Originally posted in Scientific American, May 10, 2022.
We need to protect vulnerable people from killer heat without destroying the environment
A record-breaking heat wave is sweeping South Asia, threatening hundreds of millions of people with deadly temperatures well above 100 degrees Fahrenheit. As the world heats up, billions of people need air-conditioning. This 120-year-old technology used to be considered a luxury, but in the age of climate change, it is a necessity for human survival. Understandably, this has created anxiety over the climate threat of a world overrun with ACs. But the coming boom in air-conditioning is an essential shift toward reducing the enormous gap in cooling availability that exists between rich and poor people and nations—and toward producing a more equitable world.
Of the two billion AC units currently in use across the globe, the majority are heavily concentrated in wealthy countries in North America and East Asia (with Europe, which generally has a milder climate, in a distant third). In the hottest regions of the world, AC ownership is just 12 percent compared to more than 90 percent in the U.S. and Japan. But as populations become wealthier and temperatures continue to rise, this trend will change—dramatically.
According to the International Energy Agency (IEA), the world is projected to add another four billion AC units by 2050, largely driven by demand in emerging economies such as India and Indonesia. Air conditioners can be quite energy-intensive, particularly if inefficient models are used, meaning these countries will need a lot more electricity. In fact, AC could account for 20 to 44 percent of the peak load in India’s power grid by 2050. If this power is supplied by fossil fuels—and in areas of highest growth, including India and Indonesia, it usually is—the increase will have substantial impacts on global greenhouse gas emissions.
These projections are scary. Could the need for cooling wind up cooking the planet? Actually, this is the wrong question to ask. Ditching AC is not an option, and it should not be the goal either. Instead of a threat, this should be seen as an opportunity to explore greener cooling technology and encourage the adoption of renewable energy. Meanwhile air-conditioning has the potential to equalize conditions between different countries as an essential part of climate justice. In the temperate climates of the northern U.S. and northern Europe, lack of cooling is usually a summer inconvenience. In the tropics, heat waves last longer, reach higher temperatures and are far more deadly. Last year citizens of Niamey, the capital of Niger located on the edge of the Sahara Desert, suffered through 100-degree-F heat for 174 days. In Basra, Iraq, the number of 100-degree-F days was 168; in Mumbai, the number was 62.
To understand what such heat waves mean for people physiologically, researchers use the “wet-bulb temperature,” which combines both heat and humidity to account for how the human body experiences extreme heat. At a wet-bulb temperature of about 90 degrees F, labor becomes unsafe, and if it climbs past 95 degrees F, the body can no longer cool itself, leading to illness and even death. If global temperatures rise 2 degrees Celsius (about 3.5 degrees F), as some projections show, South Asia could experience more than twice as many unsafe-labor and life-threatening temperatures than it does today. Limiting temperature rise to 1.5 degrees C (about 2.5 degrees F) will halve this exposure, but millions in the region will still be vulnerable to extreme heat stress. This isn’t a hypothetical future problem. The past nine years have all been among the top 10 warmest on record. This year heat waves came earlier than ever for South Asia, setting a March record. Heat waves in India have caused the death of at least 6,500 people since 2010. In 2015 alone about 3,500 people died in India and Pakistan during the fifth deadliest heat wave ever recorded.
While mortality rates skyrocket during heat waves, there are other detrimental impacts to consider. High temperatures have been shown to disrupt labor productivity, causing considerable economic losses in South and Southeast Asia, sub-Saharan Africa and Central America. In 2020 an estimated 295 billion potential work hours were lost globally consequent to extreme heat, with the greatest impacts in the agriculture sector of poor countries. The resulting loss of income can be devastating for workers.
How can the world avert this disaster? First, by accepting that adequate cooling is an urgent human need in a warming climate. The disruption caused by extreme heat will keep growing, and access to equitable cooling technology will be necessary to ensure the survival and economic prosperity of the billions of people living in tropical regions. In fact, the longtime prime minister of Singapore, Lee Kuan Yew, considered air-conditioning the single most important invention for his country’s development.
Manufacturers and governments must also innovate to develop affordable and efficient AC technology using refrigerants with lower climate impact. According to the IEA, today’s average AC units are only 10 percent more efficient than those sold in 2010—but effective policy and technology can double the efficiency of AC units and reduce cooling energy demand by 45 percent by 2050. To drive up efficiency, the practice of dumping older—and thus less efficient and more environmentally harmful—models in poor countries should be restricted. In addition to setting efficiency standards, governments (along with philanthropic organizations and manufacturers) must invest in driving down the cost of higher-quality air conditioner models. Switching to alternative refrigerants can also reduce cooling emissions significantly in the coming decades.
Now is the time to build cleaner and more equal energy systems. For instance, demand for cooling is shifting to tropical regions that are ideal for solar power generation, and daytime temperatures correlate closely with solar peaks. This means that AC units could be an important driver of demand at just the times when solar generation is peaking. As a result, more solar power would actually get used during peak hours, increasing the financial viability of the renewable energy sector across the world. Air conditioner deployment should also be complemented by broader efforts to reduce overall cooling energy demand. This means improving building efficiency and exploring nonelectric cooling technologies where applicable.
Cooling does not have to blow the carbon budget. In fact, if leveraged correctly, it could be a driver of equity, economic growth and the transition to clean energy.