Digital Report · Climate Adaptation & Cooling Technology
Cooling is not a luxury.
It is the infrastructure of a warming century.
The 21st century is being defined by rising heat, rapid urbanization, and a global surge in demand for cooling. This report examines cooling not as a consumer convenience but as core climate-adaptation infrastructure — essential for protecting lives, sustaining productivity, and keeping economies stable in a hotter world.
The Argument
The Century of Heat
For most of human history, warmth meant abundance. In the 21st century, heat has become a hazard — and the ability to manage it a precondition of development.
Cooling is routinely framed as comfort — an air conditioner in a bedroom, a cold drink, a walkable office on a summer afternoon. This framing is a category error. In a warming world, cooling is what keeps food safe between harvest and market, what keeps vaccines potent between a factory and a clinic, what keeps a data centre running, a factory productive, and a heatwave from becoming a mortality event. It is, in the strictest sense, infrastructure.
The term "cooling" spans four distinct systems: space cooling (keeping people comfortable and safe indoors), refrigeration (food and pharmaceuticals), cold chains (the logistics that connect them), and industrial process cooling (manufacturing and digital services). Each is growing faster than the global economy, and each is now inseparable from human health, food security, and economic output.
The central tension of the century of heat is that this infrastructure carries its own climate burden. Conventional cooling consumes roughly a tenth of the world's electricity, is often inefficient, and leaks refrigerants whose warming potential can be thousands of times that of CO2. If the world simply scales today's technology to meet tomorrow's demand, cooling could become one of the largest single drivers of warming it was meant to protect against.
This report therefore examines cooling through a single, demanding lens: how to expand access to the billions who lack it while shrinking the climate footprint of the billions who already have it. The two goals are not in conflict. Done well, they reinforce each other — efficient, low-carbon cooling is precisely the kind that can be affordably and equitably delivered at scale.
Key takeaway
Cooling is climate-adaptation infrastructure, not a consumer luxury. The century of heat will be won or lost by how societies deliver cooling — and by whether they can do so without compounding the warming that makes it necessary.
The Physical Trend
Heat Is Intensifying Everywhere
Heat is not rising uniformly — it is rising fastest in the places least equipped to cope, and its burden falls hardest on the very young, the very old, and the very poor.
The scientific picture is unambiguous. The ten warmest years on record have all occurred since 2015, and 2024 was the first calendar year in which the global average temperature exceeded 1.5°C above the pre-industrial baseline. What matters for cooling is not the global average, however, but the tails of the distribution: the frequency, intensity, and duration of extreme heat events, and the combination of heat with humidity that pushes conditions toward the limits of human physiology.
Three compounding trends define the physical challenge. First, heatwaves are becoming longer, hotter, and more frequent across every inhabited continent, arriving earlier and persisting later in the year. Second, humid heat — measured by the wet-bulb temperature, which reflects how effectively the human body can shed heat through sweat — is rising fastest in tropical and subtropical regions, where a wet-bulb threshold of roughly 35°C marks the edge of survivability for extended outdoor exposure. Third, the urban heat island effect means cities, where most people now live, run several degrees hotter than surrounding rural areas, concentrating exposure exactly where population density is highest.
The human toll is measurable and rising. Heat-related mortality among people over 65 has increased by roughly 85% since the 1990s, and heat now kills close to half a million people a year globally. The economic toll is quieter but larger: hundreds of billions of hours of labour are lost each year to heat stress, disproportionately in outdoor and informal work in the Global South — the work that builds, feeds, and services the fastest-growing economies.
Health burden
Heat-related deaths per year
People over 65 account for the overwhelming share of the increase; mortality in this group has risen ~85% since the 1990s (Lancet Countdown).
Labour loss
Potential labour hours lost to heat
Roughly 490 billion potential working hours were lost to heat stress in a recent year — a 42% increase over the early-1990s baseline (Lancet Countdown; ILO).
Why "cooling degree days" are the metric that matters
Energy planners now track cooling degree days (CDDs) — a measure of how much, and for how long, outdoor temperatures exceed a comfortable baseline. In fast-urbanizing regions across South Asia, the Middle East, Southeast Asia, and Sub-Saharan Africa, CDDs are climbing at rates that will reshape national energy systems within a generation. By mid-century, the population exposed to severe heat is projected to grow by billions, while the share of those people with access to any form of cooling remains in the single digits in the hottest and poorest regions.
The implication is not that the world must simply install more air conditioners. It is that the world must install the right cooling, in the right buildings, powered by the right energy, before the demand curve overwhelms both grids and households.
The Equity Challenge
The Cooling Access Gap
The people who contributed least to climate change face the most heat — and have the least cooling to protect them. Closing this gap is the essence of climate justice.
Roughly 2.8 billion people live in the hottest parts of the world, yet only about 8% of them own an air conditioner. More than a billion people face what analysts call a "cooling access risk" — an inability to cool their homes, their food, or their medicines. The consequences are not abstract: children die of heatstroke, vaccines spoil for lack of a refrigerator, harvests rot before they reach market, and workers lose income to days too hot to labour.
The access gap is usefully decomposed into its components. Rural poverty leaves hundreds of millions without electricity at all, or with power too unreliable to run a fan, let alone a cold store. Urban poverty concentrates people in informal, densely built housing that amplifies heat and lacks both insulation and ventilation. And a cold-chain gap — the absence of refrigerated storage and transport — means an estimated 470 million people lack reliable cooling for food and vaccines, driving food loss and undermining immunization.
This is the paradox at the heart of the century of heat: the countries with the most heat are often the least cooled, the least electrified, and the least able to pay the upfront cost of the very equipment that would protect them. If cooling access were distributed purely by climate need, the geography of air conditioning would look almost exactly inverted from what it is today.
Rural poor at risk
Off-grid and under-electrified
People in rural areas without reliable power for fans, refrigeration, or cooling — the largest single block of the access gap.
Urban poor at risk
Heat-amplifying housing
Informal urban dwellers in dense, poorly ventilated housing where the urban heat island effect bites hardest.
Cold-chain gap
No cooling for food & medicine
People lacking reliable cold chains for food and vaccines — driving post-harvest loss and undermining immunization.
Key takeaway
Cooling access is a climate-justice issue. More than a billion people live at risk from heat they did not cause and lack the means to escape — closing that gap is not charity, it is the foundational obligation of equitable adaptation.
The Solutions Landscape
The Adaptation Toolkit
The most effective cooling is often the cheapest and the lowest-carbon: shade, ventilation, water, and efficiency — long before a single kilowatt is spent on mechanical cooling.
Sustainable cooling is a cascade, not a single device. Each layer reduces the load that the next layer must carry, and each layer is cheaper and cleaner than the one below it. The toolkit begins with design, ends with smart mechanical systems, and only then reaches for the most energy-intensive options.
Layer 1 · Passive design
Shade, orientation & ventilation
Building orientation, external shading, reflective "cool roofs," thermal mass, and natural ventilation can cut cooling energy demand by a quarter to a third before any machine switches on — at a fraction of the cost.
Layer 2 · Nature-based
Trees, green roofs & water
Urban trees, green roofs, parks, and water features cool through shade and evapotranspiration, lowering local air temperatures by several degrees and improving health and biodiversity at the same time.
Layer 3 · Efficient devices
Inverter ACs & heat pumps
High-efficiency inverter air conditioners and reversible heat pumps deliver the same comfort for a fraction of the energy — the best units use half the electricity of the market average.
Layer 4 · Smart controls
Demand response & storage
Connected thermostats, thermal storage, and demand-response programs shift cooling load off peak hours, flattening grid demand and enabling more renewables without sacrificing comfort.
Layer 5 · Systems
District cooling & cold chains
District cooling networks serve whole neighbourhoods far more efficiently than room-by-room units; solar-powered cold chains bring refrigeration to off-grid rural areas.
Layer 6 · Frontier
Radiative cooling & natural refrigerants
Passive daytime radiative materials shed heat to space without energy; low-global-warming-potential refrigerants (CO2, ammonia, propane) slash the climate impact of the cooling that remains.
The refrigerant question
Efficiency is only half the climate story. The refrigerants that circulate through cooling equipment — historically hydrofluorocarbons (HFCs) — are themselves potent greenhouse gases, with global-warming potentials hundreds to thousands of times that of CO2. A single leak from one commercial refrigeration unit can offset years of efficiency gains.
The Kigali Amendment to the Montreal Protocol (2016) commits the world to phasing down HFCs, a transition that could avoid up to 0.5°C of warming by the end of the century. Its success depends on pairing the refrigerant transition with the efficiency transition — so that the replacement equipment is not only low-GWP but also radically more efficient. Done together, the two transitions can roughly halve the projected growth in cooling's climate impact.
Institutions & Rules
Governance & Policy Frameworks
Cooling will not transform itself. It needs national plans, urban heat strategies, global treaties, and — above all — enforceable standards that make the efficient choice the default choice.
Cooling has historically been governed as an afterthought — an appliance market, not a system. That is changing fast. A new architecture of cooling governance is emerging across three scales: global treaties that regulate refrigerants, national cooling plans that integrate cooling into energy and development policy, and urban heat strategies that protect the people most exposed.
At the global scale, the Montreal Protocol — the most successful environmental treaty in history — has been extended through the Kigali Amendment to phase down HFCs. The Cool Coalition, convened by UNEP, links more than a hundred governments, businesses, and cities around a shared goal of sustainable cooling for all.
At the national scale, India's Cooling Action Plan (2019) became the world's first comprehensive national cooling strategy, targeting a 20–25% reduction in cooling energy demand by 2037–38 through efficiency, passive design, and refrigerant transition. Dozens of countries have followed with their own plans, alongside Minimum Energy Performance Standards (MEPS) and labelling programmes that are quietly among the most cost-effective climate policies ever measured — because they eliminate the worst appliances from the market before they are ever sold.
At the urban scale, heat action plans — pioneered in Ahmedabad, India, and now replicated worldwide — combine early-warning systems, cooling centres, and worker protections to cut heat deaths at remarkably low cost. Cities are also using building codes, cool-roof mandates, and tree ordinances to shape the built environment for the long term.
- 1987
Montreal Protocol
The ozone treaty that became the model for global environmental cooperation — and the vehicle for cooling's refrigerant transition.
- 2016
Kigali Amendment
Parties agree to phase down HFCs; avoided warming of up to 0.5°C by 2100 if fully implemented.
- 2019
India Cooling Action Plan
First comprehensive national cooling strategy; targets 20–25% lower cooling energy demand by 2037–38.
- 2019
UNEP Cool Coalition
Multi-stakeholder alliance linking governments, industry, and cities behind sustainable cooling for all.
- 2020s
MEPS tightening worldwide
Countries raise minimum efficiency and refrigerant standards, removing the worst appliances from the market.
Key takeaway
Standards are the silent engine of the cooling transition. MEPS, labels, building codes, and heat action plans deliver outsized, durable results at low cost — they make efficiency and safety the default rather than a premium.
The Frontier
Frontier Debates: Cooling the Climate Itself
As heat outpaces adaptation, a more radical question has moved from the margins to the mainstream: should humanity deliberately cool the planet — and who gets to decide?
Beyond cooling buildings and bodies lies a contested frontier: direct climate intervention. A family of proposals known collectively as solar radiation modification (SRM) — most prominently stratospheric aerosol injection, which would mimic the cooling effect of volcanic eruptions by dispersing reflective particles into the upper atmosphere — could, in principle, reduce global temperatures rapidly and at relatively low direct cost. Marine cloud brightening and cirrus thinning are related concepts aimed at reflecting more sunlight or allowing more heat to escape.
The appeal is obvious in a century of heat: a fast, inexpensive lever against the worst temperature extremes, bought at a fraction of the cost of full decarbonization. But the risks are equally stark. SRM would not address the root cause — it does nothing for CO2 accumulation, ocean acidification, or the many non-temperature effects of greenhouse gases. Its regional impacts on rainfall and monsoons are poorly understood and unevenly distributed. And because it masks rather than removes warming, any interruption would risk a sudden, punishing rebound — the so-called "termination shock."
The deepest challenge is not technical but political and ethical. There is currently no international governance framework for deciding whether, when, or by whom such interventions could be deployed — and the decisions would carry consequences for every person on Earth. UNEP's independent 2023 review concluded that solar radiation modification is not currently a credible option for avoiding climate impacts and that no governance exists to manage it responsibly. The ethical questions — who decides, who bears the risk, and whether the mere prospect of a techno-fix weakens the resolve to cut emissions — remain entirely open.
The case for study
Potential upsides
Rapid temperature reduction at relatively low direct cost; a possible emergency brake against catastrophic heat and tipping points; cheap enough that a single state could in principle act.
The case for caution
Structural risks
No reduction in CO2 or ocean acidification; uneven regional climate effects; termination shock if interrupted; no governance; moral hazard that weakens mitigation; deep questions of consent and equity.
On the Ground
Regional Case Studies
The cooling transition is not one story but many — each region faces a different mix of heat, wealth, and infrastructure, and each is forging its own path.
South Asia · India
Heat action plans & the first national cooling strategy
India faces among the world's highest heat exposure with among the lowest AC access. Ahmedabad's heat action plan — early warnings, cooling centres, worker protections — became the global template, and the India Cooling Action Plan maps a low-carbon path that couples efficiency with access.
target cut in cooling energy demand by 2037–38.
Southern Europe
Heatwaves meet an aging, urban population
Europe is the fastest-warming continent. The summer of 2022 alone was associated with roughly 60,000 excess heat deaths, concentrated in older populations. Cities are responding with cool-roof retrofits, greening, and heat-health alert systems — but AC adoption is rising fast, raising peak-load risks.
GCC & MENA
Cooling as a share of the grid
In Gulf states, cooling can exceed half of peak electricity demand. The region is a laboratory for district cooling, desalination-linked systems, and efficiency standards aimed at bending a load curve dominated by air conditioning.
Southeast Asia
The fastest AC adoption on Earth
Rising incomes and humid heat are driving explosive air-conditioner uptake across Indonesia, Vietnam, Thailand, and the Philippines. The efficiency of the units sold today will lock in the region's electricity demand for two decades — making standards and labelling the decisive lever.
Sub-Saharan Africa
Lowest access, highest exposure, solar leapfrog
With single-digit AC access and severe heat, Africa faces the deepest cooling gap — and the greatest opportunity to leapfrog inefficient models. Off-grid solar refrigeration and solar cold chains are already transforming vaccine and food preservation in rural areas.
North America & Japan
Near-universal access, peak-load pressure
With AC in the vast majority of homes, the challenge is not access but grid stress, aging equipment, and refrigerant leakage. Heat pumps, demand response, and efficiency standards are the frontier of decarbonizing an already-cooled society.
The pattern that unites the regions
Across every case study, the same dynamic recurs: access, efficiency, and grid resilience advance together. Regions that pair rapid access expansion with efficiency standards avoid the double trap of unaffordable bills and overloaded grids; regions that treat cooling as an appliance market repeat it.
The regions succeeding fastest share three traits: a national plan that treats cooling as infrastructure, standards that keep inefficient equipment out of the market, and targeted programmes for the populations that markets alone will never reach — the rural poor, the urban informal sector, and the institutions that serve them.
The Way Forward
Scenarios for the Century of Heat
The future of cooling is not predetermined. Three divergent paths lead to very different worlds — and the difference between them is measured in lives, not just degrees.
Projections of cooling energy demand diverge sharply depending on the choices made this decade. Under a business-as-usual path — cheap, inefficient air conditioners sold into hot, growing markets — cooling electricity demand could roughly triple by 2050, straining grids and locking in emissions. Under an efficient cooling path — aggressive minimum standards, better buildings, and smart controls — that growth could be cut roughly in half. A sustainable cooling for all path adds the refrigerant transition and clean power, bending the curve toward a system that cools everyone while adding minimal climate burden.
The prize extends far beyond energy. Reliable cold chains reduce post-harvest food loss, strengthen vaccine delivery, and unlock agricultural incomes. Productive, safe workplaces protect the labour that drives emerging economies. Heat-resilient cities preserve health and livability as temperatures rise. Sustainable cooling is, in other words, a development strategy — a way to make growth itself compatible with a hotter climate.
The financing and institutional agenda is clear: build cooling into national energy and urban plans; tighten standards and enforce them; finance the upfront cost of efficient equipment for low-income households; expand clean, reliable power to the unelectrified; and accelerate the refrigerant transition in lockstep with efficiency. Each element is proven; the task is to deploy them together, at speed, and at the scale of the need.
Scenario A
Business as usual
Inefficient units flood hot markets; grids strain; emissions and bills rise. Cooling triples its electricity demand — and its climate burden.
Scenario B
Efficient cooling
Standards, buildings, and smart controls cut projected demand growth roughly in half while expanding access.
Scenario C
Sustainable cooling for all
Efficiency plus low-GWP refrigerants plus clean power: a system that cools everyone with minimal climate cost.
Conclusion
Adaptation success in the 21st century will be measured in degrees — and in access. The societies that thrive will be those that design environments, technologies, and institutions that keep people safe from heat while minimizing the climate burden of doing so. Cooling is not the whole of climate adaptation. But in the century of heat, it is the part that touches every life.