Steve Gorman, Reuters 12 Mar 09;
LOS ANGELES - California's farms and cities may be left high and dry by prolonged drought, but climate change is expected to leave much of the state's fabled shoreline awash in excess seawater before too long.
Nearly 500,000 people and $100 billion worth of property in coastal California are at risk of severe flooding from rising sea levels this century unless new safeguards are put in place, researchers reported on Wednesday.
With global warming expected to lift ocean levels along the California shore by 1 to 1.4 meters (1 to 1.4 yards) before the year 2100, large tracts of the picturesque Pacific coast also will be lost to accelerated erosion, their study found.
The report suggests that the heightened flood risk could be minimized by investing about $14 billion in a system of newly built or upgraded sea walls, levees and offshore breakwaters to reinforce some 1,100 miles of coast.
But such coastal "armoring" structures come with their own cost, the loss of beaches.
The state-funded report from the Pacific Institute, an environmental think tank, marks the first sweeping assessment of how California's entire 2,000-mile shoreline, including San Francisco Bay, and the millions who live along it may be affected by higher sea levels.
The extent of elevated oceans assumed in the study were projected by California state researchers working from medium- to high-greenhouse gas emissions scenarios of the U.N.'s Intergovernmental Panel of Climate Change.
But Heather Cooley, co-author of the report, said it does not reflect the worst-case rise in sea levels that might occur. Like most climate models, the study excludes the potential effects of melting ice sheets in Greenland and Antarctica because of uncertainty over how they will play out, she said.
Instead, the higher sea levels anticipated in the study are attributed mostly to thermal expansion -- the phenomenon by which water increases in volume as it warms.
AIRPORTS AND BIG SUR IN HARM'S WAY
Likely flood casualties include both the San Francisco and Oakland international airports, as well as 3,500 miles of roads and 280 miles of railways, 140 schools, 30 power plants and 29 wastewater treatment facilities, the study found.
But some of the aesthetic beauty and recreational values associated with the California shore, one of the state's prime natural assets, are at risk, including the famed central coastal cliffs of Big Sur. In all, 41 square miles of coast will be lost to erosion, according to the study.
"Changes to California coasts are inevitable," Cooley said. "We need to evaluate and assess what our values are and which qualities of the coast we want to maintain."
Flood damage envisioned by the study would result from storm surges occurring with greater frequency and intensity in low-lying areas once a safe distance from the shore. Areas that already lie within an existing coastal flood plain would face even greater risk.
About 260,000 people live in flood-prone areas around San Francisco Bay and other low-lying coastal communities up and down the state. That number would grow to 480,000 if sea levels were to rise 1.4 meters (1.4 yards) without any mitigating actions being taken, the report found.
Populations in San Mateo County, south of San Francisco, including the Silicon Valley towns of Palo Alto, Mountain View and Sunnyvale, are considered especially vulnerable, along with parts of Orange County south of Los Angeles.
The study estimates that nearly $100 billion worth of property, in year 2000 dollars, would be put in harm's way from flooding -- two-thirds of it concentrated around San Francisco Bay. The majority of that is residential.
Poor individuals and those of racial or ethnic minorities account for a disproportionate number of residents at risk, even though many of the projected new flood zones lie in relatively affluent areas.
"A lot of people have wondered whether California will be the next (Hurricane) Katrina, and we do have a lot of those conditions in place," said study co-author Matthew Heberger, speaking of the hurricane that flooded New Orleans in 2005.
(Editing by Philip Barbara)
California panel urges 'immediate action' to protect from rising sea levels
Global warming is projected to cause ocean levels to rise 55 inches or more by the end of the century. Report recommends phased abandonment of coastal areas and moving state infrastructure inland.
Margot Roosevelt, LA Times 11 Mar 09;
As California officials see it, global warming is happening so there's no time to waste in figuring out what to do.
California's interagency Climate Action Team on Wednesday issued the first of 40 reports outlining what the state's residents must do to adapt to the floods, erosion and other effects expected from rising sea levels.
Hundreds of thousands of people and billions of dollars of Golden State infrastructure and property would be at risk if ocean levels rose 55 inches by the end of the century, as computer models suggest, according to the report.
The group floated several radical proposals: limit coastal development in areas at risk from sea rise; consider phased abandonment of certain areas; halt federally-subsidized insurance for property likely to be inundated; and require coastal structures to be built to survive climate change.
"Immediate action is needed," said Linda Adams, Secretary for Environmental Protection. "It will cost significantly less to combat climate change than it will to maintain a business-as-usual approach."
Few topics are likely to be more contentious than coastal development. But along the state's 2,000-mile shoreline, the impact would be acute, particularly in Orange and San Mateo counties where an estimated 110,000 people would be affected, according to the 99-page state-commissioned report by the Oakland-based Pacific Institute.
Detailed maps of the coastline, published on the institute's website, show residential neighborhoods in Venice and Marina del Rey could be inundated. Ocean waters could surge over airports in San Francisco and Oakland, through the ports of Los Angeles and Long Beach, and across large swaths of Huntington and Newport Beach.
Roads, schools, hospitals, sewage plants and power plants may have to be relocated. More than 330 hazardous waste sites are at risk from floods.
California's far-reaching adaptation initiative reflects an emerging global consensus: Scientists can argue over how fast the earth is heating up and diplomats can wrangle over setting emissions caps, but politicians must begin planning for the certainty of climate change.
Dozens of world-class scientists and economists, many from the University of California and state research institutes, are examining potential effects of warming on snowpacks, wildfires, crops and electricity demand.
Further reports will examine climate impacts on hospital admissions, mortality rates, pollution and the habitats of the state's animals and plants. Dutch experts have been consulted on how to armor the coast with improved dikes and sea walls -- controversial measures that some experts contend will only increase erosion.
Detailed studies, now undergoing peer review, are to be released over the next month. Then the Climate Action Team is to send a comprehensive report to Gov. Arnold Schwarzenegger.
Sea levels along California have risen nearly 8 inches in the past century, although this varies with coastal dynamics. According to the Pacific Institute report, 260,000 Californians already live in flood zones, but are assumed to be protected by existing structures, such as levees and sea walls.
A 1.4-meter sea level rise would increase the population at risk to 480,000. Currently, 1,900 miles of roads and highways are at risk of flooding, which would grow to 3,500 miles under the sea level rise projections.
The report estimated the cost of one adaptation strategy: armoring the coast with 1,100 miles of new or modified sea walls and levies. It would cost at least $14 billion to construct, and another $1.4 billion a year to maintain.
The report's estimate of 1 to 1.4 meters (55 inches) of sea level rise by the end of the century was calculated using two models from the United Nations' Intergovernmental Panel on Climate Change, a gathering of the world's top climate scientists. One model assumes countries will cut their emissions of the planet-heating greenhouse gases, and another assumes a business-as-usual emissions level.
Despite more than a decade of warnings from scientists, global emissions are continuing to rise, fueled by rapid population growth and economic development in nations such as China and India. Unless greenhouse gases are cut significantly, earth's temperature is expected to increase between 4 and 6 degrees Celsius by the end of the century, according to the U.N. panel.
As sea water warms due to rising air temperatures, it expands, causing the level to rise. But a second major factor, the melting of the Greenland and Antarctic ice sheets, was unaccounted for in the U.N. panel's models, designed in the mid-1990s, because of uncertainty over effects and timing.
Ice sheet melting has since accelerated. Dan Cayan, a researcher at the Scripps Institution of Oceanography and a lead scientist on the state's action plan, said the 55-inch estimate in the report is "probably conservative. . . . As temperature climbs, melting is going to proceed at a greater pace. It is not necessarily going to proceed linearly, in the same proportion as it did in the past, because melting begets more melting."
