Coastal Storm Surges and Climate Change – Atlantic Canada at Risk

GLOBE-Net, October 30, 2014 – The Canadian Climate Forum (CCF) has released a paper warning coastal planners and infrastructure designers to start preparations to prevent property damage and loss of life from extreme weather events in Atlantic Canada.

It warns that by 2100, sea levels in Atlantic Canada are expected to be between 20 cm and one metre higher than today’s levels.  The CCF paper Forecasting a Sea of Change, highlights the stakes involved and the importance of considering the more extreme scenarios of sea level rise.

A storm surge is an inundation of unusually high water that is generated at a coast by strong winds and changes in air pressure. Coastal flooding can happen when a storm surge occurs close to high tide, allowing the water to reach far inland in flat lying areas.

The CCF press release cites a recent study of the Tantramar region of New Brunswick found that in the next century under current climate projections, storm surges and flooding will cost the region an additional $10 million each year, some 22 per cent above current costs.

“Canada has more than 240,000 kilometres of ocean shoreline, more than any other country in the world,” said Jim Abraham, a member of the CCF Board of Directors. “The reality of ongoing sea level rise is something we have to pay attention to and prepare for now,” he said.

In 2003, Hurricane Juan tore through Atlantic Canada, making landfall near Halifax, Nova Scotia. It caused $300 million in damage, killed eight people and left hundreds of thousands of Maritimers without power. As the global climate changes, extreme weather events are likely to become stronger.

Coastal regions like Atlantic Canada face a unique set of risks.

Relative to today’s mean sea level, a 1.9 metre storm surge in Halifax, Nova Scotia can be expected once every 300 years. In the future, with projected rises in sea level and land subsidence, a 1.9 metre storm surge could occur every ten years. This illustrates the significant negative impact on coastal cities such as Halifax, which would experience widespread waterfront flooding. “Within 40 years, flood damage to coastal houses due to climate-related sea-level rise and storm surges could cost between $1 and $8 billion per year,” said Abraham.

The Earth’s crust is slowly rising in many areas of Atlantic Canada. This movement is associated with the retreat of the glaciers at the end of the last Ice Age, and the slow rebound of the land from their weight. In Quebec (and other areas closer to the centre of the continent), the coastline is rising at a rate of about 30 cm. per century, gradually decreasing average relative sea level in this region.

The combination of the increased use of “ensemble-based techniques,” which combine information from various forecasts, and expected advances in other modelling tools over the next five years will provide planners with new data to help protect Canadians from extreme weather events in coastal communities.
“We cannot ignore extreme sea level rise scenarios just because uncertainty exists and the probability of a major event is low,” said Abraham.

The paper also outlines some of the other consequences of climate change on Atlantic Canada, including ocean acidification, which could have a significant impact on Canada’s $2 billion commercial fishing industry.

The full paper is available here

GLOBE-Net readers will also be interested in the comments of John Englander, a Speaker at GLOBE 2014 and author of the book High Tide on Main Street. See video below.

The Canadian Climate Forum is a non-governmental agency dedicated to improving understanding of weather and climate in the Earth System. It collaborates with partner agencies and individuals to accelerate the uptake and use of weather and climate knowledge to serve the needs of society and the economy.