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The highest aspirations for the Copenhagen climate talks may have been swamped, and in the meantime, sea level along much of the California coast threatens to continue its long-term rise.

The state in recent years has begun to prepare for rising sea levels expected as the result of a warming climate in which ice near polar regions melts faster and warmer ocean water expands. Policies have been developed to force new coastal building and infrastructure projects to factor in sea level rise, but discussions on how to protect existing populations and properties over the next 100 years is just beginning in many regions.

The Humboldt Bay area may be among the more vulnerable in the state. However, its small population may not immediately draw funding and resources to deal with the potential problem the way larger communities might, and officials have begun to make pleas for early assistance.

Sea level has been rising since records were first kept off the North Spit of Humboldt Bay in 1977. It's not dramatic: A mere 4.73 millimeters, or .19 inches, per year during that period. At the same time, there is some seemingly conflicting evidence that the trend is tapering off.

The Central and Northern California Ocean Observing System -- CeNCOOS -- points to a sudden and slight reversal of a 100-year sea level rise off San Francisco. Since 1997, sea level has been falling, according to a recent Moss Landing Marine Laboratory analysis of satellite data.


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CeNCOOS cautions that the analysis and data is far more complicated than it appears.

A phenomenon called the Pacific Decadal Oscillation causes big shifts in water temperature in the Pacific Ocean. In 1997, the oscillation entered a cold phase believed to be responsible for the corresponding drop in sea levels.

But, CeNCOOS experts point out that scientists today believe that over the long term, sea level is likely to continue climbing, even if it is not uniform or constant at any particular location.

”Coastal planners should be aware that the rate of sea level rise will likely not be constant, and plan accordingly,” wrote Program Director Steve Ramp, the Monterey Bay Aquarium Research Institutes' Francisco Chavez and Moss Landing's Larry Breaker. “We should not be lulled into a false sense of security because sea level off Central California is presently falling.”

The state's Climate Action Team expects the sea to rise much more sharply in coming years, as ocean temperatures rise and land ice melts. The team is predicting a 1.45-meter rise -- more than 4.5 feet -- by 2100.

If the rate of sea level rises as the team anticipates, it could put 7,800 Humboldt County residents and 570 parcels at risk during 100-year floods, the big floods that happen statistically every 100 years. A variety of other impacts come with such a rise in sea levels. Increased erosion could increasingly threaten homes along the McKinleyville bluffs and Big Lagoon, and alter North Coast beaches. Flash flooding may increase in intensity and frequency.

But the far more populated Orange, Santa Barbara, Monterey and Los Angeles counties collectively have some 154,000 people at risk, according to the climate team study, and thousands of properties. When it comes down to it, what areas are most likely to see the resources needed to cope with sea level rise?

In October, California Coastal Commission Chairwoman Bonnie Neely wrote to U.S. Sen. Dianne Feinstein, asking the California Democrat to consider supporting funding of a comprehensive planning process to help agencies and the public make informed land-use choices.

”Notwithstanding the probability that the more severe and widespread impacts of sea level rise will not be directly felt for several decades, it would be highly imprudent to sit idly by and do nothing until it is too late and we find ourselves in a solely reactive mode,” Neely wrote.

In an e-mail to the Times-Standard, Neely wrote that Humboldt County has more highway miles vulnerable to sea level rise than any other county, and increased erosion could be a much more significant risk here than elsewhere in the state. Urban communities like the San Francisco Bay area have more resources to deal with sea level rise, Neely pointed out. Places like Humboldt County need special attention, she wrote.

U.S. Highway 101, especially between Arcata and Eureka, could be particularly vulnerable. Maps from Oakland's Pacific Institute show large parts of the highway awash during big floods.

State agencies like the California Coastal Commission, Caltrans and just last week, the State Lands Commission, have made it policy to make all new projects capable of withstanding the projected sea level rise.

For example, Caltrans is planning to replace the existing Jacoby Creek bridge on Highway 101 to handle sea level rise as part of its blueprint for safety changes on the corridor between Arcata and Eureka, said Caltrans Project Manager Kim Floyd.

But Caltrans isn't planning on moving the highway. Floyd said some adaptive management policies may have to be developed that could include temporary lane closures during floods.

Generalized policies in the Coastal Act don't allow new projects to contribute to geologic, flood or fire hazards, with tsunamis, storm surge and sea level rise included in the flood portion. Protection of existing infrastructure is a different issue.

A study done of the San Francisco Bay area by the California Climate Change Center estimated that sea level rise threatens some $48 billion -- in 1990 dollars --of commercial, residential and industrial structures around the bay. Building or strengthening sea walls and levees to protect that infrastructure, the March 2009 report goes on, could cost $1 billion outright and $100 million a year for maintenance.

Coastal Commission North Coast District Manager Bob Merrill said that a study of what facilities and resources are at risk around Humboldt Bay would help determine what type of protection might be needed in the future, in part what Neely was calling for in her letter to Feinstein.

”There needs to be a more focused look at the infrastructure around the bay,” Merrill said.

Anticipated sea level rise will make it into the updated general plan for the county in some form. County Supervising Planner Tom Hofweber said that the 1.45 meter prediction -- or the best, latest information -- will be rolled into the environmental analysis of the general plan. That said, most of the county's low-lying properties are agricultural areas in which planning documents wouldn't allow development, Hofweber said.

The Planning Commission will take up the hazards section of the general plan in four or five months, Hofweber said, and it would be helpful for the state and federal governments to provide more guidance on the issues.

County public projects have been touched by the state's policy on sea level rise, and that's likely to become more regular as time wears on, said Humboldt County Department of Public Works Environmental Services Manager Hank Seeman.

”That's really going to hit the ground,” Seeman said.

When the county and the Humboldt Bay Harbor, Recreation and Conservation District asked for a permit to expand the Fields Landing boat ramp and add parking, the Coastal Commission approved it with conditions. It insisted the project was at the county's own risk, and made clear that it wouldn't approve future projects to protect the ramp from sea level rise.

Seeman said a number of other areas under county control are cause for concern. Luffenholtz and Moonstone beaches could see serious changes, he said. Drainage in King Salmon and Field's Landing -- already poor during high tides and heavy rain -- could be significantly worsened, as could be bluff erosion in McKinleyville and Big Lagoon. Seeman said that no strategy to deal with those changes has yet been generated.

”We're going to need some state assistance and guidance on that to do it more effectively,” Seeman said.

John Driscoll covers natural resources/industry. He can be reached at 441-0504 or jdriscoll@times-standard.com.