Fig. 2: Predictions of a parsimonious model.

Modal share and CO₂ emissions in cities. a Modal share of cars versus the probability \(p\) to have access to a rapid transit station, tested for various cities in the world. The red line is the prediction of a simple model³⁵, without any tunable parameter. b Prediction for the transport-related emitted CO₂ from the model described in ref. ³⁵. Even if fluctuations are not negligible, this model allows us to identify the critical parameters for CO₂ emissions: the surface area of the city, the access to mass rapid transit, and congestion effects. Figures from ref. ³⁵.