Sea-level rise threatens California’s economy 10 times more than recent extreme wildfires or severe earthquakes, according to a major new study.

U.S. Geological Survey researchers and other scientists found that rising seas, combined with storms, will wallop California by the turn of the century, with impacts occurring as early as 2040. The study published in the journal Nature translated physical impacts into socio-economic ones, finding that both the coast and inland areas will face major financial losses.

“The scale of potential impacts by the end of the century is comparable to some of the largest natural disasters in history,” said Patrick Barnard, lead author of the study and a USGS geologist.

The analysis compared the financial hit to Hurricane Katrina: “The economic value of what’s exposed to flooding is on the same order of that event,” he said.

Barnard said the impact from a combined sea-level rise and storm event will be many times greater than the worst natural disasters in California’s history, including the 1989 Loma Prieta earthquake in the San Francisco area and the 2017 and 2018 wildfires seasons.

By the end of the century, a typical storm could expose about $100 billion in property to damages, he said.

“That’s the kind of thing that could be hitting every single year,” Barnard said.

As many as 600,000 people and $150 billion in property are at risk of coastal flooding by 2100 in the state, which has the world’s fifth-largest economy. That loss is equivalent to 6 percent of California’s gross domestic product.

Adaptation costs could top $1 trillion by the end of the 21st century. The risk is even greater if there’s rapid melting of the West Antarctic and Greenland ice sheets, which could cause about 10 feet of sea-level rise by 2100.

Damages are expected to occur well before the turn of the century, Barnard said.

The seas are likely to rise by about 10 inches by 2050 based on median projections. That doesn’t sound like a lot, but as so much in California is built at sea level, even a small change can cause flooding.

“The exposure by 2040, especially if you include storms, increases by a factor of seven,” Barnard said. “Across California we’re talking about tens of billions of dollars of property exposed just over the next couple decades.”

The rate of cliff retreat will also roughly double by the end of the century, he said. That’s because sea-level rise causes waves to hit the bottom of cliffs, weakening their bases and making the tops unstable. Multimillion-dollar cliff-top homes will be at risk.

New governor must decide path forward

New California Gov. Gavin Newsom (D) and the state Legislature are grappling with how to deal with sea-level rise. In recent years, the Legislature has steered away from any stringent mandates, other than telling cities they must incorporate adaptation to sea-level rise in their planning.

The California Coastal Commission—which works to preserve the state’s beaches and coastal access and oversees development along 1,100 miles of coast—has wrestled with beach cities and residents over policies, including those governing sea walls. Environmental groups argue walls won’t allow the beach to migrate inland as waters rise.

Spokeswoman Noaki Schwartz said the coastal commission was reviewing the study.

“Per our sea-level rise guidance, we will always use the best available science,” she said.

The commission has said it plans to release new guidance early this year on sea-level rise in residential areas. A draft version outlined steps for managed retreat, or removing homes to preserve the dry beach as waters rise (Climatewire, Dec. 7, 2018). But the agency got significant pushback from cities. Schwartz said there was no update on when a new version would be released.

Mandy Sackett, California policy coordinator with the Surfrider Foundation, said state and local planners need to consider the study as they make planning rules.

“The decisions that we’re making now will play out as to the impact we see in California,” she said. “What we’re building and not building, and where we’re zoning and planning now is really going to forecast how devastating sea-level rise is to our state.”

If development is allowed in a hazardous area, it will still be there as seas rise, she said. Where development is allowed also affects decisions about sea walls.

“Right now we’re deciding which beaches to save and which ones to allow to disappear with our permitting and planning decisions,” Sackett said.

Storms and sea-level rise

The USGS analysis is one of the first to look at the combination of sea-level rise and storms. Higher oceans increase damage from storms because so many houses and other buildings along the coast are built right at sea level.

“It doesn’t take much to dramatically impact,” Barnard said.

Compared with coastal flooding from sea-level rise only, the study predicts, storms will increase the exposure of people and buildings by as much as seven times by 2040.

“It’s very important research showing the connection between storms and sea-level rise,” said Deborah Halberstadt, executive director of the California Ocean Protection Council, which helped fund the USGS study. “It is really a critical missing piece that we haven’t given enough attention to.”

The combination of sea-level rise and storms “ends up resulting in significantly greater impacts far inland from what people are anticipating,” she added. “That is very important information that this study gleaned.”

The Ocean Protection Council makes recommendations to the Legislature and the governor based on the most recent science. After the study, OPC plans to provide help to local governments, Halberstadt said, for pilot projects that explore new approaches to address sea-level rise.

She said the group is not looking for “black or white” solutions, such as forcing communities “to think about managed retreat or nothing.”

“There’s a wide spectrum of solutions and a wide spectrum of approaches,” she said.

Halberstadt said she didn’t foresee the state putting in place a more prescriptive approach to sea-level rise.

State Sen. Bob Wieckowski (D) plans to push for more adaptation policies. He introduced a bill, S.B. 13, that would create the position of chief officer of climate adaptation and resilience in the Governor’s Office of Planning and Research.

Wieckowski leads a state Senate budget subcommittee on the environment. On April 4, the panel will hear about coastal climate adaptation efforts from several state and local agencies.

“We are at a critical period here in California,” Wieckowski said. “Several recent climate reports paint a stark picture of extreme upheaval if state and global leaders do not act with urgency to cut greenhouse gas emissions and adapt to our changing climate. We must act with clarity and move aggressively to meet these challenges and build a more sustainable future.”

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at