The Intergenerational Equity: A Concept to Build for Sustainability, the Case of Global Warning

Defined as “the relation that each generation has with the last or future generations in the use... of the natural or cultural resources of planet”, Intergeneration equity (here I.E) imposes rules of optimal use of these resources on each generation. But it still remains a vague concept which needs a clear definition and poses some philosophical problems. Its emergence in right of the environment followed the scientific awakening on the ecological threats, in the years 1960 and led to a greater implication of the United Nations to coordinate international actions in environment field. The conferences of Stockholm in 1972 and Rio in 1992 answered this requirement and adopted the concept of sustainable development already mentioned in the 1987 Brundlandt report. With this concept, one attends “to provide for the needs of the present generation without compromising those of the future generations” trough the integration of the political economy and the environmental measures. This concept includes different aspects : the anguish of the present generation, the uncertainty characterizing the future one and also the practical difficulty to transmit the planet under conditions that ensure the survival of mankind and the defence of the common interest. So, its implementation should not be let to the individual actions of the States nor any bilateralism and multilateralism often in conflict with the “common interests of humanity” because principle of States sovereignty. Two possible ways can be explored to solve this institutional problem politically : The creation of a representative for the future generations to mitigate the absence of these generations in the current decision-making processes; or the creation of an international institution charged to protect the interests from the future generations and equipped with capacity higher than that of the States, as for the convention of Montego Bay signed in 1982 to control the activities of the 53 States in open sea and take care of the “common inheritance in the interest of the whole humanity”. The existence of such institutions would make it possible to force the States as well as the private individuals by preventing any contrary project with the interests of the future generations. How is this question perceived by the economic analysis? What are the philosophical background and the consequences on the analysis of global warming? In other words, is the choice of a discount rate efficient to solve the problem of different time periods posed by sustainability? To answer these questions, I suggest to analyze a typical long-term problem: the climate change, recently evoked in the Stern report (2006) and show that the policies of climate can lead to different models of consumption in time. And the very chosen strategy will depend on its effects on the households, today and in the future, evaluated through the impacts on the main indicators of wellbeing.