Development of travel plans including at least one environmental impact indication

To assist in the development of travel plans, at least one first and at least one second user input mechanism is provided via a graphical user 5 interface to a user. In response, first travel inputs and second travel inputs are received and respectively used to derive baseline and revised travel parameters, which travel parameters respectively include a baseline and revised environmental impact indication. The baseline and revised travel parameters, including the environmental impact indications, are presented 10 via the graphical user interface. Difference values between the respective baseline and revised travel parameters may be determined and likewise presented. Furthermore, cost and commute time indications may be determined in a similar fashion, i.e., based on the first and second travel inputs, and subsequently presented. The environmental impact indications 15 may be provided in the form of estimated carbon emissions.