Deadly heat waves could become a norm: a dire prediction for humanity has emerged

Extremely dangerous heat waves like the one observed on Earth in 2003 may become the new normal in the coming years. In some areas of our planet, they may recur every 2-5 years, leading to an increase in heat-related deaths.

This is according to a study published in Nature Communications. Hotter summers will lead to thousands of people dying.

The researchers recall that the heat wave of 2003 is a grim reminder of how devastating such events can be. Back then, temperatures in Europe jumped to 47.5 degrees Celsius and triggered a real disaster that killed between 45,000 and 70,000 people in just a few weeks.

In addition to the human toll, the heat wave also caused significant environmental damage: forests were engulfed in flames and crops in fields withered. Total financial damage is estimated to have reached 13 billion dollars.

And even though heat as a factor in mortality is not talked about too often, the risks have only increased over the past 20 years.

"Excessive mortality during a hot summer like 2003 was previously considered a once-in-a-century extreme event. Now we expect it to happen once every 10 to 20 years, or, in a world that has warmed by 2 degrees, every two to five years," said the study's lead author and doctoral student Samuel Lüthi.

Since 2013, researchers from the Institute for Environmental Solutions at the Zurich Swiss Graduate School of Technology, along with an international team of epidemiologists, collected data on daily excess heat-related deaths for 748 cities and communities in 47 countries in Europe, Southeast Asia, Latin America, the United States and Canada.

They calculated the relationship between average daily temperature and mortality for all 748 locations. This was used to establish the ideal temperature for each location at which excess mortality is lowest. In Bangkok, for example, this value is 30 degrees Celsius, 23 degrees Celsius in São Paulo, 21 degrees Celsius in Paris, and 18 degrees Celsius in Zurich.

At the same time, an increase in the ideal temperature by even a tenth of a degree increases excess mortality.

Regarding the difference between temperatures in cities, Luthi explained that "not all heat is the same" and much depends not only on temperature but also on physiology (acclimatization), behavior (long siestas in the middle of the day), urban layout (green space vs. concrete), population demographics and the local health care system

Using the ideal value, the researchers calculated how excess mortality would evolve with average global temperature increases of 0.7 degrees (value in 2000), 1.2 (value in 2020), 1.5 and 2 degrees.

The results show that the risk of heat waves with high excess mortality has increased dramatically over the past 20 years.

Heat mortality events that were considered unlikely in 2000 (once every 500 years) would occur 14 times every 100 years under a 2-degree temperature increase scenario. In the absence of heat adaptation, the probability of mortality during such extreme heat waves would increase by a factor of 69.

Regions particularly at risk of escalating heat waves include the Gulf and Atlantic coasts in the United States, the Pacific coast of Latin America, the Middle East, Southeast Asia and the Mediterranean region. Scientists have calculated that even under moderate climate scenarios, hot summers in these regions could result in 10 percent of all deaths in the country being heat-related.

Paris was particularly affected by the heat wave in 2003, when dehydration, heat stroke and heart attack killed 5-7% or about 2,700 people. But that figure will only rise in the future.

"We estimate that up to 15% of deaths in Paris could be heat-related in the future," Luthi said.

He explained that Europe (especially southern Europe) is one of the hot spots because two factors are at play here: temperatures are rising twice as fast as the global average and the population is aging disproportionately.

"The results scared me. While working on the study, I was always trying to look behind the numbers and see the real lives of the people affected by the changes. This is worrying," the climatologist emphasized.

At the same time, he admits that the study used conservative data on the growth of the average global temperature by a maximum of 1.5-2 degrees Celsius, but the reality suggests that the more likely figure is 2.6 degrees.

Earlier OBOZREVATEL spoke about whether humanity will be able to escape the "hellish" heat by moving to underground cities.

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