Scenario Planning Series, Part 3: Shared Socioeconomic Pathways enable us to “Choose our Own Adventure”

By: Liz Allen

Image 1: The box set art for the original 1979 "Choose Your Own Adventure" Series. Image courtesy of
Image 1: The box set art for the original 1979 “Choose Your Own Adventure” Series. Image courtesy of

I have fond memories of being a 3rd grader in the early 90s reading Choose Your Own Adventure books with my friends while seated inside a tractor tire at my Oregon elementary school’s playground. The Choose Your Own Adventure series was popular in school libraries throughout the 80s and 90s because the books invited readers to become the protagonist of an adventure novel and make choices at critical plot junctures that would determine the story’s outcome. Sometimes kids became so interested in the twists and turns of a story that they decided to read it multiple times and map out all of the possible outcomes that could befall them if they made different decisions at each juncture. In a sense, being able to model future conditions under a range of “Shared Socio-Economic Pathway” (SSP) storylines is similar to looking at a map of possible Choose Your Own Adventure outcomes. SSP storylines combine imaginative, detailed narratives with variables representing a range of behaviors, values and institutional approaches.

In the previous installment of this scenario planning series I covered the emergence of Representative Concentration Pathways (RCPs) as the central framework that IPCC climate modelers use to report global climate change projections. The four RCPs represent a range of atmospheric greenhouse gas concentrations. The RCPs do not have “built in” assumptions about social, political and technological conditions that might lead to different impacts. In order to explore the potential for climate change adaptation and mitigation in different sectors and to understand feedbacks between human behaviors and environmental impacts we need socio-economic scenarios.

The term SSP (Shared Socio-Economic Pathway) shows up with increasing frequency in climate impacts modeling literature to describe a comprehensive storyline about future technological, economic, demographic, political, social and environmental trends, and how those trends will respond to global environmental change. A “parallel research program” is proposed in which climate modelers will run global climate models using the four IPCC RCPs1, and at the same time other modelers focused on impacts, adaptation and vulnerability will develop SSPs that are internally consistent and relevant to decision-making groups.

The Millennium Ecosystem Assessment scenarios are often used as an example of internally consistent and policy-relevant SSPs. The Millennium Assessment was called for by the UN Secretary General in 2000. This research effort involved over 1000 government agencies, businesses and non-governmental organizations in 95 countries working together to document how humans have changed ecosystems and explore linkages between human health and wellbeing and environmental conditions. As part of this coordinated research effort, four Millennium Assessment scenarios were envisioned.

Image 2: Millennium Ecosystem Assessment Scenarios
Image 2: Millennium Ecosystem Assessment Scenarios

Those storylines are briefly described here:

  •  Global Orchestration: globalized world with emphasis on economic growth and public goods
  • Order from Strength: regionalized governments with emphasis on national security and economic growth
  • Adapting Mosaic: regionalized world with emphasis on local adaptation and flexible governance
  • TechnoGarden: globalized world with emphasis on green technology

In the next scenario planning blog post I’ll discuss research currently underway at WSU Vancouver’s School of the Environment. Modelers are adapting Millennium Ecosystem Assessment scenarios for the Pacific Northwest to consider the region’s water quality future. We’re facing great uncertainty about our climatic, ecological and socio-economic future, so there are good reasons to welcome tools that could help us to “Choose Our Own Adventure” and consider different policy options, see ranges of possible outcomes and plan accordingly. 

  1. For more on the proposed parallel research program, see:

 Moss, R. H., Edmonds, J. A., Hibbard, K. A., Manning, M. R., Rose, S. K., Van Vuuren, D. P., Carter T.R., Emori, S., Kainuma, M., Kram, T., Meehl, G.A., Mitchell, J.F.B., Nakicenovic, N., Roahi, K., Smith, S.J., Stouffer, R.J., Thomson, A.M., Weyant, J.P. & Wilbanks, T. J. (2010). The next generation of scenarios for climate change research and assessment. Nature, 463(7282), 747-756. 

  1. Also, further relevant discussion can be found the 2013 special report on SSPs in the journal Climatic Change 

Raskin, P. D. (2005). Global scenarios: background review for the Millennium Ecosystem Assessment. Ecosystems, 8(2), 133-142.

Liz Allen is a graduate research assistant in the School of the Environment at Washington State University where she is a member of the BioEarth Regional Earth Systems Modeling team. 


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