Mortality: Fewer cold-related deaths to offset expected rise in heat-related deaths

A new study from the Reinsurance Group of America (RGA) has found that climate change in Canada will likely drive minimal mortality increases between now and 2050, as decreases in cold-related mortality offset a projected rise in heat-related mortality.

Using a “middle of the road” emissions scenario, RGA says only a modest overall impact on temperature-related mortality is expected between now and mid-century. 

“In Ontario, each 5°C increase in summertime temperature between 1996 and 2010 was associated with a 2.5 per cent increase in mortality. Across 12 Canadian cities (2000–2020), extreme heat events increased daily mortality risk by 4.2 per cent for non-accidental deaths, 3.8 per cent for cardiovascular deaths and 11.7 per cent for respiratory deaths. Heat-related deaths have risen sharply, with two-thirds of heat-related deaths since 1981 occurring after 2016,” writes Hilary Henly, Global Medical Researcher, in RGA’s report, The impact of physical risks from climate change on future mortality in Canada.

“Cold historically accounts for a larger share of temperature-related mortality in Canada. Between 1985 and 2012, 4.46 per cent of deaths were attributed to cold exposure, compared to 0.54 per cent from heat. Warming winters are expected to reduce cold-related deaths. Studies suggest modest national-level net effects by 2050.” 

Wildfire-related particulate matter 

Air pollution-related mortality, meanwhile, is substantial (air pollution accounted for 6.1 per cent of total deaths in 2018; 0.5 per cent were from wildfire-related particulate matter). “But 2023 levels suggest this figure could be several times higher in future high-smoke years,” she writes. By 2050, wildfire-related air pollution “may represent up to half of all particulate exposure”. 

Drought, food insecurity and vector-borne diseases are expected to remain lesser concerns. The researcher also says flood-related mortality is historically quite low, under 0.3 per cent. “Localized coastal flooding risks may increase but national-level mortality impacts from sea level rise are expected to remain minimal by 2050,” Henly writes.

She adds that doubling the estimated effects of each physical risk to reflect uncertainty still results in an overall impact on mortality that researchers say is modest. Under the middle of the road scenario, she says the net increase in mortality from physical climate risk is projected to be approximately 0.8 per cent by 2050.   

“Although Canada clearly will be impacted by global warming and climate change, future mortality is projected to be less affected than for many countries,” she concludes. “Except for heat-related deaths, the data currently available on known risks does not indicate an increase in mortality due to climate change by 2050.”