Warmer planet makes social mobility harder

By the end of this century, sea levels will be a foot higher than in 2000. The average person is 31 years old today, and given that global life expectancy is 73.5 years, they may be dead by 2068. So, why should we worry? Didn’t Keynes say, “The long run is a misleading guide to current affairs”?

But climate change is affecting us now. It has a bearing on your mood, your income, and your children’s grades. University of Pennsylvania economist R Jisung Park drives home these points in his book Slow Burn. Take income first. It’s an acknowledged fact that income inequality is rising. The rich, who live, travel and work in air-conditioned spaces, are getting richer, but the poor have stagnated in a hot and sweaty place. A study by University of Chicago economists found that worker productivity in India declined 2-4% for every degree Celsius rise in temperature above the comfortable level.

If the “mean temperature” at the workplace crossed 25°C, which could mean day temperature of 30°C and night temperature of 20°C, output fell 32%, or almost a third.


Now, people who make bricks, weave cloth, etc, get paid per piece of product made, so while they suffer in the heat, their daily earnings drop. That’s not fair, but they can’t stop working because they aren’t qualified for white-collar work. Their children could break out with good education, but as Park shows with data, heat is making this harder.

When researchers correlated 4.5mn exam results of students in New York City schools with the temperature on exam day, they found that student performance fell by 3-4 points on days when the temperature exceeded 32.2°C. This is a small penalty for someone who usually scores 95%, but a setback for a child who passes with low marks. Park says “average” students are 10% less likely to pass on a hot day than on a cool day.

Now, poorer students – children of those poor labourers – typically are at a disadvantage because their homes are crowded, noisy, lack ventilation, and get hot and stuffy. So, passing exams with good marks and getting into good colleges with scholarships, indirectly, stalls upward mobility.

Generally speaking, leaving out exceptions like Singapore and UAE have 8% lower per capita income for every 1°C rise in average temperature, within US, hotter municipalities tend to be poorer. That’s because places like Mumbai will have 100 extra days of mean temperature over 32.2°C by 2060, relative to the pre-industrial age.
Beyond income and education, heat makes us more error-prone. Data from 150,000 tennis matches shows players were 7% more likely to double-fault on hotter days.

Analysis of 500 helicopter crashes showed a strong correlation between temperature and human error. And a British navy experiment in the 1950s revealed that errors in reading Morse code jumped from 11-12 per hour in the 29.4-32.2°C temperature range to 95 per hour at 40.5°C. Oh, and people start honking sooner at traffic lights on hotter days, and rates of rape and murder inch up with heat too. A warming planet clearly isn’t a good place for your average Joe and Jane.