by Arizona State University, August 2, 2020 in WUWT

A majority of the world population lives on low lying lands near the sea, some of which are predicted to submerge by the end of the 21st century due to rising sea levels.

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The most relevant quantity for assessing the impacts of sea-level change on these communities is the relative sea-level rise – the elevation change between the Earth’s surface height and sea surface height. For an observer standing on the coastland, relative sea-level rise is the net change in the sea level, which also includes the rise and fall of the land beneath observer’s feet.

Now, using precise measurements from state-of-the-art satellite-based interferometric synthetic aperture radar (InSAR) that can detect the land surface rise and fall with millimeter accuracy, an Arizona State University research team has, for the first time, tracked the entire California coast’s vertical land motion.

They’ve identified local hotspots of the sinking coast, in the cities of San Diego, Los Angeles, Santa Cruz and San Francisco, with a combined population of 4 to 8 million people exposed to rapid land subsidence, who will be at a higher flooding risk during the decades ahead of projected sea-level rise.

“We have ushered in a new era of coastal mapping at greater than 1,000 fold higher detail and resolution than ever before,” said Manoochehr Shirzaei, who is the principal investigator of the NASA-funded project. “The unprecedented detail and submillimeter accuracy resolved in our vertical land motion dataset can transform the understanding of natural and anthropogenic changes in relative sea-level and associated hazards.”

The results were published in this week’s issue of Science Advances (DOI link here).

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