Europe's deadly heat crisis: Why air-conditioning is becoming a lifesaver as heatwave, El Niño fuel debate

It's a fact of life: heat is a "silent killer". And it's no longer a future climate risk. It is a present-day public health and economic threat.

Many heat stress-driven fatalities, known as "excess death", occur indirectly through cardiovascular, respiratory and other health complications, as per the World Health Organisation (WHO).

The practical science is well established: People can live and work only within an optimum range of temperature.

Greenhouse gases from human activities have raised global temperatures, increasing the frequency and intensity of heat waves since the mid-20th century.

As a result, heat waves now begin from a warmer baseline than they once did.

It can contribute to hotter conditions on land.

Local conditions can further intensify extreme heat.

During droughts, dry soils and stressed vegetation reduce evaporation, meaning more of the sun's energy goes directly into heating the air rather than cooling the surface through moisture loss.

This feedback can substantially increase daytime temperatures.

Weather patterns determine where and when that heat becomes dangerous. One of the most important is a "heat island effect", or "heat dome" — a persistent high-pressure system that traps hot air beneath it.

Sinking air suppresses cloud formation, skies remain clear and temperatures can build for days or even weeks.

Risks rise sharply when nighttime temperatures remain elevated, preventing people, buildings and infrastructure from cooling down between hot days.

Heat-related deaths kick up debate

As Europe experiences brutally-hotter summers and more frequent heat waves, a question once considered culturally and environmentally controversial is becoming harder to ignore: Should Europe embrace air conditioning on a much larger scale?

The debate has gained urgency after new research estimated that more than 62,700 people across Europe died from heat-related causes during the summer of 2024, one of the continent's hottest years on record.

For comparison, the United States recorded about 44,447 firearm deaths during all of 2024, according to the latest federal data.

While heat deaths and gun deaths are very different phenomena and should not be interpreted as competing risks, the comparison illustrates the scale of the public-health challenge Europe faces as temperatures rise.

Why is Europe more vulnerable to heat?

Historically, much of Europe developed in a relatively mild climate.

Homes, offices and public buildings evolved over time — and were often designed — to retain warmth during winter rather than shed heat during summer.

As a result, air conditioning remains far less common than in the United States.

In many European countries, homes rely on shutters, thick walls, cross-ventilation and nighttime cooling instead of mechanical air conditioning.

That approach worked reasonably well when severe heat waves were rare.

Now, publicly-available data shows Europe is warming faster than any other continent, increasing the frequency and intensity of extreme heat events.

Public-health researchers increasingly view heat as a major mortality risk, particularly for elderly people, those with chronic illnesses and residents of densely populated urban areas.

The World Health Organisation has described heat as a "silent killer" because many deaths occur indirectly through cardiovascular, respiratory and other health complications.

What does the evidence say about air conditioning?

Evidence suggests that indoor temperatures have significant effects on sleep, productivity, learning outcomes and health.

Research highlighted by analysts and commentators in recent discussions shows that performance and comfort tend to deteriorate once indoor temperatures climb much above roughly 23°C (73°F).

Sleep duration falls, sleep efficiency declines, workplace productivity drops and educational performance suffers as temperatures rise.

Researchers studying heat-related mortality have also identified access to cooling as an important protective factor.

Public-health experts point to air conditioning, cooling centres and heat shelters as among the most effective interventions during extreme heat events.

In schools, studies have found that learning losses associated with hot weather are substantially reduced where air conditioning is available.

Why has Europe been reluctant to adopt AC?

Several factors have slowed adoption:

• Concerns about electricity consumption and carbon emissions.

• High installation costs in older buildings.

• Historic climate conditions that made AC seem "unnecessary".

• Cultural preferences for natural ventilation and energy conservation.

Critics of widespread AC deployment argue: greater cooling demand could increase energy use and worsen climate change if powered by fossil fuels.

Supporters counter that modern air-conditioning systems are dramatically more efficient than older models. They also cite that Europe's increasingly low-carbon electricity grid reduces the environmental trade-off.

Is air conditioning the only solution?

No.

Heat experts generally advocate a mix of strategies:

• Better building insulation and passive cooling.

• Urban tree cover and green spaces.

• Reflective roofs and building materials.

• Heat-warning systems.

• Public cooling centres.

• Targeted protection for elderly and medically vulnerable residents.

• Expanded access to residential air conditioning where heat risks are greatest.

Many analysts argue that these approaches are complementary rather than mutually exclusive.

Helping save lives

The growing toll from heat-related deaths has prompted a reassessment of long-standing assumptions about summer living in Europe.

The case for greater air-conditioning adoption rests on a straightforward argument: extreme heat is increasingly deadly, cooling technology is widely available, and access to cooler indoor environments can save lives.

Whether Europe ultimately follows the US model of near-universal residential air conditioning remains uncertain.

As heat waves become more frequent and deadly, the question is shifting from whether cooling is necessary to how much cooling infrastructure Europe will need to protect public health in a warmer climate.