Global warming predicted to raise sea level on West Coast up to 4 feet in places - OregonLive.com

Expect more flooding and coastal erosion as global sea levels rise more than previously predicted over the next century, a new study says. Some parts of the West Coast need to brace for up to 4 1/2 feet rises by 2100.

Estimates from the National Research Council found the higher water will primarily come from oceans warmed by an ever-hotter climate. But, these numbers are higher than past studies because the study ruled glacial melt caused by higher global temperatures will contribute significantly more than previously calculated.

The report projected that relative to 2000, seas will rise 3 to 9 inches by 2030, between 6 and 18 inches by 2050 and up to 4 1/2 feet by 2100. As time goes by, uncertainties about exponential warming or natural disasters like earthquakes or tsunamis cause greater ranges of possible change, according to the study.

In 2008, California Gov. Arnold Schwarzenegger asked state agencies and the National Research Council to assess coastal impacts of sea-level rise. Oregon, Washington and several other federal agencies joined California to sponsor the research.

There's more at stake than smaller beaches.

"As the average sea level rises, the number and duration of extreme storm surges and high waves are expected to escalate, and this increases the risk of flooding, coastal erosion, and wetland loss," said Robert Dalrymple, committee chair and Professor of Civil Engineering at Johns Hopkins University in a press release.

Oregon will probably see the least impact of the three states because aren't many big towns close to sea level, said Oregon State University's professor of oceanography, Rob Holman. He served as the Ocean Studies Board Liaison to the study. California has the most at stake, with huge cities and valuable infrastructure lined along much of its coast.

"The big concern is low-lying coastal communities and the impact of extreme storms," Holman said Friday. "It means the storms will lap higher, and when you add an extra foot it can become disastrous."

Interestingly, the study notes melting landlocked ice in Alaska could actually help lower impact of rising global sea levels on the west coast -- some chunks are so massive they have their own fields of gravity, pulling up local sea levels.

Check back for more on the study.