Hilary Beaumont

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Sea level rise is happening, so what is Halifax doing about it?

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Published on Jan. 6, 2013. Read the original story in The Chronicle Herald.

Planners John Charles, left, and Richard MacLellan outside their office at Alderney Landing in Dartmouth. (Photo by Hilary Beaumont.)

Forty-five-foot long blackened oak beams form the cathedral ceilings of the 600-year-old New College dining hall at Oxford University. Castle scenes in Harry Potter were both inspired by and filmed in Oxford buildings with similar architecture.

There’s a story students and faculty like to tell about this medieval hall, as does HRM planner John Charles — one of the people tasked with preparing Halifax for the inevitability of sea level rise.

A century ago, students noticed sawdust on the tables in the dining hall, and discovered an infestation of beetles in the ceiling’s great oak beams. The college needed more oak to replace the ceiling, so they approached the Oxford forester.

The forester supposedly answered, “Well sirs, we was wonderin’ when you’d be askin’.”

A grove of oaks had been planted when the college was founded in 1379 to replace the dining hall beams. The planners had apparently anticipated the beetle problem.

The story has gained embellishment in its retelling, however. According to the Oxford archivist, the oaks were not planted for the express purpose of replacing the beams; it is simply standard practice to replant the trees.

Nevertheless, Charles says the fable illustrates how Halifax should take on sea level rise. HRM’s planning department is already preparing for the year 2100.

“We need to start taking the long view in how we think,” the planner says.

Already the problem is lapping at his feet. Charles’s home in Prospect Village sits just eight metres horizontally and three metres vertically from the ocean. When Hurricane Juan made landfall there in 2003, the storm tossed boats, flipped buildings and gave Charles a saltwater well for six months.

Juan was a weak, class two hurricane. Wave heights climbed nine metres, and water levels surged 2.1 metres, depositing lobsters in the parking garage next to Charles’s Alderney Landing office.

But if the storm had hit at high tide, the surge could have reached 2.8 metres.

In other words, Juan wasn’t the worst-case scenario.

Picture this: In 2100, a Juan-like storm hits Halifax. Salt water floods the Halifax side of the harbour, bathing kiosks on the boardwalk, submerging Lower Water Street and, in some places, reaching as high as Hollis Street. The financial district becomes waterfront property; Bishop’s Landing, a lonely island. That is the worst-case scenario for Halifax.

The global scientific community is in overwhelming consensus that climate change is happening and that sea level will increase as a result. Exactly how much global temperatures will change and how high sea levels will rise, we aren’t sure.

The world’s nations have yet to take serious steps to slow climate change, so we should plan for the worst-case scenario, Charles reasons.

In 2007, the Intergovernmental Panel on Climate Change released predictions of world sea level rise. According to the IPCC’s worst-case scenario, the planet can expect a temperature rise of four degrees Celsius, which would yield a 57-centimetre rise in global sea levels by 2100.

Regardless of climate change, Nova Scotia as a land mass is sinking at a rate of 16 cm per century. Added together, these numbers tell us to expect a maximum sea level rise of 0.75 metres by next century. Since 2007 however, scientific observations show global sea level rise tracking “well above” the highest projected rate, and HRM planners now believe the IPCC projection is likely an underestimate.

Assuming storm intensity and frequency remain the same, and projecting an accelerated rate of change, scientific observations since 2007 give an estimated rise of 1.46 metres by 2100 — nearly double the earlier estimate.

Sea level rise isn’t the only problem, though.

A century from now, local calculations tell us Juan-like storms will yield surges of 3.4 metres, resulting in the worst-case scenario described earlier. Currently, though, Charles says HRM is planning for a 2.5-metre increase, which could change when the next IPCC report is finalized in 2014.

So far, the municipality and the province are taking a two-pronged approach to sea level rise: reducing emissions, and adapting plans as new science becomes available.

“The answer doesn’t seem that we can throw money at it,” says Richard MacLellan, HRM’s manager of sustainable planning.

Instead, he says the federal and provincial governments have “pulled a lever” to inspire local solutions. As a pre-requisite for receiving gas tax, all municipalities must submit a municipal climate change action plan to the province by 2013. Gas tax amounts to about $25 million a year for HRM.

“They could have said, here’s $25 million, go build some sea walls.” MacLellan says.

Seawalls often spring to mind in conjunction with sea level rise. But with 130 kilometres of harbour and some 2,000 kilometres of waterfront property to protect, seawalls would be too costly for HRM, and they aren’t always the best solution anyway, MacLellan says.

During a storm, seawalls deflect surge to other areas.

Instead, HRM is considering shoreline armory (large boulders stacked along beaches and embankments), and natural buffers like trees and shrubs, which naturally diffuse wave damage and prevent shoreline erosion.

As for the Halifax waterfront, land-use bylaws require new residential developments be built 2.5 metres above the high-water mark. Waterfront properties outside the harbour also have this stipulation. But there is no such bylaw for other areas of the harbour.

Residential development agreements outside the Halifax waterfront require developers to show they took into account climate change when planning. But there is currently no legislation preventing developers from putting new homes in harm’s way.

The Ecology Action Centre has been calling for such legislation for years. “Nova Scotia’s falling behind on this,” EAC Coastal Co-ordinator Jennifer Graham says. “This is actually pretty basic stuff nowadays.”

New Brunswick and Prince Edward Island both have legislated setbacks for waterfront property. N.B. groups coastal properties into those that are highly sensitive and those that are less so, and sets development guidelines for these groups. P.E.I. has required setbacks for all bodies of water including the coast.

The Ecology Action Centre thinks the province should define a coastal zone, assess properties in that zone that go up for sale and then determine whether development is suitable for those properties.

The municipal and provincial governments are educating property owners about climate change, Graham says, but without firm rules in place, they are infilling water, cutting down trees that protect the shore and building too close to the ocean.

Municipalities have the right to set horizontal and vertical setbacks, and many, like HRM, have done that. But Graham points out these are inconsistent, and smaller municipalities may not have the same planning capacities as HRM.

“We need to start building more wisely,” she says, “and until we have coastal legislation, I don’t think that’s going to happen.”

“In terms of bylaws, yes, they are vital — you need some development guidelines,” Charles says. “But it would also be nice to have provincial legislation.”

The province has been working on a coastal strategy for the last five years, setting priorities around climate change and waterfront development. But Charles says the science is changing so rapidly that the strategy might be past its best before date.

The best plans for rising tides, he thinks, are incremental.

That’s why Charles hasn’t moved his home just yet.

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Written by hilarybeaumont

January 6, 2013 at 8:54 pm

Posted in Environment

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