Hot weather can kill a lot of people.
That was the conclusion in a 2020 study led by a University of British Columbia environmental epidemiologist Kate Weinberger, who studies the links between climate change and human health.
She and four other researchers looked at 297 U.S. counties representing 61.9 percent of the American population in 2000.
They estimated that an average of 5,608 deaths each year from 1997 to 2006 could be attributed to heat.
“Our results suggest that the number of deaths related to heat in the United States is substantially larger than previously reported,” the researchers wrote in the journal Environmental Epidemiology.
Back in 2017, Environmental Health Perspectives published a study by four researchers who examined heat-related mortality risk in Vancouver.
They relied on maps of “urban heat islands” in the city where the humidex index exceeded 34.4 C.
From the Vital Statistics Agency database, they examined records of all deaths with an extremely hot day compared to a control day from 1998 to 2014.
They paid attention to neighbourhoods that tend to get hotter and where people tend to be poorer, such as the Downtown Eastside.
The researchers concluded that the risk of death was higher in neighbourhoods lacking trees and with more concrete, and where there were higher numbers of people who were unemployed or retired.
These "pockets of risk" were not only in the Downtown Eastside, but also in parts of Abbotsford, Surrey, New Westminster, and other areas.
One of the authors, UBC School of Population associate professor and B.C. Centre for Disease Control senior research scientist Sarah Henderson, pointed out in a 2017 UBC news release that the frequency and intensity of hot-weather events is increasing as a result of climate change.
“In one week in 2009, 110 people died simply because it was hot outside,” Henderson said.
In the recent heat wave, temperatures have shot up well above 34.4 C in Vancouver, exceeding those recorded in 2009.
“Although these temperatures are not hot by international standards, the 40% increase in mortality indicated that greater Vancouver was adversely affected by ambient temperatures that were high relative to seasonal norms,” Henderson and the other researchers wrote, citing a 2012 paper that she coauthored in the American Journal of Public Health.
Meanwhile, the Museum of Vancouver is drawing attention to the effect of hot temperatures in its current exhibit, That Which Sustains Us. It features a heat-island map of the city.
It shows that two of the hottest areas are in the Downtown Eastside and along the Fraser River, where the tree canopy was removed many years ago.
Areas of the prosperous West Side of Vancouver, on the other hand, are some of the coolest parts of the city because there are so many trees, according to this heat-island map.
“The hottest parts of the city are places where the death rate goes up in the summer because it’s so hot,” Museum of Vancouver curator Sharon Fortney told the Straight in a recent interview.
Another study published in the journal Geohealth in 2020 also highlighted how exposure to “high ambient temperatures is an important cause of avoidable, premature death that may become more prevalent under climate change”.
In this instance, the researchers evaluated “the relative risk of premature death associated with temperature in 10 U.S. cities spanning a wide range of climate conditions”.
They noted that during the last decade, there were between 7,400 and 16,500 premature deaths each year in the contiguous United States.
They anticipated that this annual number would rise to 60,000 to 134,000 in the contiguous U.S. by 2100 under the Intergovernmental Panel on Climate Change’s “high-warming pathway” for the 21st century, which was outlined in its 2014 report.
Under the IPCC's moderate-warming pathway, the researchers forecast that there would be 22,000 to 50,000 annual premature deaths in these 10 U.S. cities by 2100.
“The results suggest that the degree of climate change mitigation will have important health impacts on Americans,” the researchers wrote.
They cited other papers showing that temperature and mortality are not only linked during extreme heat waves, but also to moderately hot weather.