Aviation carbon taxes have occasionally been debated as a measure to curb aviation carbon dioxide (CO2) emissions. This paper presents a simulation study on the effects of high aviation carbon taxes on tourism and its related CO2 emissions. The paper investigates the scenario in which, as a result of high aviation carbon taxes, air fares increase by 50%. To assess such impacts, choice probabilities of vacation alternatives, which were conceptualized as portfolios consisting of a destination, mode of transport, accommodation type, and length of stay, were simulated by using a portfolio vacation choice model. Lower and upper bounds of the impacts were derived. Simulation results suggested that a substantial reduction of the contribution of tourism travel to anthropogenic climate change could be achieved. Tourism trani-related CO2-equivalent emissions were estimated to drop between 9% and 32%. Furthermore, it was found that the choice probability of nearby destinations (<200 km) increased considerably: between 4% and 18%. It was also found that the choice probability of short vacations (<1 week) also increased considerably: between 3% and 11%.