|The design value found in Table C-2 has been derived from historical weather data.
What will happen with the effects of global warning? Environment Canada commissioned a study on how global warming may affect the design criteria. Some findings from the study, “Climate-Resilient Buildings and Core Public Infrastructure 2020: An Assessment of the Impact of Climate Change on Climatic Design Data in Canada” are listed below.
It is certain that Canada’s climate will warm. The report projects temperatures will increase at twice the rate of the global mean temperature. The increase in seasonal temperatures will occur across the country, with greater warming happening in the north of Canada during the winter months.
The report indicated very low confidence in the effects increase of temperature on design wind pressures. The figure, “Changes in Hourly Wind Pressure q50 versus change in Temperature” shows a modest increase in wind pressures with temperature increases. However, the shaded portions of the graph show the increase will not be the same in every part of each region, and the design wind pressures may even decrease in some locations.
The authors of the report had medium confidence in their projections for precipitation. They believe annual, and winter precipitation (rain or snow) will increase everywhere in Canada, with Northern Canada having the largest increase. Summer participation is projected to be less in Southern Canada.
24-hour and 15-minute rainfall
There is even less confidence in the projections for changes in the 24-hour and 15-minute rainfalls. The report recommends accounting for a seven per cent increase in these two values for each degree Celsius increase in temperature.
It is highly likely that snow cover duration will decline over Canada with an increase in surface air temperature. Decreases in seasonal snow accumulation are projected over much of southern Canada. Northern regions of Canada are predicted to have a slight increase in snow accumulation with increased temperature. The changes in snow accumulations are shown in the following two figures.
The report “Climate-Resilient Buildings and Core Public Infrastructure 2020” can be found here, www.infrastructure.gc.ca/plan/crbcpi-irccipb-eng.html.