The South Coast shoreline is the focus of a new study published in the national science journal Ocean & Coastal Management, which provides a rough roadmap for how local governments can help their beaches and ecosystems adapt to the inundations of sea-level rise. The study, explained lead author Monique Myers, a California Sea Grant specialist affiliated with UCSB and UCSD, distills previous data-heavy reports into a handful of take-home messages for city and county planners, “because they have so much to say on what happens to our coastal regions.”
The biggest takeaway, Myers said, is that the South Coast is looking at “drastic” changes by 2050. “That’s only 30 years away,” she said. “We can’t wait to address this.” Upper beach zones and marsh habitats are predicted to disappear first as their dry sand and life-rich wrack ― where plovers nest and small crabs forage ― are smothered by lapping waves. The number of “extremely” hot days will likely double by the middle of the century, the study says, and could increase 10-fold by 2090. Longer droughts punctuated by fewer, but heavier rainstorms are also forecasted, which would lead to “pronounced changes” in watershed runoff.
A rising ocean will put locations already susceptible to coastal flooding during storms (like the Goleta Slough and the Carpinteria Salt Marsh, where the endangered Belding’s Savannah sparrow resides) at risk of drowning during daily high tides, the report states. Skinny beaches backed by infrastructure or cliffs (including Arroyo Burro and those below Isla Vista) “would narrow considerably, eroding on average by more than 25 meters by 2100,” it says. “Without interventions, 50-70 percent may experience complete erosion by 2100.” Beaches with shoreline armoring such as seawalls and revetments (Goleta Beach and Santa Claus Lane are named) are predicted to have the most rapid losses. Dune-backed beaches (Sands and Ellwood, for instance) have the best chance for survival, both in terms of biodiversity and surface area, as sand and wildlife can retreat inland with careful management.
The conclusions of the study are grim ― “In southern Santa Barbara County, opportunities to maintain sandy beaches and estuaries into the future are few.” But all is not lost, Myers insisted. “There are things that decision-makers can do.” Removing sea walls and reducing beach grooming are good examples. Establishing migration corridors for wildlife by eliminating or raising infrastructure is also important, as is creating a buffer for ecosystems to escape creeping waters. “And sediment management is huge,” she said. “Allowing more of the nice, natural sediment from the watershed to move downstream.” That means fewer dams and diversions. “There’s a lot that can be done,” Myers said.