Environmental impact assessment for climate change policy with the simulation-based integrated assessment model E3ME-FTT-GENIE

A high degree of consensus exists in the climate sciences over the role that human interference with the atmosphere is playing in changing the climate. Following the Paris Agreement, a similar consensus exists in the policy community over the urgency of policy solutions to the climate problem. The context for climate policy is thus moving from agenda setting, which has now been established, to impact assessment, in which we identify policy pathways to implement the Paris Agreement. Most integrated assessment models currently used to address the economic and technical feasibility of avoiding climate change are based purely on engineering with a normative systems optimisation philosophy, and are thus unsuitable to assess the socio-economic impacts of realistic baskets of climate policies. Here, we introduce a fully descriptive simulation-based integrated assessment model designed specifically to assess policies, formed by the combination of (1) a highly disaggregated macro-econometric simulation of the global economy based on time series regressions (E3ME), (2) a family of bottom-up evolutionary simulations of technology diffusion based on cross-sectional discrete choice models (FTT), and (3) a carbon cycle and atmosphere circulation model of intermediate complexity (GENIE-1). We use this combined model to create a detailed global and sectoral policy map and scenario that achieves the goals of the Paris Agreement with 80% probability of not exceeding 2{\deg}C of global warming. We propose a blueprint for a new role for integrated assessment models in this upcoming policy assessment context.