Air conditioners keep millions of people safe during extreme heat, but new research on climate shows that this life-saving technology is also adding to global warming.
A recent study led by the University of Birmingham explains how rising air conditioner use could increase global temperatures by 2050.
The team examined how climate change, economic growth, and cooling demand interact with each other.
The findings reveal a worrying cycle. As temperatures rise, more people install air conditioners. Greater use of air conditioning increases greenhouse gas emissions. Those emissions then push global temperatures even higher.
A planet already under pressure
Human activities have already warmed Earth by about 1.2°C (about 2.2°F) since pre-industrial times. Rising heat has caused stronger and more frequent heatwaves.
Between 2000 and 2019, nearly half a million heat-related deaths occurred worldwide. Air conditioning reduces these risks and protects vulnerable people.
At the same time, global air conditioner sales grew four times between 1990 and 2016. China and the United States now account for more than half of global sales. Electricity used for cooling has more than tripled since 1990.
Most electricity still comes from fossil fuels. This means higher cooling demand leads directly to higher carbon emissions.
Cooling demand will surge
The researchers studied five future climate pathways used by the Intergovernmental Panel on Climate Change. These pathways range from strong climate action to heavy fossil fuel dependence.
Under a middle pathway, global cooling demand could increase by about 25 percent by 2050 compared to 2010. In high-emission futures, cooling demand rises even faster.
By 2050, the world could have about 2.3 billion air conditioning units under the middle scenario. In a fossil-fuel-heavy future, the number could rise to 3.1 billion units.
Electricity use for cooling could reach about 4,493 terawatt hours in the middle pathway.
In the highest emission scenario, cooling electricity use could exceed 12,000 terawatt hours. That would represent nearly 15 percent of total building sector energy use.
Economic growth drives AC use
The study highlights an important point. Rising income drives most of the increase in air conditioner use.
Income growth explains more of the rise in AC units and cooling energy use than temperature increase alone.
“Global warming is raising temperatures and causing more heatwaves, and as economic growth in some of the worst-affected countries means more people can offset extreme heat with air conditioning,” noted Professor Yuli Shan from the University of Birmingham.
Warming fuels more cooling
“As global temperatures rise, we risk being locked into an ‘arms race’ where defending ourselves against extreme heat is causing the issue to get worse,” said Professor Shan.
“The world must transition quickly to cleaner, more efficient cooling technologies – while ensuring fair access to cooling, especially for vulnerable populations.”
The research shows that warming directly caused by hotter weather increases AC use slightly. However, economic growth adds much more to total emissions from cooling.
Air conditioners worsen climate
Under the middle scenario, air-conditioning-related emissions could reach about 3.8 gigatons of carbon dioxide equivalent per year by 2050.
In the highest emission pathway, emissions could reach about 8.5 gigatons, roughly equal to the current annual emissions of the United States.
Between 2010 and 2050, total emissions from AC use could exceed 100 gigatons in the middle scenario.
These emissions could add around 0.05°C (about 0.09°F) to global temperatures by 2050 in the middle pathway. In the worst case, AC use alone could add up to 0.07°C (about 0.13°F).
Even small temperature rise matters
This increase may appear small, but the world has very little space left to remain below the 1.5°C (about 2.7°F) target.
Refrigerant leaks are also a growing concern. By 2050, leaking cooling gases could make up a large share of AC-related emissions. Many of these gases trap far more heat than carbon dioxide.
Air conditioner use and climate impact
Cooling demand is highest in equatorial regions such as Southeast Asia, South Asia, and parts of Africa. Many of these regions have lower income levels and limited access to air conditioning.
Low-income regions could face a cooling gap of about 94 million air conditioning units by 2050 under a medium-income level.
If incomes rise to high-income levels, that gap could increase to about 150 million units. If every region reached the highest income level, the global cooling gap could rise to hundreds of millions of units.
Access may raise emissions
“The study reveals that if all low-income regions gained the same access to air-conditioning as rich regions, related global emissions would jump dramatically – adding up to 0.05°C extra warming even in the most climate-friendly scenario,” said Dr. Hongzhi Zhang from Beijing Institute of Technology.
This situation creates a serious development challenge. Expanding cooling access protects health and improves comfort. However, equal access using current technology would increase global warming.
Solutions for a cooler future
The researchers call for rapid decarbonization of electricity systems. Clean energy can greatly reduce emissions from cooling. Switching to low global warming refrigerants can cut emissions by up to 90 to 99 percent in some cases.
Improving building insulation, upgrading windows, and using more efficient air conditioners can lower electricity demand.
Simple actions such as raising thermostat settings during peak hours can reduce peak electricity load by up to 20 percent. Public awareness and energy-saving habits can also reduce cooling energy use.
Air conditioning will remain essential as global temperatures rise. The challenge is to provide safe and fair cooling for everyone while limiting additional warming.
The study is published in the journal Nature Communications.
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