Evolution of Climate Change Mitigation Scenarios

The IPCC (Intergovernmental Panel on Climate Change) is a scientific body of the United Nations that assesses the current state of climate research by analysing the scientific studies on climate change available worldwide. Its reports serve as a central source of information for international climate policy by providing insights into the causes, consequences and mitigation strategies of climate change. 

The presentation of future emission pathways is a central component of the IPCC assessment reports, which are increasingly made available through public scenario databases. In relation to these assessment reports, the article "Tracing the transformation: Energy and socioeconomic system transformation through a decade of IPCC-assessed scenarios" has now been published in the journal Nature Climate Change. Dr. Lukas Hermwille, Co-Head of the Transformative Industrial Policy Research Unit, and Wolfgang Obergassel, Co-Head of the Global Climate Governance Research Unit at the Wuppertal Institute, among eleven other scientists, examined in their article the developments and changes in the energy and socio-economic systems recorded by the IPCC over the last ten years. The researchers compare the scenarios in the IPCC´s 5th and 6th Assessment Reports as well as the IPCC´s Special Report "Global Warming of 1.5ºC" to assess the relevant factors, including policy and technology, for the development of emissions pathways. 

The analysis finds that reference scenarios without specific climate protection measures consistently show lower CO2 emissions in more recent reports. This trend is due to a combination of factors, including falling costs for low-carbon technologies and reduced expectations of economic growth, which lead to a decline in the projected share of fossil fuels in the energy and industry sectors. Ambitious mitigation pathways aligned with global warming below 1.5 to 2°C tend to lean towards greater electrification and a higher share of renewable energy in electricity generation in more recent scenarios. At the same time, reliance on coal, nuclear power, bioenergy, and carbon capture and storage (CCS) has gradually decreased due to changing costs. Despite the shrinking carbon budget caused by inadequate climate policies, mitigation costs have not increased thanks to more optimistic projections for low-carbon technologies. The analysis underlines the need for continuous recalibration of models and scenarios in order to keep pace with technological, political and social developments, as well as maintain political relevance.

The paper was written as part of the research project "NDC ASPECTS", which is funded by the European Union's Horizon 2020 research program under grant agreement no. 101003866. As part of the project, the researchers developed global and national pathways for the decarbonisation of four sectors central to climate protection and investigated international political framework conditions that can enable and promote this transformation.