Abstract

Climate change policy decisions are inescapably intertwined with future generations. Even if all carbon dioxide emissions were to be stopped today, most aspects of climate change would persist for hundreds of years, thus inevitably raising questions of intergenerational justice and sustainability. The chapter begins with a short overview of discount rate debate in climate economics, followed by the observation that discounting implicitly makes the assumption that natural capital is always substitutable with man-made capital. The chapter explains why non-substitutability matters if we are to take intergenerational justice seriously and invest aptly in mitigation. Non-substitutability simply implies that there are some forms of capital that cannot be substituted by another, and so consumption of one cannot be compensated with additional stocks of the other. The non-substitutability of critical natural capital can be defended without empirical data about preferences or the need to view the environment as a superior good, and the argument is presented through the language of keeping options open. Those alive today make decisions about what natural capital to use and what to save for future. These choices are often represented as different points in a continuum of sustainability: weak sustainability is associated with a high degree of substitutability and therefore a lot of flexibility over what capital to consume, whereas strong sustainability is more stringent on substitutability. While it may be that in economical understanding weak and strong sustainability collapse into one another, philosophically the emphasis is slightly different. The chapter discusses how normative sustainability can be supported without ignoring opportunity costs and trade-offs.