PTo understand global warming, economists use what are called “integrated assessment models” (integrated assessment modelsIAM in English): “integrated”, because they combine elements from different disciplines, economics, energy systems, Earth system sciences, etc. These models have acquired a certain visibility due to their role in the expertise process of group III of the IPCC, the one responsible for studying solutions to global warming.
These are not forecasting models, but they are designed to explore the future. What happens if we develop solar energy more or less quickly? What if we stop deforestation? If nuclear power fails? Or, what should be done, within what time frame and at what cost to limit warming to +1.5°C or +2°C?
Convergence and carbon debt
Integrated evaluation has become a discipline in its own right, with its journals and careers, involving more than 1,500 researchers and dozens of teams around the world. Models with various acronyms (FAIR, FUND, PACE, Image) are becoming more and more complex and requiring increasing computing power. In its latest report, Group III of the IPCC had a library of 3,131 scenarios generated by more than 50 families of models.
Despite this scientific proliferation, no scenario had included decay hypotheses until very recently. Not even concerning the richest countries, which, with their infrastructure, have contributed disproportionately to global warming. This is all the more strange since the questions of convergence and carbon debt are at the heart of international climate debates.
It is for this reason that an article published in Economic Systems Research in April 2024 by nine young researchers is of great importance (“Downscaling down under: towards degrowth in integrated assessment models”, Jarmo S. Kikstra et al.). This is the first time that an integrated evaluation model has explored the hypothesis of the decline of a rich country, in this case Australia. The authors generated 51 scenarios with growth rates ranging from +3% per year to –5% per year. The simple cessation of the growth of the Australian gross national product (GNP) reduces the need for renewable energy by 40% (production must still be quadrupled by 2030…) and reduces the extraction of minerals as well as the use biomass energy. Scenarios that cut a third of GNP allow for a rapid reduction in fossil fuels.
You have 34.35% of this article left to read. The rest is reserved for subscribers.