Climate Change Impact of Heat Stress on Labor Productivity and Decent Work

Sévane Ananian is a research specialist at the International Labour Organization (ILO). This thought piece was written for the 2023 Perry World House Global Shifts Colloquium, “Living with Extreme Heat: Our Shared Future,” and draws on on a 2019 ILO report by Tahmina Karimova, Tord Kjelltrom, Nicolas Maitre, Matthias Otto, and Catherine Saget,“Working on a warmer planet: The effect of heat stress on productivity and decent work.”  The colloquium was made possible in part by a grant from Carnegie Corporation of New York.

Heat stress is projected to reduce total working hours worldwide by 2.2 percent

Excessive heat is an occupational and safety hazard. Above a certain threshold of heat, the body’s internal regulation mechanisms are not able to maintain body temperature at a level required for normal functioning. This entails increased risks of discomfort, physical functions limitations, and eventually injuries and heat-related illness. Body temperatures higher than 38°C impair physical and cognitive functions, while the risk of organ damage, loss of consciousness, and ultimately death increase sharply when body temperatures rise above 40.6°C. For workers, exposure to extreme heat can cause occupational illnesses, increase risk of injury, and lower productivity through natural defense mechanisms such as slowing down, taking more frequent and longer breaks, or limiting working hours. For economies, it threatens their productivity.

Assuming a pathway toward a 1.5°C rise in global temperatures by the end of the 21st century, the ILO projected that 2.2 percent of total working hours will be lost to high temperatures globally in 2030 - a productivity loss equivalent to 80 million full-time jobs. However, since it posits that work is carried out in the shade, this estimate is conservative. If instead, work is carried out in the sun, the projected loss of working hours worldwide goes up to 3.8 percent, or 136 million full-time jobs. With the increase of temperatures beyond 2030, it is expected that climate warming will reduce labor productivity even further.

Agricultural and construction workers are expected to be the worst affected

Increased heat is felt differently across occupations and industries. Physically demanding jobs and those that involve prolonged work outside are particularly impacted by high levels of heat. In this framework, agricultural and construction workers are expected to be the worst affected. According to ILO estimates, these two sectors of activities will account for 60 percent and 19 percent of the working hours lost to heat stress in 2030, respectively.

Further increases in temperature will make agriculture unproductive in some areas, displacing many workers. Other employment sectors are projected to account for an increasing number of working hours lost to heat stress, in part because the share of these industries in total employment is expected to rise in some countries. This is especially the case for construction, which represented only 6 percent of the total hours lost in 1995.

In Southern Asia and Western Africa, the number of working hours lost to heat stress will be particularly high

Projections show that Southern Asia and Western Africa could be the regions worst affected by heat stress. Heat stress is expected to lead to the loss of approximately 5 percent of working hours in these two subregions in 2030, corresponding to approximately 43 million and 9 million full time jobs, respectively. Other regions such as Southeast Asia and Central Africa are also expected to experience a reduction in working hours above the global average. Indeed, in areas located in tropical and subtropical latitudes, the combination of extreme temperature and large shares of total employment in agriculture make heat stress a substantial risk. The European subregions should experience a smaller impact, with an estimated loss in working hours below 0.1 percent. Specifically, most of the working hours lost in Western, Northern, and Southern Europe are expected to be in the construction sector, a pattern also anticipated for North America and the Arab states.

In this context, the negative consequences of extreme heat on working hours and labor productivity are concentrated in subregions with already precarious labor market conditions and degraded employment quality. Productivity losses due to heat stress tend to be larger in regions with low social protection coverage rates, high shares of informal workers in total employment, and high working poverty rates.

International labor standards provide guidelines to adapt to heat-related hazards

The ILO’s 2015 Guidelines for a just transition towards environmentally sustainable economies and societies for all provide practical orientation for government and social partners on how to design, implement, and monitor policies and measures that can tackle the labor implications of climate change in accordance with national circumstances and priorities.

In particular, the guidelines recommend governments, employers, and workers to conduct assessments of increased or new occupational safety and health (OSH) risks that result from climate change and identify adequate prevention and protection measures to ensure occupational safety and health. By making the adoption of a national OSH policy an obligation to “prevent accidents and injury to health arising out of, linked with or occurring in the course of work”, the ILO Occupational Safety and Health Convention No. 155  promotes a framework for managing extreme heat at workplaces. The accompanying Recommendation No. 164 highlights that a national OSH policy should include measures dealing with “temperature, humidity and movement of air in the workplaces”. Other international labor standards also offer useful tools for the management of heat stress, such as the Hygiene (Commerces and offices) Convention No. 120  and the Protection of Workers’ Health Recommendation No 97.

Social dialogue is instrumental

As underscored by the ILO Guidelines for a just transition, the design and implementation of policies aiming to mitigate and adapt to climate change must involve workers and employers’ organizations alongside the government. Workers and employers are best placed to design and implement heat stress policies that meet their specific needs.

Therefore, social dialogue is instrumental to the development of national OSH policies. In addition, collective bargaining offers a framework to employers and workers to develop tailored measures dealing with high temperature, including at the sectoral and company level. For instance, a collective bargaining agreement in Canada foresees that when the designated temperature index exceeds 39°C, workers may choose either to be paid an additional 25 percent of their regular hourly rate for the shift or to be excused from the shift.

Governments, employers, and workers can reduce vulnerability to heat stress through regulation, adequate infrastructures, and technology, as well as capacity building

Guided by international standards, policy is key to facilitating behavioral changes among employers and individual workers and to promote the development of measures tackling occupational heat stress. Examples of regulations include the prescription of a maximum temperature to which workers may be exposed and the adoption of measures to prevent excessive body heat. Beyond the regulations set by governments, employers play a critical role in the implementation of effective adaptation measures to limit the impact of heat stress. As stated in ILO Convention 155, employers are to “ensure that so far as is reasonably practicable, workplaces, machinery, equipment and processes under their control are safe and without risk to health”. Heat-related hazards should hence be considered in the OSH management system implemented by the employer with the participation of the workers.

Complementary to OSH standards, measures for the improvement of early warning systems for heat events and the monitoring of on-site weather conditions are particularly relevant to enable workers and employers to adapt to heat stress conditions. Raising awareness about the effects of extreme heat, including heat-related illnesses and training on recognizing and managing heat stress are also part of the preventive measures. In addition, the enforcement of policies aiming to improve the characteristics of buildings and developing adequate infrastructures. For instance, access to a safe water supply should also be considered in the strategies to protect workers against heat stress.

In agriculture, long-term options for reducing the consequences of extreme heat include the promotion of mechanization and skill development, both to limit physical demands and to ensure higher productivity and improved food security. Policy design may also take into consideration the payment system, as evidence shows that piecework, for instance, is associated with a greater risk of health-related illness, probably because economic incentives prompt workers to work longer hours and take fewer breaks. For outdoor workers, ensuring their regular access to drinking water and shade and providing them with personal protective equipment and appropriate clothing is essential, and must be included in companies’ adaptation plans.

Social protection helps workers and their families adapt to the consequences of heat stress

Social protection policies are key to defending workers against the detrimental effects of heat that jeopardize their ability to earn income. Without social protection, not only may lost output due to heat stress translate into reduced wages and incomes, but workers are also less likely to have healthcare coverage that could help them cope with the health effects of working in high temperatures. Social protection policies, such as unemployment insurance, also have the capacity to facilitate workers transitioning to sectors that are growing. In agricultural areas, where heat stress is expected to displace workers, ensuring full social protection coverage is particularly relevant.

Mitigation efforts also reduce heat-related hazards.

Climate change mitigation is any “human intervention to reduce the sources or enhance the sinks of greenhouse gases”, including decarbonization of the energy sector, electrification of transport, promotion of sustainable agriculture, reforestation and afforestation, and investment in carbon capture and storage technologies. Mitigation involves structural changes in various sectors, including energy, transport, and agriculture and construction, which are projected to create a net employment gain at the global level.

As the COVID-19 crisis ceases to be the only OSH priority, many countries are realizing the impact of heat on workers' health and their export industry. For instance, coffee plantations in Vietnam and the tomato industry in Mexico are currently collaborating with the ILO and universities to monitor on-site temperature conditions and workers' health.

The statements made and views expressed in this article are solely the responsibility of the authors.