Health Module Context

There is scientific consensus that the climate is changing, mainly as a result of human activity, and that this situation directly endangers the health of populations. The gradual global warming and the hydrometeorological hazards which result from it (heatwaves, floods) can have consequences for health care systems and public health. Crucial public health elements affected can include the quality of air, water, foodstuffs, and housing, all of which increase the risk of disease (zoonotic or chronic).

The consequences of the impacts of climate change on public health affect the physical, mental and social health of populations in three different ways1 (see Figure 1):

  • Direct exposure to extreme events (e.g., heatwaves and flooding):
    • Extreme heat can lead to dehydration, heat stroke, and death. The elderly and those with existing medical conditions, but also outdoor workers, athletes and the homeless, are particularly vulnerable to extreme heat conditions. As Canada’s climate warms, the frequency and severity of heatwaves are expected to increase2 and also to start affecting areas such as Canada’s north which are less prepared to cope with extreme temperatures.
    • Flooding can directly endanger life and prevent access to health infrastructure such as hospitals, clinics and pharmacies. Critical infrastructure such as waste water treatment plants may be overwhelmed leading to contamination of water bodies and an increased risk of waterborne disease.
  • Indirect exposure mediated by natural systems (e.g., Lyme disease or pollen)
    • Warmer conditions may lead to an earlier start to, and a longer growing season for plants which have highly allergenic pollen3.
    • Pests and diseases whose range is limited by temperature may become prevalent in areas where they are currently absent. For example, the range of the black-legged tick, which carries the bacteria causing Lyme disease, will expand as the climate warms4.
    • Extreme heat can also lead to a build-up of air pollution, e.g., ground-level ozone, thus decreasing air quality and causing respiratory illness. Hot and dry conditions can also lead to more wild fires, more smoke and decreased air quality.5
  • Indirect exposure mediated by social and economic disruption (e.g., vulnerable populations disproportionately impacted, planning for mass evacuations in times of pandemic):
    • An increase in the frequency of weather-related disasters has psychological impacts which may increase the risk of mental illness and anxiety6,7.
    • Warmer conditions in Canada’s north are already leading to thawing permafrost, and changes in snow and ice conditions are impacting the way of life. With continued warming, traditional hunting and harvesting activities will become more challenging and food insecurity will increase. Warmer winters mean a shorter ice road season which reduces the time available to resupply remote communities, also leading to an increase in food insecurity. Community access to emergency medical care and services may also be threatened. Loss of traditional food sources has a profound impact on the cultural and spiritual well-being of indigenous peoples.8


These health impacts are then passed on to the entire population through a domino effect by overwhelming the access, quality and resilience of infrastructure, social and public services, the economy, in addition to increasing existing social and economic inequalities.

Figure 1: Diagram of the trajectories by which climate change affects health and the simultaneous and modifying influence of environmental, social and health system factors.

Source9: Adapted from Confalonieri et al, 2007

Added to the visible damage already caused by the impacts of climate change (e.g., total loss of natural and human habitats following floods or forest fires, population displacement due to coastal erosion, deadly heatwaves) are the less visible, but just as critical, progressive consequences such as profound changes in biodiversity, increase in chronic diseases or even in the percentage of population suffering from eco-anxiety.

It is therefore important that decision-makers act quickly to put in place strategies to reduce and adapt to climate change. To do this, the Health module of the site offers quick and easy access to various sets of relevant climate data and information, particularly for monitoring and setting critical thresholds and standards. As an example of good practices to follow, several case studies are presented to illustrate how climate data can be used to contribute to adaptation efforts.

Module Content

This Health module has been designed and developed to provide information about the priority issues for this sector associated with climate change. After engaging with health professionals and practitioners across Canada both through a survey and focus groups, relevant climate indices and case studies were identified, as well as the best ways of presenting climate information, both visually and for download purposes.

Extreme events, particularly extreme heat, were identified as having the most significant impacts on the health of Canadians. In response to this, a number of heat-related climate indices are available on, as well as a case study describing the impact of heatwaves in the province of Quebec. Users can explore how the number of days with maximum temperatures above a variety of temperature thresholds may change in the future in response to low, moderated and high increases in greenhouse gas emissions, and similarly for tropical nights (when minimum temperatures do not fall below specified temperature thresholds). Recognizing that Canada’s vastness means that it is not reasonable to try and define a single heatwave index which has relevance across the country, a number of heatwave indices may be calculated on the Analyze page using custom temperature threshold values.

Another growing public health concern is the increasing incidence of Lyme disease, and the potential for its further spread across Canada as the climate warms. The survival of the black-legged tick, the main vector of Lyme disease, is partially dependent on temperature (annual accumulation in excess of 2800 degree days above 0°C) and, as the climate warms, its range is projected to increase10. provides this accumulated degree day index and thus allows users to determine how this tick’s range may change in the future. The accompanying case study for Ontario also details possible adaptation actions to reduce exposure to ticks.

Both extreme heat and Lyme disease are also explored in a case study summarising a report from the Conservation Council of New Brunswick11 on the effects of climate change on the physical and mental wellbeing of people in 16 communities in that province. The impacts of drought on human health and well-being across the southern Prairies and in the interior of British Columbia, are also described in a case study focused on these regions.

Climate change impacts not only the health of Canadians, but also health systems, the hospitals and other infrastructure required to deliver health services to people. These systems are also vulnerable to climate change, not only through extreme events, such as floods, heatwaves and wild fires, which directly impact their operations, but also via the gradual change in climate over time. This will impact the efficiency of, for example, HVAC systems, which may more frequently experience conditions outside of their operating design range. In order to continue to deliver health services efficiently, health systems will need to become increasingly resilient to climate change. Relevant climate indices and options to increase building resiliency in the face of climate change are explored in a case study using examples from British Columbia12,13.

Next Steps

The Health module has been developed based on the feedback received from stakeholders in this sector. continues to seek feedback for this module and to add new content and climate indices. Please complete the Feedback form on if you have any feedback on the current content or ideas for additional case studies, climate indices, or relevant datasets that you would like to see added to the Health module.


  1. Smith, K.R., A.Woodward, D. Campbell-Lendrum, D.D. Chadee, Y. Honda, Q. Liu, J.M. Olwoch, B. Revich, and R. Sauerborn, 2014: Human health: impacts, adaptation, and co-benefits. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel,A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L.White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 709-754.
  2. Warren, F. and Lulham, N., editors (2021). Canada in a Changing Climate: National Issues Report; Government of Canada, Ottawa, ON.
  3. Anderegg, William R. L., John T. Abatzoglou, Leander D., Anderegg, Leonard Bielory, Patrick L. Kinney, Lewis Ziska. Anthropogenic climate change is worsening North American pollen seasons. Proceedings of the National Academy of Sciences Feb 2021, 118 (7) e2013284118; DOI: 10.1073/pnas.2013284118
  4. Bouchard C, Dibernardo A, Koffi J, Wood H, Leighton PA, Lindsay LR. Increased risk of tick-borne diseases with climate and environmental changes. Can Commun Dis Rep 2019; 45(4):83–9.
  5. Finlay, S., A. Moffat, R. Gazzard, D. Baker, and V. Murray, 2012: Health impacts of wildfires. PLoS Currents, 2012 November 2, Edition 1, doi:10.1371/ 4f959951cce2c
  6. Fernandez A. et al (2015). Flooding and Mental Health: A Systematic Mapping Review. [On line].
  7. Goldmann E., Galea S. (2014). Mental health consequences of disasters. Annual Review of Public Health. Volume 35 : 169-183. 14 pages. [On line].
  8. Canadian Institute of Climate Choices (2021): The Health Costs of Climate Change: How Canada can Adapt, Prepare and Save Lives. 65pp.
  9. Confalonieri, U., B. Menne, R. Akhtar, K.L. Ebi, M. Hauengue, R.S. Kovats, B. Revich and A. Woodward, 2007: Human health.ClimateChange 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of theIntergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds.,Cambridge University Press, Cambridge, UK, 391-431
  10. Ogden, N.H., L. St-Onge, I.K. Barker, S. Brazeau, M. Bigras-Poulin, D.F. Charron, C.M. Francis,A. Heagy, L.R. Lindsay,A. Maarouf, P. Michel, F. Milord, C.J. O’Callaghan, L.Trudel, and R.A.Thompson, 2008: Risk maps for range expansion of the Lyme disease vector, Ixodes scapularis, in Canada now and with climate change. International Journal of Health Geographics, 7, 24, doi:10.1186/1476-072X-7- 24.
  11. Comeau, L., & Nunes, D. (2019). Healthy Climate, Healthy New Brunswickers: A proposal for New Brunswick that cuts pollution and protects health. Retrieved from Fredericton, New Brunswick:
  12. World Health Organization . Operational Framework for Building Climate Resilient Health Systems.World Health Organization; Geneva, Switzerland, 2015. Online :
  13. Aubie Vines G., Murdock T., Sobie S., Hohenschau D. Lower Mainland Facilities Management: Moving towards Climate Resilient Health Facilities for Vancouver Coastal Health. Report Prepared for Vancouver Coastal Health; Vancouver, BC, Canada: 2018. Online :