Search

Strong wind coinciding with rainfall is an important weather phenomenon in many science and engineering fields. This study investigates changes in hourly extreme driving rain wind pressure (DRWP)—a climatic variable used in building design in Canada—for future periods of specified global mean temperature change using an ensemble of a Canadian regional climate model (CanRCM4) driven by the Canadian Earth system model (CanESM2) under the Representative Concentration Pathway 8.5 scenario. Evaluation of the model shows that the CanRCM4 ensemble reproduces hourly extreme wind speeds and rainfall (> 1.8 mm/h) occurrence frequency and the associated design (5-year return level) DRWP across Canada well when compared with 130 meteorological stations. Significant increases in future design DRWP are projected over western, eastern, and northern Canada, with the areal extent and relative magnitude of the increases scaling approximately linearly with the amount of global warming. Increases in future rainfall occurrence frequency are driven by the combined effect of increases in precipitation amount and changes in precipitation type from solid to liquid due to increases in air temperature; these are identified as the main factors leading to increases in future design DRWP. Future risk ratios of the design DRWP are highly dependent on those of the rainfall occurrence, which shows large increases over the three regions, while they are partly affected by the increases in future extreme wind speeds over western and northeastern Canada. Increases in DRWP can be an emerging risk for existing buildings, particularly in western, eastern, and northern Canada, and a consideration for managing and designing buildings across Canada. [ABSTRACT FROM AUTHOR]

Ice accretion on transmission lines can lead to serious damages from line breakage and flashover. This study investigates projected changes to design ice loads for overhead transmission lines for the 2041–2070 and 2071–2100 periods with respect to the 1976–2005 period over Canada, using transient climate change simulations of the fifth generation Canadian Regional Climate Model, for two driving Global Climate Models and two Representative Concentration Pathways. Projected changes to freezing rain characteristics are first evaluated and results suggest decreases in 50-year return levels of annual maximum daily freezing rain for the south-eastern inland and coastal regions and south-western and north-eastern coastal regions of North America, but increases for other regions. Consequently, the simulations suggest statistically significant increases in 50-year return levels of annual maximum ice thickness, particularly for regions of Quebec and west of the Hudson Bay (larger than 10 mm) and some scattered increases for south- central and western Canada (mostly smaller than 3 mm). This study also helped identify regions where both wind and ice loads will increase in future climate, which can be detrimental to the electric infrastructure. Results suggest that compound event assessments would be valuable, taking into consideration larger set of simulations, to obtain more robust projections. [ABSTRACT FROM AUTHOR]

River water temperature regimes are expected to change along with climate over the next decades. This work focuses on three important salmon rivers of eastern Canada, two of which warm up most summers to temperatures higher than the Atlantic salmon lethal limit (>28°C). Water temperature was monitored at 53 sites on the three basins during 2–18 summers, with about half of these sites either known or potential thermal refugia for salmon. Site-specific statistical models predicting water temperature, based on 10 different climate scenarios, were developed in order to assess how many of these sites will remain cool enough to serve as refugia in the future (2046–2065). The results indicate that, while 19 of the 23 identified refugia will persist, important increases in the occurrence and duration of temperature events in excess of 24°C and 28°C, respectively, in the mainstems of the rivers, will lead to higher demands for thermal refugia in the salmonid populations.Editor Z.W. Kundzewicz; Associate editor T. Okruszko [ABSTRACT FROM AUTHOR]

Atmospheric moisture loading affects the performance and durability of building exteriors. In a changing climate, designing for historical moisture loads may no longer be adequate. This study investigates potential climate change impacts on the moisture index used in the design and management of buildings over Canada. Projections are obtained for future periods experiencing different global warming levels (+1 °C, +2 °C, etc.) with respect to 1986–2016 baseline using outputs from a 15-member initial condition ensemble of the CanRCM4, a Canadian regional climate model at 50-km resolution. CanRCM4 overestimates wetting potential, underestimates drying capacity, and hence overestimates moisture loads for the baseline period. To obtain unbiased moisture indices, a simple linear bias adjustment scheme is applied to the baseline simulation and future projections. Significant increases in future moisture loads are found over the western and eastern coastal regions of Canada due to increases in rainfall amounts, driven by increases in precipitation and a warming-induced shift from snow to rain. Conversely, CanRCM4 projects significant decreases in future moisture loads over south-central and northern Canada due to increases in drying capacity, driven by increases in future near surface air temperature that are accompanied by nearly unchanged relative humidity. Internal variability of the moisture load due to the natural, chaotic variability of the climate system, is modest compared to the magnitude of the projected change signal — signal-to-noise ratio is high. The projected changes suggest that moisture protection could be a concern for designing and managing building exteriors over western and eastern coastal regions of Canada. • Atmospheric moisture loading affects the performance and durability of building exteriors. • Projected changes to moisture loads used in design buildings are evaluated over Canada. • Warming-induced shift from snow to rain increases future wetting potential across Canada. • Projections suggest increases in future moisture loads over western and eastern regions of Canada. • Moisture-resilient management and design of building exteriors are suggested over those regions. [ABSTRACT FROM AUTHOR]