The Cooling Dilemma Amid Climate Change
Are air conditioners the solution to heat, or the cause?
Record heat blanketed much of the globe in the Summer of 2023. The planet is already 1.1˚C hotter compared to the average temperature in 1850–1900. Hot extremes including heat waves have become more frequent and intense since the 1950s. At this pace, global average temperatures are estimated to rise 1.5˚C above preindustrial levels sometime between 2030-2035. By 2030, an estimated 500 million people globally, particularly in regions like South Asia and the Middle East, will be exposed to extreme heat at least 30 days or more per year, and the number of people enduring highly dangerous heat (over 120°F on a dry day, or around 95°F on a humid day), is projected to quadruple by 2030.
Aligned with these trends, over the past decade, the energy demand for space cooling has grown more than twice as fast as the overall building energy demand. Currently, roughly 2 billion air-conditioners are in operation globally, and with the growing demand for colling, two-thirds of households could have an air conditioner by 2050. However, the current cooling systems have low technical and systemic efficiency, which coupled with increasing use, strain power grids and contribute to greenhouse gas (GHG) emissions. Despite the increase in the use of air-conditioners, due to socioeconomic disparities, those who need cooling the most have no or limited access to air conditioning, putting them at risk of heat exhaustion and possibly even death. This explainer highlights critical trade-offs between existing mechanisms of cooling and its social and environmental implications. We examine the challenges and dilemmas around mechanical cooling and its implications for children.
The cooling conundrum
Excessive heat poses severe health risks, including heat-related illnesses and fatalities. In the past 20 years, the annual average count of heat-related fatalities among individuals aged 65 and older surged by a staggering 61 per cent, culminating in an estimated 300,000 fatalities. Vulnerable groups like children, the elderly, outdoor workers, and those in poorly insulated housing are at higher risk. Urban areas with dense infrastructure and limited green spaces can become especially hot. Additionally, individuals with limited mobility, social isolation, and without effective indoor cooling are also at an elevated risk of heat-related illnesses.
Air-conditioning is a lifesaving solution to excessive heat, which has averted an estimated average of 190,000 heat-related deaths annually during 2019-2021. Epidemiologic studies have shown that having household air conditioning reduces the risk of heat-related deaths by approximately 75 per cent compared to those without it. However, cooling systems have their downsides as explained below.
Energy-intensive cooling mechanism: Unfortunately, although efficiency (defined as the amount of energy necessary to cool a room) has improved over the last decades, inefficient equipment dominates the market for air conditioners mainly as customers tend to prioritize low-cost over the life-cycle cost of equipment, and manufacturers focus on lowering production costs and increasing sales volume. The typical air conditioner sold is less than half as efficient as the highest-performing product on the market. This is the case in every region of the world. This inefficiency strains the power grids, especially on hot days when space cooling can account for over half of peak electricity demand. This can lead to power outages, resulting in a higher risk of heat-related illness and death due to a lack of indoor cooling and broken cold chains in the food and health sectors. Outages can also result in carbon monoxide poisoning, gastrointestinal illness, and sickness due to the failure of electrical-powered medical equipment.
According to the International Energy Agency (IEA), by 2050, the world will see a threefold increase in air conditioner-related energy demand, equivalent to adding 10 new units per second over the next three decades. This, combined with rising temperatures and living standards, is expected to raise global air conditioner ownership from 37 per cent today to over 45 per cent by 2030 putting further stress on already overwhelmed energy grids.
Two-pronged Problem of GHG Emissions: Air conditioners need electricity to function. The energy supply needed for artificial air-conditioning generates about 4 per cent of global greenhouse gases emissions, twice as much as the entire aviation industry. In 2021, space cooling accounted for about one gigaton of CO2 emissions from the power sector, and the fine particulate matter (that is, PM2.5) pollution from fossil fuel combustion to power air-conditioners was responsible for 24,000 deaths globally in 2020.
The typical air conditioner sold is less than half as efficient as the highest-performing product on the market.
In addition, the hydrofluorocarbon (HFC) refrigerants used as coolants also escape into the atmosphere. The HFCs have high Global Warming Potential (GWP) and absorb 150 to 5,000 times more solar energy than CO2, contributing severely to global warming and creating a greater need for cooling. The 2016 Kigali Amendment to the Montreal Protocol, ratified by 155 countries as of early October 2023, mandates a reduction of the production and consumption of HFCs by more than 80% by 2047; however, mitigating GHG emissions from air-conditioners require cleaner energy production as well as phasing out HFCs through adoption of alternative technologies in the cooling sector.
In major cooling markets today, there are requirements for air-conditioners to meet Minimum Energy Performance Standards (MEPS) which specify the minimum level of energy performance that appliances and equipment must meet or exceed before they can be supplied or used. However, they are absent or not always mandatory in hot or humid countries with rapidly growing demand for air-conditioners.
Overuse of Airconditioning: In high-income countries like the United States where air-conditioner ownership is nearly 90 per cent, the behaviour around energy consumption is also a negative factor. Air conditioning is crucial during heatwaves, but its widespread and excessive use in daily life contributes significantly to its climate impact. The overuse, often seen in high-income countries, hinders the ability to adapt to hot weather, making us more vulnerable and dependent on air-conditioning. While more efficient technological solutions are emerging, behavioral adjustments are crucial to deal with cooling-related energy crunch.
Social Inequality and Heat Vulnerability: Despite deployment increasing globally, in regions with scorching climates inhabiting about 3.5 billion people, the ownership of air-conditioners is merely 15 per cent as of 2021. The people most in need of space cooling are often those with the least access to solutions. For example, only around 5 per cent of households in sub-Saharan Africa are equipped with an air-conditioning unit, about 24 per cent in India, less than 20 per cent in Indonesia, and around 30 per cent in Mexico and Brazil. This compares with more than 85 per cent in Japan, Korea, and the United States. This leaves an estimated 2-4 billion people in the Global South, or 25-50 per cent of the world’s population of the global population to the dangers of heat stress. In some European countries, particularly in the South where summer temperatures reach dangerous levels, the AC ownership is also comparatively low, though this has been rapidly changing.
Structural inequality in infrastructure and economic systems makes marginalized communities highly vulnerable to the extreme heat. Air conditioning is unavailable to households with no electricity and remains unaffordable due to high electricity bills for many low-income households with electricity. In addition, the lack of green spaces and proximity to industrial operations make lower-income districts hotter than other well-off neighbourhoods, pushing them further toward energy poverty.
Urban Heat Island Effect: Global warming impacts are felt most acutely in cities and they are heating up at twice the global average rate due to the urban heat island effect (when cities experience higher air temperatures than the surrounding countryside, due to energy from all the people, cars, buses, trains and buildings). Air-conditioners expel heat from the indoor to the outdoor environment which increases outdoor temperature significantly in densely built cities. The night-time temperatures can rise by more than 1° C, exacerbating the nocturnal heat island effect. If the current trends in urbanization and increasing heat continue, it is expected that the urban population exposed to a summertime temperature above 35˚C will increase by 800 per cent to reach 1.6 billion by mid-century.
The escalating need for cooling drives up greenhouse gas emissions, intensifying global warming and necessitating even greater cooling solutions.
Implications for children
According to UNICEF’s report on heatwaves, around 559 million children are exposed to high heatwave frequency, and around 624 million children are exposed to either high heatwave duration, severity, or extreme high temperatures.
The number of heatwave days children experience have increased. According to the 2022 report of the Lancet Countdown, during the period 2012–2021, children younger than a year experienced 600 million more person-days of heatwaves (4.4 more days per child) annually compared with the average in 1986–2005.
By 2050, virtually every child on earth (over 2 billion children) is to face more frequent heatwaves, regardless of whether the world achieves a ‘low greenhouse gas emission scenario’ with an estimated 1.7 degrees of warming in 2050.
Extreme heat poses substantial threats to children’s physical health, including an elevated risk of cardiovascular diseases, low birth weight, increased incidence of diarrhoea, heightened vulnerability to mosquito-borne diseases like dengue fever, greater susceptibility to chronic respiratory conditions, undernutrition, and the development of allergies, as well as the potential for heat stroke and heat stress.
High temperatures are also linked to increases in mental health problems in children and adolescents, including post-traumatic stress disorder and depression, owing to their unique ways of interacting with their environment, limited adaptive capacity, dependence on stressed adults, and lifelong exposure.
There are social and educational risks associated with children’s unmitigated exposure to high heat. Extreme heat can worsen educational inequalities globally. Increased exposure to hot school days reduces the rate of learning and negatively affects long-term learning and students’ academic performance. These adverse impacts are more pronounced among the low-income and minority students. It affects children’s economic prospects in the future. Keeping classrooms cool has demonstrated significant mitigation of the negative effects of heat on student achievement, highlighting the importance of cooling for children’s well-being.