Demand for air conditioning is set to surge by 2050

WHEN JOE BIDEN was a newly elected senator, he asked James Eastland, his fellow in Congress, to tell him the most significant thing that occurred during his long time in the chamber. “Air conditioning,” Mr Eastland replied. Summer in Washington is stifling, so in the past members of Congress departed by June. “Then we put in air conditioning, stayed year round, and ruined America,” he reportedly said, sardonically.

These days the main concern about air conditioning (AC) is its environmental cost. A report in 2018 by the International Energy Agency, a Paris-based energy think-tank, found that AC units and electric fans consumed nearly 10% of global electricity in 2016. Just 8% of the 2.8bn people living in the hottest parts of the world (places where the average daily temperature is higher than 25°C) owned AC units five years ago, but that proportion is expected to increase rapidly. Energy consumption by AC will rise too: the IEA expects it to triple by 2050. This will lead to increased emissions of carbon-dioxide and greenhouse gases such as hydrofluorocarbons, which are used as refrigerants in AC units and can leak into the atmosphere. The United Nations estimates that if hydrofluorocarbons are not phased out, they could cause temperatures to rise by up to an extra 0.4°C by 2100.

Apart from the impact on the environment, increasing use of AC could have social and political effects, too. A new paper by researchers from the University of California, Berkeley and the University of Mannheim set out to understand the relationships between climate, income and residential air conditioning. Their model suggested that wider use of AC will save lives that would otherwise be taken by heatstroke or the exacerbation of other health conditions—550,000 a year by 2050 in India alone—but it will disproportionately benefit those with higher incomes. Poorer people without AC are more likely to be less productive or to die than those who can afford it. Heat hinders learning and lowers test scores, causing poorer children to fall behind. And the use of AC itself contributes to global warming, making life even hotter for everyone.

The authors compiled household-level data on income and AC ownership from 16 countries, including America, China, India, Nigeria and Pakistan. They matched ownership with local climate data to create a model that tracks the adoption of AC against income levels. It found a sharp increase in ownership when annual household incomes exceed $10,000 annually.

Combining the model with forecasts of income levels and the climate over the next 30 years, they predicted that the percentage of households with air conditioning across the 16 countries would rise from an average of 35% in 2020 to 55% in 2050. The researchers forecast that rising incomes, not global warming, will account for 85% of the growth.

Finally, the paper analysed AC use by income groups in each of the 16 countries. In some countries, such as China, the gap in AC use between the richest and poorest households is projected to narrow as a larger number of low earners take home over $10,000 a year. But in countries such as Pakistan, Sierra Leone and South Africa, the gap in AC usage is predicted to widen. AC ownership is still rare in those countries. In Pakistan, for instance, 12% of the richest third of households and 0.6% of the poorest third currently have AC. By 2050 those shares are expected to rise to 38% and 5% respectively. On a hot day AC feels like a blessing. But as the planet warms up, not all will gain relief from it.