event, researchers have found. If a 30-day rainstorm similar to one that hit the then-unpopulous state in 1862 were to strike again today, it could potentially be a $1 trillion disaster — “larger than any in world history” — UCLA’s “ARkStorm 2.0” scenario modeling found last year.

“Every major population center in California would get hit at once — probably parts of Nevada and other adjacent states, too,” Daniel Swain, a UCLA climate scientist and co-author of the paper, said in a statement at the time.

Unlike a tropical storm, which passes in a number of days, the ARkStorm flood event would last a month in the form of sequential atmospheric rivers, like the kind that battered the state this past winter. The link between climate change and heavy precipitation is well understood, and the researchers found that “climate change has already doubled the likelihood of such an extreme storm scenario,” with “further large increases in ‘megastorm’ risk … likely with each additional degree of global warming this century.”




Blue

You’re out of free articles.

Subscribe today to experience Heatmap’s expert analysis 
of climate change, clean energy, and sustainability.
To continue reading
Create a free account or sign in to unlock more free articles.
or
Please enter an email address
By continuing, you agree to the Terms of Service and acknowledge our Privacy Policy
Podcast

How Trump Has All But Halted Offshore Wind

Rob and Jesse talk with Heatmap senior reporter Jael Holzman.

Offshore wind turbines.
Heatmap Illustration/Getty Images

Donald Trump’s second term has now entered its second month. His administration is doing much to slow down renewables, and everything it can to slow down offshore wind. Jael Holzman is a senior reporter at Heatmap and the author of our newsletter, “The Fight,” about local battles over renewable permitting around the country.

On this week’s episode of Shift Key, Rob and Jesse talk to Jael about the bleak outlook for offshore wind, the use of presidential authority to impede energy development, and why solar has been spared — so far. Shift Key is hosted by Jesse Jenkins, a professor of energy systems engineering at Princeton University, and Robinson Meyer, Heatmap’s executive editor.

Keep reading...Show less
Blue
Electric Vehicles

Tesla Is Now a Culture War Totem (Plus Some AI)

The EV-maker is now a culture war totem, plus some AI.

A Tesla taking an exit.
Heatmap Illustration/Getty Images, Tesla

During Alan Greenspan’s decade-plus run leading the Federal Reserve, investors and the financial media were convinced that there was a “Greenspan put” underlying the stock market. The basic idea was that if the markets fell too much or too sharply, the Fed would intervene and put a floor on prices analogous to a “put” option on a stock, which allows an investor to sell a stock at a specific price, even if it’s currently selling for less. The existence of this put — which was, to be clear, never a stated policy — was thought to push stock prices up, as it gave investors more confidence that their assets could only fall so far.

While current Fed Chair Jerome Powell would be loath to comment on a specific volatile security, we may be seeing the emergence of a kind of sociopolitical put for Tesla, one coming from the White House and conservative media instead of the Federal Reserve.

Keep reading...Show less
Green
Climate Tech

Climate Tech Is Facing a ‘Moment of Truth’

The uncertainty created by Trump’s erratic policymaking could not have come at a worse time for the industry.

Cliimate tech.
Heatmap Illustration/Getty Images

This is the second story in a Heatmap series on the “green freeze” under Trump.

Climate tech investment rode to record highs during the Biden administration, supercharged by a surge in ESG investing and net-zero commitments, the passage of the Infrastructure Investment and Jobs Act and Inflation Reduction Act, and at least initially, low interest rates. Though the market had already dropped somewhat from its recent peak, climate tech investors told me that the Trump administration is now shepherding in a detrimental overcorrection. The president’s fossil fuel-friendly rhetoric, dubiously legal IIJA and IRA funding freezes, and aggressive tariffs, have left climate tech startups in the worst possible place: a state of deep uncertainty.

Keep reading...Show less
Blue