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Climate Change and Health

The multiple impacts of climate change on the environment and the communities we live in results in a variety of health issues: 

  • Extreme heat – heat stroke, cardiovascular failure, death
  • Severe weather events – injuries, death, mental health impacts
  • Air pollution – asthma, cardiovascular disease, chronic obstructive pulmonary disease (COPD)
  • Changes affecting vector-borne diseases – Lyme disease, West Nile virus, Hantavirus
  • Increases in allergens – asthma,  respiratory disease
  • Water quality changes – illness from bacteria (e.g., campylobacter), toxicity from algal blooms
  • Food and water supply changes – decreased access to food, malnutrition, diarrheal disease
  • Environmental degradation – mental health impacts (e.g., climate anxiety), forced migration, loss of income (e.g., farmers losing crops)

For more information, visit the Climate Effects on Health webpage from the Centers for Disease Control and Prevention (CDC) and watch the video below.

There are some people who are more vulnerable to climate change effects depending on the specific climate event/impact. For information about these risks and vulnerabilities, go to the Health Canada webpage on who is most impacted by climate change. Find more information on some of these health effects below and what you can to do protect yourself.

As temperatures increase, summers become longer and winters become milder. The amount of precipitation (e.g., rain, sleet, snow) changes. These changes may allow certain living things like pathogens (cause disease) or vectors (spread disease) to:

  • Grow in number
  • Establish in new areas
  • Expand and shift in how far they reach

This puts you at greater risk of being exposed to new and established diseases that can impact our health. For example, there is evidence that the relatively recent emergence of Lyme disease in Canada has been driven by climate warming, making more of Canada suitable for the ticks that carry this and other diseases.

See the following resources for more information on climate change and infectious diseases:

Climate change causes more frequent and more extreme weather hazards that pose direct and indirect health risks. Examples of natural hazards whose frequency and intensity are influenced by climate change are:

  • Heat waves
  • Major floods
  • Wildfires
  • Coastal erosion
  • Droughts

These hazards can cause loss of life, injury, health problems, damage to property, social and economic disruption, or environmental degradation. Being prepared and knowing how to reduce your risk can help. See tips on our Emergency Preparedness webpage for how to prepare for different extreme weather events. For more information, see the following resources:

Extreme Heat and Cold Events

Severe Storms

  • Increase risk of injury, heat stroke, hypothermia, worsening of health conditions, mental health impacts, and loss of property.

Floods and Droughts

  • Increase risk of unsafe drinking water, waterborne diseases, injuries, mental health impacts, loss of property/infrastructure, and negative impacts on food systems/production.


  • Reduce air quality and increase risk of injury, respiratory issues, mental health impacts, and loss of property/infrastructure.

Erratic or Changing Weather Patterns

  • Increase risk of injuries (e.g., early melting of ice during winter makes lakes unsafe)

Climate change has widespread impacts for food systems globally and in Canada, with important health consequences. These climate change impacts touch all parts of food systems, including food production, processing, distribution, preparation, and consumption. Without adaptation, climate change will cause a negative impact on global food systems. Increasing temperatures, changes in precipitation (e.g., rain, snow, sleet) patterns, and changes in growing seasons may impact the types of crops that can be grown locally and create more favourable conditions for pests, invasive species, and plant diseases.  For more information, see the following resources:

Changes in climate are affecting air quality in Canada, and several air pollutants contribute to climate change. The negative health effects of outdoor air pollution are well-known. Air pollution can cause lung and heart symptoms and disease and is a leading environmental cause of death. For more information, see the following resources:

Climate change can be a stressor that negatively impacts a person’s mental health and well-being. Temporary climate change hazards such as extreme heat events, floods, and wildfires can cause mental health impacts because of the immediate effects these events can have on a person’s life. Trauma can affect people long-term if they fear extreme weather events will happen again. For some people, thinking about the longer-term impacts that climate change has on the planet and current and future generations can lead to ongoing stress, anxiety and depression. For more information, see the following resources:

Changes in temperature and precipitation (e.g., rain, sleet, snow) levels caused by climate change will impact water quality and amount. For example:

  • Flooding can cause physical and mental health injuries, property damage, and can impact the safety of well water if the floodwater gets into your well.
  • Recreational water, such as beaches, can become more likely to be impacted by harmful organisms such as blue-green algae.

For more information, see the following resources: