APOLLO: A Fuzzy Multi-criteria Group Decision-Making Tool in Support of Climate Policy

Multi-criteria decision-making is a daily process in everyday life, in which different alternatives are evaluated over a set of conflicting criteria. Decision-making is becoming increasingly complex, and the apparition of uncertainty and vagueness is inevitable, especially when related to sustainability issues. To model such lack of information, decision makers often use linguistic information to express their opinions, closer to their way of thinking, giving place to linguistic decision-making. However, the participation of multiple experts usually involves disagreements within the group, leading to unreliable solutions. To assist in decision-making and reduce such complexities, A grouP decisiOn fuzzy TOoL in support of cLimate change pOlicy making (APOLLO), a fuzzy decision support system, is introduced to deal with such problems in climate change and policy. The tool implements a framework for group decision-making, using 2-tuple Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), coupled with a new consensus measuring model to increase robustness of selected solutions. The operation of the software tool is showcased in a real case carried out in Austria, where stakeholders were asked to assess the risks embedded in pathways for decarbonizing the country’s iron and steel sector. Results indicate that a coherent strategy addressing funding and competition issues is necessary, with experts displaying a consensus level of 85% in that these risks are the most threatening for the transition.