The carbon footprint of food waste generated depends on where it happens in the lifecycle.  If food waste happens on a farm, the emissions from transport, storage, and use are not added to the impact of the food waste.  Clune et al. (2017) assumes food losses in its numbers including storage at the regional distribution center, so any additional food waste is attributed in the retail location and at the home of the end user.  

Food waste assumptions are taken from the US Department of Agriculture – Economic Research Service (USDA ERS, 2019): Loss Adjusted Food Availability datasets.

References

Clune, S., Crossin, E., & Verghese, K. (2017). Systematic review of greenhouse gas emissions for different fresh food categories. Journal of Cleaner Production140, 766-783.

USDA ERS: US Department of Agriculture Economic Research Service. (2019) Loss-Adjusted Food Availability.