Summary: Recent deaths from heat waves have fueled fears that climate change will make the problem far worse. Yet history shows that humans are not helpless in the face of rising temperatures. Through innovation and adaptation such as widespread air conditioning, societies have already dramatically reduced heat-related mortality in many regions. Far from being doomed, people have the tools and ingenuity to meet the challenge of hotter climates and protect human welfare.
As summer heat waves rolled across Europe in recent years, many areas saw devastating spikes in deaths due to extreme heat. Research estimated that heat-related causes were responsible for more than 61,000 excess deaths across Europe during the summer of 2022 and more than 47,000 excess deaths in 2023, while the World Health Organization elsewhere stated that “heat claims more than 175,000 lives annually” in Europe.
These unfortunate events have been fodder for environmental activists and public health authorities, who warn that climate change will necessarily increase death tolls from extreme heat. With some climate scientists viewing the “increasing threat to human life from excess heat” as “almost inevitable,” a picture of humanity’s helpless march toward a climate apocalypse is being painted.
But there’s a critical flaw in this grim overheating narrative. The dire predictions presume a direct mechanical relationship between rising temperatures and human mortality that does not exist.
To be sure, extremely hot weather poses numerous serious health hazards. High temperatures can cause acute conditions, such as heat exhaustion, heatstroke, and dehydration, while exacerbating cardiovascular and kidney diseases. Negative mental health impacts and adverse pregnancy outcomes also increase with heat exposure. Chronic exposure to sustained hot weather can result in a progressive loss of physical and cognitive capacity, worsening of chronic diseases, and cumulative impacts on well-being and productivity. These effects lead to increased morbidity and mortality, especially among vulnerable populations such as the elderly and outdoor workers.
Yet the outcome we care about—morbidity and mortality from extreme heat—depends not only on weather patterns but also on people’s adaptations—behavioral, social, and technological—to high temperatures. The reality is that people are creative problem-solvers who learn and adapt to changing conditions.
The Power of Air Conditioning
Research shows that human adaptation to rising temperatures has considerably weakened, if not broken, the link between high temperatures and mortality over time. A landmark study by economists showed that the mortality impact of extremely hot days fell by 75 percent in the United States between 1960 and 2004, driven primarily by the adoption of residential air conditioning (AC). Another study found that the number of deaths per 1,000 deaths attributable to each 10°F increase in same-day temperature decreased from 51 in 1987 to just 19 in 2005.
Comparing heat-wave impacts between regions with different levels of technological adaptation highlights the effectiveness of AC. The contrast between recent European heat waves and similar temperatures in the United States is striking. The summer of 2024 was Arizona’s hottest on record, with an average daily temperature of 99°F, with Phoenix experiencing 113 consecutive days above 100°F. In Maricopa County, where Phoenix is located, 464 residents died of heat-related causes out of a population of 4.49 million over the entirety of 2024, at a rate of 10.3 per 100,000. In contrast, the 2022 summer heat wave in Europe resulted in more than 61,000 heat-related deaths, about 11.4 per 100,000, even though the average daily temperature was only around 69°F. The hardest-hit countries, including Italy, Spain, and Greece, experienced maximum daily temperatures close to the average temperatures seen in Arizona, albeit with mortality rates two to three times higher. The difference? The widespread adoption of air conditioning.
In the United States, the residential air conditioning rate of adoption exceeds 90 percent nationally, with rates exceeding 95 percent in hot-climate states such as Arizona, Texas, and Florida. In contrast, air conditioning use in European countries remains around 19 percent overall, with much lower rates in specific countries—only about 5 percent of homes in the UK have cooling systems, and just 3 percent in Germany.
While various explanations of this gap have been offered—including supposed differences in culture—the most plausible seems to be simply a matter of weather and geography. Most European cities sit at latitudes comparable to Canada (London is north of Calgary), and historical weather patterns provided naturally mild summers. Research shows that human populations have continuously adapted to local climates, with the “minimum mortality temperature” closely tracking local temperature patterns. As conditions change, so do people’s investments and behaviors, as we can already see in the increasing rate of AC adoption across Europe—where AC unit sales have doubled since 1990 and continue to accelerate.
The market forces driving AC adoption deserve special attention. As markets for cooling technologies expand, economies of scale drive down costs and improve performance. The same window air conditioner that cost thousands of dollars (inflation-adjusted) in the 1950s now costs a few hundred dollars, while using half the energy. The same competitive forces that reduced computer and smartphone costs are making air conditioning increasingly affordable—the International Energy Agency expects the number of air conditioning units globally to triple by 2050, increasing from 2 billion to 5.6 billion, with two-thirds of the world’s households having AC.
Beyond Air Conditioning: The Full Spectrum of Adaptation
While AC is one of the most effective technological responses to heat challenges implemented thus far, it represents just one solution among many. Human ingenuity operates across multiple levels, from individual behavioral changes to planet-wide interventions. This multilevel approach also helps to illuminate how technological adaptations depend on economics and institutional context, not simply on technical factors alone.
A Note About Conventional Behavioral and Social Adaptations
Before examining technological solutions, it’s worth considering conventional social and behavioral adaptations to extreme heat: increased hydration, appropriate clothing, avoiding outdoor activity during peak temperatures, and adjusting work schedules. Social solutions predominate at higher levels, from community wellness checks to early warning systems and public education campaigns.
While these nontechnological adaptations have their place as first-line responses, they have limitations. Beyond requiring consistent vigilance and behavioral modification, social and behavioral adaptations cannot directly address the core problem of dangerously hot ambient temperatures.
Micro Level: Individual and Building-Level Solutions
At the micro level, personal technological solutions are emerging rapidly. Wearable neck fans provide portable cooling, while phase-change materials integrated into clothing can absorb and release body heat to maintain comfortable body temperatures. Cooling vests used by outdoor workers can significantly reduce heat stress during physical labor.
At the building level, property rights and market competition create especially strong incentives for innovation. When people own their buildings, they internalize both the benefits and costs of cooling investments, with competition driving responsiveness to changing preferences, spurring adaptation without government mandates.
Many innovations use passive cooling techniques in countless forms. Modern wind-catchers, or badgirs, inspired by Persian architecture, can reduce indoor temperatures by 8–20°F without any energy input. Double-skin facades act as insulation while channeling air flows to cool buildings. Companies such as Pirta have developed specialized coatings that reflect more than 99 percent of solar radiation, enabling cool roofs that reduce indoor temperatures. Radiative cooling materials from companies such as SkyCool Systems dissipate heat to space even during daytime, achieving subambient cooling without energy input. Green walls provide natural cooling through evapotranspiration, while phase-change materials integrated into building materials create structures that use day-night temperature fluctuations for natural temperature regulation. Together, these innovations in various combinations have further potential in mitigating urban heat island effects.
Meso Level: Community and Urban-Scale Solutions
Moving beyond individual buildings, large indoor complexes represent an intermediate scale of adaptation. The West Edmonton Mall in Canada, spanning 5.3 million square feet, maintains year-round climate control for shopping, entertainment, and even indoor beaches. Dubai plans to build a 4,000-mile network of air-conditioned walkways connecting major buildings and city-areas. These massive climate-controlled environments—enabled by technological innovations, effective property rights, and economies of scale—provide refuge and maintain economic activity during extreme heat.
At the city scale, density contributes to urban heat island effects but can also work to the advantage of heat-mitigation solutions. District cooling systems such as those in Singapore can be 40 percent more efficient than individual building systems, leveraging massive economies of scale. These systems work by concentrating all cooling production in one or more large optimized plants that chill water to near-freezing temperatures, then pumping this cold water through insulated underground pipes to multiple buildings across a district, where heat exchangers in each building transfer the cooling to internal air systems—thus eliminating the need for individual air conditioning units in every structure. Time-of-use electricity pricing naturally spreads cooling demand throughout the day, reducing peak loads and infrastructure requirements.
Los Angeles’ cool pavement program that employs reflective pavement coatings has shown surface temperature reductions of 10–12°F on treated streets and ambient air temperature reductions of 0.5–3.5°F. Singapore’s comprehensive greening program has helped moderate urban temperatures despite rapid development.
Macro Level: Regional and Global Solutions
At the macro level, technologies are being developed that could modulate the planet’s temperature directly. Solar geoengineering proposals could provide regional or global cooling. Stratospheric aerosol injection, mimicking volcanic eruptions’ cooling effects, could reduce global temperatures within months. Marine cloud brightening could provide targeted regional cooling for especially vulnerable areas such as coral reefs. The massive scale of these interventions could potentially protect billions of people simultaneously.
These mega-solutions highlight important economic factors that come with increasing scale. At planetary scales, property rights can’t feasibly be defined or enforced, hindering the internalization of benefits and costs. However, the potential economies of scale are enormous. An organization might undertake such projects if it expects sufficient benefits to justify the costs, even without capturing all benefits—similar to how philanthropists fund various activities for the public interest today.
Looking further ahead, the prospect of energy abundance through fusion power could fundamentally transform our cooling capabilities. With essentially unlimited clean energy at near-zero marginal cost, we could deploy massive atmospheric cooling systems, power continent-spanning networks of air conditioning, or even implement science-fiction-scale projects like orbital sunshades—effectively refrigerating vulnerable regions or the entire planet. What seems economically impossible today becomes feasible when energy scarcity no longer constrains our adaptive capacity.
Institutional Flexibility Enables Diverse Solutions
There isn’t one big solution to the challenge of extreme heat. Instead, myriad solutions—each partial and imperfect—work together without being planned or necessarily designed as such. It’s beyond human abilities to design the complex tapestries of adaptations that solve big problems. Instead, we can cultivate robust institutional arrangements that support their emergence.
Institutional flexibility enables diverse approaches to coexist and compete, allowing different regions to experiment and adapt solutions to their specific conditions. This experimentation generates knowledge that benefits adaptation efforts globally, as successful innovations spread through market mechanisms and technology transfers.
The Path Forward
The evidence is clear: Humans don’t have to passively accept increased heat-related mortality. Through technological innovation supported by appropriate institutions, we can adapt to rising temperatures while maintaining and improving quality of life.
Climate change presents real challenges, but human ingenuity—when supported by property rights, market mechanisms, and institutional flexibility—has consistently overcome environmental obstacles throughout history. The same innovative capacity that enabled survival in harsh climates from the Arctic tundra to desert regions can address the challenges of a warming world.
Yet frustratingly, even as evidence mounts that technological adaptation saves lives, many environmental organizations and public health institutions actively resist or ignore AC as a solution. The World Health Organization’s “Heat and Health” fact sheet from May 2024 mentions AC once, buried in a list of recommendations, and even then conditionally: “If using air conditioning…”. In an August statement about 175,000 annual heat deaths in Europe, the organization omitted any mention of AC at all, focusing instead on demonstrably less effective behavioral changes. Its published guidance for Europe begrudgingly admits to AC’s effectiveness in a few places, followed immediately by emphasized caveats. Indeed, the single full-page focused on AC’s benefits, out of roughly 200 pages, is followed immediately by two and a half pages about its drawbacks.
This ideological opposition to technological solutions—rooted in eco-puritanism rather than concern for human welfare—prioritizes energy conservation over human lives. When organizations claim to care about heat deaths while ignoring an incredibly effective existing technological solution, they reveal a troubling willingness to sacrifice human welfare on the altar of environmental orthodoxy.
In many European countries, byzantine regulations govern exterior modifications to buildings, including air conditioning installations. In France, installing an AC unit that alters a building’s external appearance can require a multistep process and approval from multiple agencies, or even a majority vote of property co-owners for co-op residents. In Germany, strict noise regulations often prohibit AC installation in residential areas. These restrictions increase costs and complexity, reducing adoption rates and leaving residents vulnerable—a deadly form of aesthetic preservation that values architectural purity over human life.
For those concerned about absolute living standards and human welfare, the implications are clear. Markets and property rights have already enabled dramatic reductions in heat mortality where they’ve been allowed to function. Extending these benefits globally doesn’t require complex international agreements or massive wealth transfers—it simply requires allowing people the freedom to invest in their own comfort and survival. As incomes rise and technology advances, cooling solutions will become accessible to ever-broader populations, continuing the remarkable decline in heat-related mortality that markets have already delivered in developed nations.
Finally, while heat-related deaths capture headlines, research consistently shows that cold weather kills more people globally than hot weather. A comprehensive 2021 study in The Lancet Planetary Health found that 8.52 percent of global deaths were linked to cold temperatures, while less than 1 percent were linked to hot temperatures—roughly a 9:1 ratio. That doesn’t diminish concerns about heat-related mortality, but it provides important context about the relative scale of temperature-related health risks.
Doomsday predictions about inevitable heat mortality are pessimistic as well as condescending, viewing humans as passive, hapless creatures who will plod along to their doom—rather like frogs basking in a pot of water on a stove. A realist would recognize humans’ capacity for institutional and technological innovations that have characterized our species throughout history. The path forward requires institutional arrangements that foster and guide humans’ creative energies toward continual adaptation and problem-solving.
