Method development for including land-use change greenhouse gas emissions in Life Cycle Assessment

Abstract

The UNEP-SETAC framework is the most well-known framework for including land use and land-use change (LULUC) impacts in life cycle assessment (LCA) in scientific literature. Yet issues regarding the framework’s validity have been recognized by several researchers and the framework has not been implemented in common LCA practices. Due to the need in both policy and science for a consensus on a method to include greenhouse gas (GHG) impacts deriving from LULUC in LCA, research in an improved framework is warranted. Therefore, the objective of this master thesis was to evaluate the UNEP-SETAC framework and propose improvements, with the overall goal to advance the method development of LULUC frameworks that quantify LULUC GHG emissions of agricultural products in LCA studies.

A significant issue that was found was the UNEP-SETAC framework’s applicability to an attributional LCA (ALCA). The framework provides the LCA practitioner with various methodological choices that should be taken based on either an ALCA (i.e., an LCA that provides information on what portion of global burdens are associated with a specific product life cycle) or consequential LCA (CLCA; i.e., an LCA that provides information on the environmental burdens that occur, directly or indirectly, as a consequence of a decision). The analysis showed that the UNEP-SETAC framework is not suitable in its current form for an ALCA study.

To advance method development, several weaknesses of the UNEP-SETAC framework were addressed in an improved conceptual framework. Using this improved framework for ALCA studies leads to additive results of all measurable anthropogenic emissions, relative to a pre-anthropogenic baseline. For CLCA, the forgone sequestration can be quantified to indicate the impact of using the land for the functional unit, relative to abandoning the land and letting it regenerate.

A comparative LCA case study comparing the LULUC GHG emissions of sunflower oil cultivated in France and palm oil cultivated in Indonesia showed different results using the UNEP-SETAC framework and the improved conceptual framework. When using the UNEP-SETAC framework, it could be concluded that that the use of land for 1 kg of sunflower oil caused more GHG emissions, while when using the improved conceptual framework, it could be concluded the use of land for 1 kg of palm oil caused more GHG emissions. The results of the case study illustrated that the choice of LULUC framework can invert the conclusions of LULUC GHG emissions between two alternatives. This showed that it is highly important that the academic community reaches consensus on using one type of framework.

It is essential that governmental and international bodies are aware of the weaknesses in the UNEP-SETAC framework that were identified in this thesis, as they potentially lead to inverted conclusions and a misinterpretation of results. For mitigation strategies of LULUC GHG emissions to be successful, it is important that the scientific community develops a more sound framework for including LULUC GHG emissions in LCA.