Climate Change and Health

Did you know your health will be affected?
Health Overview

We often think about climate change as something abstract or remote. We hear scientists talking about melting ice caps, see images of drought in faraway places, or browse through news coverage of exotic weather disasters.

But climate change is having effects right here and right now in Canada. And the risks aren’t just theoretical or abstract. The effects of climate change promise to be up close and personal, affecting the everyday lives and health of Canadians. As Jeff Eyamie of Health Canada says, “The most immediate and personal impact of climate change is the health impact.”

Physicians and other health experts have long been aware that environmental and climate conditions affect human health, and are very concerned about the many ways climate change will impact our physical and mental well-being. Kim Perrotta, of the Canadian Association of Physicians for the Environment, bluntly describes climate change as “the biggest public health challenge of this century." [1]

"We often talk about the indicators of health,” says Perrotta. “Things like housing, air quality, water quality, income, and education have a much greater impact on human health than does access to health care. Climate change impacts all of those things." Along similar lines, Eyamie warns that “the evidence suggests that people are going to lose years from their lives because of the health impacts from climate change-affected hazards.”

The health risks affected by climate change involve all aspects of our lives. They include the direct threat of rising temperatures, but also increased problems with air quality, worsening and emerging disease risks, and challenges to our mental, emotional, and community health.

Heat waves

In 2018, Canadians in southern Ontario and Quebec experienced a massive heat wave that lasted nearly a week. If you were in that area, you probably remember hiding inside air-conditioned buildings for comfort and safety. In Quebec, that heat wave left dozens of people dead, and their families and friends in mourning. [2]

There’s no doubt that with climate change we’re going to see more heat waves. Even temperate coastal cities such as Vancouver are preparing for extreme heat impacts. Worryingly, these future heat waves are projected to last much longer than the ones we’ve experienced in the recent past.

See our article “Extreme Heat and Health” and our special report Heat Waves and Health for more on the risks of heat in a changing climate.

Air quality

Heat waves weren’t the only climate change-related health impact that made headlines in Canada in 2018. British Columbia was ablaze yet again with record-breaking wildfires, the smoky air causing serious air quality problems across Western Canada, and whole communities facing mental health effects from sudden evacuations.

Kim Perrotta notes that research shows that poor air quality has a wide range of health risks: “Certainly from a short-term health impact, it could put people in the hospital, it could aggravate asthma, it's going to aggravate heart conditions. It could lead to premature deaths, but probably there's long-term health impacts from it too.”

As climate change continues to intensify, Canadians may be exposed to decreasing air quality, and it’s important that individuals and communities are prepared. See our article “Climate Change, Air Quality, and Public Health” for more on the connections between climate change and air quality.


Canadians might be surprised to hear that climate change can also increase the spread of certain types of infectious disease. Infectious diseases are caused by bacteria, viruses, or parasites that are spread through food, water, or animal and insect “vectors” such as mosquitoes and ticks. Impacts of climate change, such as increases in temperature, precipitation, floods, and droughts, are changing the range and spread of these diseases.

Dr. Jean Zigby, a family physician and palliative care specialist, notes that “the spread of infectious disease is occurring further and further north, and so we're seeing the reemergence of a lot of infections which previously were held back thanks to our periodic cold weather."

Two vector-borne infectious diseases which are increasingly impacting Canadians under climate change are Lyme disease and West Nile Virus. For example, warming temperatures across central and eastern Canada have played a role in the establishment of blacklegged ticks, which can transmit Lyme disease. The reported cases of Lyme disease in Canada have already increased from about 150 in 2009 to almost 1,500 in 2017 [3], and it is predicted that by 2020 most Canadians will live in areas with Lyme-infected ticks.

Theresa Tam, the Chief Public Health Officer of Canada, describes infectious diseases as “one of the most important” emerging public health issues in Canada. Her team at the Public Health Agency of Canada (PHAC) is exploring the complex ways that climate is impacting the spread of these diseases in order to protect Canadians.

“Temperatures and precipitation not only increase the range and spread of [insect] vectors, they speed up the life cycle,” explains Tam. “Not only the life cycle of say the tick or the mosquito, but also how fast the pathogen inside the vector spreads and multiplies. And then the interface within human exposure to that vector, are all affected by climate change.”

Experts are preparing not only for the direct impacts of these increasing diseases, but the other potential climate changes which may affect the ability of our health infrastructure and systems to adapt and control these illnesses. [4]

Mental health

Extreme heat, wildfire smoke, worsened smog and air quality, new diseases: these health impacts are all expected to worsen with climate change. We’re also likely to see changes to food and water quality and quantity, more extreme weather events like storms, slow-onset events like drought, and more, all of which pose threats to safety and health. [5] And all of these physical threats bring social and mental health risks with them as well.

Above and beyond the mental health effects of physical threats such as disease and heat waves, the fact that climate change is transforming the environmental conditions of life takes a psychological and emotional toll. Dr. Jean Zigby says that climate change "affects us enormously psychologically. Climate change tends to make us much more fragile emotionally." He notes that “we have to deal with the chronic anxiety of our youth now, understanding the fact that their world is going to change very dramatically and not likely for the better unless a very serious stance is taken by our government and by our communities"

Community health

The health risks of climate change aren’t just individual. Dr. Jean Zigby points out that “climate change causes an enormous amount of stress on the whole community. It causes an erosion of infrastructure so people have a harder time getting around. It makes it harder for us to produce food."

We all rely on key resources that will be stressed and threatened by climate change. These include communications, transportation, food and health systems. The impacts of climate change mean these key shared community resources will likely have less capacity to support us, even as they face increased demands thanks to climate change.

More generally, environmental stress can cause social problems, unrest, and violence. Zigby says, "we know that, historically when places become drier and food becomes more scarce, conflict is much more likely to occur. We know as well that hotter communities tend to have more crime and that people tend to be less patient with each other. And so it's important to realize that we're facing challenges on an emotional, on a social level, as well as on a biological level.”

Take Action

Promoting healthy communities and personal well-being in the 21st century means coming to terms with the health impacts of climate change.

Fortunately, many Canadian communities are taking steps to manage these new risks. And in the process, they’re rethinking our relationship with the planet and building healthier, stronger communities.

Kim Perrotta emphasizes that when we take action to reduce the health risks of climate change, there can be huge financial and wellness benefits above and beyond reducing climate risk. She says, "There can be immediate and very significant health benefits for all of us when we take action to fight climate change. Many climate solutions actually provide immediate health co-benefits for the jurisdiction that takes action. By investing in public transit and active modes of transportation, for example, we can increase levels of physical activity and decrease air pollution, which will in turn reduce chronic diseases and acute health impacts; health issues that cost Canadians hundreds of billions of dollars each year. ”

Dr. Zigby agrees, saying that “Reducing our greenhouse gas emissions also are likely to improve air quality, and it's likely to improve people's ability to get adequate exercise. What we're seeing is that the solutions to climate change are actually the same solutions that we need to continue bolstering the determinants of our health."

Here are just a few ways that acting on climate change can benefit our health:

  • Renewable energy, such as solar or wind power, is a clean way to get the power that runs our communities. Scaling up renewables means less water pollution and air pollution that harms us, not to mention less reliance on fossil fuels that cause pollution in the first place.
  • Greening our cities through parks, trees, and urban agriculture encourages physical activity and healthy local food, while making beautiful places to live in. Smart landscape and city design can help us manage the effects of extreme heat, reduce damage from extreme events such as floods, and more.
  • Developing public and active transportation helps keep people healthy and safe. It also reduces reliance on fossil fuel-based transportation like cars.
  • Investing in climate-related health research and stronger health systems helps us adapt to climate change. It means that health professionals and their patients have the resources they need to deal with challenges now and in the future.

We can take action as individuals, say making climate-friendly consumer choices and making lifestyle changes that promote health and well-being. But the most wide-reaching and effective changes require larger-scale shifts of policy and legislation. Perrotta notes that "if we want to have people cycling and walking, then we need to have safe cycling infrastructure. We need to make space for it on our roads.” So our individual responsibility to take climate action includes demanding collective action on the part of our business and political leaders.

The health risks of climate change can sound intimidating and worrying, but there are creative, innovative strategies that can promote healthy and sustainable communities and help respond to the challenge of climate change. Taking climate action seriously means building more sustainable, pleasant, thriving communities. And taking an energy-efficient and climate-friendly approach to building and living in our communities will have important health benefits above and beyond helping with climate change.

“The technologies are out there, the solutions are out there, the policies are out there,” says Perrotta. “What's missing is the political will, and in order to get the political will we need the public to understand how urgent it is that we transform our economies and our communities, and how wonderful it can be once we do that."


  1. The Lancet Countdown on health and climate change: from 25 years of inaction to a global transformation for public health.
  2. Benjamin Shingler, “After Heat Wave Deaths, Mourning Quebec Families Wonder What Could Have Been Done Differently,” CBC News, July 11, 2018.
  3."Climate change means more disease, deaths for Canadians, Lancet report finds," Global News, November 28, 2018.
  4. Ogden, N. H. (2017). Climate change and vector-borne diseases of public health significance. FEMS microbiology letters, 364(19), fnx186.
  5. Jacinthe Seguin (Ed.). Human Health in a Changing Climate: A Canadian Assessment of Vulnerabilities and Adaptive Capacity. Health Canada, 2008.
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