Processes for determining carbon dioxide emission impact. In one process, a carbon dioxide emission impact is determined for each stage of a multi-stage trip. A traveler may make adjustments to the trip to offset the carbon dioxide emission impact of the entire trip and achieve a desired sustainability level for the trip. In another process, that may be used in the first process, the carbon dioxide emission impact for a vehicle is determined based on the entire life span of the vehicle, including a carbon dioxide emission impact for a production stage, a carbon dioxide emission impact for a usage stage, and a carbon dioxide emission impact for an end of life stage.