Abstract: Methods and systems are provided for producing tradeable environmental attributes such as carbon offsets from the physical movements of users. The solution incorporates the use of a modal shift optimization application executed on a user's device. The application locates alternative transport options, and monitors the user's physical movements as the user travels to the destination using one of the alternative transport options. A carbon offset system receives the user's trip data and calculates project greenhouse gas (GHG) emissions for the user's journey. The carbon offset system also calculates baseline GHG emissions for a baseline transport option (e.g. single-occupancy private vehicle trip), based at least in part on the baseline emissions factor and a discount factor. The carbon offset system extracts the GHG emissions savings by determining a difference between the baseline and project emissions, which can be validated and verified for the production of carbon offsets.