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The heat waves that are multiplying under the effect of global warming have a major human cost, with deaths in the thousands, but when the thermometer panics, the economy as a whole is also affected.
More frequent, intense and extended each year, heat waves are the deadliest extreme climatic events in the world. Rarely considered from an economic angle, they nevertheless have serious consequences, in terms of lives lost, pressure on the health system, but also a drop in productivity and impact on agriculture.
L’European Environment Agency (EEA) estimates that between 1980 and 2000 these extreme climatic events cost between 27 and 70 billion euros in 32 European countries. In France, according to a study published in 2021 by thenational public health agency Francethe heat waves from 2015 to 2020 cost between 22 and 37 billion euros due to the deaths, medical costs and loss of well-being caused.
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The health consequences
Heat waves are responsible for 9% of the approximately 2 million deaths attributed to weather disasters between 1970 and 2019 worldwide, the proportion having increased significantly over the past decade.
In Europe, heat waves account for around 90% of mortality linked to weather disasters between 1980 and 2020, according to theEuropean Environment Agency (EEA).
>> See also: “Heat wave: a very significant cost also for the economy”
And the trend is not going to improve. According to Météo-France, the heat waves recorded since 1947 on a national scale have been significantly more numerous in recent decades. Over the last 35 years, they have been 3 times more numerous than over the previous 35 years. The number of days of heat waves has been multiplied by 9.
Decline in labor productivity
In addition to the human costs, heat waves also have a productivity impact. Heat also reduces worker productivity.
At 33-34°C, an average worker “loses 50% of their working capacity”, according to theInternational Labor Organization (ILO). In 2030, heat could reduce total hours worked worldwide by 2.2%, the equivalent of 80 million full-time jobs, according to the organization. And at an estimated cost of $2.4 trillion in 2030, up from $280 billion in 1995.
The loss of productivity particularly affects outdoor workers, farmers or construction workers.
“Heat stress from climate change will reduce outdoor work capabilities globally,” insist UN climate experts (IPCC)estimating that some regions will lose between 200 and 250 days of outdoor work by the end of the century.
Thus, the remarkable heat waves of 2003, 2010, 2015, 2018 in Europe caused damage estimated at around 0.3 to 0.5% of European GDP, with peaks of more than 2% of GDP in certain southern regions, according to a study published in the Nature review in 2021.
And this impact could be multiplied by almost five by 2060 compared to 1981-2010 if measures are not taken to limit warming, warns the study.
The effects on agricultural production
Climate-sensitive, agriculture is also threatened by these heat waves. Heat waves and droughts are therefore major threats to food.
Drought has a direct effect on crops. And if a short period of high heat does not always cause major damage, it can reinforce the dryness of the soil, as is the case in France at the moment.
The 2019 heat wave in France had led to a yield drop of 9% in corn and around 10% in wheat compared to the five-year average, according to the French Ministry of Agriculture. Another example, in the United States, the 2012 heat wave led to a 13% drop in corn production, causing a rise in prices worldwide.
Heat waves also reduce the production of dairy cows and therefore the supply of milk. And the IPCC notes the impact of heat stress on the mortality and productivity of farm animals in general.
The question of the adaptation of the agricultural sector to heat waves, and more generally to exceptional climatic events, therefore remains.