The episode in detail
Decarbonisation scenarios that rely on cycling
Kévin Jean, a public health researcher, worked with his lab to assess the health benefits of France’s carbon neutrality scenarios. The source material: the roadmaps from négaWatt, a long-standing player since the 2000s, and ADEME’s four scenarios, ranging from the most frugal to the most technological. These scenarios describe how to transform society to reach carbon neutrality by 2050, with one consistency constraint: energy consumption cannot exceed energy production.
The négaWatt scenario projects multiplying cycling by 7 between 2020 and 2050. An impressive figure on the surface, but one that would still leave France below the current levels of the Netherlands or Denmark. Transport accounts for a third of CO2 emissions in France, and active travel is a major lever for cutting them.
10,000 deaths avoided per year thanks to walking and cycling
By modelling the health effects of the négaWatt scenario, Kévin Jean’s team reaches a striking result: around 10,000 deaths avoided per year from 2040, purely from the physical activity generated by walking and cycling. For comparison, France would need to cut alcohol consumption by 25 to 40% to achieve the same result.
“10,000 deaths avoided per year, that’s a public health policy in itself. There aren’t many interventions that prevent that number of deaths.”
In monetary terms, these benefits represent around 35 billion euros in avoided health costs each year. The gain in life expectancy for the total population is 3 months, equivalent to what was lost at the height of the Covid crisis.
Electric bikes: 75 to 90% of the effort of a standard bike
Electrically assisted bikes play a key role in these decarbonisation scenarios. Contrary to popular belief, meta-analyses show that riders put in between 75 and 90% of the physical effort of a standard bike on an e-bike. You pedal, the joints work, the heart rate rises.
“On an electric bike, you put in between 75 and 90% of the effort you’d put in on a standard bike. The reduction is fairly small.”
Better still, studies show that e-bike users cover more distance and make more trips, offsetting the lower intensity with a higher volume of activity. E-bikes make it possible to include older people in poorer physical condition, and to replace car trips of 10 to 20 kilometres. Their energy footprint stays minimal: the electricity consumption of an e-bike is comparable to lighting a home. And one electric SUV battery could make 60 e-bike batteries.
Not all scenarios are equal for health
The comparison between the ADEME scenarios reveals a striking finding. The most technological scenario, the one that simply replaces petrol and diesel cars with electric ones without changing behaviour, generates no health gain at all. It even produces losses, since the trend towards ever less physical activity continues.
“Different decarbonisation choices can result in very different public health impacts.”
The frugal scenarios, on the other hand, achieve benefits comparable to négaWatt’s. The four scenarios are equivalent from a climate standpoint, carbon neutrality by 2050, but not from a health standpoint. Electrifying the car fleet, moreover, does not eliminate air pollution: electric cars, being heavier, emit more particles through tyre and road surface abrasion.
The tipping point for cycling in Paris
Kévin Jean observes a tipping point in Paris, where cycling has surged over three years thanks to a combination of factors: good-quality cycling infrastructure, transport strikes, the Covid crisis, climate concerns and political will. This tipping point remains local: peri-urban and rural areas haven’t reached it.
The co-benefits beyond physical activity
Physical activity is the main health gain, but the co-benefits of cycling are numerous. Noise reduction, a cardiovascular risk factor whose health cost in France is comparable to that of air pollution according to ADEME. Improved air quality, which benefits everyone, including infants and older people. Road safety, since pedestrian mortality risk is directly linked to vehicle weight. The freeing up of urban space: in Paris, half of public space is devoted to roads and car parking.
“When you make the transition to more cycling-friendly cities, you free up enormous amounts of space for green spaces, for more welcoming cities.”
