The global sea level rise and Dorchester

Predictions of global sea level rise are all over the map, with new studies and findings being released almost every week. Some, particularly those that imagine a total polar ice melt, would put our fair city under as much as 25 feet of water. But by the more responsible and scientifically defensible predictions, Dorchester’s coastline could rise anywhere from around one foot to 2 meters by the end of this century, depending on how well the world does curbing carbon emissions from fossil fuels.

“Anything below seven feet right now could be underwater by 2100,” said Ellen Marie Douglas, Assistant Professor of Hydrology at UMass-Boston’s Environmental Earth and Ocean Sciences department. “That higher [estimate] is feasible but not as likely. I saw two papers that pointed to one meter as the more likely [global] rise.”

And, she added, another new study focusing on the impact on ocean and wind currents recently added around eight inches to that one-meter total for New England in particular.

Scary predictions like these, though even the most conservative among them get worse each year, are nothing new. What is new is the government is listening intently. Local, state, and federal governments are moving beyond acknowledging the coming rise and starting to take action both to slow it down and mitigate what can no longer be avoided.

President Barack Obama recently unveiled tough new automobile emissions standards, finally moving the U.S. in the direction that much of the developed world has already started to travel.

Governor Deval Patrick recently tried to push through a 19- and 11-cent gas tax, which failed in the Senate last month (with Dorchester’s own Sen. Jack Hart casting a dissenting vote), but did demonstrate a executive-level desire to discourage car-travel and funnel monies into rapid transit—a clear path toward lowering emissions and helping keep ocean levels closer to where they are.

In April, with former Vice-President Al Gore on hand, Mayor Thomas Menino also got in the act, calling together a Climate Action Leadership Committee to chart a response to climate change, including a potentially-rising coastline.

Douglas’s predictions, including a handful of potential 100-year flood maps she created for East Boston in 2030 and 2100, were presented with other material in a presentation by committee member Dr. Peter Frumhoff, setting the stage for the work ahead.

“My take is that Boston is prepared to take a serious leadership role in climate change,” said Frumhoff in an interview last week. “The mayor was clear in his mission to be bold.”

And with good reason, particularly for Dorchester.

There’s growing consensus around something near six inches to a foot of sea level rise by 2030, which when looked at by Douglas, changed predictions for the all-important 100-year flood map for East Boston significantly. A flood of that magnitude would over a dozen city blocks underwater at high tide, by Douglas’s estimation.

By 2100, the predictions range from around two and a half feet to seven feet of global sea level rise. Either of these, coupled with a 100-year flood at high tide and other factors taken into account by Douglas, could flood the majority of East Boston.

In Dorchester, even a three foot rise or more would likely turn Columbia Point—including the Bayside Expo Center, the Harbor Point housing development, and Boston College High School—into a swamp, Patten’s Cove into a threateningly large tide pool next to the Boston Globe building, and Port Norfolk into a industrial-looking Venice, though with very shallow canals for streets. A rise approaching seven feet would pretty much sink Columbia Point, along with swaths of Boston Proper and Back Bay.

Douglas’s team did the East Boston 100-year flood mapping work with a grant from the National Oceanic and Atmospheric Administration (NOAA), and when the entire study is finished it will include a second “environmental justice” neighborhood in Massachusetts, possibly Dorchester. In the next week or two, Douglas said they would make a choice between Dot and Everett.

As far as dealing with all these possibilities, the city is focusing on lowering emissions by 80 percent of 1990 levels by mid-century, while also looking at possible mitigations for sea level rise and other effects of climate change such as higher summer temperatures.

“We’re already seeing some rise in temperatures and the frequency of storm surges,” said Jim Hunt, Menino’s chief of environment and energy services. “The mayor has pulled together internationally renowned climate scientists to leading engineers to develop a plan that most importantly continues Boston in reducing our emissions. But also, these experts are working on recommendations for how Boston should adapt to the changes we are likely to see.”

Among the ideas already floating around in the sea rise mitigation milieu are sea walls, dams, more basement pumps, and even a giant flood control structure across Boston Harbor from Deer Island to Long Island—as was proposed by Boston architect Antonio DiMambro in 1988 and more recently plugged by an op-ed writer in the Boston Globe. But as every scientist and official involved in these efforts frequently reminds, the water will keep coming unless emissions are brought under control.

“Getting a handle on what everybody agrees is at the heart of this—which is fossil fuels—is going to be politically difficult,” said Bruce Berman of Save the Harbor/Save the Bay, who spends many of his days out on the water. “I think these changes will come, but I’m concerned about the pace they will come.”