Extreme heat study a warning for Canada

A Canadian co-author of research that finds extreme heat risks from climate change in U.S. cities are much higher than previously thought says the study is also a warning for Canada.

Scott Krayenhoff of the University of Guelph says cities in southern Canada are likely to face similar dangers as places like New York, where extreme heat exposure is forecast to increase by 30 times by the end of the century.

Krayenhoff says the study, published this week, is the first to factor in climate change, city population growth and the warming effects of cities themselves.

He says that explains why his estimates of eventual heat exposure are many times higher than previous ones.

U.S. agencies say extreme heat already kills more Americans than any other weather event.

Krayenhoff says the worst effects are most likely to be in the U.S. sunbelt, but adds cities like Vancouver aren't that far from Seattle, where heat exposure is expected to increase by a factor of 10.