In 2005, heavy rains washed out a section of Toronto’s Finch Avenue, causing $642 million in insured damage

On April 16th from 1-2pm Eastern time, ACT water policy author and Chair of the Canadian Partnership Initiative of the UN Water for Life Decade Bob Sandford presented on The Loss of Stationarity in a national webinar (requires Adobe Connect to view) hosted by the Canadian Climate Change Adaptation Community of Practice.

Stationarity is the notion that seasonal weather and long-term climate conditions fluctuate within a fixed envelope of relative certainty. Stationarity therefore implies stability and a relatively high degree of certainty when it comes to predicting and managing the effects of weather and climate on our cities and our agriculture.

For instance, the fact that we have determined that natural phenomena fluctuate within a fixed envelope of relative certainty suggests that winters will only be so cold and summers so hot; that melt from winter snow packs will always contribute roughly the same amount of water to our rivers; that rivers will rise only so high in spring and fall so low in autumn, etc.

Stationarity therefore gives us the comfort we need to build our houses to withstand winds of a certain speed and snowfalls of a certain weight. It suggests we have to build storm sewers only to a certain size because we know from history that rainstorms last only so long and result only in so much runoff.

Stationarity is also the foundation for determining insurance rates related to risks associated with the protection of our homes, property and food crops from fires, flood, tornadoes, hurricanes and droughts, as well as the foundation of the reliable function of the natural ecosystem processes that provide a stable and resilient backdrop to human existence.

Now, increasing average temperatures, climate change impacts on weather patterns, and extensive changes in land use globally are altering the patterns of water’s movement through the global hydrological cycle. This means that statistics from the past related to how surface, subsurface and atmospheric water will act under a variety of given circumstances are no longer reliable.

Unfortunately, we have made the stationarity associated with those statistics – the notion that natural phenomena fluctuate within a fixed envelope of certainty – the foundation of risk assessment in engineering upon which we depend for the construction of our buildings, roads, bridges and other infrastructure. We have also made stationarity the foundation of planning for the future.

We have built our society and the entire infrastructure that supports it around that range which we now increasingly realize no longer represents reality.

We do not as yet have an adequate replacement for stationarity statistics. Until we find a new way of substantiating appropriate action in the absence of stationarity, risks will become increasingly difficult to predict or to price. So will the prospect of conflict associated with those risks.

Bob discussed the implications of the loss of stationarity and answered questions afterwards.