As the world warms and heat waves become more frequent and more dangerous, people turn up the AC.

It's very effective at cooling buildings and the people inside them.

But air conditioners are also power-hungry appliances with a small unit in a single room using more electricity than four fridges.

There are currently around 1.6 billion air conditioners in the world and that number is expected to triple by 2050, where 10 new units will be installed every second for the next three decades.

At that point, emissions from powering all that air conditioning could be as high as 2 billion tonnes of CO2 a year, about the same as India produces now.

This is the ever-accelerating feedback loop of air conditioning.

Higher temperatures lead to more AC.

More AC drives ever-higher temperatures.

And while this cycle continues, people will suffer from the ill effects of extreme heat.

It isn't only about the immediate danger of death or illness during a heat wave either.

Higher temperatures can make air quality worse and chronic conditions flare up.

Some studies suggest our thinking and decision-making is more sluggish when it's hotter.

Extreme heat can leave people poorer too, as working hours shrink and infrastructure like roads and power become unreliable.

One way to address the problem is to simply build a better air conditioner.

There are UN-backed initiatives to improve the efficiency of AC so it uses less power and produces fewer pollutants.

But rather than betting on new or better tech, it's also possible to change our approach to cooling and comfort.

Humanity lived without air conditioning for much of its history.

Some of the most charming aspects of ancient cities, from Mediterranean courtyards to narrow city streets, are actually ingeniously engineered cooling measures that either block out direct sunlight or use cool stones and plants to keep the nearby air pleasant throughout baking afternoons.

The picturesque white villages of southern Spain have partly been painted that way because light colours absorb less heat.

This often went alongside ways of living that were adapted to the hot weather.

Taking a siesta meant avoiding work during the hottest periods of the day.

Those who traditionally lived in the desert wore looser, lighter clothing, like robes.

Placing a wet towel on the head or neck is common in India.

Simply ensuring you know of a cool place to move to during intense heat, like a basement or shaded room, can also help.

Our predecessors also developed some clever cooling technologies.

Step wells, an ancient technique that builds small pools of water into a structure, often deep underground to cool adjacent areas, have long been common in India.

While across the Middle East, striking towers called wind catchers that direct cool air towards buildings have been used for centuries.

More recently, people have relied on electric fans to circulate cool air, which use very little electricity.

Including efficient ceiling fans in buildings would go a long way to reducing the quantity of air conditioning used.

Many of these approaches are called passive cooling measures because they don't consume energy, but in a sense air conditioning created a different kind of passivity.

It allowed people to design frighteningly inefficient buildings and cities full of sealed, all-glass skyscrapers and concrete surfaces and simply cool them down with AC.

Reversing this mistake for a warming world requires an active approach.

Designing buildings, cities and reconfiguring our daily lives to ensure we can deal with overheating before it happens and treat air conditioning as a last resort.

Fortunately, greener, more carefully built spaces for living should have other benefits, from the savings that come with efficient homes to the health and well-being effects of plentiful green space and safer outdoor temperatures in towns and cities.

Like the climate crisis itself, cooling is a global challenge.

An Oxford University study showed that if average global temperatures missed the 1.5 degree target set by the Paris Agreement and hit 2 degrees, nations already facing heatwaves, like those in Central Africa, will see the most extreme temperatures.

But northern countries could see the biggest jump in the number of uncomfortably hot days, days when people will need additional cooling.

In Switzerland and the UK, for instance, that number will go up by 30%, the biggest increase globally.

The researchers warned that these countries are dangerously unprepared, with their homes and cities built with a very different climate in mind.

In the UK, homes are built like greenhouses, one of the lead researchers said.

Air conditioning is incredibly convenient, but it would be a disaster for the climate if it continues to be the worldwide remedy for rising temperatures.

The goal must be to turn air conditioning into a technology of last resort, using the clever green solutions of the past and adapting the way we live and work in a hotter world.

Transcription by ESO. Translation by —