SAN FRANCISCO ― Much of Southern California’s iconic coastline, from Santa Barbara to San Diego, could be “completely eroded” due to rising sea levels by the end of the century, a new study predicts.
Between 31 and 67 percent of the iconic beaches, dunes and cliffs in the area may be washed away by 2100 thanks to climate change unless something’s done to protect the shores, according to the study published recently in the Journal of Geophysical Research.
“This is not a problem that’s going away,” said United States Geological Survey scientist Patrick Barnard, one of the co-authors. “But we can mitigate it.”
The question isn’t whether the seas are rising — it’s a matter of how much. Previous conservative estimates by a United Nations panel said the oceans would rise by 1 meter by the end of the 21st century, but newer data showing the accelerated melting of Antarctic ice may double that rate.
That’s a vital question for the 310 miles of Southern California the scientists examined. The region is home to nearly 20 million people and features some of the most desired real estate in the country, in places like the low-lying Westside neighborhoods of Los Angeles or suburban communities in Orange County.
Beaches provide the “first line of defense” against storms, Barnard said. If humans don’t intervene more decisively to counteract erosion, flooding will become more common and severe in places like LA’s Venice neighborhood, Barnard said.
“It is likely that beaches in Southern California will require substantial management efforts … to maintain beach widths and prevent impacts to coastal infrastructure,” the study said.
Researchers used data from 1995-2010 collected from GPS and LIDAR technology that measured small changes in elevation and shoreline formation to come up with a model that predicted the beaches’ future.
The erosion of two-thirds of the region’s beaches is possible if sea levels rise by 2 meters, researchers wrote.
Averting the worst-case scenario calls for replenishing beaches and dunes with more sand — a temporary solution that officials already use — and building sea walls, levees and other mechanisms, Barnard said. The current approach for beach management, however, isn’t capable of confronting the coming changes, he said.
“It’s been primarily a Band-Aid approach for many years,” he said. It’s unclear how much money must be invested in infrastructure, but Barnard said it would easily be “more than a billion” dollars.
Other options such as a moving homes and businesses inland is not realistic for one of the most densely populated areas of the country, though it could be carried out in some instances for important infrastructure, Barnard said.
California officials who reviewed the study said the economic activity along the coast generates $40 billion a year in the state.
“The prospect of losing so many [of] our beaches in Southern California to sea level rise is frankly unacceptable,” state Coastal Commission Executive Director John Ainsworth said in a statement. “The beaches are our public parks and economic heart and soul of our coastal communities. We must do everything we can to ensure that as much of the iconic California coast is preserved for future generations.”
Historically, there’s been more accretion (or growth) in the size of the region’s beaches, yet the trend is expected to reverse, researchers said.
Some beach communities are already reeling from recent, devastating storms. Parts of Santa Barbara County in particular have been adjusting to more turbulent times.
Rising sea levels pose a problem to many American coastal areas. Parts of the Gulf Coast and Atlantic seaboard have risen much more than along parts of the West Coast, according to the Union of Concerned Scientists.
“We’ve really urbanized the coast in a lot of regions,” said Barnard. “We’ve built up these places with the implicit assumption is that the environment is never going to change. But the reality is they’re some of the most dynamic settings.”