Climate change is likely to add more than $100 billion a year to Canada's health-care costs by mid-century, says a report by a federally funded research group.
The Canadian Institute for Climate Choices says effects on health are likely to be heaviest among those who are already disadvantaged.
"Heat waves, air pollution — we see that those disproportionately impact people with certain health status and people who don't have the same resources as the average Canadian," said co-author Ryan Ness.
The report draws on some of the latest research to model how a less predictable climate with more extreme events could affect the health of Canadians. It looked at two cases: one in which little is done to curb greenhouse gas emissions and one in which global warming is kept under 2.5 degrees C.
Up until 2050, there is little difference between the two scenarios, Ness said.
The report considered air quality, new diseases and hotter temperatures.
"Those are all impacts we already know are happening. There is a clear connection to climate change and a good body of science on how people's health outcomes relate to those stresses," Ness said.
Air quality is the biggest factor.
Rising temperatures are linked with increased ground-level ozone, which helps create smog. Larger and more frequent wildfires also degrade air quality.
The report predicts the Canadian economy will lose $86 billion by 2050 due to illness and lost productivity due to those factors.
It also quotes research estimating that by mid-century, Ontario and Manitoba will experience about 75 days a year over the threshold at which heat-related deaths begin to occur. The report suggests hospitalizations due to hot weather will increase by at least 21 per cent.
Mental health is harder to quantify, said Ness.
"The effects of extreme weather on mental health and the subsequent economic and human toll is really not on the radar so far."
But he points to research done after the Fort McMurray, Alta., wildfire — a blaze scientists say was made more possible by climate change — that showed significant increases in depression, anxiety and substance abuse. Depression already costs Canada $34 billion a year, the report says.
Other effects on mental health — impaired outdoor recreation, the loss of habitats Indigenous people depend on — can't yet be quantified. That doesn't mean they're not important, Ness said.
"Those are things a dollar value can't be put on but must be considered."