Underwater destiny for many N.J. towns?

New Jersey may have been stronger than the storm, but the sea will prove stronger in the long run, scientists fear. Dozens of its towns – including such familiar places as Atlantic City, Hoboken, Beach Haven and Wildwood -- may already be doomed to partly flooded futures. Some neighborhoods are already precariously close to sea level, as evidenced by projects that have committed more than a billion dollars to replenish Jersey beaches and protect them over several decades. Even climate-change skeptics acknowledge that sea levels have been slowly rising. "It's rare that you'll find someone to say that sea level isn't rising," said Jon Miller, a professor of coastal engineering at Stevens Institute of Technology. "That's hard to refute." "If I had a house at the Jersey Shore I would want it to be built as high as it could possibly be," he added. The rise this century could be dramatic – as much as 6.6 feet -- depending on how much global warming melts ice in Greenland and Antarctica, according to a report from the National Oceanic and Atmospheric Administration. If this century mimics the last one, NOAA says, seas would rise just another eight inches. If the oceans warm and expand, the rise could double that. Add melting from ice sheets and glaciers and a four-foot rise is the expectation by 2100. Four feet would be disastrous. It's enough for high tide to overrun half of the populated areas of 25 New Jersey towns – including half of Margate, Strathmere and Brigantine – and five in Delaware, displacing as many as a quarter-million people, according to “Cities Below Future Seas,” an interactive tool from Climate Central, a Princeton-based research group. See list: "39 N.J. Towns Most at Risk to Rising Seas" These are not all towns with narrow beaches. Indeed, the tool's simulations of coming flooding shows that bayside streets may be hardest hit, so even Wildwood, with its broad beach, is in jeopardy. And some low-lying towns aren't even at the Shore, including Hoboken and Secaucus in North Jersey, Pennsville in Salem County, and Gibbstown in Gloucester County. Such a rise has already become inevitable, says ecologist Ben Strauss, a Climate Central vice president.  “It appears that the amount of carbon pollution to date has already locked in more than 4 feet of sea level rise past today’s levels,” he said. “That is enough, at high tide, to submerge more than half of today’s population in 316 coastal cities and towns (home to 3.6 million) in the lower 48 states,” including Miami, Virginia Beach, Sacramento and Jacksonville. Lower the "threat threshold" to 25 percent, and New York and Boston join the list, according to Strauss. The timetable may be uncertain, Strauss said, but he’s convinced the end result is as clear as the fate of a bag of ice left out at room temperature. The idea of such long-term impact is supported by a recently released draft of a report by the UN-appointed Intergovernmental Panel on Climate Change. Four feet might even be an underestimate. "Most scientists tell me that number is too low," Strauss said. Some scientists suspect global warming could generate more hurricanes in the Atlantic, and former Vice President Al Gore even speculated about monstrous Category 6 hurricanes spawned by global warming. But sea level changes are looking like the more real worry, said Philip Klotzbach, part of the hurricane prediction team at Colorado State University. "If you look at global tropical cyclone activity around the globe, right now we’re at a 30-year low,” and several dozen earlier Atlantic storms were more powerful than Sandy, he said. Raise sea levels, though, and coastlines everywhere become more vulnerable to storms of all sizes, suggesting that in coming decades, policymakers may face increasing pressure to shift from rebuilding after hurricanes and major nor'easters to beginning a strategic retreat. Hurricanes can seem like Mother Nature's mood swings. Regularly flooded streets might drive home the message that the answer's in the air. Miller hopes there's still time to stave off disaster, by engineering buildings and beaches that can better survive the wind, rainfall and storm surges of major storms, while cutbacks in greenhouse-gas emissions help the atmosphere heal. "I think you do have to attack the problem from both ends," Miller said. Perhaps new technologies will scrub carbon dioxide out of the atmosphere. That's the goal of Sir Richard Branson's Virgin Earth Challenge, a contest with a $25 million prize. Other alarming scientific reports assert that the heat in coming decades will make recent record years seem cool, and that severe spring thunderstorms will be more frequent in the Eastern United States, all because of global warming. Last year, a geophysicist even argued that climate change could trigger more volcanic eruptions and earthquakes. Although 97 percent of top climate scientists agree that the planet is in the midst of human-accelerated climate change, skeptics persist, who argue that you can’t prove a drastic future before it arrives. “It's all very speculative,” says H. Sterling Burnett, an analyst with the National Center for Policy Analysis. Barrier islands may eventually disappear unless there’s another ice age, he said, but he has doubts that computer models can accurately predict what lies ahead. Evidence will become increasingly ominous, then undeniable, Strauss predicts. Sandy's storm surge set a record for Atlantic City that might not be broken soon. But by mid-century, the odds start stacking up, Strauss said. A 2 percent annual chance of topping Sandy in the 2040s will grow to 13 percent in the 2060s, jump to 33 percent in the 2070s, then rocket to 100 percent in the 2080s, projections suggest. “Places are going to have that sharp transition from never getting flooded or rarely getting flooded to always getting flooded," he said. "... That’s the heart of it. That’s how people are going to experience this.” At current greenhouse-gas production rates, by late this century even some Pennsylvania towns start showing as destined to have sections submerge. The most vulnerable are Bristol, Croydon and Tullytown in Bucks County, and Eddystone and Marcus Hook in Delaware County. At that level - an inevitable rise in sea level of 20 feet - more than 1.5 million people in New Jersey would be affected, including in Camden and Gloucester City. Miller's more hopeful. "I don't think it's a losing battle yet," he said. "But we may get to a point that it does become a losing battle." Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.