Fiona hitting Canada? Blame it on global warming.

Fiona hits Canada. (NASA)

By Ryan P. Mulligan

Atlantic Canada has been rocked by the effects of one of the largest and most dangerous ocean storms to ever hit the region. Hurricane Fiona made landfall as a powerful post-tropical storm Saturday along the east coast of nova scotiaPrince Edward Island and Newfoundland and Labrador, bringing heavy rain, damaging winds and massive waves.

The storm surge – a rise in sea water levels – led to power outages, flooded roads and, in southwestern Newfoundland, the houses were washed away. The southwest coast of Newfoundland was particularly affected by extreme waves and storm surges, which were highest on the east side of the storm’s track.

The huge storm had very low atmospheric pressure (931.6 mb) – which is the lowest on record for a tropical storm that made landfall in Canada. Low pressure weather systems are associated with strong winds and heavy rains.

Offshore, wave heights exceeded 8 to 10 meters on the Scotian Shelf and reached 17 meters at the benches of Banqureau wave buoy.

past storms

Historically, the 1869 Saxby Gale was a huge storm that caused major flooding in Nova Scotia. Other more recent storms, such as Hurricane Juan in 2003 and Hurricane Dorian in 2019 had big impacts, but their intensity also diminished just before making landfall in Nova Scotia.

Hurricanes of Fiona’s size and strength don’t typically maintain their wind speeds this far north. This makes Hurricane Fiona a pivotal event in the Canadian coastal ocean, as it raises the question of when it will happen again.

How did Fiona arrive in Canadian waters with such size and intensity? This is linked to its source of heat: the ocean. Ocean warming may be related to increasing storm intensity landfall and the development of powerful hurricanes.

Thus, climate change leads to warmer ocean waters at higher latitudes. A warmer future increases the likelihood of more intense storms reaching Canadian shores.

a photograph of a rough ocean with high waves
Storm surge is sea water level rise – here waves hit the shore at Eastern Passage, Nova Scotia on September 24.

Types of impacts

Depends on hurricane size and strengthwhere it makes landfall and the shape of the coast it hits, the impacts can be very different.

In addition to large waves and storm surges, hurricanes bring heavy rainfall which floods the ground surface and may affect coastal groundwater systems.

These storms bring strong currents that can erode sediments and alter the shape and forms of the ribs. They can also affect water quality by suspending and spreading contaminants in ports.

A fallen tree rests on top of a house
Tree knocked down by Hurricane Fiona damages home in Halifax, NS

Hurricanes the size of Fiona may not happen again anytime soon – or a storm of similar intensity could hit Atlantic Canada again in the next few years. We are making progress with recent enhancements to
hurricane forecast
and real-time coastal modeling.

Being able to predict the size, frequency and impact of storms helps inform warnings, decisions, responses and policies. These predictions are key to being prepared for the next big storm when it does.

Ryan P. Mulligan is Professor of Civil Engineering and Director of the Beaty Water Research Centre, Queen’s University, Ontario.

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