Long-term scenarios generally project a steep increase in global travel demand, leading to an rapid rise in CO2 emissions. Major driving forces are the increasing car use in developing countries and the global growth in air travel. Meeting the 2 °C climate target, however, requires a deep cut in CO2 emissions. This paper explores how extensive emission reductions may be achieved, using a newly developed travel model.
This bottom-up model covers 26 world regions, 7 travel modes and different vehicle types. In the experiments, we applied a carbon tax and looked into the model’s responses in terms of overall travel demand, modal split shifts, and changes in technology and fuel choice. We introduce two main scenarios in which biofuels are assumed to be carbon neutral (not subject to taxation, scenario A) or to lead to some greenhouse gas emissions (and therefore subject to taxation, scenario B). This leads to very different outcomes. Scenario A achieves emission reductions mostly through changes in fuel use. In Scenario B efficiency improvement and model split changes also play a major role. In both scenarios total travel volume is affected only marginally.