Blog Viewer

Extreme heat, fire, and flooding: how climate change can impact your patients

Examples you can expect to see in your practice, and tools and resources that can help

By Zachary Daly, Kaitlin Bloemberg, & Caroline Murphy
April 2, 2024
Through such events as extreme heat, floods, and wildfires, we are witnessing increases in the spread of disease, adverse effects on physical and mental health, and disruptions to our health-care system.

We are nurses, from varied backgrounds, who care deeply about the issue of climate change. As has been made clear in Health Canada’s recent report, Health of Canadians in a Changing Climate (2022), climate change, driven largely by human activities and greenhouse gas emissions, is already impacting the health of people living in Canada. Through such events as extreme heat, floods, and wildfires, we are witnessing increases in the spread of disease, adverse effects on physical and mental health, and disruptions to our health-care system (Berry & Schnitter, 2022).

Unfortunately, over time, negative health impacts are expected to increase, as the overall impacts of climate change escalate. Nurses, across various settings, will experience the consequences of these health impacts both first- and second-hand.

The Canadian Nurses Association (CNA), in their position statement Climate Change and Health, has stated that “the nursing profession plays an integral role in helping individuals, families and communities adapt to climate change” (CNA, 2017, p. 2).

However, a recent Canadian study found that some nurses do not see how climate change relates to their nursing practice, even though they view the issue as important (Kalogirou et al., 2020). This disconnection arises in conversations with colleagues. Thus, our goal is to provide concrete and specific examples of how climate change can arise in practice, as well as point to tools and sources of information that can help guide nurses’ response to climate change.

While this article is not intended to be comprehensive, we hope to demonstrate that climate change is a nursing issue and to provide a useful starting point for your own conversations with colleagues and patients about this topic.

This paper is organized around three types of events that are made more common and severe because of climate change, and which negatively impact human health and health service delivery: extreme heat events, wildfires, and floods. We then turn to a brief discussion on how you can become involved in climate change prevention and management.

Extreme heat events

One area through which climate change manifests in clinical practice is during extreme heat events, sometimes called heat waves, which are expected to become more common in Canada in future decades. During such events, there is an increase not only in deaths among patients and community members, but in exacerbations of health conditions. Depending on greenhouse gas emission levels, heat-related mortality is predicted to increase across Canada by approximately 155 to 390 per cent by 2080.

The health effects of extreme heat events, both in the short and long term, are extensive. People may experience such conditions as dehydration, heat exhaustion, and heat stroke. Extreme heat events are also associated with hospitalization and mortality due to cardiovascular disease, as well as with kidney- and diabetes-related complications.

As with many climate events, the individuals most affected by extreme heat events are those who are already considered more vulnerable because of various physical and socio-economic factors. Seniors are at particular risk (Berry & Schnitter, 2022).

Extreme heat can also interact with the medications patients take. A number of commonly used medications, including selective serotonin reuptake inhibitors (SSRIs), can interfere with an individual’s ability to regulate their temperature, potentially putting them at greater risk of overheating during an extreme heat event.

Other medications, such as anti-Alzheimer’s and anti-Parkinson’s drugs, diuretics, and anti-arrhythmics, may also require additional monitoring. Dehydration, which can occur during extreme heat events, can put individuals taking lithium at greater risk of toxicity (Health Canada, 2011).

But beyond the physical complications of exposure to extreme heat at the individual level, there is also the potential strain on the health-care system. As an example, analysis of historical data from Ontario found that extreme heat was associated with a 22 per cent increase in pediatric emergency room visits (Wilk et al., 2020).

A tragic and recent example of the dangers of extreme heat comes from the 2021 heat dome in British Columbia, which resulted in 619 deaths — many of them in neighbourhoods with higher levels of social or material deprivation (BC Coroners Service, 2022). Furthermore, there was a major impact on emergency services: data shows that at their peak, call volumes to 911 doubled, wait times to speak with a dispatcher and for first responders to attend increased, and in a small number of cases, callers were put on hold for extended periods of time or even told that no ambulance was available (BC Coroners Service, 2022).


Wildfires are also expected to increase in number and size across Canada due to increased temperatures, drought and dead trees, and lightning strikes brought on by climate change. While wildfires can result in direct injuries, such as burns, more widespread is the impact of smoke.

Wildfire smoke is a dangerous mix of substances such as nitrogen oxides, carbon monoxide, volatile organic compounds, and fine particulate matter (PM 2.5). Exposure to wildfire smoke is linked to all-cause mortality, alongside respiratory conditions including asthma and chronic obstructive pulmonary disease (COPD), as well as potentially exacerbating cardiovascular conditions.

Furthermore, experiencing wildfires has also been associated with generalized anxiety disorder. In Canada, seniors, children, those experiencing social inequities, and Indigenous populations have been identified as being at heightened risk of these varied health impacts (Berry & Schnitter, 2022).

As with extreme heat events, the health impacts of wildfires add to the strain facing the health-care system and can interfere with the delivery of services. Research from the Northwest Territories found a direct association between PM 2.5 concentrations and hospital admissions for COPD, as well as emergency room visits for pneumonia and asthma (Howard et al., 2020).

In one extreme example of how wildfires can impact the health-care system, Eggertson (2016) powerfully describes the work of nurses and doctors to evacuate patients from the emergency department at Northern Lights Regional Health Centre in Fort McMurray in 2016 due to an approaching wildfire. As the situation deteriorated, some patients had to be evacuated in nurses’ private vehicles, and medical staff were forced to set up a field hospital to triage and treat busloads of hospital patients.


Flood risk is expected to increase in parts of Canada, particularly urban areas, as a result of climate change-induced shifts in storm, precipitation, and snow-melt patterns. As with other climate change events, the health impacts of floods are wide-ranging.

Most immediately, floods can cause an increase in drownings, acute trauma, hypothermia, infections, and vector-borne diseases, as well as exposures to toxic chemicals, burns, and electrocutions.

Flooding can also be associated with damage to key infrastructure, such as water-treatment facilities, roads, and power production, which can in turn result in further impacts on health. Those most likely to experience these impacts include people with pre-existing conditions, those in rural areas, children, and adults over 65 (Berry & Schnitter, 2022).

Evacuations have additional consequences, such as stress and loss of access to important medications. Health system impacts can include the consequences of having to transfer patients to different hospitals, as occurred during flooding in 2017 in Montreal (Shingler et al., 2017).

Experiencing floods has also been associated with anxiety, depression, and post-traumatic stress disorder (PTSD). Research following the 2018 St. John River flood in New Brunswick, found that community members who had to evacuate or relocate experienced negative impacts to their mental health. Critically, many continued to experience heightened anxiety long after the flood waters had subsided (Woodhall-Melnik & Grogan, 2019).

Putting it all together

It is clear that climate change has impacted health and health-care delivery in Canada, and it will continue to do so. Climate change is, therefore, a nursing issue. So what can nurses do about it?

At the most immediate level, nurses can work to educate themselves, colleagues, and patients about the many ways in which climate change impacts human health. Fortunately, there are tools that can help guide nurses in assessing and responding to these impacts, such as the Nursing Toolkit for Planetary Health, which was co-developed by the Canadian Federation of Nurses Unions (CFNU) and the Canadian Association of Nurses for the Environment (CANE) (CFNU & CANE, 2023), as well as more specific resources such as A CLIMATE, a tool developed for assessing climate change-related health consequences in emergency departments (Nicholas et al., 2020).

Nurses can become involved in sustainability efforts, such as waste reduction initiatives, at their places of work. However, broader, more systemic action is also needed.

CNA is clear that “nurses need to promote climate change adaptation (that is, responding to the effects of climate change) and mitigation (taking action to reduce it)” (2017, p. 1), including by using our trusted collective voice and engaging with climate change and environmental policy-making at all levels of government. One way that nurses can do this is by becoming involved in organizations such as CANE, of which we are all members, and which has chapters across Canada.

Overall, nurses must increase awareness of how climate change impacts human health. We must be actively engaged in efforts to reduce harms to current and future generations. We are at a critical crossroads, and the time to act is now.


We would like to thank other members of CANE-BC for their helpful feedback, suggestions, and support in writing this article, including Megan Tomlinson, RN, Agnes Black, RN, MPH, and Helen Boyd, RN, MA.


Berry, P., & Schnitter, R. (Eds.). (2022). Health of Canadians in a Changing Climate: Advancing our Knowledge for Action. Ottawa, ON: Government of Canada.

British Columbia Coroners Service. (2022). Extreme Heat and Human Mortality: A Review of Heat-Related Deaths in B.C. in Summer 2021. British Columbia Coroners Service.

Canadian Federation of Nurses Unions [CFNU], Canadian Association of Nurses for the Environment [CANE]. (2023). Nursing Toolkit for Planetary Health.

Canadian Nurses Association [CNA]. (2017). Position Statement: Climate Change and Health.

Eggertson, L. (2016). Fort McMurray evacuates patients in “surreal” flight. Canadian Medical Association Journal, 188(9), E175–E178.

Health Canada. (2011). Extreme Heat Events Guidelines: Technical Guide for Health Care Workers. Water, Air and Climate Change Bureau, Healthy Environments and Consumer Safety Branch, Health Canada. Ottawa, Ontario, 149.

Howard, C., Rose, C., Dodd, W., Kohle, K., Scott, C., Scott, P., ... & Orbinski, J. (2021). SOS! Summer of Smoke: a retrospective cohort study examining the cardiorespiratory impacts of a severe and prolonged wildfire season in Canada’s high subarctic. BMJ Open, 11(2), e037029.

Kalogirou, M.R., Dahlke, S., Davidson, S., & Yamamoto, S. (2020). Nurses’ perspectives on climate change, health and nursing practice. Journal of Clinical Nursing, 29(23–24), 4759–4768.

Nicholas, P.K., Breakey, S., McKinnon, S., Eddy, E.Z., Fanuele, J., & Starodub, R. (2021). A CLIMATE: A Tool for Assessment of Climate-Change–Related Health Consequences in the Emergency Department. Journal of Emergency Nursing, 47(4), 532–542.

Shingler, B., Laframboise, K., & Neill, B. (2017, May 7). Montreal, Laval declare states of emergency over flooding. CBC.

Wilk, P., Gunz, A., Maltby, A., Ravichakaravarthy, T., Clemens, K.K., Lavigne, É., ... & Vicedo-Cabrera, A.M. (2021). Extreme heat and paediatric emergency department visits in Southwestern Ontario. Paediatrics & Child Health, 26(5), 305–309.

Woodhall-Melnik, J., & Grogan, C. (2019). Perceptions of mental health and wellbeing following residential displacement and damage from the 2018 St. John River Flood. International Journal of Environmental Research and Public Health, 16(21), 4174.

Kaitlin Bloemberg currently works in palliative care as a registered nurse and studied the impacts of extreme heat events during her MSN studies at the UBC School of Nursing.
Caroline Murphy is a retired family nurse practitioner with 31 years in nursing and 15 years as a family nurse practitioner, focusing on seniors health.
Zachary Daly is currently working on a PhD in nursing at the UBC School of Nursing, where he is studying the mental health impacts of climate change on youth; prior to that, his area of practice was in child and adolescent mental health.
The authors are all members of the Canadian Association of Nurses for the Environment (CANE), BC chapter, and its public awareness team subcommittee.