Vast swathes of California’s beaches could be lost to climate change, a recent paper has predicted, with 25-70 percent of the state’s beaches completely eroded by the end of this century.
The study, published in March, was produced by five scientists from the USGS Pacific Coastal & Marine Science Center, the University of Illinois at Chicago, and the University of New South Wales – Sydney.
The five looked at San Francisco’s Ocean Beach, and studied satellite imagery of the beach over two decades.
They then took the entire 1,100-mile coastline of California and used their models to predict how climate change would affect the beaches, using a predicted rise in sea levels of 1.6 feet to 10 feet over the next 80 years.
They found that 25-70 percent of the state’s beaches could be lost.
Pismo Beach in California, near San Luis Obispo, is among those cited by the researchers as being at risk
Newport Beach, just south of Los Angeles, is also considered at risk
‘By 2100, the model estimates that 25 to 70 percent of California’s beaches may become completely eroded due to sea-level rise scenarios of 0.5 to 3.0 m, respectively,’ the authors wrote.
‘The satellite-data-assimilated modeling system presented here is generally applicable to a variety of coastal settings around the world owing to the global coverage of satellite imagery.’
The authors warned that several well-known beaches were at risk – among them Point Arena and Humboldt Bay in Northern California; Pismo Beach and Morro Bay in Central California; and Newport Beach and San Clemente in Southern California.
The study, cited by the news website SFGate, is yet to be peer reviewed.
It follows on from a similar study in 2017, by the same group of researchers, who found then that 31 to 67 percent of beaches in Southern California were at risk of being destroyed.
‘The model predictions, although subjected to considerable uncertainty, indicate that significant impacts to the shoreline may occur due to accelerated sea-level rise,’ the authors conclude.
‘It is likely that many beaches in California will require substantial management efforts (e.g., beach nourishments, sand retention, armoring, dune restorations as well as other engineering and nature-based solutions) in order to maintain existing beach widths and the many services they provide.’
San Clemente, another Los Angeles-area beach, is vulnerable over the next 80 years, the researchers concluded
Morro Bay, 200 miles north of Los Angeles, is threatened by rising sea levels, the team said
Experts are deeply concerned about rising sea levels, but disagree on the predicted rise.
The National Oceanic and Atmospheric Administration predicted last year that sea levels would rise up to eight inches in California and along the West Coast in the next 25 years.
Mark Merrifield, a coastal oceanographer at Scripps Institution of Oceanography in La Jolla, told The Guardian that the satellite models used by the five researchers should be taken with a degree of skepticism, because they were new.
‘Beach morphology models in general have limited skill in predicting contemporary change, there are few datasets available for validation of the methodology, and projections of future wave and water level conditions introduce another level of uncertainty,’ he said.
But Sean Vitousek, the lead author on both studies, said they proved that action must be taken now, even if people disagreed about the precise extent.
‘Beaches are perhaps the most iconic feature of California, and the potential for losing this identity is real,’ he wrote in 2017.
‘The effect of California losing its beaches is not just a matter of affecting the tourism economy.
‘Losing the protecting swath of beach sand between us and the pounding surf exposes critical infrastructure, businesses and homes to damage.’