The report is available at this link. Yes it is dated (2002) and predates several extreme rainfall events in Southern Ontario and Alberta, but it is valuable in that it shows how unusual, extreme weather events and disasters - even more recent ones - should be evaluated to answer the question "Are recent unusual weather events and related impacts and disasters caused by natural variability or climate change?"
As stated in the report "The following provides an update on that analysis through a case-by-case discussion of various types of unusual weather events that have occurred in Canada and elsewhere over the past five years or so." It explores a range of topics:
- Temperature Related Events
- Unusual Annual and Seasonal Temperatures
- Mild Winters
- Summer Heat Waves
- Longer Growing Seasons
- Water Related Events
- Extreme drought
- Lake/River levels and flows
- River Flooding
- Coastal Flooding
- Convective storms
- Winter storms
- Tropical storms
- Oceanic and Sea Ice Behaviour
- El Niño/La Niña
- Arctic sea ice
- Ecological and Social Infrastructures
- Permafrost decay
- Ecological impacts (including forest fires)
- Community Impacts
- Aggregate social costs of weather related disasters
- Environmental refugees/disasters
|SENES 2012 Toronto's Future Weather & Climate Driver Study rainfall values and trends do not agree with Pearson Airport data values and trends provided by Environment Canada - Days with greater than 25 mm rainfall.|
|SENES 2012 Toronto's Future Weather & Climate Driver Study rainfall values and trends do not agree with Pearson Airport data values and trends provided by Environment Canada - Maximum Daily Rainfall|
The trend in daily maximum can also be assessed by the change in return period values representing common 2-year to rare 100-year return period intensities. The following table shows trends in 24-hour intensity values for 4 periods up to 1990, 2003, 2007 and 2013. The intensity trends are flat or decreasing as the last 23 years of record have been added, suggesting the maximum daily rainfall depth is not increasing as suggested by the SENES climate model.
When the basic values are so far off the existing data and initial trends predicted by climate change models, one has to seriously question the value of the weather prediction exercise. And given IPCC says 25 mm storms will increase, the SENES' Toronto study says they will go down, and real data shows no trend in these frequent events (i.e., the 2-year intensity is flat 1990 to 2013), you have to wonder that the value is for climate model predictions. Environment Canada provides a similar caution on Global Climate Models (GCMs) in the CO2 / Climate Report saying:
Looking at average maximum daily values, the SENES data is more in line with Pearson Airport data for existing values as shown below. But the Pearson data shows no upward trend as would be expected if the average daily maximum is to increase from 48 mm per day now to 86 mm per day in the future period. The actual data trend is very flat and random:
"Weather events beyond the expected range of weather behaviour to which local ecosystems and socio-economic infrastructure have adapted over time can have major ecological, social and economic impacts. Some of these impacts can be beneficial, but most are deleterious.Some of the recent climate trends and events, internationally and within Canada, cannot as yet be distinguished from those that could occur due to natural climate variability."
Separating the facts that there are indeed impacts from extreme weather that society has not adapted to (system capacities are too small for old weather and today's weather), from the premise of many that the weather has changed significantly due to climate change is an ongoing dilemma for those charged with advancing data-driven, evidence-based approaches to flood risk mitigation.
Those linking the 2016 Fort McMurray wildfire directly to climate change factors should strive to follow a rigorous review process as followed by Environment and Climate Change Canada in their climate report. ECCC offered the following:
"Average annual forest losses in Canada due to wildfire since 1980 is about 2.4 million ha. This
appears to be a significant increase from the average losses in the decades prior to 1980, at least partly due to a long term natural cycle involving an aging Canadian forest more prone to fire. However, there is also evidence that climate may be an important factor. Annual loss rates vary considerably from year to year, largely due to changes in fire weather conditions."
Given the facts on rainfall trends, we clearly need Design Standard Adaptation instead of Climate Change Adaptation to address the current extreme weather impacts.
Parliamentary Budget Office gets it wrong on Saskatchewan rainfall trends. Recent report contradicts Environment and Climate Change Canada's Engineering Climate Datasets.
Urban flood risk under climate change - Mississauga study ignores basics of hydrology and floodplain hydraulics to say a lot about nothing.