Environmental sustainability and capacity preservation: the case of ecosystem assimilative capacity in the economic analysis of optimal pollution.

Summary This thesis started from an initial questioning of the compatibility of economic models of pollution optimization with the requirements of sustainable development. It focuses on dynamic models of pollution regulation and natural capital management. In the light of a sustainability criterion requiring a sufficient preservation of the pollution assimilation capacity of the environment, we analyze in a first part the optimal pollution trajectories in a framework of intertemporal maximization of the discounted utility. The standard dynamic theoretical models of flow (Ch. 1) and stock (Ch. 2) pollution control without capital accumulation are modified to allow an explicit valuation of this assimilation capacity. They are illustrated respectively by the role of riparian zones in the absorption of leached nitrates and by the assimilative capacity of CO_2 by the biosphere. This review shows that compatibility between sustainability requirements is not ensured in all cases, which leads us to seek different forms of modeling, more in line with the objectives of sustainable development. In a second part, we bring together the bases of an approach to pollution regulation with those of the management of a renewable natural resource. This perspective leads us to explore the alternatives to the criterion of maximizing discounted utility represented by criteria such as the Green Golden Rule, the Maxim (Ch. 3) or Sustainability (Ch. 4). From the intuitions gathered in the first two parts, we propose in the last part (Ch. 5) a simplified model of growth with physical and natural capital. This model, characterized by the endogenous depreciation of natural capital, allows us to extend our thinking on sustainability to economic capacities in terms of preservation of environmental capacities.