Rising sea levels to intensify Southern California cliff erosion

Sea level rise can be difficult for climate models to accurately predict because there are so many different variables driving climate change.

However, one thing that climate researchers agree on is that even if the Paris Accord goals are met, we can expect to see at least to 2 to 4 feet of sea level rise by 2300.

While studies that focus on sea level rise often emphasize the risks posed to coastlines and beaches, new research found that rising waters will cause cliffs along Southern California’s coast to experience serious erosion.

The study was conducted by researchers from the United States Geological Survey (USGS) and the results show that 300 miles of coastal California cliffs could erode twice as fast as normal by 2100 and lose 135 feet of bluff top.

To put that into context, Patrick Barnard, a USGS geologist, explained the seriousness of erosion by calculating how many tons of sand and rocks would be shed from the cliffs.

“It’s a huge volume of material,” Barnard told the Washington Post. “We place this in a context of dump truck loads. It would be 30 million dump trucks full of material that will be eroded from the cliffs.”

Thousands of homes and properties currently sit atop those cliffs and serious levels of erosion could cause billions of dollars in damage and displace residents.

To estimate erosion and sea level rise, the researchers modeled different sea level rise scenarios for 2100 with levels ranging from one and a half feet to over six feet.

Next, the researchers used models to predict how the cliffs would respond to sea levels rising including crumbling and found that 300 miles of cliffs could lose anywhere between 62 and 135 feet.

The erosion puts California in a precarious position, either focus conservation on the bluffs or beaches.

Cliff erosion could be good for the beaches because it would provide much-needed sand and material to prevent beach erosion but the costs of damage and displacement would take a heavy toll.

“Coastal change, cliff retreat, sea level rise, and extreme storms could expose more than 250,000 residents and $50 billion in property to erosion or flooding in Southern California by the end of the century,” said Barnard.

The researchers note that there is a good deal of unpredictability when it comes to sea level rise and erosion and the study only presents potential scenarios.

How California’s cliffs will respond to sea level rise is not well understood and more research is needed in order to dictate appropriate conservation measures.

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By Kay Vandette, Earth.com Staff Writer