Too Hot to Work: Extreme heat is Silencing Human Productivity
Extreme heat is more than a background inconvenience; it is increasingly determining how well, and sometimes whether, we can work. It begins at sunrise, almost gently. As the morning advances, the warmth settles on the skin and then on the mind. Focus slips, movement slows, and even the simple act of thinking can feel like wading through thick air.
When I was younger, I used to hear people say that “people from certain places are lazy.” It was a casual, unexamined judgment, one of those statements people repeated without context. As I grew older and joined the workforce, I realised something striking: many of the places being described were among the hottest parts of Kenya, where the sun does not simply shine; it presses down. They included the Coast, parts of Western Kenya and towns across the North Eastern region.
Later, while working with the Red Cross in Kenya’s Coastal and Northeastern regions, the reality became undeniable. We began fieldwork at sunrise, effectively racing the heat. By midday, the sun could become physically unbearable. Work slowed, conversations shortened, and people rested during the hottest hours. Even the most committed teams had to pause.
This summer in Europe brought those memories back with force. The heat has been relentless, and I have felt it in my concentration, in fatigue arriving too early, and in the frustration of unfinished plans. I have achieved perhaps 40% of what I intended to do. That figure is personal, not scientific, but the experience is real: heat can sharply reduce what a person is capable of doing. In a warming world, it ceases to be merely a question of comfort; it is becoming an economic and social problem.
The Science of Heat and Human Productivity
Before you question it, hear me out. In hot conditions, the body must work harder to regulate its core temperature. Blood flow to the skin increases, and sweating helps dissipate heat. During physical activity, this places additional strain on the cardiovascular system; fluid loss can contribute to dehydration and fatigue if it is not replaced.
Heat also affects the mind. Thermal discomfort and physiological strain can impair sustained attention, vigilance and some aspects of cognitive performance. Hot nights compound the problem by disrupting sleep and recovery, meaning the next working day can begin with a deficit before the work itself has even started.
Heat is not the only temperature problem. Excessive cold can also reduce performance. There is no single temperature at which everyone works best: the effects depend on the task, humidity, radiant heat, air movement, clothing, acclimatisation, health, hydration and the degree of control people have over their environment. Sedentary indoor work is therefore very different from heavy physical labour, in which the body already generates substantial internal heat.
Across offices, factories, farms and construction sites, however, the direction of the evidence is clear: excessive heat can mean slower work, more errors, reduced physical capacity and more frequent breaks. At severe levels, it also increases the risk of heat illness and occupational injury. Self-pacing then stops being a matter of preference and becomes a form of protection.
The Economic Cost of Rising Temperatures
Rising temperatures impose what could be described as a growing “heat tax” on human productivity. The International Labour Organization has estimated that by 2030 heat stress could lead to the loss of 2.2% of total working hours worldwide: This is equivalent to around 80 million full-time jobs and approximately US$2.4 trillion in economic losses.
The burden will not be evenly distributed. Air-conditioning, shade, hydration, rest breaks and shifting working hours can reduce exposure, but access to these protections is unequal. Workers outdoors, people in informal employment and communities without reliable cooling infrastructure face much greater risks.
The largest productivity losses are expected in hotter economies where labour-intensive outdoor work remains common. Sub-Saharan Africa and South Asia are particularly exposed, especially through agriculture and construction. Research from India has also shown how rising temperatures can reduce industrial output and increase absenteeism.
Wealthier nations in Europe and North America generally have more capacity to adapt, but construction, agriculture, transport and other outdoor occupations remain vulnerable. And as European heatwaves intensify, the assumption that heat-related productivity is primarily a problem of poorer countries becomes increasingly difficult to sustain.
Europe’s Heatwave Wake-Up Call: Will Wealthy Nations Finally Confront the Climate Crisis?
I have heard speculation that as heatwaves become more frequent and begin affecting wealthy countries more directly, those countries may finally act more decisively on climate change. Perhaps. But the world should not have to wait until the consequences become unbearable in whatever part of the world, before acting.
There are legitimate reasons for mistrust. Developed countries pledged in Copenhagen in 2009 to mobilise US$100 billion annually in climate finance for developing countries by 2020. The target was not reached on time: OECD figures put climate finance at US$83.3 billion in 2020 and US$89.6 billion in 2021, before it exceeded the threshold in 2022 at US$115.9 billion. Reaching the target late was significant, but it did not erase the earlier shortfall.
The Glasgow Climate Pact also urged developed countries to at least double their collective provision of adaptation finance from 2019 levels by 2025. That commitment matters because adaptation is no longer theoretical. Countries are already paying for heat, drought, floods, changing disease patterns and damage to food and water systems.
At COP28, countries agreed to transition away from fossil fuels in energy systems, accelerate action during this critical decade, phase down unabated coal power and phase out inefficient fossil-fuel subsidies. The challenge is translating such international language into national policies, investment decisions and measurable emissions reductions.
The same implementation problem is visible in loss and damage. A dedicated fund has been established and operationalised, an important institutional step, but the central question remains whether financing can grow to match the scale of climate-related losses faced by vulnerable countries. Unlike the US$100 billion climate-finance goal, there was no agreed quantified contribution target for wealthy countries to the Loss and Damage Fund, so it should not be described as a broken numerical pledge. The issue is adequacy and delivery.
This is precisely why the COP31 Presidency’s third letter is important. It presents COP31 less as an exercise in inventing another set of promises and more as a platform for implementation. Its Action Agenda is intended to strengthen partnerships, mobilise finance and investment, and turn climate priorities into scalable, country-owned solutions.
The Presidency identifies ten priority themes, including clean energy and electrification, methane and waste reduction, climate-resilient cities, green industrialisation, food security, oceans, resilient health systems and a Climate Implementation Bridge designed to help countries develop finance-ready project portfolios.
That distinction matters. The defining challenge is increasingly not whether the world understands climate change, but whether governments and institutions can convert ambition into infrastructure, finance, adaptation and measurable results.
The Future of Work in a Warming World
Rising temperatures are and will continue to reshape labour markets, particularly in regions where outdoor work dominates and cooling infrastructure is limited. Agriculture, construction, and manufacturing are especially exposed because heat can reduce productivity, increase absenteeism, and create serious health and safety risks.
It is reasonable to expect displacement from some heat-exposed activities if working conditions become repeatedly unsafe or economically unviable. But describing this as an inevitable wave of “heat-driven unemployment” goes further than the evidence allows. The outcome will depend heavily on adaptation: changes in working hours, mechanisation, cooling, occupational protections, urban design, technology and the ability of workers to move into less heat-exposed jobs.
That makes climate-resilient employment and skills a central part of adaptation. Investment in resilient infrastructure, accessible cooling and worker protection must be accompanied by training and economic diversification. Productivity also needs to become part of the climate-policy conversation. Emissions targets and adaptation plans cannot be separated from the economic reality of how people earn a living.
We must recognise extreme heat as both a labour-rights issue and a productivity challenge. The question is no longer simply how hot the planet will become. It is whether people will still be able to work safely, think clearly and sustain their livelihoods as temperatures rise. The future of work in a warming world should not be defined by exclusion and lost opportunity, but by our ability to build resilience before the heat makes the decisions for us.
Extreme heat is more than a background inconvenience; it is increasingly determining how well, and sometimes whether, we can work. It begins at sunrise, almost gently. As the morning advances, the warmth settles on the skin and then on the mind. Focus slips, movement slows, and even the simple act of thinking can feel like wading through thick air.
When I was younger, I used to hear people say that “people from certain places are lazy.” It was a casual, unexamined judgment, one of those statements people repeated without context. As I grew older and joined the workforce, I realised something striking: many of the places being described were among the hottest parts of Kenya, where the sun does not simply shine; it presses down. They included the Coast, parts of Western Kenya and towns across the North Eastern region.
Later, while working with the Red Cross in Kenya’s Coastal and Northeastern regions, the reality became undeniable. We began fieldwork at sunrise, effectively racing the heat. By midday, the sun could become physically unbearable. Work slowed, conversations shortened, and people rested during the hottest hours. Even the most committed teams had to pause.
This summer in Europe brought those memories back with force. The heat has been relentless, and I have felt it in my concentration, in fatigue arriving too early, and in the frustration of unfinished plans. I have achieved perhaps 40% of what I intended to do. That figure is personal, not scientific, but the experience is real: heat can sharply reduce what a person is capable of doing. In a warming world, it ceases to be merely a question of comfort; it is becoming an economic and social problem.
The Science of Heat and Human Productivity
Before you question it, hear me out. In hot conditions, the body must work harder to regulate its core temperature. Blood flow to the skin increases, and sweating helps dissipate heat. During physical activity, this places additional strain on the cardiovascular system; fluid loss can contribute to dehydration and fatigue if it is not replaced.
Heat also affects the mind. Thermal discomfort and physiological strain can impair sustained attention, vigilance and some aspects of cognitive performance. Hot nights compound the problem by disrupting sleep and recovery, meaning the next working day can begin with a deficit before the work itself has even started.
Heat is not the only temperature problem. Excessive cold can also reduce performance. There is no single temperature at which everyone works best: the effects depend on the task, humidity, radiant heat, air movement, clothing, acclimatisation, health, hydration and the degree of control people have over their environment. Sedentary indoor work is therefore very different from heavy physical labour, in which the body already generates substantial internal heat.
Across offices, factories, farms and construction sites, however, the direction of the evidence is clear: excessive heat can mean slower work, more errors, reduced physical capacity and more frequent breaks. At severe levels, it also increases the risk of heat illness and occupational injury. Self-pacing then stops being a matter of preference and becomes a form of protection.
The Economic Cost of Rising Temperatures
Rising temperatures impose what could be described as a growing “heat tax” on human productivity. The International Labour Organization has estimated that by 2030 heat stress could lead to the loss of 2.2% of total working hours worldwide: This is equivalent to around 80 million full-time jobs and approximately US$2.4 trillion in economic losses.
The burden will not be evenly distributed. Air-conditioning, shade, hydration, rest breaks and shifting working hours can reduce exposure, but access to these protections is unequal. Workers outdoors, people in informal employment and communities without reliable cooling infrastructure face much greater risks.
The largest productivity losses are expected in hotter economies where labour-intensive outdoor work remains common. Sub-Saharan Africa and South Asia are particularly exposed, especially through agriculture and construction. Research from India has also shown how rising temperatures can reduce industrial output and increase absenteeism.
Wealthier nations in Europe and North America generally have more capacity to adapt, but construction, agriculture, transport and other outdoor occupations remain vulnerable. And as European heatwaves intensify, the assumption that heat-related productivity is primarily a problem of poorer countries becomes increasingly difficult to sustain.
Europe’s Heatwave Wake-Up Call: Will Wealthy Nations Finally Confront the Climate Crisis?
I have heard speculation that as heatwaves become more frequent and begin affecting wealthy countries more directly, those countries may finally act more decisively on climate change. Perhaps. But the world should not have to wait until the consequences become unbearable in whatever part of the world, before acting.
There are legitimate reasons for mistrust. Developed countries pledged in Copenhagen in 2009 to mobilise US$100 billion annually in climate finance for developing countries by 2020. The target was not reached on time: OECD figures put climate finance at US$83.3 billion in 2020 and US$89.6 billion in 2021, before it exceeded the threshold in 2022 at US$115.9 billion. Reaching the target late was significant, but it did not erase the earlier shortfall.
The Glasgow Climate Pact also urged developed countries to at least double their collective provision of adaptation finance from 2019 levels by 2025. That commitment matters because adaptation is no longer theoretical. Countries are already paying for heat, drought, floods, changing disease patterns and damage to food and water systems.
At COP28, countries agreed to transition away from fossil fuels in energy systems, accelerate action during this critical decade, phase down unabated coal power and phase out inefficient fossil-fuel subsidies. The challenge is translating such international language into national policies, investment decisions and measurable emissions reductions.
The same implementation problem is visible in loss and damage. A dedicated fund has been established and operationalised, an important institutional step, but the central question remains whether financing can grow to match the scale of climate-related losses faced by vulnerable countries. Unlike the US$100 billion climate-finance goal, there was no agreed quantified contribution target for wealthy countries to the Loss and Damage Fund, so it should not be described as a broken numerical pledge. The issue is adequacy and delivery.
This is precisely why the COP31 Presidency’s third letter is important. It presents COP31 less as an exercise in inventing another set of promises and more as a platform for implementation. Its Action Agenda is intended to strengthen partnerships, mobilise finance and investment, and turn climate priorities into scalable, country-owned solutions.
The Presidency identifies ten priority themes, including clean energy and electrification, methane and waste reduction, climate-resilient cities, green industrialisation, food security, oceans, resilient health systems and a Climate Implementation Bridge designed to help countries develop finance-ready project portfolios.
That distinction matters. The defining challenge is increasingly not whether the world understands climate change, but whether governments and institutions can convert ambition into infrastructure, finance, adaptation and measurable results.
The Future of Work in a Warming World
Rising temperatures are and will continue to reshape labour markets, particularly in regions where outdoor work dominates and cooling infrastructure is limited. Agriculture, construction, and manufacturing are especially exposed because heat can reduce productivity, increase absenteeism, and create serious health and safety risks.
It is reasonable to expect displacement from some heat-exposed activities if working conditions become repeatedly unsafe or economically unviable. But describing this as an inevitable wave of “heat-driven unemployment” goes further than the evidence allows. The outcome will depend heavily on adaptation: changes in working hours, mechanisation, cooling, occupational protections, urban design, technology and the ability of workers to move into less heat-exposed jobs.
That makes climate-resilient employment and skills a central part of adaptation. Investment in resilient infrastructure, accessible cooling and worker protection must be accompanied by training and economic diversification. Productivity also needs to become part of the climate-policy conversation. Emissions targets and adaptation plans cannot be separated from the economic reality of how people earn a living.
We must recognise extreme heat as both a labour-rights issue and a productivity challenge. The question is no longer simply how hot the planet will become. It is whether people will still be able to work safely, think clearly and sustain their livelihoods as temperatures rise. The future of work in a warming world should not be defined by exclusion and lost opportunity, but by our ability to build resilience before the heat makes the decisions for us.
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