Climate change is already reducing labor productivity. Researchers are now revealing the potential costs and exploring the best mitigation tactics.

As climate change continues to cause temperatures to rise around the world, employees working outdoors or with little access to air conditioning, are likely to suffer a significant hit to productivity, a problem that has received very little attention.

Large economic benefits could be gained if global temperature rise is limited to 2℃ through avoiding heat-related labor productivity loss.

“The impacts of lower-level heat on labor productivity can be imperceptible as it rarely causes direct physical harm,” explains Wenjia Cai, a professor in global change economics at Tsinghua University in Beijing, China. “While more extreme heat conditions are still considered an anomaly.”

The problem with lower-level heat is that many workers, such as manual construction or agricultural laborers, must slow down, or heat-related sicknesses and injuries increase, which also slows production.

Though necessary, this loss of productivity can be expensive. In China, for example, Cai and her colleagues estimated¹ that high heat cost the country US$33 billion due to labor productivity loss in 2021. That represented 1.4% of China’s total national work hours.

Climate change will only exacerbate this issue, says Cai. Her team have surmised from current literature² that by 2100 the impact of increased heat on worker productivity globally will be 0.31–2.6%.

The variation in these figures is partly due to the uncertainty of climate data projections, she explains, which can differ widely across climate models and scenarios. Despite this, “all scenarios in our study show that climate change would pose a significant threat to the world economy through reducing labor productivity,” says Cai.

The first hot spots

The effects on workers is more evident in regions that are being exposed to dangerously high ambient temperatures.

“South and South-east Asia, Sub-Saharan Africa, and Central America are located at low latitudes, nearer to the equator, and already experience high heat exposure, so even modest rises in temperature can push heat into a dangerous zone for laborers in these regions,” Cai says. In a recent study³ of 2,900 workers in India, Cai and her colleagues found that 84% of workers suffered from heat-related illnesses, such as heat cramps and heat stroke.

The socioeconomic situation of some regions also exacerbates this problem, she says, especially in areas that “rely heavily on agriculture and construction”. Due to poor economic development, workers in these regions may work in conditions that lack heat protection, such as shade coverings and air conditioning; affected workers may also find it harder to access public health systems; and, employers may lack the funds for adaptation technologies.

In extreme conditions, deaths due to heat stress are also not uncommon. High heat days can lead people to experience accelerated heart rates, vasodilation, water and electrolyte loss, and increased blood viscosity, ultimately resulting in a higher risk of death among patients with cardiovascular disease, for example. A 2022 meta-analysis by a different Chinese team suggested that non-accidental deaths increase by almost 20% during Chinese heatwave days due to heat stress complications.

Cai also points out that very hot days appear to be increasing in China. “In 2021, compared with the 1986–2005 average, people in China had an average of 7.85 (113%) more heatwave days.” Indeed, in 2022 China experienced the longest and hottest heatwave since national records began in 1961. In that same year, Cai and her colleagues published a paper suggesting⁴ that heatwaves could cause more than 20,000 deaths a year in China by 2090, even under the modest warming scenario of aiming for an only 2°C average global temperature rise by 2100.

Building resilience

One solution is better heat stress awareness and management by employers, Cai says. This is reflected in the Chinese government’s Administrative Measures on Heatstroke Prevention plan, which was released in 2012, and is designed to help address temperature-related productivity issues. In part, it requires employers to provide measures to protect their workers, including reducing intensity and cutting down working hours when outdoor temperatures reach 35°C, and indoor temperatures reach 33°C.

In a study of insurance claims before and after the plan was adopted, Cai and her colleagues showed⁵ that the plan has been effective — reducing heat-related injury claims by workers by 13% in Guangzhou in southern China across a two-year period. Nonetheless, she points out that the measures “often go ignored, especially by private companies employing large informal workforces with little incentive for compliance”.

Governments should also address rising temperatures through carbon mitigation, says Cai. Recently, one of her students, Mengzhen Zhao, led a study⁶ on labor productivity and carbon mitigation. “The results showed that by 2100 about 51.8% of global climate change mitigation costs could be offset by economic benefits from reduced labor productivity losses,” says Zhao. By including other benefits, such as cleaner air, the cost-benefit ratio is even better, she argues.

“Overall, framing climate change mitigation primarily as a burden or sacrifice ignores the vast opportunities and advantages of building more resilient societies and economies,” says Zhao.

Cai also pinpoints several other ways that governments can help build resilience against temperature related productivity losses. “Firstly, countries can establish a robust early warning system that provides alerts on impending heat risks. This can help protect vulnerable populations and facilitate coordination among relevant agencies and stakeholders,” she says.

“Secondly, strong occupational heat stress standards must be established and enforced — compliance incentives and monitoring are needed.”

Thirdly, Cai recommends adjusting work schedules and tasks during hot weather. “Options like shifting schedules earlier or later, and taking more frequent breaks can reduce heat risks,” she says.

Wenjia Cai is a professor in global change economics at Tsinghua University.

Further measures protect workers from the heat with air conditioning, fans, shades, or ventilation — or improve workers’ knowledge of how to stay safe through education and regular training on the risks of heat-related illness.

“Transitioning more global economies to greener, sustainable models can mitigate future heat risks,” adds Cai. “But the shift requires policy, technology, and financial adaptations at levels from individual businesses right up to industrial sectors and city governments.”

References

1. Cai, W., Zhang, C., Zhang, S., et al. The 2022 China report of the Lancet Countdown on health and climate change: leveraging climate actions for healthy ageing The Lancet Public Health 7(12), E1073–E1090 (2022)

2. Zhao, M., Lee, J., Kjellstrom, T., Cai, W. Assessment of the economic impact of heat-related labour productivity loss: a systematic review Climatic Change 22, 167 (2021)

3. Venugopal, V., Cai, W., Shanmugam, R., et al. Study to assess the impacts of heat stress on productivity losses in India Safety and Health at Work 13, supplement, 121 (2022)

4. Chen, H., Zhao, L., Cheng, L., et al. Projections of heatwave-attributable mortality under climate change and future population scenarios in China The Lancet Regional health-Western Pacific 28, 100582 (2022)

5. Su, Y., Cheng, L., Cai, W., et al. Evaluating the effectiveness of labor protection policy on occupational injuries caused by extreme heat in a large subtropical city of China Environmental Research 186, 109532 (2020)

6. Zhao, M., Huang, X., Kjellstrom, T., et al. Labour productivity and economic impacts of carbon mitigation: a modelling study and benefit-cost analysis The Lancet Planetary Health 6(12), E941–E948 (2022)

Editor: Guo Lili