The SSP storylines served as the starting point for the development of the quantitative SSP elements. Each storyline provides a brief narrative of the main characteristics of the future development path of an SSP. The storylines were identified at the joint IAV and IAM workshop in Boulder, November 2011. A brief summary of the storylines are provided here for comprehensiveness. For further details and extended descriptions of the storylines, see O'Neill et al. (2012). SSP1 -Sustainability:This is a world making relatively good progress towards sustainability, with sustained efforts to achieve development goals, while reducing resource intensity and fossil fuel dependency. Elements that contribute to this are a rapid development of low-income countries, a reduction of inequality (globally and within economies), rapid technology development, and a high level of awareness regarding environmental degradation. Rapid economic growth in low-income countries reduces the number of people below the poverty line. The world is characterized by an open, globalized economy, with relatively rapid technological change directed toward environmentally friendly processes, including clean energy technologies and yield-enhancing technologies for land. Consumption is oriented towards low material growth and energy intensity, with a relatively low level of consumption of animal products. Investments in high levels of education coincide with low population growth. Concurrently, governance and institutions facilitate achieving development goals and problem solving. The Millennium Development Goals are achieved within the next decade or two, resulting in educated populations with access to safe water, improved sanitation and medical care. Other factors that reduce vulnerability to climate and other global changes include, for example, the successful implementation of stringent policies to control air pollutants and rapid shifts toward universal access to clean and modern energy in the developing world. SSP 2 -Middle of the Road (or Dynamics as Usual, or Current Trends Continue, or Continuation, or Muddling Through):In this world, trends typical of recent decades continue, with some progress towards achieving development goals, reductions in resource and energy intensity at historic rates, and slowly decreasing fossil fuel dependency. Development of low-income countries proceeds unevenly, with some countries making relatively good progress while others are left behind. Most economies are politically stable with partially functioning and globally connected markets. A limited number of comparatively weak global institutions exist. Per-capita income levels grow at a medium pace on the global average, with slowly converging income levels between developing and industrialized countries. Intra-regional income distributions improve slightly with increasing national income, but disparities remain high in some regions. Educational investments are not high enough to rapidly slow population growth, particularly in low-income countries. Achievement of...

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Extended Data Fig. 2 | Fuzzy sets for resource availability criteria. These are visual representations of the fuzzy sets for each indicator, including set shapes and thresholds, corresponding names and indicator ranges. Extended Data Fig. 3 | Fuzzy sets for economic viability criteria. These are visual representations of the fuzzy sets for each indicator, including set shapes and thresholds, corresponding names and indicator ranges. Article Extended Data Fig. 4 | Fuzzy sets for social equity and environmental sustainability criteria. These are visual representations of the fuzzy sets for each indicator, including set shapes and thresholds, corresponding names, and indicator ranges.