If you want to understand the bind the world faces
adapting to climate change, there may be no better example
than that of the simple air conditioner.
As the world warms and heatwaves 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 heatwave 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.
Stepwells, 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 wellbeing 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.