CLIMATE POLICY BETWEEN NATIONAL CHOICES AND GLOBAL SCENARIOS Implications of cognitive and ethical positioning.

Summary This book analyzes the way in which national strategies to combat the greenhouse effect can be determined according to the cognitive and ethical stances of national states with regard to global climate scenarios. It distinguishes between cognitive approaches of the "predictive", "Thomistic" or "symmetrical" type, crossed with ethical stances designated as "egocentric", "altruistic-dynastic", "intragenerational solidarist", "cosmopolitical altruistic" and "Kanto-millian universalist". To evaluate these configurations, it is assumed that the choices made by a state are based on an assessment of the climate damage associated with different greenhouse gas concentration scenarios. The central indicators used are the present value of the damage caused by the emission of a ton of CO2 and the level of the discount rate. Within this classical framework, where the concept of damage is tested in order to apprehend long-term phenomena, the evaluation determines which cognitive-ethical configurations justify the "Factor 4" target in 2050: there are a reduced number of them, either of a "cosmopolitical altruism (international and intergenerational)" or of a "Kanto-millennial universalism", if this target is chosen according to the climate problem alone. Assuming that a value of 100 € / tCO2 in 2030 is an obligatory point of passage towards "Factor 4" in 2050, such ethical choices imply the recognition of a high 2010 present value for the damage caused by the emission of a ton of CO2e (at least 53 € / tCO2, i.e. an order of magnitude higher than the 2013 price of carbon on the ETS market) and the adoption of a characteristic discount rate which, depending on the configurations studied, cannot be higher than 3.25%. Such values should be considered as logical conditions to be respected for all derived choices and in particular when determining the best intertemporal emission reduction path. Another result: taking into account the impact of the date of emission on climate damage, it turns out that "cosmopolitical altruism" and "Kanto-millennial universalism" lead to strictly opposite recommendations regarding the profile of the best temporal trajectory of "consumption" of an emission budget fixed for the period 2011-2050: the first one calls for concentrating emissions at the beginning of the period, and the second one calls for starting with a "reduction shock". In total, none of the configurations justifying the "Factor 4" target agree with the simple application of a Hotelling rule that would increase the value of the ton of CO2 at the standard discount rate for public investment.