Pedro Guertler、Larissa Gross／脫貧之路 空調、冷鏈需求增加 地球將變得更熱

As records tumble across Europe in a second heatwave of the summer and as people across China and North America are also feeling the heat, we can literally sense how influential cooling is for our wellbeing, productivity and environment.

Cool buildings and vehicles, as well as cooling in industrial processes and "cold chains" that ensure our food and medicines are safe, are things we either take for granted or increasingly come to expect.

With demand for cooling expected to soar in major developing economies as the world becomes warmer and hundreds of millions of people become able to afford their first air conditioner, unmanaged cooling growth could cause a surge in greenhouse gas emissions and hamper our ability to manage global warming.

Yet solutions to this challenge do exist. Efficient and clean development of cooling can make a significant contribution towards respecting the 1.5C and 2C Paris temperature limits. Moreover, those limits can check the need for cooling, reducing the scale of the challenge it poses.

Cooling in a warming world

In a warming world, access to cooling is not a luxury: vulnerable populations depend on it for nutritious food, safe medicines, productivity and protection from extreme heat.

Some 470 million people in poor rural communities in hot climates lack access to electricity and therefore to conventional space cooling and refrigeration technologies. This includes "cold chains" for the transport of temperature-sensitive goods such as medicines, or getting food from farm to fork with minimal wastage. This lack of access to cooling can limit good health outcomes, agricultural productivity and opportunities for economic self-sufficiency.

Food loss and waste amounts to one third of all food produced for human consumption, placing avoidable pressures on land-use and associated greenhouse gas emissions. Smallholders lacking access to electricity disproportionately suffer supply chain losses of food, which are at least twice as high as in the most efficient supply chains. Incomplete and broken cold chains are a key contributing factor to this loss.

Some 630 million people on the lowest incomes in the hottest cities – often in poor quality housing – may only have intermittent access to cooling services or struggle to afford them. This can compromise food safety and exacerbate vulnerability to heat stress from increasingly frequent and intense heatwaves brought about by human-induced climate change.

Energy system challenges

There are 1.6bn residential air conditioners in use today. Most households in hot countries have not yet purchased their first air conditioner (AC), and ownership could rise to 5.6bn by 2050.

Business-as-usual development of space cooling, with incremental improvements in energy efficiency standards, means that energy demand for it could triple by mid-century to 6,200 terawatt hours (TWh). This is the equivalent to over a quarter of today's global power consumption for all uses and could require power generation investment of some $3.2tn.

On hot days, space cooling demand can place significant stress on power grids. Almost exactly two years ago during summer in Beijing, cooling for buildings contributed more than half of daily peak power demand.

In Indonesia and India, business-as-usual cooling growth would mean AC contributes over 40% of peak power demand over the course of a year by 2050, up from 10-15% today. Daily peaks already nudge 60% in some Indian cities.

Today's unmet cooling needs extend well beyond cooling buildings into cold chains, mobility and industry. Looking at this wider range of uses, while ensuring full access to cooling to protect vulnerable people from the effects of heat extremes and broken cold chains could mean energy demand as high as 15,500TWh in 2050 – two thirds of today's global power demand – even if aggressive energy efficiency and demand-response standards for cooling equipment were to be pursued.

Greenhouse gas emissions

Current, conventional cooling technologies, such as air-conditioning and refrigeration, rely on human-made refrigerants – usually fluorinated (F) gases, such as hydrochloroflourocarbons (HCFCs)  – that can be 10,000 times more potent than CO2 in causing global warming.

Left unchecked, F-gases could account for nearly 20% of total greenhouse gas emissions by 2050. This is why the phase down of the current generation of F-gases under the Kigali Amendment to the Montreal Protocol – and its ratification by national governments – will have such important consequences for efforts to limit global warming.

Cooling's large and growing demand for electricity – in the major growth markets often generated with coal – means that it poses a serious challenge to reducing power sector emissions.

In 2017, the amount of residential AC load connected to the world's power grids – estimated at 100 gigawatts (GW) – exceeded that year's record addition of solar capacity, some 94GW. This suggests unmanaged cooling growth could play a significant part in keeping fossil-fueled sources of electricity on the system.

Systemic solutions

There are abundant solutions to managing cooling demand in a warming world, while allowing for increased access.

The most rapid option is the introduction and better enforcement of more stringent efficiency standards for equipment. Adopting standards equivalent to the most efficient AC available on the market today could halve halve 2050 energy demand for space cooling.

Finding ways to reduce reliance on "conventional" cooling is also likely to be needed if the world is to meet its climate goals, while ensuring access to cooling grows.

This could include a mix of "responsive" cooling equipment and cold storage to manage peak demand for electricity, as well as smarter building codes incorporating passive cooling design and cooler urban planning.

It also includes simple solutions such as more reflective "cool roofs" and shifting the delivery of cooling to district energy systems in cities and off-grid systems in remote areas.

Delivering these solutions will require regulation, finance and business models – for example "cooling as a service" – sensitive to national and local contexts and geared to meeting cooling requirements.

It will also mean including all those with a stake in the need for and provision of cooling services across environment, health, agriculture, productivity, innovation and trade.

The critical first step is to recognise the strategic significance of cooling, not only in relation to climate mitigation and resilience to warming, but also for security and prosperity.