Rising tides threaten communities on the beach -- and far from it, too

The mud in Folsom Lake, near Sacramento, Calif., is dry and chapped, like cracked heels. The bottom of the reservoir, once under water, now is largely barren, save for its shallow center and a smattering of stray puddles.

That's because California is in the midst of one of the worst droughts in state history. Conditions are so bad that Gov. Jerry Brown declared a state emergency in January. He urged state residents to voluntarily reduce personal water consumption by 20 percent.

In the context of having so little water, it might seem strange to worry about having too much. And yet, that's exactly the dilemma facing California today. Even as it reels from drought, it must begin planning for floods. And make no mistake: Floods are coming. Not only to California, but to coastal cities across the country and around the world, which face a certain influx of water as oceans rise under the specter of climate change.

"We analyzed 55 different water level stations throughout the United States and found that for about two-thirds of them, sea level rise from climate change has already more than doubled the risk of extreme flooding," says Dr. Ben Strauss, director of the Program on Sea Level Rise at Climate Central, a nonprofit organization dedicated to communicating the science and effects of climate change.

Based on the analysis, Climate Central developed Surging Seas, an interactive website (sealevel.climatecentral.org) that maps the flood threats from sea level rise and storm surges. The map shows how more than 3,000 coastal communities in the contiguous United States would be affected if sea levels were to rise from 1 to 10 feet.

"Sea level rise is already happening, and its continuation is inevitable," Strauss says. "At some point it will be obvious to every family living in a coastal area, and every community will be looking to protect itself."

A scary proposition

Multiple forces are colluding to make the oceans swell.

One is warming oceans. "Because of that, you have an expansion of ocean waters, and the only place they can go is up," says Rachel Cleetus, a senior economist in the Climate and Energy Program at the Union of Concerned Scientists, an alliance of citizens and scientists who collaborate on solutions to global problems.

Another is melting land-based ice forms such as glaciers and ice sheets. "You're adding volume to the world's oceans, and that's causing them to rise," Cleetus says.

Because the rate of ice loss is accelerating, oceans are rising faster than ever before. Cleetus says sea level could rise anywhere from 8 inches to 6.5 feet by the end of the century. Some scientists put estimates as high as 10 or 15 feet. That's on top of approximately 8 inches of sea level rise already logged in the last century.

"Those 8 inches of sea level rise from climate change are already making every single coastal flood bigger, deeper and more damaging," Strauss says.

Although scientists typically project sea level rise through the year 2100, communities likely will be impacted much sooner than that. The culprit? Incremental storm surges.

"Think about a game of basketball, where sea level is the court and your house is the hoop. If you raise the floor of the court, gradually, smaller and smaller players will be able to dunk," says Dr. Andrew Kemp, assistant professor of coastal processes and climate change at Tufts University. "It's not like it's going to be business as usual until 2099, when you have to sell your house because next year the whole thing is going to be permanently underwater. Long before that happens, you're going to see smaller and smaller storms that cause floods more and more frequently."

And that's to say nothing of big storms, which likely will be more frequent in a warmer climate.

Last year, the National Oceanic and Atmospheric Administration released a study about how climate change contributed to Superstorm Sandy. The findings were intimidating: "What they found was, if you have the amount of sea level rise that we are expecting to see, 50 years from now you'll see flooding like that experienced by New York and New Jersey during Sandy every other year. That's a scary proposition," says Rob Moore, senior policy analyst and head of the Water & Climate team at the Natural Resource Defense Council, an environmental advocacy group.

A river runs through it

By 2100, sea level rise could threaten an average of 9 percent of the land within 180 U.S. coastal cities, according to a 2011 report from the University of Arizona. The report names Miami, New Orleans, Tampa and Virginia Beach as among the U.S. cities most vulnerable to sea level rise.

But if you think that sea level arise affects only oceanfront homes on beaches and islands, think again. In fact, sea level rise promises to impact inland neighborhoods, too, particularly in low-lying areas near rivers and streams.

In Boston, for instance, sea level rise could bloat the Charles and Mystic Rivers, endangering Cambridge and Everett, Mass. In Southern California, flooding from the San Gabriel River could easily inundate the city of Rossmoor, although it's five miles from the coast. In the mid-Atlantic, the Potomac River could swallow Alexandria, Va. Even parts of Seattle — like Georgetown, which is 4.5 miles from Elliott Bay, and more than 100 miles from the Pacific Ocean — could be sopping wet at high tide in a matter of decades.

"There are pockets of vulnerability around the whole nation," Strauss says.

One of the most surprising pockets is Sacramento, 25 miles southwest of drought-stricken Folsom Lake. At least 80 miles inland, it sits at the nexus of the Sacramento and American Rivers, both of which flow into the Pacific Ocean by way of San Francisco.

"Sacramento was a river delta, and the way they secured the land 150 years ago was to build levees and let the land dry out," explains oceanographer John Englander, author of High Tide on Main Street: Rising Sea Level and the Coming Coastal Crisis. "Of course, nobody thought sea level would change that much in a century, so now the design of those levees is insufficient to protect the city."

The Sacramento neighborhood of North Natomas is a window to the potential impacts of sea level rise. In the early 2000s, it blossomed. Building was prolific, businesses were growing and home values were rising.

Then came Hurricane Katrina.

Because Sacramento has the same levee system as New Orleans, the U.S. Army Corps of Engineers decided to inspect it in 2006. Deficiencies, it found, were rampant and levee failure imminent. The Federal Emergency Management Association (FEMA) declared North Natomas an immediate flood risk and began requiring flood insurance of all local mortgage holders. Soon after, in 2008, it put a moratorium on new construction in North Natomas that won't be lifted until the levees are repaired, a project that's still ongoing six years later while FEMA awaits federal funding.

"Everything came to a stop," says North Natomas real estate agent Joan Dunn. "Builders moved out, land became vacant and the market started to crash. Everything went downhill."

Homeowner and general contractor Chris Lattuada bought his North Natomas home in 2000. Because he had already purchased flood insurance, he was grandfathered in at a low annual premium of approximately $300 when FEMA made it mandatory. Other families, however, have seen premiums quadruple to $1,300 annually, he says. That, combined with the building moratorium, has him concerned about the value of his home and the future of his community.

"Home values went way up when there was a boom, but now they've gone back down to where they were when we purchased," Lattuada says. "What troubles us is: Are values going to stay stagnant because of the flood issue? They were going to build more schools, more houses, more businesses. But now it's all stopped. What does our neighborhood look like in the end?"

The answer depends largely on the levees. "If the levees aren't fixed, and we have a disaster, we're screwed," Dunn says.

Although he lives on the opposite coast, in Branford, Conn., homeowner Rick Bourne knows the feeling. When his parents died in 2012, he decided to sell their home, located approximately a mile inland from the Long Island Sound. Because flood insurance was required with the mortgage, Bourne paid a surveyor $1,000 for an elevation certificate that would help the insurance company quote a premium for potential buyers. Although local premiums previously averaged around $1,200 a year, the new quote was $10,000.

"Immediately, anybody who was interested in the house gave up on it," says Bourne, who took nearly a year to sell the home. "We eventually found a cash buyer who didn't need flood insurance, since they were paying cash. They purchased it, but at an extremely lower rate; the house originally was listed for $280,000, and we ended up selling it for $220,000."

Danger: Keep Out

The pain points of living in a flood plain — stringent building restrictions, low home values, high insurance premiums — will only become more painful as water levels rise. And although it may sound harsh, that's kind of the point.

"I really sympathize with people," Cleetus says. "This is not an easy conversation to have. People have lived in certain places for a long time, and there's a lot of emotional attachment. Our home is the biggest investment most of us have. But you want people to understand that there's a cost to living in high-risk areas."

To that end, Congress in 2012 passed the Biggert-Waters Flood Insurance Reform Act, which requires the National Flood Insurance Program that's administered by FEMA to raise insurance rates to reflect actual risk. Hence the premium hikes in places like North Natomas and Branford.

"In the past, the government has provided subsidies to people, giving them discounted insurance rates if they live in flood-prone areas. By doing so, we've actually made it easier for people to continue living in harm's way," Moore says. "Those subsidies have now been phased out. As a result, flood insurance rates have gone up dramatically because the real level of risk is now captured in the premiums people pay."

To help low-income families cope with new actuarial rates, lawmakers are considering a number of solutions, including tax incentives and voucher programs. Meanwhile, those with the financial means can secure lower rates by installing hurricane shutters or raising their home. At the community level, costly solutions like seawalls, wetlands and barrier islands could keep sea level rise and storm surge at bay. If waters rise high enough, however, all of the above eventually will fail.

Ultimately, then, the best solution might be the hardest to swallow: retreat.

"We need to pull back, in essence, from the shore," says environmental and land-use planning consultant Barry Chalofsky. "If you live (in a coastal floodplain) and you're counting on your house to be your nest egg when you retire, or you want to pass it on to your children, I would strongly think about elevating your property, then selling it over the next five to 10 years."

Back in North Natomas, however, Lattuada's staying put. "If it actually started flooding, of course properties would devalue and people would move away. But that hasn't happened," he says. "There's risk everywhere. I'm not worried. We don't plan to leave any time soon."