Building Better Predictive Computer Models for a Sustainable Future

Fotograf Peter Mesenholl (Credit:

Computer models play a significant role in environmental policy; however they only offer a partial picture of the industrial system.

Whether it is renewable energy, carbon tax, electric automobiles, or sustainable consumption, sustainable development needs strategies that incorporate people's needs without destroying the environment. Before such strategies are implemented, their potential impact on economy, environment, and society needs to be tested.

These tests can be performed using computer models that portray future economic and demographic development and scrutinize the interplay between the climate and industry as well as other important natural systems.

Along with his Norwegian and US colleagues, junior professor Dr. Stefan Pauliuk at the Faculty of Environment and Natural Resources at the University of Freiburg took up the most wide-ranging review of five key so-called integrated assessment models.

The results were published in the scientific journal "Nature Climate Change", and reveal that these models display extensive deficits in their illustration of the industrial system, which could result in faulty estimates of the societal advantages and potential environmental impacts of new climate policies and technologies.

Integrated evaluation models create scenarios for the most cost-effective switch toward a sustainable supply of energy and materials and at the same time keeping the planetary boundaries in mind.

The scenarios generated by the models are an important instrument for environmental policy-making. They show that it is technically feasible to achieve a central goal in global climate policy: Namely, to limit average global warming to a maximum of two degrees Celsius compared to the level at the beginning of the Industrial Era.

Dr. Stefan Pauliuk, University of Freiburg

The model results were important during the preliminary negotiations prior to the Paris Agreement that came into effect in November 2016 with the focus to mitigate climate change. The results also impact the most recent evaluation report issued by the Intergovernmental Panel on Climate Change (IPCC), where they generally link the mitigation options illustrated for several sectors such as transport, buildings, or energy supply.

Because the models' results are so important to decision makers, the questions arises about their validity and robustness.

Dr. Stefan Pauliuk, University of Freiburg

As a consequence, the researchers gave more attention to the way in which the models depict the industrial system; that is, the worldwide value chain of processing, production, and use of materials, consumer goods, and energy as well as recycling. The industrial system is the supply center of all synthetic goods.

At the same time, it is also the basis of all emissions released into the natural environment. But the illustration of the industrial system in these models is imperfect, according to the researchers.

In particular, the cycle of materials, for instance of iron and copper, but also the representation of urban infrastructure is completely missing.

Dr. Stefan Pauliuk, University of Freiburg

This fact may restrict the predictive capacity of the models and additional research is required: "It remains to be shown how ignoring core parts of the industrial system influences the feasibility of certain scenarios to mitigate climate change. In addition, important strategies to reduce emissions such as recycling, material efficiency, or urban density have not been considered at all."

Researchers are now called to develop the models further to more precisely depict the cycle of materials and other details relating to the industrial system. The final goal is to attain more practical prognoses for resource and climate policies.

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