Up to 70% of California beaches could disappear by end of the century – the Guardian

Excerpt:
A new study uses satellites to predict what California’s famous coastline could look like by 2100.

California is known for golden sands and endless waves, but much of the state’s famous shoreline could vanish in the future. That’s according to a new study, which found that between 25% and 70% of California beaches might be washed away by the end of the century, leaving only cliffs or coastal infrastructure in their wake.

The study used satellite data collected over the past two decades to examine California’s 1,100-mile-long coast. Researchers from the US Geological Survey (USGS) used those satellite images, combined with models of climate crisis-driven sea level rise ranging from 1.6 to 10ft, to estimate the shape and position of the state’s coastline by 2100. The amount of sea level rise will depend on how much carbon is pumped into the atmosphere now and in the future.

The paper, which is in the process of being peer-reviewed for publication, follows on from a 2017 study conducted by the same researchers focused on the rate of coastal erosion in southern California. That study found a similar fraction of southern California beaches – between 31 and 67% – were susceptible to vanishing.

“Beaches are perhaps the most iconic feature of California, and the potential for losing this identity is real,” wrote Sean Vitousek, the researcher who led both the 2017 study and the current one. “Losing the protecting swath of beach sand between us and the pounding surf exposes critical infrastructure, businesses and homes to damage. Beaches are natural resources, and it is likely that human-management efforts must increase in order to preserve them…”

The new study is the first time that satellite-derived shorelines have been used for this type of analysis, says Mark Merrifield, a coastal oceanographer at Scripps Institution of Oceanography in La Jolla, who was not involved in the research. But he warns that the predictions have a wide amount of uncertainty, so they should be taken with some skepticism, he says. “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…”