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Summary

In Atlantic Canada, Environment Canada, Fisheries and Oceans and Natural Resources Canada are working together to examine impact of the storm surges and rising sea-levels, both of which are likely to increase as a result of climate change.

Transcript of Video

Jane Gilbert
Some dire predictions about the effects of global warming. This week, politicians and scientists are meeting in Argentina, to find a way to reduce the pollution that causes the problem. And at the same time, scientists in Canada are warning that the Maritimes could be in for a particularly rough ride, because of the earth's changing climate. And if Canadians want to see how bad the problem could be, they should take a look south.

Jay Ingram
Hurricane season 1998 has been especially fierce on the Atlantic. In August, Bonnie ripped across the southern US causing millions of dollars of damage. This month, Hurricane Mitch has ravaged much of Central America. More than 10,000 people killed, millions more dislocated. But what about Canadian coastlines? Could this kind of devastation strike where we live?

Jim Abraham
Tropical cyclones frequently weaken when they move over the colder waters surrounding Atlantic Canada. However, there are rare occasions where, rather than weakening, they reintensify. And those occasions are when they interact with a frontal system, therefore causing a significantly higher storm surge than otherwise might be expected.

Jay Ingram
At the Canadian Hurricane Centre in Halifax, they're tracking Lisa, hovering just outside Newfoundland marine waters. Atlantic Canada has more storms than any other part of the country, and there's a growing scientific consensus that our changing climate will make matters worse.

Jim Abraham
The concern, especially here in Atlantic Canada where we're in the middle of the... some of the strongest winter storms, and of course the tropical cyclones, the hurricanes that affect us in the fall, that perhaps with more energy in the system with the global warming, more heat and more moisture available for these storms to intensify, perhaps these storms, in a global warming scenario, will be more frequent, and even worse and even more intense.

Jay Ingram
Along the coast of the Bay of Fundy, there's another concern. Sea levels are rising here by up to 35 centimetres a century. And global warming is expected to push the water higher still.

John Shaw
The predictions for future climate change indicate that the sea level is going to increase perhaps by about 50 centimetres over the next century, mainly because the temperature of the ocean is going to increase. And in an area like Atlantic Canada, that 50-centimetre increase has to be added on to a good part of the sea level rise that we already have. In other words, sea level in this marsh could rise by 70 centimetres over the next century.

Jay Ingram
Big storms push water levels higher still, something called a storm surge. Add very high tides to the mix, and you get the potential for major flooding. Hard to predict and impossible to prevent.

Charles O'Reilly
The occasion of a storm surge flood is a bit like a crapshoot. Unlike an earthquake when we speak of one hundred year event... the probability doesn't increase as time goes on. It's when you have the combination of extreme weather in concert with extreme tides, when they decide to get together, naturally, that's what describes the problem. It may occur tomorrow and another one may occur the year after and not again for two or three hundred years. So we're dealing with probabilities here.

Jay Ingram
O'Reilly studies the tides here at Burnt Cove Head, near the tip of the Bay of Fundy. The world's highest tides have been recorded here, and at low tide you can see how the waves have carved the shoreline. This gauge shows the water level is zero now, and see that knob-shaped rock in the distance? Look what happens to it, six hours later, at high tide. The gauge is barely visible. The tide measures just over 16 metres, enough to cover a five-story building. On this day, the water is at its highest peak in 19 years. Part of a natural tidal cycle that varies with the rotation of the earth and the gravitational influences of sun and moon. If a big storm struck on a day like this, there could be trouble.

Charles O'Reilly
To start with, if there was even a small storm right now, the platform on which we're standing would not be here. And with a large storm, we probably could experience another two metres, or perhaps even two and a half metres - a surge, which would go that much higher off the cliffs.

Jay Ingram
The real concern is for low lying lands just up the coast. Land that's cut off from the sea, for now, by a network of old earthen dikes. When salt marshes are left alone, they adjust naturally to rising tides. The mud beneath the surface is mostly silt and clay brought in by the tide. When Dr. Shaw analyzes these samples, he finds the marsh has risen nearly a metre over the past three centuries, keeping pace with sea level rise. Dikes get in the way of this natural process.

John Shaw
Many of those natural marshes were diked many years ago to create agriculture land. So for a time, those diked areas have not been able to keep pace with sea level rise. And every year that goes by, they are lower and lower, relative to the level of the water outside the dike. And the problem is, if we ever have a storm surge that overtops the dike, those agricultural lands will be flooded and the floods will persist for quite a long time.

Jay Ingram
That's what happened in October of 1869 during the Great Saxby Gale, when a tropical storm coincided with an extreme high tide, to create a two metre storm surge. Hundreds of acres of farmland were ruined, buildings ripped apart. Dozens of people died along the Fundy coast. Communities like Maitland, Nova Scotia were inundated with salt water.

Charles O'Reilly
During the Saxby flood the waters came in over the dikes, they rolled into the streets, went up into the stores, perhaps around window level, several feet above the floor. And inundated the area perhaps as far as a quarter of a mile inland.

Jay Ingram
O'Reilly has worked with colleagues at Environment Canada to reconstruct the storm carefully. This computer-generated image shows how high the water reportedly went in Truro, Nova Scotia. The storm hit a couple of days before the highest astronomical tide, so the damage could have been even worse. This is what happened 107 years later, when the Ground Hog Day gale hit Yarmouth, Nova Scotia. Again, the storm missed the peak tide, but the water surged a metre and a half higher than usual. And the damage was in the tens of millions of dollars.

The damage today could be far worse, thanks to climate change. Cities like Saint John, Truro and Yarmouth could all bear the brunt. Researchers believe it's just a matter of time before a storm and a high tide coincide once again.

Charles O'Reilly
The real question is not if it's going to happen, the real question is when it's going to happen, and when it does occur, it's going to cause devastation that several generations have not seen.

John Shaw
Storms like the Saxby Gale are very, very rare, and because they're very rare, people are not as prepared for them as they might otherwise be. The other problem of course, our coastal infrastructure has developed significantly since the time of the Saxby Gale. The population is higher, the amount of coastal development is significantly higher, and we're more at risk than we were 120 years ago.

Jay Ingram
That's why researchers continue to study the tides with a network of gauges to chart their ebbs and flows. That's why they track every storm with a system of weather buoys out in the Atlantic. With modern forecasting methods, we might get a day or two's notice, before the next big one strikes.


Jane Gilbert
Tonight's Earth Tones was produced along with Natural Resources Canada, Environment Canada, and the Department of Fisheries and Oceans.