Across the world, climate change is making it too hot to learn.
Teachers are increasingly trying to educate students in dangerously hot classrooms, often in old school buildings built to withstand cold weather rather than heat. Unicef says hundreds of millions of schoolchildren globally missed out on education in 2024 after heatwaves forced the closure of their schools.
Low- and middle-income countries are the worst hit, especially in cities where the urban heat island effect drives temperatures even higher.
Heat is reaching levels resulting in major consequences for health, ranging from short-term impacts such as dehydration and heatstroke to longer term problems such as kidney failure. And, of course, all these hours of education lost to extreme heat also have long-term social and economic impacts.
Two years ago in Argentina, a school drew much public attention after saying pupils could come to school in swimwear because it was so hot. In China, rows have broken out online over whether hot classrooms are character building or a health threat. And in the US, researchers are now monitoring individual classrooms as they try to work out how to deal with overheating buildings.
Yet there are scant guidelines in place anywhere for what constitutes a temperature too hot for learning, nor what to do to mitigate against the heat in schools. Advice and policy need to catch up – and quickly, say a growing number of experts.
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Classrooms were poorly ventilated, overcrowded, and in some cases reached dangerously high temperatures, directly compromising student wellbeing and learning outcomes. Yet schools had minimal preparedness or response measures in place
Kriti Bhuju, communication specialist, Mercy Corps Nepal
The impact of heat in classrooms
Researchers have shown definitively that hot classrooms make it harder to learn. A 2018 study analysing 10 million US students’ test scores concluded that “without air conditioning, each 1°F [0.56°C] increase in school-year temperature reduces the amount learned that year by 1 per cent”.
Other research suggests that hot classrooms negatively impact the ability to work, or learn, more than similarly hot offices do. Data suggests that the same temperature change impacts learning in children more than office work in adults, although the reasons for this are not clear. Jisung Park, who led that 2018 study and now works at the University of Pennsylvania, has tried to disentangle the complex reasons underlying poor school performance, and consequently economic strength, in some hot countries.
Building on the 2018 work, his team looked at standardised achievement data for 58 countries and 12,000 US school districts. They added in detailed weather and academic calendar information and saw that when school days got hotter, there was a decrease in learning as measured by tests. The learning lost to hot days accumulates, and the consequence is lower earning potential for those individuals.
To those on the ground, this is no surprise.
Nepal: Educators struggle in Himalayan heat
In Nepal, heatwaves have been growing in strength and length in recent years. In a country more well known for the chill of the Himalayas than blistering heat, there are very few guidelines in place for dealing with hot classrooms.
“Heatwaves are becoming a common hazard in Nepal,” says Kriti Bhuju, an influencing and communication specialist for Mercy Corps Nepal, a development and relief organisation.
“Despite their growing frequency and intensity, heatwaves are much less considered in the risk assessments and the disaster management plans,” she notes.
This prompted the organisation to instigate a survey of schools in Madhesh province in the south of the country. They found extreme heat there was resulting in increased absenteeism, and more reports of headaches and fatigue, compromising students’ ability to concentrate during lessons.
“Classrooms were poorly ventilated, overcrowded, and in some cases reached dangerously high temperatures, directly compromising student wellbeing and learning outcomes,” Bhuju says. “Yet schools had minimal preparedness or response measures in place.”
Heat hasn’t been considered a looming threat in Nepal, Bhuju says. Disaster management focuses on flooding, earthquakes and landslides, rather than slow-onset hazards like heat, she adds. Bhuju hopes that their survey results can feed into policy, particularly local heat-management plans and heat-resistant infrastructure.
“Integrating heatwave preparedness into the Comprehensive School Safety Framework would be a crucial step forward,” Bhuju says, referring to Unicef’s global strategy to protect students and education from hazards of all kinds.
UK: Rich countries struggle too
In the UK, another country not typically thought of as hot, researchers are trying to gather enough information to pre-empt a future scenario in which schoolchildren might miss education because of extreme heat.
At the University of York, Lynda Dunlop is a climate change education and sustainability researcher, and Paul Hudson works in disaster risk reduction. Together they ran a survey in summer 2024 asking staff at around 300 schools across the country about their experience of extreme heat. They found 90 per cent of respondents had experienced heatwaves, with most saying they were negatively impacted and saw negative impacts on their students. The survey, which is yet to be published, also looked at around 85 schools’ policies for managing hot classrooms.
“Extreme heat, for the UK at least, isn’t necessarily a huge problem today for schools, but it’s going to become increasingly problematic as we move into the future,” says Hudson.
Schools aren’t as easy to manage as a workplace, Hudson and Dunlop suggest, because of the differences between children and office staff. A primary-school child will be less likely to have the autonomy or knowledge to move to a cooler area than a teacher or high school student, for example.
US: Mass monitoring to beat the heat
In the United States, Patricia Fabian at the Boston University School of Public Health has collated a huge data set from a school district in her local area. Her team used heat and air quality sensors installed in over 3,600 rooms within school buildings. Their results show that within a single school building, the difference between the coolest and hottest classrooms could be more than 14°C on a hot day.
Collecting this data and having sensors in classrooms can allow real-time remediation, like moving to a cooler part of the building, or turning on a window air-conditioning unit in a particular room even if the rest of the school is not too hot, Fabian says. (Window units can be installed cheaply, but can be less efficient to run than central systems that are designed to cool entire buildings.)
“Schools are very resource constrained, and so if they can sample and know what the indoor … conditions are, whether it’s temperature, carbon dioxide or anything else, they can pinpoint which classroom might have more problems,” she says.
Such data can also feed into longer term strategies for school administrators: “They can make decisions about where to concentrate the resources for putting air conditioning or trees, or they can make decisions about heat action plans,” Fabian notes. During heatwaves, it could be that school is actually the coolest place for a child to be.
The average US public school was built nearly half a century ago, according to a 2024 survey. These facilities were not built to function in our present-day climate. Regions – ranging from Nepal to the UK, the US and even further afield – that historically experienced milder temperatures during the academic year are less likely to have air conditioning or other ways of dealing with heat in schools.
Seeking school heat solutions
Asked if Nepal has guidelines on how hot classrooms are allowed to get, Bhuju’s answer is short: “Not exactly,” she says, though a government policy introduced last year does mandate weather monitoring at “all local levels”.
Although some countries and regions have imposed maximum temperatures for indoor work, most have no school-specific national guidelines.
What each study highlights is that even more data is urgently needed if evidence-based policy changes are to be enacted. This includes data on how hot classrooms are getting, what temperature is too hot for students to learn in, when schools are supposed to close, and how best to cool things down.
Remediation to cope with heat can be split into two broad areas: infrastructure changes like providing shading, greening the grounds and air conditioning; and behavioural changes like altering school uniform policies, wearing hats outside, moving lessons to cooler rooms and having more breaks for drinks.
For many schools, air conditioning is the one change that will make it possible for children to continue attending, often via window-based AC units. Across the world, such schemes are increasing as temperatures – and the health risks they bring – rise.
In the Maldives, minister of education Ismail Shafeeu has announced that all of the country’s 3,704 classrooms will have air-conditioning units installed by the end of 2025 as part of the Cool School Project. In the US, a June 2020 report by the Government Accountability Office estimated that 41 per cent of public school districts need to replace or update heating, ventilation and air conditioning (HVAC) systems in at least half their schools. That’s roughly 36,000 schools across the country.
But without cheap renewable electricity supplies, air conditioning carries a high financial and environmental cost. A study looking at Europe and India to 2050 suggests that rolling out more air-conditioning units could increase annual electricity demand by 2 per cent in Europe and 15 per cent in India. With this increase, India alone would emit an extra 120 million tonnes of carbon dioxide.
Air conditioning may be a band aid that allows pupils to continue learning. But if schools are to remain cool and safe enough, more sustainable ways to keep temperatures sufficiently low are urgently needed.
This article was originally published on Dialogue Earth under a Creative Commons licence.
