Climate-Resilient Buildings and Core Public Infrastructure: an assessment of the impact of climate change on climatic design data in Canada

Background

Many aspects of Canada’s infrastructure are directly affected by climate variability and change. Observations provide information about historical climate and are therefore the baseline against which future change is compared. In the context of Environment and Climate Change Canada's (ECCC) contributions to Canadian codes and standards, this historical information has been provided by the Meteorological Service of Canada in their regular updates to historical climatic design data. In contrast, the focus of Climate Research Division (CRD) of ECCC's Science and Technology Branch is on information about future climate change, as needed to assess the impacts of a changing climate and plan adaptation measures. This information cannot be reliably obtained by analysis of historical data and extrapolation of observed trends. Instead, quantitative information on future climate change relevant to Canada’s Buildings and Core Public Infrastructure (B&CPI) requires climate model-based projections driven by a range of greenhouse gas emission scenarios. The credibility of climate model outputs differs for each climatic design variable and thus projections of changes in each type of climatic design value must be accompanied by an assessment of model limitations and an evaluation of uncertainty. The development and communication of future climate projections, and their uncertainty, relevant to codes and standards – spanning the late 20th century to the end of the 21st century – are the subjects of this project. ECCC’s CRD, in collaboration with the Pacific Climate Impact Consortium and the National Research Council, undertook this activity in support of the Pan Canadian Framework on Clean Growth and Climate Change, and in support of the Green Infrastructure objectives of the Canadian government.

Report overview

The report provides an assessment of how climatic design data relevant to the National Building Code of Canada (NBCC 2015, Table C-2) and the Canadian Highway Bridge Design Code (CHBDC/CSA S6 2014, Annex A3.1) might change as the climate continues to warm. The approach in this report is based on an assessment of the current understanding of climate change from national and international assessments, as well as in other relevant literature, and is supplemented by ongoing research efforts within ECCC’s CRD and elsewhere, and by targeted research conducted specifically for this project. Design decisions should always be made following the appropriate codes and standards. It is important to note that it remains the responsibility of the users of these climatic data to determine whether it is suitable for their particular purpose.

Chapter 2 provides basic information on climate modelling and a general description of the models and methods used to develop and assess projections for each climatic design variable. This chapter includes a worked example for annual mean temperature change, bringing together the scientific assessment and quantitative climate model projections to suggest a possible approach to adjusting future design data that takes into account the degree of confidence in the projected changes that the science allows. Subsequently, chapter 3, chapter 4, chapter 5 and chapter 6 apply this approach to each of the four broad classes of B&CPI climatic design variables (temperature, precipitation and moisture, wind, and snow and ice). Appendix 1 includes tables of projected changes for each climatic design variable under different global warming levels (from +0.5°C to +3.5°C above the 1986-2016 global mean temperature ^{Footnote 1i}). Scenarios describing how future design data may change relative to the 1986-2016 period are tabulated for locations similar to those in NBCC Table C-2 and are accompanied by assessments of confidence and indications of projection uncertainty, as supported by reference to specific sections of chapter 3, chapter 4, chapter 5 and chapter 6.

Importantly, assessments in this report are made at the regional-to-national scale. While location specific projections are offered in all cases, the specific data at individual locations should be considered to have lower confidence than the regional-to-national scale assessments. Furthermore, confidence varies greatly between different types of design data, with the result that many of the projections may not be suitable for direct application, but instead might be best used for resilience and risk assessments that consider physically plausible future climatic conditions. Chapter 7, which summarizes the main conclusions of the project, therefore also includes suggestions on how projections might be used when considering the impact of climate change on Canada’s B&CPI climatic design variables. Finally, Appendix 2 includes links to published papers associated with targeted research conducted under this project.