(Washington) Heat waves, intensified by climate change, have a cost that runs into the trillions of dollars for the world, but their economic impact is much greater for the poorest countries, reinforcing inequality, calculated a new study on Friday.
Posted yesterday at 4:47 p.m.
“The cost of extreme heat has been borne disproportionately by the countries and regions least responsible for global warming, and it’s a tragedy,” Justin Mankin, a professor at Dartmouth College, told AFP. one of the two authors of this study published in the journal Science Advances.
“Climate change occurs in a landscape of economic inequalities, and works by amplifying them,” he added.
Between 1992 and 2013, extreme heat events cost the global economy an estimated $16 trillion, according to this study.
But while in the richest countries the losses were equivalent to 1.5% of annual GDP per capita, for the poorest countries the cost was 6.7%.
The reason for this difference is simple: the poorest countries are for many those located in the tropics, therefore having a warmer climate. Thus, during a heat wave, temperatures become exceptionally high.
These results resonate strongly almost a week before the opening of COP27. The question of compensation claimed by the most vulnerable countries, disproportionately affected although least responsible for climate change, should be one of the key points of debate there.
Conservative estimate
The costs caused by heat waves come from multiple sectors: first of all agriculture, with for example less abundant harvests intended for export. Health problems also put a strain on the health care system, and excess mortality deprives labor. Outdoor workers, such as in the construction industry, are less productive. Infrastructure, such as roads or rails, can sometimes even melt, and block transport.
For their calculations, the researchers focused on the five days of extreme heat each year. They conducted their study at the regional level, heat waves being localized events.
“The general idea is to look at extreme heat variations, […] and to see to what extent this is reflected in the variations in economic growth” of each region, explained Justin Mankin. “Then, in a second step, we look at how climate change caused by humans has influenced these extreme heats”, based on international models.
The results obtained are certainly underestimated, according to the study.
First, because the chosen measure of the five days of extreme heat per year does not reflect the increased frequency of these waves, or their duration. In addition, other costs, such as those of fires made more favorable, are not taken into account.
But already, “the fact that the economic consequences of extreme heat alone are so great should make us all think,” says the researcher.
“Costs of inaction”
Previous studies on the cost of heat waves have mainly focused on certain sectors.
However, calculating the overall economic impact is essential, according to scientists.
“You need to know what the costs are, so you have a frame of reference against which to compare the cost of action,” explains Justin Mankin.
For example: the establishment of “cool places”, alert systems, reinforced emergency services, the installation of air conditioners… Temporary and targeted solutions for these heat waves could prove to be very profitable, according to the ‘study.
“These five hottest days, these 2% of the year, have a very significant effect on economic production,” says Justin Mankin. So “the economic dividends of responding to these five hottest days could turn out to be high. »
But beyond adapting to this new climate, “we must also invest enormously” to combat climate change itself, he underlines, first and foremost through the reduction of greenhouse gas emissions.
And this in order not to see the “costs of inaction” explode even more.