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Ill Tidings of a Rising Sea

Precautions are needed to deal with a warming trend expected over the next half-century, a study says.

March 25, 1997|DARYL KELLEY | TIMES STAFF WRITER

Unless mitigating measures are taken, rising sea levels over the next 50 years could swamp hotels, power plants, a military base and as many as 4,100 low-lying houses along the Ventura County coastline during big storms, according to a new study of global warming by a USC research team.

"Coastal residents would lose the use, perhaps permanently, of roads, structures, power lines, railroads, recreational facilities, trailer parks and camping areas," said environmental sociologist Angela Constable, lead author of the report.

The new study focused on Ventura County because so much of the Oxnard Plain is near sea level, the researchers said. Still, they figured that whatever effects global warming had there would have implications for the state's other coastal counties, where populations are expected to double over the next 50 years.

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Researchers said they expect that the sea level will rise by about two feet by 2040 in Ventura County, and that local governments' reaction to the threats of rising water and beach erosion will determine how much damage actually occurs.

The USC team concluded that governments could offset much of the potential damage with stricter building standards, higher sand berms on beaches and construction of rock groins and underwater breaks in the ocean to alter wave action and erosion.

Unless new coastal homes in Ventura County are built on stilts, such as those supporting houses in storm-battered Florida and South Carolina, million-dollar beachfront dwellings could be ruined, the research team concluded. The city of Oxnard, for one, already requires new beach houses to be elevated about three feet above the ground.

"This is not an overnight scenario," said Constable, a doctoral candidate at USC. "You don't wake up one morning and the sea has risen. And we assume that Ventura County and other coastal areas will provide mitigations. But without them, you would lose all of those homes."

Along the Ventura County coast, researchers say, the shoreline could recede by 50 to 75 yards over five decades and, during severe storms, ocean water could damage structures such as the Ventura Pier, Ventura Harbor, Ventura's sewage plant, two Edison power plants, the Mandalay Beach Resort, Channel Islands Harbor and a portion of the Naval Air Weapons Station at Point Mugu.

Flooding could occur in houses within a block of the shoreline, including streets in Ventura's Pierpont Bay, Oxnard Shores, Hollywood Beach, Silver Strand and Surfside in Port Hueneme, the researchers concluded.

Using estimates of a two-foot rise in sea level, which the researchers consider the most likely scenario, based on global warming studies by a United Nations task force, houses for 9,100 people could be damaged during storms, Constable said.

Researchers also evaluated the effects of a 10-foot ocean rise, which they consider highly unlikely but possible during large storms, and found that homes of 40,000 residents would be at risk.

But that is without local governments responding to what many scientists believe are the effects of global warming--higher seas and a pattern of more severe storms, the researchers said.

There is broad agreement among scientists that the Earth has gotten warmer by an average of more than 1 degree during the last century. And many scientists say that is the result of global warming--a change in climate caused by carbon dioxide and other gases from autos and industry that trap warm air in the atmosphere and create a greenhouse effect.

Numerous studies have found that sea levels are rising. For example, scientists at the Scripps Institution of Oceanography at UC San Diego found in 1992 that the sea level off Southern California was rising about an inch a decade because ocean water expands as it warms. Some scientists also suspect that the warming has already begun to melt glaciers, which would raise sea levels.

The degree to which global warming could raise sea levels has been a subject of intense scientific debate for at least a decade, and the USC researchers caution that recent studies have scaled back early projections.

For example, the Intergovernmental Panel on Climate Change, a United Nations task force of 2,500 scientists, had considered 26 inches to be the most likely rise in sea level from a two- to five-degree increase in the Earth's atmosphere by 2100. But last year the panel reduced its projection to 20 inches.

The USC study is pertinent because it couples the projected sea rise with the effects of shoreline retreat resulting from coastal development and natural wave action, said USC geographer Douglas J. Sherman, co-author of the study.

"There are still very good reasons for concern, but the sense of almost panic is gone," Sherman said. In Ventura County, the USC team said that planning efforts, should include wider setbacks from the ocean for new construction.

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