According to the latest study to calculate the human cost of climate change, more than a third of the world's heat deaths each year are directly attributable to global warming.
But scientists say it's only part of the climate's total toll – even more people die from other extreme weather that is exacerbated by global warming such as hurricanes, floods and droughts – and from warming with rising temperatures. The number of deaths will increase rapidly.
Dozens of researchers who looked at heat deaths in 732 cities around the world from 1991 to 2018 calculated that 37 percent of human-caused warming resulted from higher temperatures, according to a study Monday in the journal Nature Climate Change. There were reasons.
The study's lead author said that number is only about 9,700 people from those cities, but it is far higher worldwide.
“These are heat-related deaths that are really preventable. This is something we do directly,” said Ana Vicedo-Cabrera, an epidemiologist at the Institute for Social and Preventive Medicine at the University of Bern in Switzerland.
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Cities in South America had the highest percentage of heat deaths due to climate change. Vicedo-Cabrera pointed to southern Europe and southern Asia as other hot spots for climate change-related heat deaths.
The researchers found that So Paulo, Brazil, has the most climate-related heat-related deaths, an average of 239 per year.
The study found that about 35 percent of heat deaths in the United States can be attributed to climate change. That's a total of more than 1,100 deaths a year in nearly 200 US cities, up from 141 in New York. Honolulu had the highest share of heat deaths at 82 percent due to climate change.
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The scientists used decade-long mortality data across 732 cities to plot curves to show how each city's death rate varies with temperature and how heat-death curves varied from city to city. Some cities adapt to heat better than others because of air conditioning, cultural factors and environmental conditions, Vicedo-Cabrera said.
The researchers then observed the temperatures and compared them to 10 computer models that simulate a world without climate change. The difference is heating up due to humans. By applying that scientifically accepted technique to individual heat-death curves for 732 cities, the scientists calculated additional heat-death deaths from climate change.
"People keep asking for evidence that climate change is already affecting our health. This attribution study directly answers that question using the epidemiological methods of science," said Dr. Jonathan Patz, director of the Global Health Institute at the University of Wisconsin. answers, and the amount of data the authors gathered for analysis is impressive." .
Patz, who was not part of the study, said it was the first to detail heat deaths related to climate change, not the future.