The article presents the results of a study of the process of transporting grain from the territory of Ukraine in global supply chains. In order to study the negative impact of the transport sector, a simulation model of the existing logistics system was developed, namely, using only road transport. The model was developed using Java SE technology based on the agent-based and discrete-event principles. As a result of a series of experiments based on the grain supply chain through the Mykolaiv commercial port, it was found that the actual CO2 emission rates per unit of transport work are 12.8 kg per tonne and 32.9 kg per 1000 tonne-km.