Following on from his contribution to the special number “Energy Prospects and Greenhouse Effect” (Futuribles 315, January 2006), which gave an account of the main foresight scenarios played out on the stabilization of greenhouse gas emissions, Patrick Criqui (with Constantin Ilasca) shows here how scenarios in this area have evolved since 2007. Though the long-favoured approach consisted in starting out from global targets for the reduction of greenhouse gas emissions, set at international conferences, and building national policy scenarios around them (the so-called “top-down” approach), the rapid economic growth of the emerging countries (particularly China) and the return of the USA to international climate change negotiations have altered the state of play. Since the Copenhagen Agreement of late 2009, it would seem, then, more logical, argue Patrick Criqui and Constantin Ilasca, to start from policies and targets set out at the national level in developing scenarios on global climate change (the so-called “bottom-up” approach).
Criqui and Ilasca lay out this paradigm change in detail. For example, they present the forward view of greenhouse gas emissions as it looked before Copenhagen, based mainly on assessments of the costs associated with the mitigation policies required to limit climate warming. They then analyse various so-called “post-carbon” transitional scenarios (which are supposed to sound the death-knell of the era of massive CO2 emissions), combining climate policy, energy sustainability and modes of economic development. Lastly, they show the turnabout that has been developing since the Copenhagen Agreement and the now manifest tension between ambitious global objectives (limiting global warming to 2°C up to 2100) and national realities leading to more limited commitments (particularly in the emerging economies) – a new context which might give rise to new families of scenarios, incorporating this sacrificing of global well-being on the altar of (sadly, less sustainable) national prosperity.