Sea levels off the California coast would rise by six inches by 2030, and an average of three feet by 2100, according to a new report.
However, Northern California, Oregon and Washington could expect a less dramatic increase — about four inches by 2030 and two feet by 2100 — because seismic activity was causing land to rise north of the San Andreas Fault and drop south of it.
The National Research Council released the finding, contained in a study of how melting ice sheets and warming oceans associated with climate change will raise sea levels along the country's Pacific coast, on Friday.
Further, the report warned, more severe weather events causing flooding and coastal erosion were expected to accompany higher sea levels, and a major earthquake in northern California could cause the sea level to rise as much as six feet immediately, the Associated Press cited the report as saying.
Such a major earthquake occurred 300 years ago, but became more likely as time passed.
"Rising seas increase the risk of coastal flooding, storm surge inundation, coastal erosion and shoreline retreat, and wetland loss, it read," USA Today reported.
"The cities and infrastructure that line many coasts are already vulnerable to damage from storms, which is likely to increase as sea level continues to rise and inundate areas further inland."
USA Today pointed out that about 72 percent of the California coast was covered by sandy cliffs, with the rest consisting of beaches, sand dunes, bays and estuaries.
However, seaside cliffs would retreat about 30 yards over the next 100 years, and sand dunes even further, KTVU cited Robert A. Dalrymple, a professor of civil engineering at Johns Hopkins University and chairman of the group that wrote the report, as saying.
Oregon's coastline was relatively protected by tough basalt formations, however long stretches of Washington were low-lying sandy beaches, Dalrymple warned.
"Anything close to the seas is vulnerable," he said.
Also, coastal wetlands would resist erosion for about 50 years but eventually be overwhelmed without sand barriers and room to move inland.
While the report noted computer modeling as suggesting that storms would be stronger as global warming progressed, Dalrymple said there was no clear consensus in scientific literature.
According to USA Today, the finding was consistent with earlier projections, though this study took a closer look at the California, Oregon and Washington coastlines.
Globally, sea levels had risen about 8 inches over the last century, but the rate has been increasing rapidly, report author Gary Griggs, director of the Institute for Marine Sciences at the University of California at Santa Cruz, reportedly said.
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