A NASA-led study has pinpointed parts of the California coast that are sinking into the ocean, including major cities such as Los Angeles and San Francisco.
The Golden State is the most populous in the US with nearly 40 million residents, including 68 percent of Californians living along the coast.
Researchers from NASA’s Jet Propulsion Laboratory (JPL) and the National Oceanic and Atmospheric Association (NOAA) teamed up to investigate which parts of California are most vulnerable to sea level rise.
The results revealed that sea levels will rise more than twice as much as previously expected in parts of San Francisco and Los Angeles by 2050.
That’s because the land in these areas is actually shifting downward as sea levels rise due to climate change, intensifying the rate of submersion.
Over the next 25 years, ground sinking could result in more than a foot of sea level rise in and around Los Angeles, and up to 17 inches in parts of the San Francisco Bay Area, like the city of San Rafael.
That’s roughly double the previous regional estimates for these metro areas of 6.7 and 7.4 inches, respectively.
In San Rafael, just one foot of sea level rise would inundate entire neighborhoods, shopping centers and even some schools, according to NOAA’s Sea Level Rise Viewer.
On their latest map of the state, NASA scientists revealed where the land was sinking the most, with those areas of California sinking the deepest highlighted in darker and darker shades of blue.
Scientists mapped land sinking (shown in blue) in coastal California cities and in parts of the Central Valley. NASA also tracked where the grounds was rising, a condition called uplift (shown in red)
Lead author Marin Govorcin, a remote sensing scientist at NASA JPL, said in a statement: ‘In many parts of the world, like the reclaimed ground beneath San Francisco, the land is moving down faster than the sea itself is going up.’
Govorcin and his colleagues used satellite radar to track vertical land motion — or the upward and downward movement of the ground — along more than a thousand miles of California coast.
This shifting results from human activities such as groundwater pumping and wastewater injection as well as natural processes like tectonic plate movement.
To measure ground sinking along California’s coast, the researchers analyzed radar data from European Space Agency (ESA) satellites, as well as motion velocity data from ground-based stations in the Global Navigation Satellite System.
These observations were gathered between 2015 and 2023, allowing the team to see changes in land elevation over time and identify sinking hot spots that are most vulnerable to rising sea levels.
In the San Francisco Bay Area, hot spots include San Rafael, Corte Madera, Foster City, and Bay Farm Island – where the land is sinking by more than 0.4 inches per year largely due to sediment compaction.
Slow-moving landslides in the Big Sur mountains below San Francisco and the Palos Verdes Peninsula in Los Angeles have also resulted in rapid ground sinking.
The Palos Verdes Peninsula is well-known for its landslides, but a separate NASA study published in September of last year found that this Los Angeles community is sinking toward the Pacific at a staggering rate of four inches per week.
In San Rafael, just one foot of sea level rise would inundate entire neighborhoods, shopping centers and even some schools, according to NOAA’s Sea Level Rise Viewer. The study predicts 17 inches of local sea level rise for this area over the next 25 years
The Palos Verdes Peninsula is sinking toward the Pacific at a rate of four inches per week
Several homes were destroyed in a landslide that barreled through the Palos Verdes Peninsula in July 2023
This coastal suburb is home to roughly 11,000 people.
In northern California, erosion has lead to sinking hot spots at marshlands and lagoons around San Francisco and Monterey Bay.
Ground sinking was most extreme in central California, although this region is not coastal and therefore not as vulnerable to sea level rise.
In the Central Valley, groundwater pumping is causing the land to sink at a rate of eight inches per year.
By 2050, sea levels in California are expected to rise between six and 14.5 inches above levels for the year 2000, the researchers concluded.
Their findings are published in the journal Science Advances.
State and federal water agencies have spent an estimated $100 million repairing ground-sinking-related damages in California since the 1960s, according to the state’s Central Valley Flood Protection Board.
And as sea levels continue to rise, so will the cost.
