Seas rise, Nova Scotia sinks

While Venice sinks, the Dutch strengthen their dikes. The Gulf of Mexico eats a football-field sized piece of Louisiana every hour. Every pocket of the planet can feel the fact that the oceans keep climbing higher.

And climbing faster. The data on record – almost 200 years’ worth, with anecdotal evidence reaching back further – affirms that sea levels have long been rising; but things have accelerated.

Global warming is the commonly accepted culprit. As water gets warmer its molecules spread out, increasing the water’s volume. In a glass of water, the difference is minute; when that glass is big enough to cover more than 70 per cent of the globe, the difference is substantial.

Meanwhile, glaciers both north and south are undergoing their own molecular change – melting, thus adding incalculably large volumes to the planet’s growing oceans.

Halifax’s unhappy fate is to be caught between two inevitabilities.

While the oceans inch upwards, the land itself is sinking.

Level rise and subsidence

Left: the past, present and future global sea level, according to the Intergovernmental Panel on Climate Change. Right: the ongoing subsidence in Halifax. Both charts come from the “Sea Level Rise Adaptation Planning for Halifax Harbour”, presented to Halifax city council in February 2010.

 

“So we get this double whammy, this double impact of sea level rise,” says James Boxall, geography professor and director of the GISciences Centre at Dalhousie University.

“That’s what makes Halifax unique. We actually have a device in the harbour that’s measuring the amount of subsidence every year, so we know that as we sink and the sea rises, you’re getting this multiplier effect.”

Boxall was one of the researchers behind a 2010 report to Halifax city council, which sought to lay a scientific foundation for the city’s coastal planning practices and help it adapt to sea level rise.

Using LiDAR mapping – a process by which a laser-toting aircraft is used to map terrain in minute detail – they examined the height and shape of the land to identify places most at – risk of flooding in the event of a storm surge.

LiDAR mapping

Left: a detailed map of Point Pleasant Park elevation made with LiDAR mapping technology. Source: “Sea Level Rise Adaptation Planning for Halifax Harbour”.

 

Then they took the latest projections for sea level rise from the UN’s Intergovernmental Panel on Climate Change – pegged at 0.57 metres in 2007 – and added the effect of land subsidence, or sinking.

The most likely scenario, researchers found, is that Halifax’s landmass will sink about 16 centimetres in the next hundred years. Combined with the rising waters, they project the sea will be 0.73 metres higher to the shore.

Even with the “double whammy” that figure is likely too small, explains Boxall.

Compared to those of other researchers, the IPCC’s projections are conservative to begin with, but they also don’t take into account the water added by melting glaciers. The enormity of these ice caps and all the variables at play would make such estimates untenable, Boxall says.

Listen to James Boxall:

Worries about the next Juan

But calm water can be contained easily enough. The real question is what would happen when extraordinary weather is thrown in the mix.

“I think that we had known that climate change was an issue; perhaps it wasn’t as much of an issue until Hurricane Juan hit in 2003,” says John Charles, a municipal planner with HRM and another force behind the 2010 report.

The storm struck in September 2003 causing significant damage, with part of its eye passing directly over Halifax Harbour. Water levels reached 2.1 metres, with waves as high as nine metres, the report says.

Had the storm hit at high tide, the waves and surge could have reached even higher.

“I think if you can call anything a motivation [for our research] it was the impact of that hurricane that we saw along the coastline,” says Charles.

 

What their research found is that, when a hurricane like those we have today is combined with the projected sea level rise, the storm surge could cause water levels more than 20 per cent higher than during Juan.

With climate change taken into consideration, following the IPCC’s sea level rise projections, water levels could rise by as much as 2.67 metres, the report found.

This scenario, like all the others in the 2010 HRM report, assumes that the storm climate is unchanged, that storms are neither stronger nor more frequent due to climate change.

Depth scenario in case of a storm surge, in one hundred years. Source: “Sea Level Rise Adaptation Planning for Halifax Harbour”"

Depth scenario in case of a storm surge, in one hundred years. Source: “Sea Level Rise Adaptation Planning for Halifax Harbour”.

Depth scenario in case of a storm surge, in one hundred years. Source: “Sea Level Rise Adaptation Planning for Halifax Harbour”"

Depth scenario in case of a storm surge, in one hundred years. Source: “Sea Level Rise Adaptation Planning for Halifax Harbour”.

“In the long term it is something to be concerned about but it’s something we can plan for,” says Charles, who has recently gotten involved with research on the economic impacts of sea level rise in Halifax.

“If we have that sort of [hundred-year] planning horizon, then we can make intelligent choices right now.”

Listen to John Charles:

Building smart beside the sea

Some developers are already making those intelligent choices. John Charles points to King’s Wharf – a set of condo towers built and being built on the Dartmouth waterfront – as a poster child for building with sea level rise in mind.

Francis Fares, head of Fares Real Estate Inc. and the developer behind the towers, says that, despite the added costs and complications, every precaution is worthwhile when investing in a coastal property.

“When we planned this development, we took into consideration from day one rising sea levels, global warming, tsunamis and all those things,” says Fares.

“We established our base for this whole development at about 1.8 metres above the high-water mark … The lowest parking level would be at that level,” Fares says.

Above that lowest point there is another level of parking and a ground floor of commercial space before you reach the lowest residential apartments.

This distance meets and exceeds the requirements set out by the city, which ensure residential spaces and vital infrastructure aren’t on the ground floor of coastline properties.

“If there is ever water to come in our building it means half of downtown Halifax is underwater,” says Fares.

Listen to Francis Fares:

The need for leadership

As Fares knows well, building beside water – especially salt water – is more complicated and costly than building inland.

Robin Tress knows it too. She’s the coastal adaptation coordinator at Halifax’s Ecology Action Centre, and this complexity is why she wants Nova Scotians to have stronger tools for developing their shorelines intelligently.

“We absolutely need to be planning for the sea level rise that is going to come,” says Tress.

“One of the problems people face when they want to do that is that the information necessary to plan appropriately isn’t available to the public in most cases.”

Instead, the information – like the mapping Boxall and Charles did, for example – is spread out among 14 different provincial and federal government bodies, not to mention all the municipalities that are involved as well.

Listen to Robin Tress:

For about a decade, says Tress, the EAC has been pushing the provincial government to instate legislation that protects the coast and gives clear boundaries for developers, while providing a one-stop resource instead of a bureaucratic maze.

And, a few years ago, they nearly got some of what they wanted.

In 2011 the Nova Scotia government was seeking input on its Coastal Strategy. Though not a law, it was meant to be a singular framework for how the province’s coastlines would be managed and developed.

“That was looking really good for a while. They did lots of public consultation; people really bought into this idea of having one piece of guidance that would tell people across Nova Scotia how to work with the coast,” says Tress.

“And then it just disappeared.”

 

Though a draft of the strategy was published, the initiative fell off the Dexter government’s radar before the final version was approved, says Tress.

The EAC, however, hasn’t dropped the cause. They are thinking about what direction to take, what partners to make, and what to do next.

The current government hasn’t indicated an interest in reviving the strategy, she says.

“It’s just sitting there, it’s ready to go. It was a great first step that could have taken us toward a coastal act.”

Halifax Mayor Mike Savage says that the challenges brought by sea level rise are not something the city can confront on it’s own.

“It’s possible that there will need to be expenditures,” says Savage.

“We hope that we will have willing partners with two levels of government to help us mitigate the cost.”

Listen to Mike Savage:

Meanwhile, the oceans continue to climb, and any day know the world will learn the latest estimates of just how fast they’re doing that.

The sea level rise projections that Halifax’s research is based on are about to become outdated. The world’s climate-change experts are currently meeting in Copenhagen, and are due to release the latest IPCC report on Nov. 2.

This will be the fifth assessment report from the IPCC, the fourth one – on which Boxall, Charles and company based their work – having been released in 2007 and the original one dating back to 1990.

One can safely assume this new report will say the seas are rising faster.

“The whole notion that there’s a debate about this, there’s no debate,” says Boxall.

“This is measurable. We’re seeing it. It’s going to continue.”

Credits

A feature by Geoff Davies and Nael Shiab.
A question? A comment? Contact us!

This project is part of a Master of Journalism class at the University of King’s College, under the supervision of Terra Tailleur, Assistant Professor.

Special thanks to:

Mike Savage, Mayor of Halifax Regional Municipality

John Charles, Planner, Regional & Community Planning, City of Halifax

Robin Tress, Coastal Adaptation Coordinator, Halifax Ecology Action Centre

James Boxall, Director of GISsciences Centre, Dalhousie University

Francis Fares, Developer, Fares Real Estate Inc. (King’s Wharf)

Jonathan Derouchie, Web Developer and Creative Director at Organism

Music: Seeing The Future, by Dexter Britain