The 100-Year Storm
Statistically, a 100-year storm is an event that has a one per cent chance of occurring in any one given year. In the last five years, North America has had a handful of these storms. There could be several more in the next year or none for hundreds of years. In theory.
Climate change is skewing the odds-devastating storms affecting hundreds of thousands of people and causing billions of dollars in damage are becoming commonplace. Record-breaking rainfall in Ontario, flooding on the coasts, bizarre temperatures and erratic weather are wreaking havoc on infrastructure — especially wastewater and stormwater systems.
The 2007 findings of the United Nations Intergovernmental Panel on Climate Change indicate that in parts of North America over the next century, average annual temperatures will increase more than the global average and total annual precipitation will also increase.
Based on this, it’s reasonable to assume that stormwater pipe diameters and storage volumes will need to increase. In a presentation at WaterTech 2008 this past April, Mike Hulley of XCG Consultants said, “It remains a challenge to encourage all Canadian provinces and municipalities to use the existing historical rainfall database in their design guidelines, let alone accommodate potential shifts in climate. Implications of climate change should be addressed in system configuration and type, design of new infrastructure, retrofit of existing systems and maintenance.”
Municipalities that have built infrastructure to withstand 100-year storms are still being surprised by severe weather-a single event can wipe out a municipal budget. Insurance companies are taking the hits (Katrina cost US$40 billion of insured damage) and charging them back to policyholders with increased premiums, more specific coverage exclusions and new definitions for what constitutes an “act of God.”
As stated in the article on page 50 of our September-October issue (“Unexpected Effects” by Sabrina Gherbaz and Patricia Koval), “Very little attention has been paid to potential legal liability for failing to adapt infrastructure to climate change-related risk.” That will have to change.
There is no doubt that the uncertainty about weather impacts on infrastructure is increasing risk and driving up costs, further widening the infrastructure gap. CSA and Engineers Canada are considering updated standards for infrastructure as a result. The Confederation Bridge between New Brunswick and Prince Edward Island was built a metre higher than currently required to accommodate sea level rise over its hundred-year lifespan. Adaptation strategies like this are now essential.
Climate change adaptation is not just a term for scientists and tree huggers — it’s a mainstream issue. It’s what you and I are going to be doing in the future as we hunker down for many, many more 100-year storms in our lifetime.