| Summary: | Human activity has greatly affected the natural environment. The production and consumption of materials and products have contributed to the destruction and degradation of ecosystems worldwide. Evidence suggests that we increasingly endanger the ability of the environment to support our way of life. Efficient use of materials (e.g. waste prevention) and circulation of materials (e.g. recycling) are widely acknowledged means to reduce the impacts of production and consumption. However, for many reasons, the efficient and circular use of materials is not sufficient to meet targets for environmental sustainability. To better understand this issue, the thesis explores the climate change mitigation benefits of changes in material use in the global paper life cycle. Efficient and circular use of materials is defined as the fulfilment of the potential of waste to be used as a resource and measured through a recovery potential indicator. A quantitative model describes material flows, energy flows, and GHG emissions of the global paper life cycle from 2012 to 2050. The emissions are compared with targets based on the carbon budget for staying below 2 degrees average global warming. The model scenarios reflect varying degrees of use of waste as a resource. The results show that full use of waste as a resource is not sufficient to meet the GHG targets for the paper life cycle but strong decarbonization of energy inputs is. In fact, increased recycling yields more emissions unless the decline in energy from combustible waste from virgin pulping is compensated for with low carbon fuels. The thesis concludes that the recovery potential indicator is suitable for analysing large material systems and may be used in public policy. To address climate change, guiding principles for material use need to consider the energy and carbon intensity of material processing and should be constantly evaluated.
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