The growth of e-commerce has been accompanied by concerns about its environmental sustainability compared to that of bricks-and-mortar offline shopping. The media often considers e-commerce to be less sustainable despite the lack of conclusive studies to support this viewpoint. There are a few quantitative studies available in the literature that demonstrate that the differences in overall emissions strongly depend on the type of industry and the boundaries considered.
A study by Siragusa and Tumino applies an activity-based approach to assess the environmental impacts (in terms of kgCO2e) of the online and offline purchasing processes in the grocery industry for all shopping phases: replenishment, pre-sale and sale, picking and assembly, delivery, and post-sale. The assessment model was applied in Italy, where e-grocery has experienced significant annual growth.
This study compared the two purchasing processes while not only considering last-mile delivery but also including the energy consumed in all the other transport activities from the point of divergence (specifically, the replenishment of the store and of the dedicated warehouse that fulfills online orders) and by buildings, both warehouses, and stores.
Overall, the results indicate that e-grocery is potentially more sustainable than bricks-and-mortar shopping, with emissions ranging from 10 to 30 percent lower, depending on the specific context.
The results of the present study indicate that the last-mile step or customer’s trip – which represents the core of most studies – is responsible for only a portion of the overall emissions. This study also confirmed that the basket size is crucial: the results indicate that when it decreases, e-commerce starts to lose its environmental advantage over offline shopping.