Surging tides
How sea-level rise could sever a vital transport link in Canada
This story was produced with the support of Internews’s Earth Journalism Network.
Chignecto Isthmus, Nova Scotia, Canada – Seven years ago, the sun, moon and Earth aligned to produce a tidal surge in the Bay of Fundy, pushing the sea within centimetres of a national rail line connecting the eastern Canadian provinces of Nova Scotia and New Brunswick.
The water lapping at the edges of the train tracks marked the zenith of an 18-year astronomical cycle due to repeat in about a decade’s time – and fuelled concerns among locals conscious of the ever-present flood risk.
Today, even a heavy storm risks inundating the slender Chignecto Isthmus, a 21km-wide (13-mile) land bridge at the edge of the Bay of Fundy that serves as a vital economic corridor, carrying about $27bn ($35bn Canadian) in trade annually (PDF). The Bay of Fundy already boasts the highest tides in the world, and with sea levels in this region set to rise by about a metre by 2100 – and possibly by more than double that under extreme scenarios – the risks facing this tiny strip of land have never been greater.
“This might be the most vulnerable spot in eastern Canada,” said David Kogon, mayor of the town of Amherst, Nova Scotia, which lies at the southern boundary of the isthmus. By 2100, sea level rise could potentially put up to a third of his town underwater and sever the only viable transport link between the province of one million people and the rest of the country.
“This province was born from the sea and is centred around our ocean frontage … so the sea level rising is going to be an issue,” Kogon told Al Jazeera.
Across Nova Scotia, coastal communities are grappling with their exceptional vulnerability to climate change, as rising waters threaten to consume more and more land. With coastal erosion affecting many towns and cities, the provincial government in 2019 passed legislation to regulate what can and cannot be built on 13,000km (8,000 miles) of coastline, while local bylaws control how high above sea level new buildings must be constructed (PDF).
The Chignecto Isthmus, which connects Amherst to the New Brunswick town of Sackville to the north, is in a particularly precarious situation: Experts have long warned that unchecked sea level rise could one day fully submerge this strip of land, turning Nova Scotia into an island. While the isthmus itself is sparsely populated, a major flooding event could directly affect several thousand people in the two towns and have countrywide economic ramifications.
Protected by a system of earthen dykes originally built in the 1600s to facilitate the development of farmland, the isthmus houses critical utility and transportation infrastructure, including the CN Rail line and the Trans-Canada Highway. The Chignecto corridor is also the only route for wildlife, such as bobcats and endangered moose, to move in and out of Nova Scotia. A number of bird species that rely on these forested wetlands are at risk, while the isthmus “serves as a critical stopover site” for migratory waterfowl, according to the Nature Conservancy of Canada.
But the dykes built to keep seawater off this land have failed on multiple occasions, most spectacularly during an 1869 tropical storm known as the Saxby Gale. Named for Stephen Martin Saxby, a British naval instructor and amateur astronomer whose warnings of the looming torrent went unheeded, the storm devastated the isthmus and wiped out farms as floodwaters breached the dykes.
For years, as climate change has led to increasingly severe and more frequent storm events not just in eastern Canada but around the world, experts and residents have been calling for a long-term solution.
“Sea levels are going to keep rising, extreme events are going to keep happening … and so that’s going to have economic consequences that are just going to get more and more expensive to deal with, and more and more challenging to deal with,” Jeff Ollerhead, a coastal geomorphologist at New Brunswick’s Mount Allison University who has studied the Bay of Fundy, told Al Jazeera.
Looming threat
In 2018, the Canadian government announced that it would co-finance, alongside the Nova Scotia and New Brunswick provincial governments, a $540,000 ($700,000 Canadian) engineering study to explore options to protect the Chignecto Isthmus from the effects of climate change. After being delayed by more than a year, the findings were released this past March.
The study acknowledges that without the existing earthen dykes, built to a height of about 8.5m above CGVD28 – a tidal datum defined by mean sea levels at a series of Canadian tidal gauges – “much of the isthmus would be inundated by today’s sea levels resulting in significant negative socio-economic impacts locally, regionally and even nationally”.
The study, completed by the consulting firm Wood Environment & Infrastructure Solutions, lays out three options for the governments to consider: raising the existing dykes to a height of 10.6m, building new dykes, or raising the existing dykes to 10.6m and reinforcing them with steel sheet pile walls at select locations.
But experts who have reviewed the study say it raises several red flags – from the lengthy timeframe for implementation, to a narrow focus that neglects other potential solutions, to the hefty price tag that would have to be borne at least in part by cash-strapped regional governments.
As the risk of flooding looms large in Amherst and Sackville, work to protect the area should have started decades ago, Ollerhead said.
“The threat is real, and it could happen in the next six months,” he said, noting that saltwater inundation could destroy agricultural lands and massively disrupt the national transportation network. “If there was a major, major storm that happened to come straight up the Bay of Fundy, the dykes could be overtopped today.”
'We're not ready for it'
Geoff and Robyn Giffin’s farm has been in the family for decades. But they know the location of their sod fields, directly abutting the dykes in western Amherst, puts their livelihood in jeopardy. On a recent afternoon, as the muddy tide slowly rose, the tall grasses covering the dykes swayed in a strong wind.
“It’s a major concern, because if we were to have a breach of saltwater inundating those fields, salt is kind of the worst enemy of the type of crop that we’re growing,” Geoff Giffin told Al Jazeera.
About 10 years ago, a tidal control mechanism failed and caused saltwater to flood a portion of their fields, affecting the farm’s productivity for years, as soil remediation can be a long and expensive process. A larger flooding event across the farm’s hundreds of acres of land would be devastating, Giffin acknowledged, noting that “urgent action” is needed.
“No matter how you slice it, climate change has been having impacts for a while now, and they’re only building – and our governments need to be looking at this with extremely clear eyes, and recognising that there’s going to be widespread impacts,” he said, adding that all levels of government need to work with communities “to try to come up with a solution that’s going to protect as much as possible”.
“Without question it’s going to happen; we’re going to see the water overtop the dykes,” he told Al Jazeera.
Amherst resident Jim Lamplugh is also concerned about the prospect of flooding in this area, having watched the rise and fall of the tides for years. In 2021, he organised a presentation called the Isthmus Project, bringing together a number of key community stakeholders for a public discussion on the risks.
“Our interest in it comes from having lived and watched first-hand as these storms, [2019’s Hurricane Dorian] for example, would come through,” Lamplugh told Al Jazeera. Often after a really high tide, “you’d go along and you’d find driftwood on those railway tracks”.
He worries in particular about the effects of sea level rise on the Chignecto transportation corridor. Canada is connected to the world via the Port of Halifax, from where goods are then shipped by truck or train across the isthmus and into the rest of the country. A significant flooding event could paralyse this trade route, experts say, causing disruptions and delays across Canada and potentially leading overseas exporters to seek alternative ports if Halifax is deemed unreliable. This would exacerbate the economic isolation already felt in Atlantic Canada, which comprises the country’s poorest provinces.
CN Rail did not respond to Al Jazeera’s inquiries on whether its rail service had ever been disrupted due to extreme tidal surges in the region, but locals believe the threat of a cut-off is growing by the day.
“The impact [of flooding would be] staggering, absolutely mind-boggling,” Lamplugh said. “Trains aren’t going to go, the trucks aren’t going to go, the people aren’t going to go. We’re not ready for it. We are at risk.”
Future generations
Experts say sea level at the Chignecto Isthmus will likely rise by between 1m and 2.5m by 2100, with the latter representing a worst-case scenario, according to recent estimates. Various factors are taken into consideration when drawing up such estimates, from the sinking of land on a local scale, to the melting of Antarctic ice on a global scale.
But while the government-commissioned report focuses on rebuilding or raising the dykes by a couple of metres, amid what critics say was an overly limited study mandate, there are questions around how much long-term protection this would actually provide. According to Tim Webster, a research scientist at Nova Scotia Community College who chairs the provincial branch of the Canadian Institute of Geomatics, such a solution may only hold back the water for a few decades.
With peak tides in this area pushing the water level close to 7m, a storm surge of 1.5m, which Webster says is not uncommon, already tests the limits of the 8.5m dykes. When a potential sea level rise of 2.5m is factored into the equation, water could be overtopping the new dykes in less than a century, he said. Even if the sea rises more slowly, the risk hangs heavy for future generations.
Indeed, the issue of intergenerational equity in the context of climate policy, which focuses on building a sustainable world for future generations, has become increasingly important amid the ongoing scramble for global resources, experts say.
“If we don’t limit climate change, we pass the planet on to future generations in far worse condition than we received it and strengthen the inequities among people in future generations,” Edith Brown Weiss, a professor emeritus at Georgetown Law in the United States with expertise in environmental issues, told Al Jazeera.
But policymakers today are not paying enough attention to this bigger long-term picture, she added: “In addressing sea level rise and climate change, it may be appropriate to build earthen dykes in the immediate term.
“From an intergenerational view, it is essential to develop long-term viable solutions, because sea levels will continue to rise.”
Questions over funding
Meanwhile, plans to raise or rebuild the Chignecto dykes to stave off the imminent flood risk remain shrouded in financial uncertainty.
Both the Nova Scotia government and the consulting firm that prepared the engineering report directed Al Jazeera’s questions to the New Brunswick department of transportation and infrastructure, which led the study. A spokesperson for the department, Alycia Bartlett, said the options in the report were under review “to determine the best approach for protecting this important trade corridor”.
She did not provide a timeline for selecting a recommendation but confirmed that once an option was chosen and funding was in place, the process of planning, design and construction, including any required environmental impact assessments, would take about 10 years.
“We understand the importance of this issue,” Bartlett told Al Jazeera in an emailed response. “That’s why we will put in the time and work required with our partners in Nova Scotia and Ottawa to implement the right solution that will protect this crucial trade corridor for many years to come.”
More generally, to combat climate change, Canada has been developing its National Adaptation Strategy, a work-in-progress that aims “to help communities and residents of Canada better adapt to and prepare” for its effects, including sea level rise and coastal erosion. But the federal government’s role in funding work to protect the Chignecto Isthmus remains unclear.
Jen Powroz, a spokesperson for Infrastructure Canada, the federal government department responsible for public infrastructure policy, said Ottawa “understands the critical role that the Chignecto Isthmus corridor plays in New Brunswick and Nova Scotia’s economic lifeline, and is aware that rising sea levels caused by climate change could directly affect the corridor”.
As to whether the federal government would make a financial contribution to help rebuild the dykes, the department did not provide a definitive answer. Powroz told Al Jazeera via email that the provinces “can apply to funding through Infrastructure Canada’s various programs that offer support for adaptation, resilience, and disaster mitigation projects”.
Which government agencies would shoulder the higher operating costs is also unclear. Bartlett in New Brunswick said the province and its neighbour Nova Scotia were “working together with our federal partners to identify and move forward with the right solution”, and the question of funding “has not been determined at this time”.
Will Balser, a coastal adaptation coordinator at the Ecology Action Centre, a Halifax-based environmental charity, questioned how the tens of millions of dollars needed for the Chignecto project would ultimately materialise.
“This is a notoriously difficult thing to fund,” he told Al Jazeera, noting that the challenge is heightened due to the involvement of three separate governments. “We’re between two provinces and federal funding, and ongoing or infrastructure maintenance funding is even more sporadic or difficult to pin down with an election cycle, or in this case with three election cycles.”
Kogon said Ottawa would have “no choice” but to deliver, noting: “I don’t think that at the federal level they have any real viable option but to maintain the protection of … the transportation corridor through the isthmus, because it’s so vitally important to the economy of the entire country.”
And with the 18-year tidal cycle peaking in about a decade, bringing another massive surge, time is of the essence, Johnson said: “They’re going to have the return of our king tides … and if they don’t have something in place, then we could have some significant consequences as a result.”
Alternative solutions
Amid this urgency, experts contend that the government should be looking at a broader range of options – such as building a bridge or tunnel to connect Nova Scotia and New Brunswick, or large-scale salt-marsh restoration – to maintain the critical transport link and protect the sensitive coastal environment in the longer term.
According to Kristina Hill, an associate professor at the University of California, Berkeley with expertise in urban design and environmental planning, earthen dykes are generally a better strategy for holding back water than concrete and steel walls, “because they can be raised and even relocated without a loss of useful material”. Wider dykes, rather than taller ones, can avoid the risk of catastrophic failure in the event of overtopping, but as sea levels keep rising, it may no longer be worth trying to manage a non-urban landscape with increasingly expensive strategies, she told Al Jazeera.
“Once people decide to accommodate saltwater, a bridge or causeway would be better than a wide roadway dyke,” Hill said. “But a floating road would be even better … because as sea levels continue to rise, so does the crossing. But costs would need to be compared.”
This province was born from the sea and is centred around our ocean frontage ... so the sea level rising is going to be an issue
Balser, who worries every Canadian spring and hurricane season that water will overtop the existing dykes, said the Chignecto study should have emphasised nature-based solutions, such as restoring a salt-marsh buffer alongside the dykes to absorb some of the tidal impact. The concept is briefly mentioned in the study (PDF) as a possible factor if the government chooses to build new dykes, rather than raise or reinforce the existing ones.
In addition to their ability to absorb wave energy during storms or high tides, salt marshes are highly productive ecosystems that support a diversity of species and offer prime foraging space for fish and birds, said Ollerhead at Mount Allison University. More than three-quarters of the original salt marsh in parts of the Bay of Fundy has been lost since the arrival of early European colonists, he said, noting that any solution for Chignecto should incorporate restoring portions of it. Such a system would require less upkeep and potentially generate an additional revenue stream via carbon credits, he added.
“If you build a dyke right on the edge [of the bay, where many of the current ones are], you’re going to be constantly pouring money and materials over the edge, trying to keep that dyke where it is – whereas if you move the dyke back maybe 300 metres [and] develop a salt marsh … vegetation would provide natural protection,” Ollerhead said. “You could probably reduce your ongoing maintenance costs by a considerable margin by adopting a more strategic way of managing the system.”
This plan is not without controversy, as it would require sacrificing a portion of coastal agricultural land, drawing opposition from landowners. But such a solution would still be cheaper in the long run and better for the environment, experts say. Because a salt marsh would sequester carbon, it could generate carbon credits to sell to other companies, helping to pay for the work to protect the isthmus, Ollerhead said.
Others say the provinces should simply allow nature to take its course.
David Knockwood, a member of Fort Folly First Nation, whose broader Mi’kmaq territory encompasses the Chignecto Isthmus, told Al Jazeera that it was unwise to expend so much effort in attempting to hold back the ocean. The crisis today, he said, “is a result of not working with the land, and trying to be the master over it”.
He was not impressed with any of the three options laid out for the government’s consideration.
“I was always hoping in the back of my mind that there would be plans to let the [water] flow freely again,” Knockwood said, adding that if a storm like Saxby Gale were to sweep through the region today, “it wouldn’t take much more than that to overcome the new standard of what they’re looking to implement” on the isthmus.
“Trying to control nature instead of working with it is a futile effort,” he said. “It’s just pushing the problem down the road.”