Californians alive today will see unprecedented flooding from global warming

jc-mg-200-names.jpgJon Christensen writes: Sea level rise from global warming is likely to lead to unprecedented coastal, bay, and inland tidal flooding in California within the next several decades. And never before seen floods are likely to begin occurring annually within the lifetimes of Californians now under 40 years old, according to new research from Climate Central, an independent nonprofit organization of journalists and scientists based at Princeton University.

This is no longer an abstract, distant threat or a scene from a Hollywood movie. Real people alive today will experience these floods in California. A new interactive map developed in a collaboration among Climate Central, Stamen Design, and New America Media--in which I participated--shows the who, what, where, when, and why of these "surging seas."

"We chose a simple but powerful map design to bring out the human dimension of this problem: one dot per individual who could be affected," said Eric Rodenbeck, founder and creative director of the interactive mapmaking firm Stamen Design. "Real humans will be seriously affected by rising sea levels."

Of the $36.5 billion in property and 145,000 people occupying land less than three feet above the high tide line in California--the level expected to be topped annually in the near future--more than 90 percent are within the San Francisco Bay Area or in the Sacramento-San Joaquin River Delta. More than half are in San Mateo County alone.

LongBeachCC.jpgThe threat to coastal communities in Los Angeles in the near term is not as dramatic. (Click here to see the interactive map.) Sea level rise will likely lead to unprecedented coastal flood heights in the Los Angeles area within 30 to 50 years. But nearly the entire coastline is high enough to stay dry for much longer--except for parts of Long Beach, including the port. Nearly 12,000 people and $3 billion in property occupy land less than three feet above the high tide line in Los Angeles County, with 90 percent of those totals concentrated in Long Beach and Venice. After accounting for protection from features like beach ridges and tidal gates, exposure drops to 6,000 people and $1.4 billion, nearly all in Long Beach, as well as 32 road miles, and 34 sites that are listed as potential sources of contamination by the U.S. Environmental Protection Agency.

BSFCC.jpgy contrast, annual coastal floods likely will affect as many as 90,000 residents in San Mateo County--the most vulnerable county in California--who live on land less than 3 feet above the high tide line along San Francisco Bay. (Click here to see the interactive map.) More than $21 billion in property is at risk, along with 220 sites listed by the Environmental Protection Agency as potential contamination threats, and schools, churches, community centers, police and fire stations, and more. Levees and flood control structures may protect around a quarter of these areas from floods at the three-foot level, but only 10 percent of the area when floods are likely to crest above four feet in the following decades.

"Sea level rise means more floods, reaching higher--and that's already happening today," said Ben Strauss, Climate Central's lead scientist on the new study and mapping project. "In Southern California, floods threaten small bays and port areas. The open coast won't flood--but erosion will increase on beaches and rocky shores. While California's beaches face increased erosion, inland floods appear to pose the biggest threat where you might least expect it."

Different California communities clearly will be affected differently. New America Media led a collaborative reporting project on the different local impacts of sea level rise involving six Bay Area ethnic and community media reporters. "We found that communities are responding, but there is a dangerous information gap about sea level rise and policies to address it among impacted ethnic communities," said Ngoc Nguyen, NAM's environment editor. NAM is now looking to expand coverage of the issue among ethnic media in other areas of the state and nationally.

California is, of course, one state. And what affects the north will affect the south, if not directly in the same way, then through statewide policies and spending to mitigate and adapt to climate change.

Last month we highlighted here a more far-out artistic interpretation of Venice Beach under the 10-foot sea level rise eventually expected to result from the melting of the West Antarctic Ice Sheet, which now seems to be inevitable. You can visualize that on these maps too, though it's not likely to occur for another couple of centuries.

In the near term, there is a lot more we can do to reduce carbon emissions, stem global warming, and adapt to the changes that many of us will see in our lifetimes now.

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