This Scenario Explorer presents an ensemble of quantitative, model-based climate change mitigation pathways underpinning the Special Report on Global Warming of 1.5°C (SR15) by the Intergovernmental Panel on Climate Change (IPCC) published in 2018. The ensemble was also used and extended in the IPCC's Special Report on Climate Change and Land (SRCCL, 2019). 

iamc_logo © IPCC 2018
IAMC 1.5°C Scenario Explorer hosted by IIASA

As part of the IPCC's Special Report on Global Warming of 1.5°C (SR15), an assessment of quantitative, model-based climate change mitigation pathways was conducted. To support the assessment, the Integrated Assessment Modeling Consortium (IAMC) facilitated a coordinated and systematic community effort by inviting modelling teams to submit their available 1.5°C and related scenarios to a curated database. The compilation and assessment of the scenario ensemble was conducted by authors of the IPCC SR15, and the resource is hosted by the International Institute for Applied Systems Analysis (IIASA) as part of a cooperation agreement with Working Group III of the IPCC.

The scenario ensemble contains more than 400 emissions pathways with underlying socio-economic development, energy system transformations and land use change until the end of the century, submitted by over a dozen research teams from around the world. The criteria for submission included that the scenario is presented in a peer-reviewed journal accepted for publication no later than May 15, 2018, or published in a report determined by the IPCC to be eligible grey literature by the same date.

Usage in the IPCC's Special Report on Global Warming of 1.5°C

Many figures, tables and quantitative assessment in the IPCC's Special Report on Global Warming of 1.5°C (SR15, 2018) are based directly on this scenario ensemble, including Figure SPM 3a shown blow.

The open-source notebooks to generate figures and statistics are available here.

Summary for Policy Makers - Figure 3A © IPCC
Summary for Policy Makers - Figure 3A The main panel shows global net anthropogenic CO2 emissions in pathways limiting global warming to 1.5°C with no or limited (less than 0.1°C) overshoot and pathways with higher overshoot. The shaded area shows the full range for pathways analysed in this Report. The panels on the right show non-CO2 emissions ranges for three compounds with large historical forcing and a substantial portion of emissions coming from sources distinct from those central to CO2 mitigation. Shaded areas in these panels show the 5–95% (light shading) and interquartile (dark shading) ranges of pathways limiting global warming to 1.5°C with no or limited overshoot. Box and whiskers at the bottom of the figure show the timing of pathways reaching global net zero CO2 emission levels, and a comparison with pathways limiting global warming to 2°C with at least 66% probability. Four illustrative model pathways are highlighted in the main panel and are labelled P1, P2, P3 and P4, corresponding to the LED, S1, S2, and S5 pathways assessed in Chapter 2. Descriptions and characteristics of these pathways are available in Figure SPM.3b. {2.1, 2.2, 2.3, Figure 2.5, Figure 2.10, Figure 2.11}

Usage in the IPCC's Special Report on Climate Change and Land

The scenario ensemble was also used in the IPCC's Special Report on Climate Change and Land (SRCCL, 2019) and extended by several timeseries on prices related to agriculture. To acknowledge the significant contribution by several authors of the SRCCL regarding the additional analysis and extension of the scenario ensemble, the list of authors was amended with Release 2.0 and a new DOI was issued for the extended data.