Changements climatiques, changements du littoral et évolution de la vulnérabilité côtière au fil du temps : comparaison de territoires français, canadien et sénégalais

The vulnerability of coastal zones to the impacts of climate change and risks is the result of the synergy of natural and human impacts on the natural environment, which together create a vulnerable socio-ecological system. In order to account for that duality, theoretical approaches such as the exposition/sensitivity or risk/hazard couples have been developed for the evaluation of climate vulnerability indices or in risk management. Often, these approaches are only implemented in a punctual manner and do not integrate the historical evolution of the territory and of its vulnerability. Here, we address the historical dimension of vulnerability, that is how the planning, use and vocation of the territories have contributed to create vulnerability. We will describe how the climate vulnerability of certain territories in France, Senegal and Atlantic Canada is determined by the evolution of land use, of demographic, economic, environmental, social and cultural aspects that evolve on different time scales, secular in some cases, more recent in others. It can be observed that different historical trajectories, e.g. the development of coastal tourism, the opening of the territory through new transport means, the evolution of coastal activities such as fishing or demographic change resulting from adverse climatic conditions in the hinterland can make a territory vulnerable to the impacts of climate change and hazards. The synergy between these different transformations of the coastal zone and the new element of climate change draw the portrait of a constantly evolving vulnerability.