This thesis investigates the Shared Socioeconomic Pathways (SSPs), which underpin the IPCC Working Group III (WGIII) reports and contemporary climate mitigation policy, through an International Political Economy (IPE) theoretical lens. As the SSPs aim to describe and quantify long-term socio-economic futures at national and international scales, they rely on political-economic assumptions that have received limited systematic scrutiny from IPE scholarship.
The core of the analysis focuses on the Integrated Assessment Models (IAMs) used to generate SSP-based scenarios, with a comparative case study of IMAGE, MESSAGE, and REMIND – models collectively accounting for 59% of the 1,202 vetted scenarios used in the most recent WGIII report. The empirical material consists of thirteen semi-structured interviews with modelers and extensive technical documentation, which are examined using a newly developed IPE-based assessment framework comprising seven categories and thirty indicators.
The analysis shows a systematic disconnect between SSP narratives and their implementation in dominant IAMs. Despite stated ambitions to represent socio-economic dynamics, these models largely omit social heterogeneity, state structures, firms and profits, and both domestic and international power relations. In particular, Computable General Equilibrium models such as MESSAGE and REMIND – built around “single representative consumer-producer agents” with perfect foresight performing optimized decisions over multi-decade horizons – appear structurally ill-suited to representing plausible future ecological and social transformations.
To contextualize these modelling choices, the thesis complements the empirical models’ studies with a historical-sociological genealogy of the institutions producing dominant IAMs. Drawing primarily on secondary sources, this analysis situates contemporary modelling practices within intellectual traditions shaped by mid- to late-twentieth-century cybernetics, thermodynamics, neoclassical economics, and claims to “neutral science” developed in a Cold War context.
By offering a systematic, theory-driven IPE critique of SSP-IAM coherence, this thesis contributes a novel perspective to existing debates on climate modelling. It underscores the need for more explicit representation of political and economic agencies in socioeconomic scenarios and highlights the importance of deeper social science integration in advance of upcoming IPCC assessments.
