According to the latest research that calculates the human costs of climate change, more than one-third of high-temperature deaths in the world each year are directly attributable to global warming.

But scientists say this is only a small part of the overall loss from climate change – more people die from other extreme weather that is exacerbated by global warming such as storms, floods, and droughts – and the number of deaths from high temperatures will increase exponentially as the temperature rises. increase.

According to a study published in the journal Nature Climate Change on Monday, dozens of researchers studied high temperature deaths in 732 cities around the world from 1991 to 2018, and calculated that 37% were high temperatures caused by man-made warming caused.

The lead author of the study said that this is equivalent to about 9,700 people from these cities each year, but the number is much higher globally.

“These high-temperature-related deaths are actually preventable. It is our direct cause,” said Ana Vicedo-Cabrera, an epidemiologist at the Institute of Social and Preventive Medicine at the University of Bern, Switzerland.

The highest proportion of high-temperature deaths caused by climate change are cities in South America.

Vicedo-Cabrera pointed out that Southern Europe and South Asia are other hot spots for high temperature deaths related to climate change.

Researchers have found that São Paulo, Brazil, has the highest number of deaths from high temperature related to climate, with an average of 239 people per year.

“Negative” health effects

Studies have found that about 35% of high-temperature deaths in the United States can be attributed to climate change. In approximately 200 cities in the United States, more than 1,100 people die each year, of which 141 people die in New York. Honolulu’s climate change caused the highest percentage of deaths from high temperatures, at 82%.

Scientists used decades of mortality data in 732 cities to draw a curve, detailing how each city’s mortality rate changes with temperature and how the heat-death curve varies from city to city. Vicedo-Cabrera said that due to air conditioning, cultural factors and environmental conditions, some cities are better able to adapt to high temperatures than others.

The researchers then compared the observed temperature with 10 computer models that simulate a world without climate change. The difference is caused by human warming.

By applying scientifically recognized techniques to individualized heat-death curves in 732 cities, scientists calculated the additional heat-death caused by climate change.

“People continue to demand proof that climate change has affected our health. This attribution study uses the most scientific epidemiological methods to directly answer this question, and the amount of data collected by the author for analysis is impressive,” University of Wisconsin Global Health Research Director Jonathan Patz said.

Patz was not involved in the study, and he said this is one of the first people to detail high temperature deaths related to climate change, not in the future.

“Climate change is not a distant future,” Antonio Gasparrini, senior author and professor of biostatistics and epidemiology at the London School of Hygiene and Tropical Medicine, told AFP.

“In addition to the known environmental and ecological impacts, we can already measure the negative health effects,” Gasparini said.

Scientists warn that fatal heat waves that may have occurred once in a century before climate change began may occur more frequently in the middle of this century.

The emerging field of attributable climate science measures the extent of global warming’s impact on typhoon intensity, drought duration, or storm surge damage, such as typhoon intensity, drought duration, or storm surge damage.

But Dan Mitchell, a researcher at the Cabot Institute of Environmental Studies at the University of Bristol, points out that very few studies have tried to do the same for human health.

“This shift in thinking is essential… so that global leaders can understand the risks,” he said in a commentary on Natural Climate Change.