Heat waves exacerbated by climate change have cost the global economy trillions of dollars in the past 30 years, a study published Friday showed, with poor countries paying the heaviest price.

Also, these unbalanced economic effects contribute to widening inequalities around the world, according to the study.

"The cost of extreme heat waves caused by climate change has so far been borne disproportionately by the countries and regions least responsible for climate warming," Justin Mankin, a professor at Dartmouth College and one of the authors of the study published in the journal Science Advances, told AFP. ".

"Climate change comes at a time when economic inequality prevails in the world, and it is exacerbating it," he added.

The study showed that periods of extreme heat waves between 1992 and 2013 cost the global economy about $16 trillion.

But while rich countries lost about 1.5 percent of their annual GDP per capita during their dealings with heat waves, poor countries lost about 6.7 percent of their annual GDP per capita.

The reason for this disparity is simple, because poor countries are often located near the tropics, which naturally makes their climates warmer. And during heat waves, it gets exceptionally hot.

This study was published a few days before the launch of the Climate Summit (COP27) in Sharm El Sheikh, Egypt, where it is expected that the issue of compensating the countries most vulnerable to the repercussions of climate change, although they are the least responsible for this phenomenon, is one of the main topics.

The costs incurred by heat waves come from several factors: the implications for agriculture, strained health systems, a less productive workforce, and damage to infrastructure, such as melting roads.

- 'Cost of inaction' -

The researchers involved in the study focused on the five hottest days each year in certain regions where extreme heat waves are considered an extreme weather phenomenon.

"The general idea is to look at differences in extreme temperatures (...) and see to what extent that is reflected in differences in economic growth" for each region, Mankin explained.

"Then, in the next step, we look at how human-caused climate change affects these extreme temperatures."

But the results of the study almost certainly underestimate the true cost of extreme heat waves, according to the research, as studying only five days a year does not reflect the increasing frequency of these climatic phenomena, nor are all potential costs included.

Previous studies on the topic have focused on the costs of heat waves in specific sectors, although scientists say it is important to research the costs of climate change comprehensively.

“You want to know what those costs are so that you have a frame of reference against which to compare the cost of moving and taking measures,” for example building cooling centers or installing air conditioners versus the “cost of inaction,” Mankin said.

"The economic gains from responding to the five hottest days of the year could be enormous," he added.

But Mankin noted that the most important response is to reduce greenhouse gas emissions to slow climate warming at the source.

"We must adapt to the climate in which we live now, and we must invest heavily to combat climate change," he concluded.
AFP