 is a Professor in the Department of Medicine at Ìý²¹²Ô»åÌý is Distinguished Research Professor, Emerita at .
As climate change and disrupted weather patterns impact countries around the world, leaders must act to mitigate the negative effects on public health.
Leaders from six western countries and Japan will soon gather in Kananaskis, Alta., for the Group of Seven (G7) meeting from June 15 to 17, 2025. In the lead-up to this meeting, the Royal Society of Canada hosted the Science 7 (S7). This is an engagement meeting of the leading academies of the G7 member countries.
Following discussion and deliberation, aimed at advancing science for society were published, entitled Advanced Technologies and Data Security, Sustainable Migration and Climate Action and Health Resilience.
One of us (Sharon Straus) oversaw the . This statement draws attention to the health impacts of climate change and recommends several mitigation strategies.
Wide-ranging health impacts
the growing impact of delayed climate action. The data are clear. Extreme weather events such as heat, floods, droughts and wildfires are having wide-ranging health impacts.
In the 10 years between 2014-2023, there was a 167 per cent increase in heat-related deaths in those aged 65 years and older compared with the 10 years between 1990-99. Extreme weather events also directly impact food and water security, as well as infectious diseases and chronic diseases.
The health consequences of climate change are not only the result of environmental factors. Of equal importance are recent decisions eliminating funding for programs that mitigate the risks of climate change.
Consider for example, the multiple threats to recent progress in eliminating malaria. The published in December 2024 by the World Health Organization estimated that 2.2 billion malaria cases and 12.7 million malaria deaths were averted between 2000 and 2023.
Now, many countries anticipate a . Antimalarial drug resistance, mosquito resistance to insecticides, changes in temperature and humidity affecting mosquito survival and the emergence of new mosquito species — combined with the recent from the — are leading to a perfect storm.
Economic impact of climate change
The economic burden of climate change, which includes more health-care use, lost productivity, adaptation and mitigation expenses — to say nothing of the costs of rebuilding — is massive.
Much of that burden is borne by those who live in low- and middle-income countries (80 per cent of the world’s population) and who are the lowest contributors to .
To put this in perspective, in 2021, the estimated the costs of annual adaptation for vulnerable countries at US$70 billion and predicted this would increase to US$140-300 billion by 2030.
In addition to the costs of adaptation aimed at reducing vulnerability to climate change, there are the costs associated with losses resulting from climate change. The 2024 estimated that the average annual economic losses due to extreme weather-related events reached US$227 billion between 2019-2023. This value exceeds the gross domestic product of approximately 60 per cent of the world’s economies.
What about Canada?
In Canada, warming is happening with resulting heat, wildfires and floods. There is also evidence of significant impacts on and , leading to an increased need for health care.
Indigenous communities, older adults and those who have experienced homelessness are disproportionately impacted by climate change. , especially those living in remote and northern areas, are particularly vulnerable.
Currently there are and drinking water advisories in First Nations communities across Canada. The lack of safe, clean drinking water can exacerbate climate-related food and water insecurity and lead to infectious disease transmission.
The is growing and many of these . These older adults are and are at .
Similarly, frail older adults are at . It is worth remembering the during the COVID-19 pandemic on those living in long-term care homes.
Climate change costs health-care systems more each year. The recently estimated that health-related hospitalizations will increase by 21 per cent by mid-century. Our health systems are not prepared for this.
In addition, the costs of death and reduced quality of life from heat-related climate change is estimated to rise between $3 billion and $3.9 billion by the middle of this century. Factoring in other impacts such as those from air pollution, flooding and wildfires, the total estimated costs are in the tens to hundreds of billions.
S7’s recommendations
The S7 statement on Climate Action and Health Resilience includes seven recommendations. Addressing the disproportionate impact of climate change on populations who are particularly vulnerable and investing in innovative solutions are among them. Particularly critical are societal and political innovations that involve affected communities, including Indigenous communities.
The S7’s climate and health resilience recommendations include:
Developing and optimizing climate change mitigation strategies to transform health and social services (such as early warning infectious disease systems and biomonitoring).
Developing new regulations nationally and internationally to transform health, public health and social services, increasing their readiness and safeguarding health from climate change impact.
Providing economic and regulatory incentives to foster adaptation and resiliency of health systems.
Investing in innovative solutions (including vaccine development for emerging diseases, wastewater surveillance) to mitigate climate change and its health risks.
The G7 summit is an opportunity to centre climate change discussions and act on the S7 recommendations. Bold investment in innovations that address the health challenges resulting from climate change will benefit us all and and resilience.
Climate change is a health issue, a social justice issue and an economic issue, and the time to act is now. Scientists, policymakers, clinicians and the public must work together.
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