WASHINGTON (dpa-AFX) - Land along California's coastline is inching down and up due to natural and human-caused factors, a NASA-led study has found.
Using California as a case study, a NASA-led team has shown how seemingly modest vertical land motion could significantly impact local sea levels in coming decades.
The elevation changes may seem small - amounting to fractions of inches per year - but they can increase or decrease local flood risk, wave exposure, and saltwater intrusion.
By 2050, sea levels in California are expected to increase between 6 and 14.5 inches higher than 2000 levels. Melting glaciers and ice sheets, as well as warming ocean water, are primarily driving the rise. As coastal communities develop adaptation strategies, they can also benefit from a better understanding of the land's role, the team said. The findings are being used in updated guidance for the state.
'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,' said lead author Marin Govorcin, a remote sensing scientist at NASA's Jet Propulsion Laboratory in Southern California.
The new study illustrates how vertical land motion can be unpredictable in scale and speed; it results from both human-caused factors such as groundwater pumping and wastewater injection, as well as from natural ones like tectonic activity. The researchers showed how direct satellite observations can improve estimates of vertical land motion and relative sea level rise.
Researchers from JPL and the National Oceanic and Atmospheric Administration (NOAA) used satellite radar to track more than a thousand miles of California coast rising and sinking in new detail. They pinpointed hot spots - including cities, beaches, and aquifers - at greater exposure to rising seas now and in coming decades.
Not all coastal locations in California are sinking, according to the study. The researchers mapped uplift hot spots of several millimeters per year in the Santa Barbara groundwater basin, which has been steadily replenishing since 2018. They also observed uplift in Long Beach, where fluid extraction and injection occur with oil and gas production.
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