How Boston is rethinking its relationship with the sea
Sea levels are rising, the land is sinking. It's going to become a big problem for some cities on the US East Coast, so in Boston people are thinking the unthinkable - copying Venice and Amsterdam, and becoming a city of canals.
Two years ago, when the still vicious tail-end of Hurricane Sandy slammed into Boston, it was luck rather than planning that saved the city's streets from deep floods.
If it had hit four hours earlier, during the full-moon high tide, it is likely a storm surge would have inundated the city, submerging its low-lying areas under several feet of water.
The narrow escape concentrated minds, because there's another problem threatening to overwhelm the city's flood defences - climate scientists are predicting a sea-level rise on the US east coast of up to six feet (2m) by the end of the century.
On top of this, Boston has seen an increase in rain and snow over the past few decades and has to contend with the fact that the whole of the US East Coast is sinking as the West Coast around the San Andreas Fault rises.
This is why Boston's city planners and architects are contemplating the radical idea of turning its most historic district - the elegant 19th Century terraced houses of the Back Bay - into a network of canals.
"Much of the model has been how do we keep the water out? Everybody's afraid of the water," says Dennis Carlberg, sustainability director at Boston University and co-chair of Boston's sea-level rise committee.
"So we wanted to turn that conversation on its head and say, well what if we let water in? How can we make life better in Boston by bringing water in?"
The canal idea was floated when architects, developers, real estate experts and business owners were brought together in May to discuss ways of preserving the city's buildings in this watery cityscape of the future.
"It can't be that we provide a giant dam at the Boston harbour and solve all our problems that way," says Boston's Chief of Environment, Energy and Open Space, Brian Swett.
"The way we solve this has to be vibrant, liveable, exciting and enhance our quality of life."
One of the vibrant solutions that came out of that brain-storming session in May, hosted by non-profit organisation the Urban Land Institute, was to turn Boston into the Venice of the US north-east.
- Boston is the world's eighth most vulnerable city to financial loss because of sea-level rise, according to a 2013 World Bank study
- Other US cities ahead of Boston on this list are Miami (2nd), New York (3rd) and New Orleans (4th)
- The Intergovernmental Panel for Climate Change (IPCC) predicts sea levels will rise by between 3ft and 6.6ft on the US East Coast by the end of the century
The canals would criss-cross the streets of the Back Bay - a neighbourhood of Boston which was actually a tidal bay before it began to be filled in and built on 150 years ago.
Its rows of four to five storey brownstone houses arranged in a grid pattern were immortalised in the writings of Henry James and are considered to be the best preserved examples of 19th Century urban design in America.
This is also one of the most expensive places to live in New England, with a five-storey town house selling for $15-20m. Even a one-bedroom basement flat costs $1m.
"Currently the Back Bay streets are about four feet above high tide, so if the sea level rises as predicted, they would be under water part time by the end of the century," says Harvard Business School's John Macomber, who was brought in to assess the financial implications of the Urban Land Institute's ideas.
"If the sea level rises higher than that, the city would look a lot like it did in the time of George Washington," he says referring to a time when Beacon Hill, at the eastern edge of the Back Bay, was an island connected to the mainland by a narrow isthmus.
The canals would mitigate sea-level rise by draining water into lower-lying back alleys and some main streets in an alternating pattern which would end at the major thoroughfare of Boylston Street, which has a subway line underneath it.
It's a solution to climate change which has the potential to make the historic district even more attractive, if it works. But there is a problem.
"If you compare Boston to Venice or Amsterdam, the difference is they have very small tidal ranges," says John Macomber.
"The tide change in Boston is about eight feet a day, so the canals would be either high part of the time or low part of the time. So we would have to decide whether they would be really deep or tidal," he says.
The canals would also have to contend with freezing temperatures in winter, but it seems that, unlike Amsterdam's, they may not be suitable for skating on.
"The question is whether in a climate where it can snow for six months of the year you want canals that are always open and partly full of slush, sand and salt," says Macomber.
A less ambitious solution to sea-level rise would be simply to shore up the foundations of Back Bay houses and make sure important infrastructure, such as electrical and mechanical equipment, was lifted up above the likely level of any flooding.
This kind of solution may have to be implemented in many of Boston's districts not just the Back Bay.
Last year, the Federal Emergency Management Agency (Fema) changed its 100-year flood zone map which indicates areas likely to be affected by extreme flooding to include many more properties in the city.
"We've looked at raising the ground floor elevation as much as possible," says architect Amy Korte, who is working on building design in Boston's up-and-coming Innovation District.
"We asked how do we raise critical equipment and create a new vision for what good urban design can be," she asks.
Another solution would be to re-introduce natural wetland habitats that would act as a sponge for excess water.
"It's a great non-technology natural solution," says Dennis Carlberg.
"As sea level rises, we are going to be losing this natural sponge globally, so trying to add some of it back is an important thing to be paying attention to."
Whether or not the Back Bay becomes the Venice of North America, at the very least this project has helped raised awareness of how much Boston is going to change over the next few decades.
And by including financial planners and business leaders in the brain-storming sessions, those trying to raise awareness of climate change hope to move the argument away from political controversy and on to practicalities.
"If you want property values to stabilise or remain where they are, at some point you need to invest," says Harvard's John Macomber.
"The idea is to find the sweet spot to invest in a sensible way."
He compares this project in Boston to the situation in Florida where, he says, "the high tide at full moon bubbles up through the storm drains and yet it's not useful in a political environment to say anything is happening".
Boston's Chief of Environment, Brian Swett, says the evidence is clear and the city cannot afford to look the other way.
But, he says, he is not without hope.
"Boston's been around for 400 years and we're going to be around for another 400."
Amsterdam is already more than 700 years old, and Venice more than 1,500. So canals can work - even if they do make it more difficult to park.
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