Tuesday, May 3, 2011
In a new study, UC-San Diego researchers said sea level rise is returning to the North American coast after a 30-year break.
Scripps Institution of Oceanography scientists said the sea level in the Eastern Pacific may rise due to a shift in climate.
Reseachers said sea levels along the coast of North America has been steady the past few decades, but now their study shows shifting wind patterns could cause coastal sea-level rise to accelerate.
Peter Bromirski is the lead author of the new study. He said wind stress patterns can act to suppress or raise sea level.
Bromirski said damage from rising sea level may be more apparent along the West Coast in 10 or 20 years.
"If you have a storm and waves during high tide, then you have more energy reaching farther shoreward and that ends up in beach (erosion) along with coastal erosion and potentially more flooding," said Bromirski
He said global sea-level-rise increased by 50 percent during the 1990s, a level usually linked to global warming.
Bromirski said rising sea level has consequences for coastal development, beach erosion and wetlands inundation.
Damage from higher sea levels could cause increased damage during coincident high tides, storm surges and extreme wave conditions.
Scientists date the current phase of a Pacific Ocean climate cycle, called the Pacific Decadal Oscillation, to the mid- to late-1970s.
Bromirski said the current "warm" phase is characterized by the upward movement, or upwelling, of cold water toward the surface along the West Coast.
Despite a few El Niño-induced surges in sea level during that time, the coastal-sea-level trend has mostly been steady.
Bromirski said when the cycle shifts to its negative "cold" phase, coastal ocean waters will become characterized more by a down-welling regime, where the amount of colder, denser water currently brought to the surface will be reduced. Resulting warmer surface water will raise sea level.
Bromirski and fellow Scripps oceanographers Art Miller, Reinhard Flick and Guillermo Auad studied the wind stress patterns that characterize the different phases of the Pacific Decadal Oscillation.
The authors write that a change in wind stress patterns may be foreshadowing a Pacific Decadal Oscillation regime shift, causing an associated persistent change. That will result in a concomitant resumption of sea level rise along the U.S. West Coast to global or even higher rates."
The study was funded by several state and federal agencies, including the California Department of Boating and Waterways.