2011, Mastrandrea, Michael D., Mach, Katharine J., Plattner, Gian-Kasper, Edenhofer, Ottmar, Stocker, Thomas F., Field, Christopher B., Ebi, Kristie L., Matschoss, Patrick R.

Evaluation and communication of the relative degree of certainty in assessment findings are key cross-cutting issues for the three Working Groups of the Intergovernmental Panel on Climate Change. A goal for the Fifth Assessment Report, which is currently under development, is the application of a common framework with associated calibrated uncertainty language that can be used to characterize findings of the assessment process. A guidance note for authors of the Fifth Assessment Report has been developed that describes this common approach and language, building upon the guidance employed in past Assessment Reports. Here, we introduce the main features of this guidance note, with a focus on how it has been designed for use by author teams. We also provide perspectives on considerations and challenges relevant to the application of this guidance in the contribution of each Working Group to the Fifth Assessment Report. Despite the wide spectrum of disciplines encompassed by the three Working Groups, we expect that the framework of the new uncertainties guidance will enable consistent communication of the degree of certainty in their policy-relevant assessment findings.

2020, Schweizer, Vanessa J., Ebi, Kristie L., van Vuuren, Detlef P., Jacoby, Henry D., Riahi, Keywan, Strefler, Jessica, Takahashi, Kiyoshi, van Ruijven, Bas J., Weyant, John P.

To halt climate change, we must reduce anthropogenic CO2 emissions to net zero. Any emission sources must be balanced by natural or technological carbon sinks that facilitate CO2 removal (CDR) from the atmosphere. The integrated scenario framework represents how socio-economic trends and social values interact with biophysical systems in exploring future climate change and decarbonization pathways. This primer introduces the integrated scenario framework and its application to explore options for offsetting emissions with CDR. © 2020 The AuthorsTo halt climate change this century, we must reduce carbon dioxide (CO2) emissions from human activities to net zero. Any emission sources, such as in the energy or land-use sectors, must be balanced by natural or technological carbon sinks that facilitate CO2 removal (CDR) from the atmosphere. Projections of demand for large-scale CDR are based on an integrated scenario framework for emission scenarios composed of emission profiles as well as alternative socio-economic development trends and social values consistent with them. The framework, however, was developed years before systematic reviews of CDR entered the literature. This primer provides an overview of the purposes of scenarios in climate-change research and how they are used. It also introduces the integrated scenario framework and why it came about. CDR studies using the scenario framework, as well as its limitations, are discussed. Possible future developments for the scenario framework are highlighted, especially in relation to CDR. © 2020 The Authors

2021, Rockström, Johan, Gupta, Joyeeta, Lenton, Timothy M., Qin, Dahe, Lade, Steven J., Abrams, Jesse F., Jacobson, Lisa, Rocha, Juan C., Zimm, Caroline, Bai, Xuemei, Bala, Govindasamy, Bringezu, Stefan, Broadgate, Wendy, Bunn, Stuart E., DeClerck, Fabrice, Ebi, Kristie L., Gong, Peng, Gordon, Chris, Kanie, Norichika, Liverman, Diana M., Nakicenovic, Nebojsa, Obura, David, Ramanathan, Veerabhadran, Verburg, Peter H., van Vuuren, Detlef P., Winkelmann, Ricarda

Keeping the Earth system in a stable and resilient state, to safeguard Earth's life support systems while ensuring that Earth's benefits, risks, and related responsibilities are equitably shared, constitutes the grand challenge for human development in the Anthropocene. Here, we describe a framework that the recently formed Earth Commission will use to define and quantify target ranges for a “safe and just corridor” that meets these goals. Although “safe” and “just” Earth system targets are interrelated, we see safe as primarily referring to a stable Earth system and just targets as being associated with meeting human needs and reducing exposure to risks. To align safe and just dimensions, we propose to address the equity dimensions of each safe target for Earth system regulating systems and processes. The more stringent of the safe or just target ranges then defines the corridor. Identifying levers of social transformation aimed at meeting the safe and just targets and challenges associated with translating the corridor to actors at multiple scales present scope for future work.

2014, Kriegler, Elmar, Edmonds, Jae, Hallegatte, Stéphane, Ebi, Kristie L., Kram, Tom, Riahi, Keywan, Winkler, Harald, van Vuuren, Detlef P.

The new scenario framework facilitates the coupling of multiple socioeconomic reference pathways with climate model products using the representative concentration pathways. This will allow for improved assessment of climate impacts, adaptation and mitigation. Assumptions about climate policy play a major role in linking socioeconomic futures with forcing and climate outcomes. The paper presents the concept of shared climate policy assumptions as an important element of the new scenario framework. Shared climate policy assumptions capture key policy attributes such as the goals, instruments and obstacles of mitigation and adaptation measures, and introduce an important additional dimension to the scenario matrix architecture. They can be used to improve the comparability of scenarios in the scenario matrix. Shared climate policy assumptions should be designed to be policy relevant, and as a set to be broad enough to allow a comprehensive exploration of the climate change scenario space.