Enabling politically sensitive climate change impact assessments for the 21st century

What are key climate-driven social risks, and how might societal development moderate these risks? The SSP-RCP scenario framework has been developed by the IPCC community to study long-term interactions between climate and society and constitutes the cornerstone of current assessments of climate change impacts. The RCPs represent alternative warming scenarios (hazards) whereas the SSPs describe alternative development scenarios that define exposure and vulnerability to these hazards. Despite their widespread use, the quantitative SSP scenarios suffer from two major shortcomings: (i) they ignore political dimensions of vulnerability, implicitly assuming that governance does not matter for climate-driven risk; (ii) they use economic models that ignore growth disruption risks, resulting in future growth projections for low-income countries that vastly exceed past growth even in the most pessimistic scenarios. The joint result of these shortcomings is a quantified scenario framework that severely underestimates future vulnerability to climate change.POLIMPACT aspires to remedy this problem. Using cutting-edge methods, including dynamic statistical simulations, machine learning, and expert elicitation, the project will develop a new portfolio of empirically grounded and rigorously validated governance, conflict, and economic development scenario projections, consistent with the SSPs, that for the first time enables accounting for political sources of vulnerability in climate change impact assessments. The scientific merit of the novel scenario products will be demonstrated by comparing impact estimates for poverty and hunger relying on the existing SSP framework with updated results using the extended, politically sensitive projections. If successful, POLIMPACT will initiate a step-change in climate change impact modeling, radically improving the quality and real-world relevance of climate change impact assessments for key social risks over the 21st century.