Climate change and public health fact sheets

Climate Change and Public Health

What is climate change?

Climate change refers to any significant long term change in current normal climate conditions, such as temperature, precipitation, extreme weather events, snow cover and sea level rise. There is a clear scientific consensus that the world's climate is changing, largely as a result of human activities, and that this will bring about changes in weather conditions and other natural systems. Although the specific impacts will vary depending on the region of Canada in which you live, in general climate change is anticipated to result in generally warmer temperatures, shorter and milder winters, longer and hotter summers, more frequent and/or more intense severe weather events such as hurricanes, thunderstorms, wildfires, floods and droughts.

Canadians are accustomed to accounting for weather and changes in weather in their day-to-day lives. However, climate change would present new health concerns for most Canadians.

Where is climate change happening in Canada?

Climate change will impact all areas of the country. The nature and the extent will vary across Canada and some of the key projected changes by region are:


  • Dramatically higher temperatures
  • Increased precipitation
  • Loss of permafrost and sea ice

West Coast

  • Higher temperatures
  • Sea level rise, coastal flooding
  • Increased snow, glacier retreat
  • More severe spring floods
  • More frequent and intense summer drought


  • Hotter and drier weather conditions
  • Increased severity and length of droughts
  • Greater frequency of flooding
  • Warmer winters

Quebec and Ontario

  • Hotter summers
  • Warmer winters with less snow
  • More storms and heavy rain events


  • Rising sea-level
  • Greater risk of flooding
  • Coastal erosion
  • More intense storms

What are the health risks associated with climate change?

Weather and climate can have direct impacts on our health and can cause, for example, hypothermia in cold weather; heat stress on hotter days; and injuries or loss of life from severe weather (e.g. floods). They can also indirectly impact health through, for example, water contamination after intense rainfall, cardio-respiratory problems from smog, and increased risks from food-borne and vector-borne diseases during hot weather.

Direct and indirect health impacts could be worsened with climate change. For example, it is anticipated that many larger Canadian cities would experience a significant rise in the number of smog days and longer heat waves. This could increase heat related illnesses and deaths, especially in those most vulnerable to heat, such as the elderly.

Climate change can impact health in the following ways:

Infectious Diseases

  • Changes in precipitation and temperature could increase the amount of water-borne and food-borne diseases and diseases transmitted through insects (also known as vector-borne diseases).
  • Changes in climate can lengthen the transmission seasons of certain vector-borne diseases and expand their geographic range.
  • More variable precipitation patterns can increase the risk of water-borne diseases. In Canada it has been shown that there is an increased risk of having a water-borne disease outbreak with higher precipitation.

Extreme Weather Events

  • Climate change could increase the frequency, timing, intensity and duration of many extreme weather events such as severe storms, floods, hurricanes, wildfires and droughts.
  • Extreme weather events can cause a range of direct and indirect health effects, from mental disorders to infectious diseases.
  • Hurricanes and forest fires are also recurring natural disasters that raise important health risks for Canadians and may worsen as the result of a changing climate.

Higher Temperatures

  • Heat causes heat stroke, heat syncope (fainting) and heat cramps, and can worsen many pre-existing conditions such as cardiovascular and respiratory diseases.
  • Extreme heat can also increase the levels of pollen and allergens that trigger asthma attacks.

Air Quality

  • Poor air quality is already a serious public health issue in Canada and expected to become an even greater burden as climate change continues.
  • Heart disease, respiratory disease and allergies are some of the major health issues related to air pollution.

Who will be most affected by climate change?

Climate change impacts on health will disproportionately affect vulnerable populations, including the poor, elderly, and the young and those who are chronically ill. Also included are the socially disadvantaged and people living in vulnerable geographical areas (e.g. North).

How can I protect myself?

  • You can take several steps to protect yourself and your family from weather-related events and the risks posed by climate change, such as:
  • Visit the Get Prepared website for useful advice on how to put together an emergency kit and make a family evacuation plan.
  • Learn more about the disease threats in your area (e.g. Lyme disease, West Nile virus): consult your local public health office for more information.
  • If there are mosquitoes or other biting insects where you live, wear long-sleeved clothing and use insect repellent.
  • During a heat wave, wear light, loose-fitting clothes; drink plenty of water; and stay in the shade or air-conditioned places such as your home, office, library or local shopping centre.
  • Check the Air Quality Health Index and limit outdoor activity during poor air quality days, as recommended.
  • If you have a medical condition and are concerned about your health, discuss this with your doctor or health care professional.
  • Wash fruit and vegetables before you eat them to remove bacteria, pesticides and other organisms.
  • Visit your local public health website for up-to-date information on climate change and health in your region.
  • Be prepared - people with heart or lung problems should make sure they have enough medications and relievers on hand in case of emergency.
  • Talk to a family doctor or health care professional if you have concerns about your health or health of a family member.

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