Prise de décision en contexte d’incertitude pour l’adaptation au changement climatique // Decision-making under deep uncertainty for climate change adaptation

Thèse en cours de Niklas Gärtner

Supervisors : Julie Jebeile (Universität Bern) and Isabelle Ruin

Summary :
My doctoral research focuses on decision-making under deep uncertainty in the context of climate change adaptation. State-of-the-art climate science generates a vast array of heterogeneous information, often accompanied by significant uncertainties due to the high complexity of climate change. These uncertainties arise from sources such as ensembles of climate models (multi-run, multi-model, multi-scenario), climate proxies, reanalysis data, and storylines, and are expressed in terms of model spreads, probabilities, and likelihoods. In this context, decision-makers face considerable challenges, particularly when different pieces of evidence conflict, as is the case when successive generations of climate models disagree – even on the direction of projected changes. How, then, can practitioners ground their decisions and actions on such a complex and sometimes contradictory evidence base ?
To address this question, my research explores theoretical and practical dimensions of decision-making under deep uncertainty. Initially, I review the literature to identify the most suitable theoretical frameworks for decision-making in this context, evaluating approaches based on utility theory, reasoned action, and trust. This involves clarifying normative expectations for e.g. robust and precautionary decisions while also accounting for contextual factors such as the vulnerability, resilience, and adaptive capacity of the territories in question – considering their economic, social, environmental, and biodiversity dimensions.
To test the applicability of decision-making theories, I will analyze both experimental and real-world contexts. Experimental work will leverage climate service demonstrators, such as those developed by ‘PC3-DEMOCLIMA,’ while real-life studies will focus on monitoring and analyzing how territorial actors integrate the TRACC (Reference Warming Trajectory for Adaptation to Climate Change) into their planning documents. By combining theoretical insights with practical applications, my research aims to provide actionable guidance for making informed, evidence-based decisions in the face of deep uncertainty.