How Many Deaths Does My Car Journey Cause?

I was asked how many future climate deaths are caused by the CO₂ emitted from a longish commute in a fossil-fuelled car. When expressed in terms of future minutes of lives lost per hour driven, the answer is surprisingly bad. See below.

The Nature paper The Mortality Cost of Carbon (MCC) estimates that, if we later hit 2.4°C of warming, then adding 9,318 metric tons of carbon dioxide in 2020 causes one excess death globally in expectation between 2020-2100. For more explanation, please see How Many Children Can One Oil Depot Kill?

The Commute

Consider the 32-mile journey from Cambridge to Bedford taking 50 minutes, according to Google Maps. Let's assume the car's fuel efficiency is 40 miles/gallon. And we know that burning 1 gallon of petrol or diesel emits approximately 10 kgCO₂.

Therefore this car journey emits 32 / 40 x 10 = 8 kgCO₂ and causes 8 / 1000 / 9,318 = 0.000000859 future deaths.

Most climate deaths are likely to occur in the Global South, where life expectancy is around 70. Let's guestimate that the millions of future deaths caused by man-made climate change cause the victims to lose an average of 35 life-years.

So our car journey (averaged over future climate deaths) leads to a loss of 0.000000859 x 35 = 0.000030 life-years, ie 16 life-minutes.

Scaling this up we find:

A typical 1-hour drive in a fossil-fuelled car causes 19 life-minutes to be lost in future climate impacts

Notes

It's important to note that this is a central estimate, and the range in the MCC paper is very wide! Please see How Many Children Can One Oil Depot Kill? - Notes & Sources.

That said, this figure is likely to be an underestimate for the following reasons:

• The MCC study considers only directly temperature-related deaths; there will be many more deaths that it does not cover, eg from food shortages, drought and forced migration.
• It doesn't take into account the emissions caused by manufacturing the car.

What Can I Do?

Switch to an electric car or public transport. If that's not possible, see How To Offset Your Carbon Emissions.

Credits

Thanks to Dr Hannah Copley for posing this question.