However, our agricultural system uses fossil fuels to produce food. Growing food on an American farm emits something like 0.0064 pounds (2,9 grammes) of carbon dioxide equivalents for every calorie produced. That means a runner eating a standard American diet is responsible for the emission of 19.2 pounds (8,7 kg) of carbon dioxide during a marathon.
You might be surprised at how these totals compare to driving. The EPA estimates that the average vehicle on American roads emits 0.87 pounds of carbon dioxide per mile (247 grammes de CO2 par km). So, over 26.2 miles (42 km), a car would account for just 22.8 pounds (10,34 kg) of greenhouse gas — about 19 percent more than the runner.
source : https://www.syracuse.com/news/2012/11/even_a_runner_leaves_a_carbon.htm
Pour résumer :
Un coureur fait un marathon, il aura émit 8,7 kg de CO2 dans l'amotsphère
Une voiture essence qui fait 42 km, elle émet 10,34 kg de CO2 dans l'atmosphère
Soit seulement 19% de plus qu'un joggeur
El famoso réchauffement climatique à cause des voitures