Climate scientists are now unequivocal about at least one thing: while efforts to curb greenhouse gas emissions remain—more than ever—crucial to limit the consequences of climate change in the decade(s) to come, the phenomenon is now partly irreversible. In concrete terms, this means that some of its impacts are inevitable. The frequency, intensity, and geographic distribution of these future impacts on various regions remains to be clarified. Yet, it seems certain that many will have to face changes in climatic and environmental conditions: this will inevitably require a rethinking of current development models.
Therefore, adaptation to climate change now appears to be as important and urgent as strategies aimed at limiting greenhouse gas emissions; as endorsed by the Paris Agreement itself at the global level (Magnan et Ribera, 2016). Anticipating the effects of climate change is no longer one option among many but a necessary condition to ensure the sustainable development of regions at all levels. The question that then arises is how these effects can be anticipated for the purposes of adaptation (Tubiana et al., 2010). Since the goal of adaptation is to reduce vulnerability in the long run, an important first step in formulating a response lies in the appropriate evaluation of the vulnerability of regions to climate change (Nguyen et al., 2016).
This joint paper aims to present two different approaches of vulnerability assessment: the “structural vulnerability” approach developed by FERDI, and the “vulnerability trajectories” approach developed by IDDRI. The objective is to confront these two approaches in order to draw up an analysis of potential pathways to adaptation, be it at the local level through regional public policy or at the global level through the international negotiations of the United Nations Framework Convention on Climate Change (UNFCCC). With a view to being as concrete as possible, this comparison of approaches is applied to a case study on which both FERDI and IDDRI have extensive expertise: Reunion Island (located in the south-western Indian Ocean), and, more specifically, the vulnerability of its coastal zones to sea-related risks.