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Climate Change Impacts in Nova Scotia & HRM

According to Environment Canada, Nova Scotia (along with Newfoundland and Labrador) receives the most storms of any region in Canada due to its proximity to the Gulf Stream. This is attributed to ‘nor’easters’, which are most prominent during the winter and early spring.

These storms can generate wave heights in excess of 14 metres, and storm surges of more than one metre. Numerous climate projections point to more variability in climate, with the possibility of more frequent and more intense extreme events. Sea-level rise due to thermal expansion (warming of ocean waters) from global warming, and isostatic subduction (post ice age drop in coastal land mass) make this Maritime region moderately to highly vulnerable to extreme weather (see Map).

Tracks of tropical cyclones (hurricanes) typically begin in the eastern South Atlantic, and progress across the ocean, curving northward then north-eastward, south of Atlantic Canada. Some of the stronger systems make landfall, and track west of Atlantic Canada. These storms feed off the warmer water of the tropical North Atlantic, and typically diminish in strength as they track over the colder waters south of Atlantic Canada.

Hurricane strength is classified by wind speed. Category 1 begins when wind speeds attain 118 km/h. Minimum wind speed for a Category 2 is 154 km/h, Category 3 is 178 km/h, Category 4 is 211 km/h, and a Category 5 is 249 km/h.

GOES Satellite Imagey. Photo Credit: NOAAWith global warming, sea water is temperature is rising, and may be causing a northward shift in cyclonic activity. Thus, it is expected that stronger hurricanes are more likely to track over Atlantic Canada. Thus, Atlantic Canada is at greater risk from tropical storms and hurricanes. In fact, some studies have suggested that intense storms in the northern hemisphere, including hurricanes, may actually increase in number with global warming. If so, Atlantic Canada would be extremely vulnerable to an increase in category 4 and 5 hurricanes.

The coast of Nova Scotia is often subjected to high-energy wave action associated with hurricanes and other tropical storm systems. Typically, tropical storms and hurricanes weaken as they approach the Province, once they pass over the cooler water north of the Gulf Stream. In the recent case of hurricane Juan in September 2003, the waters along the Atlantic coast of NS were 30C warmer than normal, which allowed the storm to retain its strength as it made landfall.

Impact of Rising Sea Level & Sensitivity Assessment

The Atlantic Region has the greatest length of sensitive coast in Canada. This is especially so with Prince Edward Island’s Gulf coast, the head of the Bay of Fundy, and Nova Scotia’s Atlantic coast.

The Geological Survey of Canada (GSC) has assessed the sensitivity of Canada’s coast to physical changes from sea level rise, based on the land elevation, landform, rock type (erodability), past sea level trends, tidal range, wave height, and the existing rate of shoreline movement.7 According to the GSC survey of Canada’s coasts, 3% are highly sensitive, 30% are moderately sensitive, and 67% rate low sensitivity.