Reaching climate targets: analytical models must include all stakeholders

When designing climate policy, the behaviour of all stakeholders in society and the economy should be taken into account. Image: InfiniteFlow – stock.adobe.com

The next UN Climate Change Conference, COP 30, will begin in two weeks in Belém, Brazil. Every year, the international community agrees on targets to curb global warming. However, implementation by national governments, business stakeholders and citizens is lagging behind. An international group of researchers, including Stefan Nabernegg and Nina Knittel from the University of Graz, sees one reason for this discrepancy in the assessment models used for negotiations on climate targets. These models usually ignore the behaviour of institutions, households and individuals. However, for climate policy to be truly effective, such aspects must be taken into account. In a recent publication in the scientific journal PNAS, the researchers propose combining analysis models from different decision-making levels in order to better understand the gap between global climate agreements and local implementation and how to close it.

“The negotiations at the UN climate conferences are based on so-called integrated assessment models, which show how much greenhouse gases need to be reduced in order to slow down the rise in temperature. At the same time, they take into account what is still economically feasible,” explains Stefan Nabernegg, climate economist at the Wegener Center at the University of Graz. What these models do not take into account are factors that determine the specific behaviour of institutions, households and individuals, such as financial markets or social norms. However, these play an important role in the acceptance of climate protection measures, for example.
“In our international research, we looked at the potential of model couplings to include all levels – climate policy, economy and behaviour,” reports Nabernegg. “This allows us to show which beliefs, preferences and actions of decision-makers can facilitate or hinder the implementation of measures. This is important information for policymakers,” says the researcher.

Model couplings also highlight how individual behaviour, changing social norms and trends can influence macroeconomic developments. For example, individual decisions in favour of environmentally friendly mobility, plant-based diets or investments in photovoltaics lead to shifts in consumer behaviour that affect markets and financial systems, which in turn influences the possibilities for financing climate policy. With their work, the international research team led by Tatiana Filatova from TU Delft/Netherlands, first author of the current publication, calls for further advancement of model coupling.

Publication:
The power of bridging decision scales: model coupling for advanced climate policy analysis
PNAS, 15 September 2025, https://www.pnas.org/doi/10.1073/pnas.2411592122

The Environmental Systems Sciences programme with a focus on economics provides knowledge about the interactions between environmental change, climate policy, economics and society.

Gudrun Pichler

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