This dissertation treats a topic that has received increasing attention as of late, namely that of the environment and in particular increasing levels of CO₂ emissions caused by transport. The aim of the dissertation is to explain how a shipper, through various measures, can reduce transport-related CO₂ emissions when centralising a distribution system and how this affects the provision of cost efficient customer service. Earlier research has stated that this type of structural change is considered unfavourable from an environmental viewpoint as it increases the amount of transport work generated by the system and thereby transport-related CO₂ emissions. The argument that is made in this dissertation, however, is that transport work is only one aspect to consider when evaluating how transport-related CO₂ emissions are affected by this type of structural change. The reason for this being that a change in structure and management of the same can enable a shipper to make other changes within the distribution system that can prove beneficial from an environmental perspective as they decrease the amount of CO₂ emissions per tonne kilometre.

Theoretically, the dissertation has its foundation in two different areas in logistics research. The first area concerns logistics and the environment, where the frame of reference examines measures discussed in previous research with reference to how a shipper can reduce CO₂ emissions related to transport. The second area treated in the frame of reference concerns how costs and service are affected by the structural change of centralising a distribution system and how this relates to the measures discussed in the first part of the framework.

From a methodological viewpoint, the dissertation is based on case studies. These are presented in four appended manuscripts (a licentiate thesis and three papers), where the results of these studies are used as empirical input for the synthesising analysis that is led in the dissertation.

A key deliverable from the research presented in this dissertation is a classification of measures that increase transport-related CO₂ emissions and measures that decrease transport-related CO₂ emissions when a distribution system is centralised. By presenting this classification, the dissertation extends previous research on the environmental impact of various logistics strategies, where centralised distribution is an example of such a strategy. With regards to this classification, it is concluded that a shipper that seeks to centralise its distribution system in a more CO₂ efficient manner will aim to identify a structural configuration that minimises the increase in transport work. This is imperative as there is a close link between transport work and CO₂ emissions. Hence, a CO₂ efficient centralised distribution system will include more central warehouses than that advocated by earlier research on centralised distribution. This in turn implies that a shipper may not reach the full potential in economies of scale as advocated in earlier research. However, such a configuration will simultaneously lead to less transport work, whereby a shipper will be able to offset the increase in transport work by employing measures that decrease the amount of transport-related CO₂ emissions per amount of transport work. The results also indicate that in addition to reducing transport-related CO₂ emissions, some of these measures come with a cost incentive. By employing such measures, a shipper can come to compensate for the potential loss in economies of scale caused by employing a structural configuration that seeks to minimise the increase in transport work rather than to maximise economies of scale. By this means, the dissertation contributes to research on centralised distribution by considering how a reduction in transport-related CO₂ emissions is interrelated with the provision of cost efficient customer service.