Safeguarding our livelihoods – Towards a minimum standard for assessing human impacts on nature in Integrated Assessment Models

Poster abstract for “Researching and Shaping Climate Futures” SoSe 2025

Integrated assessment models (IAMs) are strongly shaped by ethical and political dimensions, but due to insufficient model commentaries, the actual assumptions and purposes often remain opaque to the public (Schaumann, 2023). This is concerning, as IAMs outline the range of possible climate futures in the discussion on mitigation pathways.

Which role does Nature play in these models? Which feedbacks and impacts between natural and human systems are assumed in IAMs? And which gaps are present in accounting for how our wellbeing depends on ecosystem services?

Chaplin-Kramer et al. (2024) map out the current state of integrated social-economic-ecological modelling that incorporates biodiversity and ecosystem services. They identify several research frontiers, among them incorporating dynamic feedbacks of ecosystem services on the social-economic system and linking ecological impacts to human well-being. They point out that decision makers are much more likely to include these aspects in their planning if models explicitly account for them. This raises the question of valuation – how do we put a price tag on the diverse material and non-material ecosystem services? Or should we better find a non-monetary measure?

An approach in the latter direction is ecological-economic viability analysis as described by Baumgärtner et al. (2009). To quote them, “Viability means that the different components and functions of a dynamic, stochastic system at any time remain in a domain where the future existence of these components and functions is guaranteed with sufficiently high probability.”  The strongly normative aspect is openly acknowledged, as in a first step it has to be decided which components of a system are worth to be sustained. However, due to the complexity of the earth system, this method is not considered feasible for questions on a planetary scale. In this context, the planetary boundaries framework provides an interesting perspective.

Van Vuuren et al. (2025) link the planetary boundary framework to the scenario outcomes of the Integrated Assessment Model IMAGE4. Their study projects trends from current policies and explores the impacts of additional interventions on earth system stability. The conclusion is a clear failure in keeping human impacts within the safe planetary boundaries.

Both approaches described above avoid the question of monetarisation or explicit valuation of ecosystem services by asking the question “Are model scenarios compatible with sustaining a stable biosphere?”. In my poster, I want to argue for the need to incorporate such evaluations much more prominently in the development and use of IAMs. Even if nature’s impacts on human wellbeing are not modelled explicitly, some sort of “minimum standard” to assess human impacts on biosphere stability seems very important to me – especially if a model’s stated purpose is to inform decision making. My aim is to map out present shortcomings, existing approaches and challenges in mainstreaming this kind of evaluation in IAMs, with a focus on non-monetary approaches.

References:

Schaumann, F. (2023): What to expect of integrated assessment models: insights from philosophy, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13832, https://doi.org/10.5194/egusphere-egu23-13832, 2023

Chaplin-Kramer, R. et al. (2024): Integrated modeling of nature’s role in human well-being: A research agenda. Global Environmental Change, 88. https://doi.org/10.1016/j.gloenvcha.2024.102891

Baumgärtner et al. (2009): Ecological-economic viability as a criterion of strong sustainability under uncertainty. Ecological Economics, 68. doi:10.1016/j.ecolecon.2009.01.016

Van Vuuren et al. (2025): Exploring pathways for world development within planetary boundaries. Nature, 641, pages 910–916. https://doi.org/10.1038/s41586-025-08928-w