Since the 1990s, heat waves caused by climate change have cost the global economy trillions of dollars. This is the conclusion of a study that correlated detailed economic data for regions worldwide with average and extreme temperatures in these regions. The countries most affected are those that have contributed the least to climate change. According to the researchers, the results raise questions about global equity and underscore the importance of investing in adaptation.
Man-made climate change is increasingly causing extreme weather events. Numerous studies have already shown that droughts, floods and storms cause serious economic damage, for example by destroying crops and destroying buildings. One of the most immediate effects of climate change are heat waves. According to studies, the temperatures on the hottest days of the year rise much faster and more strongly than the average temperatures. However, the economic damage caused by heat waves has so far not been studied sufficiently.
Great damage from heat waves
“Heat waves are one of the most direct and tangible effects of climate change that people feel, and yet they have not been fully factored into our assessments of climate change costs and future costs,” says Christopher Callahan of Dartmouth College in New Hampshire. To fill this gap, he and his colleague Justin Mankin combined economic data for regions around the world with information about heat waves. As a measure of heat intensity, they used the average temperature for the hottest five-day period of the year for each of the regions analyzed.
The result: Between 1992 and 2013, heat waves likely caused between $5 trillion and $29.3 trillion in economic damage worldwide. “Critically, warm tropical regions have both lower incomes and suffer most from rising extreme temperatures,” the authors write. “The losses amount to 6.7 percent of gross domestic product per capita per year for the lowest-income regions, but only 1.5 percent for the highest-income regions.”
Insufficient adjustment
The main reasons for the losses are the negative effects of high temperatures on human health and productivity, as well as on agriculture. “Our results show that modern-day humans are poorly adapted to extreme heat, even in regions that are used to heat,” Callahan and Mankin said. Technical adjustments in industrialized nations include, for example, the installation of air conditioning or other structural measures. In addition, most of the work takes place indoors anyway.
“In low-income regions, the adjustments are primarily behavioral,” the authors explain. “This includes resting in the shade, drinking more water and shifting to non-outdoor work when possible. However, there are physiological threshold values for extreme heat stress in humans and in agriculture that call into question the effectiveness of behavioral adaptations.” Investments in adaptation measures, including public cooling systems and expanded emergency care for the hottest days, are therefore particularly important in the regions that are particularly affected of the year. “The level of expenditure on adaptation measures should not only be assessed in terms of the price of these measures, but in comparison to the costs of doing nothing. Our research shows that doing nothing comes with a significant cost,” Callahan said.
Climate justice issues
From the authors’ point of view, the current study also raises questions of climate justice. Because the economic costs of extreme heat and the costs of necessary adaptation measures hit those countries that have contributed the least to climate change. Prosperous regions in Europe and North America, on the other hand, which are fueling climate change through their high greenhouse gas emissions, have so far only felt comparatively minor effects. Some very cool regions have so far even benefited slightly economically from global warming.
“We have a situation where the people who are causing global warming and extreme heat changes have more resources to withstand those changes. In some rare cases, they even benefit from it,” says Mankin. “Due to climate change, there is a massive international transfer of wealth from the poorest countries in the world to the richest countries in the world – and this transfer must be reversed.” support poorer ones to adapt to the changes caused by climate change.
“Global events like the Covid-19 pandemic have shown how closely intertwined the supply chain and the global economy are,” Mankin said. “In low-income countries, there is a disproportionate number of people working outdoors, which often produce the raw materials so vital to the global supply chain – there is definitely potential for upward spillovers.”
Source: Christopher Callahan (Dartmouth College, NH, USA) et al., Science Advances, doi: 10.1126/sciadv.add3726