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The roads ahead: Narratives for shared socioeconomic pathways describing world futures in the 21st century

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Long-term scenarios play an important role in research on global environmental change. The climate change research community is developing new scenarios integrating future changes in climate and society to investigate climate impacts as well as options for mitigation and adaptation. One component of these new scenarios is a set of alternative futures of societal development known as the shared socioeconomic pathways (SSPs). The conceptual framework for the design and use of the SSPs calls for the development of global pathways describing the future evolution of key aspects of society that would together imply a range of challenges for mitigating and adapting to climate change. Here we present one component of these pathways: the SSP narratives, a set of five qualitative descriptions of future changes in demographics, human development, economy and lifestyle, policies and institutions, technology, and environment and natural resources. We describe the methods used to develop the narratives as well as how these pathways are hypothesized to produce particular combinations of challenges to mitigation and adaptation. Development of the narratives drew on expert opinion to (1) identify key determinants of these challenges that were essential to incorporate in the narratives and (2) combine these elements in the narratives in a manner consistent with scholarship on their inter-relationships. The narratives are intended as a description of plausible future conditions at the level of large world regions that can serve as a basis for integrated scenarios of emissions and land use, as well as climate impact, adaptation and vulnerability analyses.
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The Roads Ahead: Narratives for Shared Socioeconomic Pathways describing
World Futures in the 21st Century
Brian C. O’Neill,a,* Elmar Kriegler,b Kristie L. Ebi,c Eric Kemp-Benedict,d Keywan Riahi, e,f
Dale Rothman, g Bas van Ruijven,a Detlef P. van Vuurenh,i, Joern Birkmann,j Kasper Kokk, Marc
Levy,l William Soleckim
a National Center for Atmospheric Research (NCAR), PO Box 3000, Boulder, CO, 80305.
boneill@ucar.edu; vruijven@ucar.edu
b Potsdam Institute for Climate Impact Research, PO Box 601203, 14412 Potsdam, Germany.
kriegler@pik-potsdam.de
cClimAdapt, LLC, 13212 42nd Ave NE, Seattle WA, 98125, USA. krisebi@essllc.org
d Stockholm Environment Institute, 15th Floor, Witthyakit Building, 254 Chulalongkorn
University, Chulalongkorn Soi 64, Phyathai Road, Pathumwan, Bangkok, 10330, Thailand.
eric.kemp-benedict@sei-international.org.
e International Institute for Applied Systems Analysis. Laxenburg. Austria. riahi@iiasa.ac.at
f Graz Univeristy of Technology. Graz. Austria
g Frederick S. Pardee Center for International Futures, Josef Korbel School of International
Studies, University of Denver, 2201 South Gaylord Street, Denver, CO 80208-0500, USA.
drothman@du.edu
h PBL Netherlands Environmental Assessment Agency. Bilthoven. The Netherlands.
detlef.vanvuuren@pbl.nl
i Copernicus Institute for Sustainable Development. Faculty of Geosciences. Utrecht University.
The Netherlands
j Institute for Environment and Human Security, United Nations University, Platz der Vereinten
Nationen 1, D-53113 Bonn, Germany. birkmann@ehs.unu.edu
k Soil Geography and Landscape Group, Wageningen University, the Netherlands.
kasper.kok@wur.nl
l Center for International Earth Science Information Network (CIESIN), Columbia University, 61
Route 9W, PO Box 1000, Palisades, NY 10964 USA. mlevy@columbia.edu
m CUNY Institute for Sustainable Cities and Department of Geography, Hunter College City of
New York, 695 Park Avenue, New York, NY 10021, USA. wsolecki@hunter.cuny.edu
* Corresponding author. Email: boneill@ucar.edu; Tel: 1-303-497-8118; Fax: 1- 303-497-1333.
Submitted to Global Environmental Change, 2 July 2014
Resubmitted 12 December 2014
*Title page (with author details, acknowledgements or affiliations)
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Abstract
Long-term scenarios play an important role in research on global environmental change. The
climate change research community is developing new scenarios integrating future changes in
climate and society to investigate climate impacts as well as options for mitigation and
adaptation. One component of these new scenarios is a set of alternative futures of societal
development known as the Shared Socioeconomic Pathways (SSPs). The conceptual framework
for the design and use of the SSPs calls for the development of global pathways describing the
future evolution of key aspects of society that would together imply a range of challenges for
mitigating and adapting to climate change. Here we present one component of these pathways:
the SSP narratives, a set of five qualitative descriptions of future changes in demographics,
human development, economy and lifestyle, policies and institutions, technology, and
environment and natural resources. We describe the methods used to develop the narratives as
well as how these pathways are hypothesized to produce particular combinations of challenges to
mitigation and adaptation. Development of the narratives drew on expert opinion to (1) identify
key determinants of these challenges that were essential to incorporate in the narratives and (2)
combine these elements in the narratives in a manner consistent with scholarship on their inter-
relationships. The narratives are intended as a description of plausible future conditions at the
level of large world regions that can serve as a basis for integrated scenarios of emissions and
land use, as well as climate impact, adaptation and vulnerability analyses.
Keywords
Scenarios, climate change, impacts, mitigation, adaptation, narratives, shared socioeconomic
pathways
1 Introduction and background
Long-term global scenarios have played a key role in climate change analysis for more than 20
years (Pepper et al., 1992; Nakicenovic et al., 2000; Raskin et al., 2005; van Vuuren et al., 2012).
While other approaches to characterizing the future exist (Lempert et al., 2004; Webster et al.,
2003), alternative scenarios are an important method for exploring uncertainty in future societal
and climate conditions (Jones et al., 2014). Scenarios of global development focus on the
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uncertainty in future societal conditions, describing societal futures that can be combined with
climate change projections and climate policy assumptions to produce integrated scenarios to
explore mitigation, adaptation and residual climate impacts in a consistent framework.
Often, societal development scenarios consist of qualitative and quantitative components (Raskin
et al., 2005; Rothman et al, 2007; Ash et al., 2010; van Vuuren et al., 2012). Quantitative
components provide common assumptions for elements such as population, economic growth, or
rates of technological change that can be meaningfully quantified and that can serve as inputs to
models of energy use, land use, emissions, and other outcomes. Qualitative narratives (or
storylines) describe the evolution of aspects of society that are difficult to project quantitatively
(such as the quality of institutions, political stability, environmental awareness, etc.), provide the
logic underlying those elements of scenarios that are quantifiable (and their relationships to each
other), and provide a basis for further elaboration of the scenarios by users.
A process is under way in the climate change research community to develop a new set of
integrated scenarios describing future climate, societal, and environmental change (Moss et al.,
2010). This process started with the development of Representative Concentration Pathways
(RCPs) that describe a set of alternative trajectories for the atmospheric concentrations of key
greenhouse gases (van Vuuren et al., 2011). Based on these, climate modelers produced a
number of simulations of possible future climates over the 21st century (Taylor et al., 2012). In
parallel, other researchers are producing a new set of alternative pathways of future societal
development, described as Shared Socioeconomic Pathways (SSPs), and using integrated
assessment models (IAMs) to produce additional quantitative elements based on them, including
future emissions and land use change. A conceptual framework has been produced for the
development of SSPs (O'Neill et al., 2014) and for how to combine IAM scenarios based on
them with future climate change outcomes and climate policy assumptions to produce integrated
scenarios (Ebi et al., 2014; van Vuuren et al., 2014; Kriegler et al., 2014) and support other kinds
of integrated climate change analysis.
However, the specific content (as opposed to the conceptual framework) of the SSPs and
associated IAM scenarios has, until now, not been presented in the peer-reviewed literature. The
focus of this special issue is to present that content. The SSPs describe plausible alternative
changes in aspects of society such as demographic, economic, technological, social, governance
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and environmental factors. Like many previous characterizations of future societal development,
they include both qualitative descriptions of broad trends in development over large world
regions (narratives) as well as quantification of key variables that can serve as inputs to
integrated assessment, large-scale impact models and vulnerability assessments (Alcamo, 2001).
In this paper we present the SSP narratives, describing the methods used to develop them, their
main features, and open questions regarding their design and use. Along with the narratives, we
provide tables that summarize trends in key elements of the SSPs. Other papers in this special
issue describe the quantitative elements of the SSPs, including population and educational
composition (K.C. and Lutz, 2014), urbanization (Jiang and O‘Neill, submitted to this issue), and
economic growth pathways (Crespo Cuaresma; Leimbach et al.; Dellink et al.; submitted to this
issue). An additional set of papers focus on the integration of the narratives and basic elements of
the SSPs into IAM simulations describing the possible evolution of land use, energy and
agricultural systems and resulting GHG emissions under different SSPs and climate policy
assumptions.
Within the conceptual framework for integrated scenarios, the SSPs are designed to span a
relevant range of uncertainty in societal futures. Unlike most global scenario exercises, the
relevant uncertainty space that the SSPs are intended to span is defined primarily by the nature of
the outcomes, rather than the inputs or elements that lead to these outcomes (O‘Neill et al.,
2014). As such, the design process begins with identifying a particular outcome and then
identifies the key elements of society that could determine this outcome. This approach is
typically associated with backcasting, where an end state is already in mind as the pathways are
being developed, although not necessarily assuming that these states are all desirable (Vergragt
and Quist 2011). Such a backcasting scenario approach has proven effective in focusing on those
areas of the uncertainty space that are most important in choosing among alternative options
(Groves and Lempert, 2007). Although the domain of application of climate change scenarios
includes a large range of specific decision-making situations, they generally cover options to
mitigate or adapt to climate change. Therefore, the SSP outcomes are specific combinations of
socioeconomic challenges to mitigation and socioeconomic challenges to adaptation (Figure 1).
That is, the SSPs are intended to describe worlds in which societal trends result in making
mitigation of, or adaptation to, climate change harder or easier, without explicitly considering
climate change itself.
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While the focus on challenges to mitigation and adaptation allows for a more systematic
exploration of uncertainties relating to climate policies, the SSPs can also be useful in other
contexts relating more broadly to sustainable development. This is due to the fact that socio-
economic challenges to mitigation and adaptation are closely linked to different degrees of socio-
economic development and sustainability, a topic we discuss in Section 4. Thus, the SSPs can be
applied to the analysis of sustainable development problems without specific reference to
mitigation and adaptation challenges even though these challenges were the starting point for
their design. It is, of course, possible that a backcasting approach that took broader sustainable
development rather than climate change challenges as a starting point would yield a somewhat
different set of SSPs. To this end, the approach taken here for climate change research may
provide a useful example for the development and use of new scenarios in sustainable
development research.
While the SSPs, and the scenario process more broadly, are intended to be policy relevant (hence
the framing in terms of challenges to two types of policy responses), the intended direct users of
the SSPs are primarily the research and assessment communities. The framing of SSPs in terms
Figure 1: Five Shared Socioeconomic Pathways (SSPs) representing different
combinations of challenges to mitigation and to adaptation. Based on Figure 1 from
O‘Neill et al., 2014, but with the addition of specific SSPs.
Socio-economic challenges
for adaptation
Socio-economic
challenges for mitigation
SSP 1:
(Low Challenges)
Sustainability
Taking the Green Road
SSP 3:
(High Challenges)
Regional Rivalry
A Rocky Road
SSP 4:
(Adapt. Challenges Dominate)
Inequality
A Road Divided
SSP 5:
(Mit. Challenges Dominate)
Fossil-fueled
Development
Taking the Highway SSP 2:
(Intermediate Challenges)
Middle of the Road
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of challenges facilitates research based on the SSPs that collectively can characterize a range of
uncertainty in the mitigation required to achieve a given climate outcome, or the adaptation
possibilities associated with that outcome. Development of such a research base, and its
assessment, is a key goal of the scenario process. Thus, the SSPs are not meant primarily as a
direct communication tool for climate policy advice, but rather as a tool to enable the research
community to produce effective assessments for climate policy makers. In addition, the SSP
framing will facilitate improved understanding of the determinants of challenges to mitigation
and to adaptation. The SSPs are developed based on the best current hypotheses about which
elements of societal development pathways are the most important determinants of these
challenges. Use of the SSPs in impact, adaptation and mitigation studies will test those
hypotheses and lead to learning that can be used in future iterations of SSP development.
We consider the narratives presented here to be part of ―basic SSPs‖; that is, they contain enough
information to sketch alternative development pathways that are plausible and that enable them
to be located in a particular area of the challenges space. However, for many applications,
―extended SSPs‖ are likely to be required, which would contain additional, more detailed
information for particular regions, sectors, or variables (van Ruijven et al., 2014) or that would
be enhanced according to specific needs (e.g. vulnerability and risk assessment tools at national
or sub-national level; Birkmann et al., 2013). For example, scenario analyses that focus on a
particular national or sub-national region, or on a particular sector (such as water, health, or
agriculture), will likely benefit from extending these narratives and their associated quantitative
assumptions (Ebi, 2014). Extended SSPs should use assumptions that are consistent with the
basic SSPs, but that support modeling and analysis that goes beyond the key variables provided
in the basic SSPs.
In section 2 we describe the development of the narratives. Section 3 presents summaries of the
individual narratives (full versions are presented in the Supporting Information), along with
thoughts as to how the future societal development pathways they depict could plausibly emerge
from current developments. In section 4 we step back to look at the set of narratives as a whole,
noting the key distinctions across the narratives as well as how they relate to other existing
global scenario narratives and the broader sustainable development context. Section 5 discusses
open questions and concludes.
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2 Methods: Development of narratives
The development of the SSP narratives was driven by three considerations: (1) the general
purpose of narratives of societal development in the context of climate change scenarios; (2) the
experience with narratives developed for past climate change and related scenarios; and (3) the
specific role of the SSPs in the current scenario framework as characterizing societal futures that
have particular combinations of challenges to mitigation and adaptation.
The general purpose of narratives of societal development in climate change scenarios is to
provide broad descriptions of future conditions that are relevant for both the analysis of
emissions drivers and mitigation strategies, and the analysis of societal vulnerability to climate
change, climate impacts and potential adaptation measures. To this end, narratives aim to
convey a basic ―storyline‖ that can guide the specification of further elements of the scenario,
including quantitative elements such as population and economic growth patterns. A narrative of
global development should also be able to guide regional and sectoral extensions of the
scenarios, including the formulation of regional narratives that fit within the overall global
picture. Finally, narratives should be sufficiently generic to allow useful coverage of the space of
relevant futures by representing much broader categories of possible development pathways.
This distinguishes narratives underlying climate change scenarios from much richer storylines
that are sometimes used in decision-making contexts to illustrate the consequences of specific
courses of action.
Previous narratives used in climate change scenarios conveyed the general nature of future
development through key characteristics such as economic growth, regional integration, societal
sustainability and environmental sustainability. These characteristics were also used to define
sets of representative futures that cover a desired space of uncertainty for use in scenario
analysis. Interestingly, the types of narratives (and their combinations into sets) employed in past
scenarios exhibited similarities and recurrent themes (de Vries, 2005; Raskin et al., 2005; van
Vuuren et al., 2012). This fact may point to the relevance of these themes to climate change
analysis, but may also reflect a certain lock-in to a particular way of framing environmental
scenario analysis.
As noted earlier, the current scenario framework calls for the SSPs, and therefore the narratives,
to portray worlds that have varying challenges to mitigation and to adaptation. These challenges
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refer to characteristics of society, not to the amount of climate change or the stringency of the
mitigation policy (factors that are not included in SSPs). Thus, the narratives were constructed
from socioeconomic and environmental (but non-climate) elements judged to be important
determinants of these challenges. While much is known about these determinants, there is still
substantial uncertainty (O‘Neill et al., 2014), particularly regarding determinants of the
challenges to adaptation (Rothman et al., 2014; Schweizer and O‘Neill, 2014).
Taken together, these considerations implied a method that iterated between desired
characteristics of the full narratives and identification of specific narrative elements and
assumptions (Figure 1). Content for the SSPs was developed in a variety of approaches,
essentially through expert judgment with a wide variety of experts from the IAM, IAV,
development, futures studies, and vulnerability and risk research communities providing input
through a series of dedicated meetings.1 A first meeting resulted in the adoption of a set of
incipient SSP narratives (O‘Neill et al., 2012) that were further developed at a subsequent
meeting through broader discussion of the drafts and initial quantifications of key drivers. An
author group (consisting of the authors of this paper) was formed to revise the narratives in light
1 For descriptions of the process, see Ebi et al., 2014, and http://sedac.ipcc-
data.org/ddc/ar5_scenario_process/parallel_nat_scen.html. Much of this process was carried out under the auspices
of the International Committee on New Integrated Climate change assessment Scenarios (ICONICS;
https://www2.cgd.ucar.edu/research/iconics), which was formed to facilitate development and use of the new
scenarios, including the SSPs and their quantitative and qualitative elements.
Figure 2: Flow diagram of process for developing SSP narratives.
Define objective: narratives
covering uncertainty space of
challenges to adaptation and
mitigation
Identify key elements related to
challenges to mitigation and
adaptation
Combine elements: construct
narratives that imply desired
challenges to mitigation and
adaptation
Do narratives
meet
objective?
No Yes Finalize
pathway
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of feedback and to produce a paper documenting them and their production. As part of that
process, draft narratives were posted for comment by the scientific community, and 38 pages of
comments from 18 reviewers were collected and considered.
Lists of potential narrative elements considered to be important determinants of challenges to
mitigation or adaptation were generated through expert discussions at the meetings described
above, as well as through formal (Schweizer and O‘Neill, 2014) and informal (Wilbanks and
Ebi, 2014) expert elicitation. Ultimately, variables in six broad categories were considered to be
important to represent in the SSPs: demographics, human development, economy and lifestyle,
policies and institutions (excluding climate policies), technology, and environment and natural
resources. This list is not meant to be exhaustive, but to provide sufficient guidance for
developing basic narratives that depending on future research needs can be further adapted
and extended. Principal determinants of challenges to mitigation, for example, include
determinants of energy and land use, technological progress, and international policy institutions.
In the case of challenges to adaptation, institutional factors, future inequality and poverty as well
as possible attainment or failure in achieving different development objectives play a critical
role.
The process of creating narratives from these elements was informed by pre-existing narratives
from the IPCC Special Report on Emission Scenarios (Nakicenovic et al., 2000), the Millennium
Ecosystem Assessment (Carpenter et al., 2005), and the UNEP Global Environment Outlook
(GEO) scenarios (UNEP, 2002, 2007), among other global scenario exercises (van Vuuren et al.,
2012). Possible illustrative starting points for SSP narratives were described in a number of
papers (Kriegler et al., 2012; O‘Neill et al., 2014; Schweizer and O‘Neill, 2014), including
analogies to SRES scenarios (Van Vuuren and Carter, 2014), and were considered by meeting
participants and the narratives author group. Discussions among the author team and further
development and revision of the narratives were informed also by work on the concept of
challenges to adaptation (Rothman et al., 2014) and on the role of governance and political
economy (Lane and Montgomery, 2014).
It was decided to develop five SSPs to span the challenges space, necessitating five different
narratives (Figure 1; O‘Neill et al., 2014). Four of the narratives (SSP1, SSP3, SSP4, SSP5)
describe the various combinations of high or low challenges to adaptation and mitigation, all of
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which were considered plausible enough to warrant SSP development. A fifth narrative (SSP2)
described moderate challenges of both kinds, and is intended to represent a future in which
development trends are not extreme in either of the dimensions, but rather follow middle-of-the-
road pathways relative to the span of plausible outcomes for each element. Most approaches to
scenario design advocate an even number of scenarios to discourage use of a single scenario as a
central case (Kok et al., 2006). However, this strategy has not always been successful, with
scenario users sometimes selecting one scenario as either ‗most likely‘ or ‗closest to a model
baseline‘. This tendency convinced the SSP design group to explicitly provide a central pathway.
The central case is not meant to be more likely than any of the other storylines or pathways. In
fact, historical development of GHG emissions has often followed trajectories close to the upper
bound of the range of earlier emissions scenarios, such as those from SRES (Nakicenovic et al,
2000). Including a central case was also intended to ensure that the pathways fill the challenges
space and that the other four SSPs not drift towards the middle space, which might otherwise be
perceived as not well covered.
3 Results: The basic SSP narratives
This section presents summaries of the five narratives developed to occupy each of the domains
of the challenges space, along with some thoughts as to how the future societal development
pathways they depict could plausibly emerge from current developments. Somewhat more
discussion is provided for those SSPs, notably SSP4, which are less well represented in previous
scenario exercises. More complete versions of all of the narratives are included in the Supporting
Information. We employ the metaphor of a road or pathway in naming the SSPs in order to
emphasize that they are intended to describe the evolution of global and regional development
trends over time, rather than static snapshots of conditions at a particular point in time.
3.1 SSP1: Sustainability Taking the Green Road
The world shifts gradually, but pervasively, toward a more sustainable path,
emphasizing more inclusive development that respects perceived environmental
boundaries. Increasing evidence of and accounting for the social, cultural, and
economic costs of environmental degradation and inequality drive this shift.
Management of the global commons slowly improves, facilitated by increasingly
effective and persistent cooperation and collaboration of local, national, and
international organizations and institutions, the private sector, and civil society.
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Educational and health investments accelerate the demographic transition,
leading to a relatively low population. Beginning with current high-income
countries,the emphasis on economic growth shifts toward a broader emphasis on
human well-being, even at the expense of somewhat slower economic growth over
the longer term. Driven by an increasing commitment to achieving development
goals, inequality is reduced both across and within countries. Investment in
environmental technology and changes in tax structures lead to improved
resource efficiency, reducing overall energy and resource use and improving
environmental conditions over the longer term. Increased investment, financial
incentives and changing perceptions make renewable energy more attractive.
Consumption is oriented toward low material growth and lower resource and
energy intensity. The combination of directed development of environmentally
friendly technologies, a favorable outlook for renewable energy, institutions that
can facilitate international cooperation, and relatively low energy demand results
in relatively low challenges to mitigation. At the same time, the improvements in
human well-being, along with strong and flexible global, regional, and national
institutions imply low challenges to adaptation.
SSP1, with its central features of commitment to achieving development goals, increasing
environmental awareness in societies around the world, and a gradual move toward less
resource-intensive lifestyles, constitutes a break with recent history in which emerging
economies have followed the resource-intensive development model of industrialized countries.
To some extent, elements of this scenario can already be found in the proliferation of ―green
growth‖ and ―green economy‖ strategies in industrialized and developing countries (UNEP,
2011; UNESCAP, 2012), although their efficacy has been questioned (Bina and La Camera,
2011). As emphasized by Ocampo (2011), for these strategies to succeed there would need to be
innovation in both industrialized and developing countries and adequate human and financial
resources. Such innovation has been spurred by environmental policy (Ambec et al., 2013; Porter
and van der Linde, 1995), and this SSP assumes that policy changes are driven by changing
attitudes. The focus on equity, and the de-emphasis of economic growth as a goal in and of itself
in high-income countries, leads industrialized countries to support developing countries in their
development goals, including green growth strategies, by providing access to human and
financial resources and new technologies.
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3.2 SSP2: Middle of the Road
The world follows a path in which social, economic, and technological trends do
not shift markedly from historical patterns. Development and income growth
proceeds unevenly, with some countries making relatively good progress while
others fall short of expectations. Most economies are politically stable. Globally
connected markets function imperfectly. Global and national institutions work
toward but make slow progress in achieving sustainable development goals,
including improved living conditions and access to education, safe water, and
health care. Technological development proceeds apace, but without fundamental
breakthroughs. Environmental systems experience degradation, although there
are some improvements and overall the intensity of resource and energy use
declines. Even though fossil fuel dependency decreases slowly, there is no
reluctance to use unconventional fossil resources. Global population growth is
moderate and levels off in the second half of the century as a consequence of
completion of the demographic transition. However, education investments are
not high enough to accelerate the transition to low fertility rates in low-income
countries and to rapidly slow population growth. This growth, along with income
inequality that persists or improves only slowly, continuing societal stratification,
and limited social cohesion, maintain challenges to reducing vulnerability to
societal and environmental changes and constrain significant advances in
sustainable development. These moderate development trends leave the world, on
average, facing moderate challenges to mitigation and adaptation, but with
significant heterogeneities across and within countries.
SSP2 does not imply a simple extrapolation of recent experience, but rather a
development pathway that is consistent with typical patterns of historical experience
observed over the past century. For example, emerging economies grow relatively
quickly and then slow as incomes reach higher levels, the demographic transition occurs
at average rates as societies develop, and technological progress continues without major
slowdowns or accelerations. Thus it is a dynamic pathway, yet one in which future
changes in various elements of the narrative are consistent with middle of the road
expectations, rather than falling near the upper or lower bounds of possible outcomes.
There are likely many reasons that trends in SSP elements could end up being moderate,
and no specific stance is taken here as to motivating forces.
3.3 SSP3: Regional Rivalry A Rocky Road
A resurgent nationalism, concerns about competitiveness and security, and
regional conflicts push countries to increasingly focus on domestic or, at most,
regional issues. This trend is reinforced by the limited number of comparatively
weak global institutions, with uneven coordination and cooperation for
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addressing environmental and other global concerns. Policies shift over time to
become increasingly oriented toward national and regional security issues,
including barriers to trade, particularly in the energy resource and agricultural
markets. Countries focus on achieving energy and food security goals within their
own regions at the expense of broader-based development, and in several regions
move toward more authoritarian forms of government with highly regulated
economies. Investments in education and technological development decline.
Economic development is slow, consumption is material-intensive, and
inequalities persist or worsen over time, especially in developing countries. There
are pockets of extreme poverty alongside pockets of moderate wealth, with many
countries struggling to maintain living standards and provide access to safe
water, improved sanitation, and health care for disadvantaged populations. A low
international priority for addressing environmental concerns leads to strong
environmental degradation in some regions. The combination of impeded
development and limited environmental concern results in poor progress toward
sustainability. Population growth is low in industrialized and high in developing
countries. Growing resource intensity and fossil fuel dependency along with
difficulty in achieving international cooperation and slow technological change
imply high challenges to mitigation. The limited progress on human development,
slow income growth, and lack of effective institutions, especially those that can
act across regions, implies high challenges to adaptation for many groups in all
regions.
SSP3, with its theme of international fragmentation and a world characterized by regional rivalry
can already be seen in some of the current regional rivalries and conflicts, but contrasts with
globalization trends in other areas. It is based on the assumption that these globalization trends
can be reversed by a number of events. For example, economic woes in major economies could
spark increasing discontent with globalization and spur protectionist instincts. Alternatively,
regional conflict over territorial or national issues could produce larger conflict between major
countries, giving rise to increasing antagonism between and within regional blocs. Such a
reversal of globalization trends due to regional conflict has happened before, for example on the
eve of World War I (e.g. Ferguson, 2005). Regional rivalries reduce support for international
institutions and development partners, thus weakening progress towards development goals,
resulting in a substantial changes to current trends in population growth, human health and well-
being, and environmental protection in some low- and middle-income countries.
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3.4 SSP4: Inequality A Road Divided
Highly unequal investments in human capital, combined with increasing
disparities in economic opportunity and political power, lead to increasing
inequalities and stratification both across and within countries. Over time, a gap
widens between an internationally-connected society that is well educated and
contributes to knowledge- and capital-intensive sectors of the global economy,
and a fragmented collection of lower-income, poorly educated societies that work
in a labor intensive, low-tech economy. Power becomes more concentrated in a
relatively small political and business elite, even in democratic societies, while
vulnerable groups have little representation in national and global institutions.
Economic growth is moderate in industrialized and middle-income countries,
while low income countries lag behind, in many cases struggling to provide
adequate access to water, sanitation and health care for the poor. Social cohesion
degrades and conflict and unrest become increasingly common. Technology
development is high in the high-tech economy and sectors. Uncertainty in the
fossil fuel markets lead to underinvestment in new resources in many regions of
the world. Energy companies hedge against price fluctuations partly through
diversifying their energy sources, with investments in both carbon-intensive fuels
like coal and unconventional oil, but also low-carbon energy sources.
Environmental policies focus on local issues around middle and high income
areas. The combination of some development of low carbon supply options and
expertise, and a well-integrated international political and business class capable
of acting quickly and decisively, implies low challenges to mitigation. Challenges
to adaptation are high for the substantial proportions of populations at low levels
of development and with limited access to effective institutions for coping with
economic or environmental stresses.
SSP4, with its emphasis on both across- and within-country inequality, seems less well
represented in previous scenario literature, and we discuss its assumptions in more detail here. Its
central feature of rising inequality is assumed to arise from a number of factors discussed in the
inequality literature, including skill-biased technology development (where technology replaces
many low-skill jobs; Jaumotte et al., 2008; Lansing and Markiewicz, 2012) or capital returns
(Piketty, 2014). Another key factor is the assumed generally low and highly unequal investments
in education. Expanded education has been an important contributor to lowering inequality in the
recent past (OECD, 2011; Cornia, 2012); this narrative assumes the converse, that limited access
to education can increase inequality. In addition, less affluent groups are assumed to have weak
political power, fewer economic opportunities, and limited access to credit (Vindigni, 2002;
15
Bénabou, 2000), constraining both educational opportunities and income growth and making
inequality more persistent. At the same time, those at the top end of the income scale (Atkinson
et al., 2010; Roine et al., 2009) see their relative position reinforced through institutional changes
that strengthen their bargaining power at the expense of low earners (Kumhof and Ranciere,
2010; Piketty et al., 2011). Across countries, the assumption that growth results in separation into
different country income groups is consistent with the idea of ―convergence clubs‖ (Galor, 1996;
Quah, 1996a, 1996b) as opposed to the conditional convergence hypothesis (Barro and Sala-i-
Martin, 2003).
There is very mixed evidence on the current inequality trends within and across countries. Wage
inequality across countries has generally been increasing since 1980 in both OECD and non-
OECD countries (Galbraith, 2011). While a simple population-weighted measure of international
income dispersion is falling, this is almost entirely due to China, and except in the very recent
past, the measure has been rising when China is excluded (Milanovic, 2012). Historical
experience regarding within-country inequality is mixed, while SSP4 assumes that it increases in
the long term. For some countries this means that recent trends will eventually reverse. This is
plausible because such improvements can be temporary. For example, falling inequality within
Latin America appears to be largely due to expanded education and reforms introduced by leftist
governments (Cornia, 2012). SSP4 assumes increasingly restricted access to education, which
could plausibly halt or reverse improvements. In addition, (Galbraith, 2011) notes that downturns
in inequality from populist governments rarely endure.
It is also important to note that this pathway envisions a slow down, but not a halt to or reversal
of the growth of the global middle class. Kharas (2010) defines the global middle class as
consisting of people with daily expenditure between $10 and $100. He estimates that there are
1.8 billion people in the global middle class in 2009 (~25% of the global population), and that
this total could rise to 4.8 billion (~60%) in 2030, due almost entirely to East Asia. The SSP4
narrative assumes that growth is substantially smaller than it is in this outlook, but does not
assume that it is halted entirely.
Finally, the assumptions that inequality and a perception of scarce energy resources lead to a
decline in social cohesion and increased potential for conflict are consistent with scholarship in
these areas. Empirically, there is a significant negative relationship between inequality and social
16
cohesion across a variety of measures (trust, solidarity, dysfunction; Uslaner, 2002; Bjørnskov,
2008; Wilkinson and Pickett, 2009; Kemp-Benedict, 2011; Paskov and Dewilde, 2012).
Similarly, there is historical precedent for conflict over energy resources in consuming countries
(England, 1994) and in producing countries (Ross, 2004), with potential for intensification if
resources are further constrained (Lee, 2005).
3.5 SSP5: Fossil-fueled Development Taking the Highway
Driven by the economic success of industrialized and emerging economies, this
world places increasing faith in competitive markets, innovation and
participatory societies to produce rapid technological progress and development
of human capital as the path to sustainable development. Global markets are
increasingly integrated, with interventions focused on maintaining competition
and removing institutional barriers to the participation of disadvantaged
population groups. There are also strong investments in health, education, and
institutions to enhance human and social capital. At the same time, the push for
economic and social development is coupled with the exploitation of abundant
fossil fuel resources and the adoption of resource and energy intensive lifestyles
around the world. All these factors lead to rapid growth of the global economy.
There is faith in the ability to effectively manage social and ecological systems,
including by geo-engineering if necessary. While local environmental impacts are
addressed effectively by technological solutions, there is relatively little effort to
avoid potential global environmental impacts due to a perceived tradeoff with
progress on economic development. Global population peaks and declines in the
21st century. Though fertility declines rapidly in developing countries, fertility
levels in high income countries are relatively high (at or above replacement level)
due to optimistic economic outlooks. International mobility is increased by
gradually opening up labor markets as income disparities decrease. The strong
reliance on fossil fuels and the lack of global environmental concern result in
potentially high challenges to mitigation. The attainment of human development
goals, robust economic growth, and highly engineered infrastructure results in
relatively low challenges to adaptation to any potential climate change for all but
a few.
SSP5 foresees accelerated globalization and rapid development of developing countries,
including a significant improvement of institutions and the economic participation of
disadvantaged population groups. Such trends have little historic precedent, particularly on the
global scale. Only a limited number of nations have managed the transition to a market economy
with effective institutions (Lane and Montgomery, 2014), and the long-term prospects of
17
currently rapidly developing economies such as China, India and Brazil remain uncertain.
However, two historically unprecedented developments in the recent past suggest a break from
past trends. First, the economic success of emerging economies and more recently least
developed countries has given rise to an emergent global middle class that has been lacking in
most regions of the world (Kharas, 2010). The new middle class could stabilize global economic
development by promoting robust growth in demand for services and goods. It may also generate
societal pressure toward improved institutions and more participatory societies as for example
has been observed in Brazil. Second, the digital revolution enables a global discourse of a
significant and increasing fraction of the global population for the first time in human history
which may lead to a rapid rise in global institutions and promote the ability for global
coordination (Keohane and Nye, 2000).
4 The SSP Narratives: Relationships to each other and to existing
narratives
As important as the individual narratives are in and of themselves, we need to also consider them
as a set. Are they sufficiently distinct in their socioeconomic challenges to mitigation and
adaptation to meet the needs specified in the conceptual framework? Do they span a wide range
of development outcomes? And how do they relate to other existing global scenario narratives?
Regarding the needs of the conceptual framework, the SSP narratives aim to capture the
combinations of challenges to mitigation and adaptation illustrated in Figure 1. SSP1 leads to
low challenges to both mitigation and adaptation due to a combination of substantial income
growth, a reduction in inequality, strong institutions, and a sustained value shift over time that
prioritizes sustainable development. As discussed above, SSP2 is a scenario in which elements
follow middle-of-the-road trends, leading to intermediate challenges to both mitigation and
adaptation. In contrast, SSP3 leads to high challenges to both mitigation and adaptation resulting
from slow growth in income and slow technological change, ineffective institutions, and low
investment in human capital.
SSPs 4 and 5 are mixed scenarios in which a particular set of challenges dominates. SSP4 is a
world in which it may not be too difficult to mitigate climate change, but would be quite difficult
to adapt to it. A central feature of this pathway is growing inequality both across and within
countries, including in the currently industrialized world. Mitigation challenges are relatively
18
low due to modest economic growth combined with availability of technologies and expertise
within the portion of the economy in which power is concentrated, while adaptation challenges
are high for the substantial portion of the population with relatively low income education and
little access to effective institutions. In SSP5, economic growth is very high, enabling many
development goals to be achieved within short time frames, so that challenges to adaptation are
relatively low. However energy demand grows rapidly and the energy system continues to rely
heavily on fossil fuels, leading to high challenges to mitigation.
Figure 3 summarizes the pathway elements that lead to the particular combinations of challenges
represented by each SSP. For example, high challenges to mitigation are hypothesized to be
driven in these narratives by fossil-dominated energy supply either globally or regionally, along
with a lack of capacity (or desire) for international cooperation on global environmental issues.
These challenges are exacerbated in SSP5 by very high energy demand and in SSP3 by slow
technological change. In contrast, low challenges to mitigation are driven by development of
low-carbon energy technologies (or the capacity for that development) and effective means of
cooperating on international policy. These challenges are further reduced in SSP1 by a general
orientation toward environmental sustainability.
High challenges to adaptation are assumed to be driven by a combination of slow development,
low investments in human capital, and increased inequality. These challenges are exacerbated in
SSP3 by ineffective institutions and barriers to trade, and in SSP4 by high inequality within (as
well as across) countries. In contrast, low challenges to adaptation are driven by rapid
development and formation of human capital and reduced inequality, further reduced in SSP5 by
highly engineered infrastructure and in SSP1 by an orientation toward environmental
sustainability.
19
Regarding the range of development pathways the SSPs describe, Tables 1-3 summarize
assumptions about key elements of the narratives. The tables show that the SSPs span a wide
range of assumptions about individual elements of the pathways. Demographic trends vary
widely. For example, SSPs 1 and 5 experience low population growth paths at the global level
driven in part by rapid improvements in education, fast income growth, and rapid urbanization,
leading to relatively rapid declines in fertility in high fertility countries. In contrast, SSPs 3 and 4
experience high population growth rates, a consequence of much slower improvements in
education and income in high fertility countries. In countries where fertility is already low, there
Socioeconomic
challenges for mitigation
SSP 3:
Slow tech.
change
SSP 1, 4:
Actual or potential low-
carbon tech. change;
Effective institutions and
int’l cooperation
SSP 3, 5:
Fossil-dominated
energy supply;
Lack of international
cooperation
SSP 1:
Env ironmental
awareness
SSP 5:
High energy
demand
Socioeconomic
challenges for adaptation
Mitigation Challenges
Figure 3: A summary of SSP elements that contribute to high or low challenges to
mitigation (a) and adaptation (b). Elements listed toward the top or bottom of the challenges
space in figure (a) apply to pathways with high or low challenges to mitigation, respectively,
while elements listed toward the left or right side of the challenges space in figure (b) apply
to pathways with low or high challenges to adaptation, respectively.
(a)
(b)
20
is no single widely accepted theory of the determinants of future fertility change (Basten et al.,
2014). Therefore, demographic trends in these countries are not chosen primarily by appealing to
existing theory, but rather to either contribute to the challenges each SSP is intended to present
or to increase the range of demographic outcomes achieved across the full set of SSPs. For
example, the combination of low fertility and migration in SSP3 would produce a very old age
structure in the industrialized world, which could make it more difficult to cope with some types
of climate change impacts. SSP5 assumes high net immigration and fertility above replacement
level in the high-income countries in order to provide one pathway in which industrialized
country population growth is more substantial.
Economic development is rapid and broad-based in SSPs 1 and 5, which gives rise to substantial
reductions in inequality, both between and within countries, and is accompanied by continued
globalization and international trade. SSP 1 differs in that there is a pronounced value shift,
resulting in somewhat less rapid economic growth as compared to SSP5, but compensated by
other factors such as better environmental quality and higher level of equity. Accounting for
better livelihoods, the environment, equity as well as other factors, overall welfare is higher in
SSP1 as compared to SSP5. In contrast economic growth is slow and inequality is compounded
in SSPs 3 and 4, with inequality within countries especially high in SSP4. SSP3 also envisions
substantial obstacles to global trade, with implications for development as well as for challenges
to adaptation.
Regarding the relationships of the SSP narratives to those in previous scenario sets, previous
scenarios were commonly grouped according to assumptions they made about key driving forces
rather than according to outcomes of the narratives such as their implied challenges to mitigation
and adaptation. The SRES scenarios, for example, are typically described as spanning a space
defined by their degree of economic vs environmental orientation, and their regional vs global
orientation (Nakicenovic et al., 2000). The two approaches to developing or describing narratives
are not mutually exclusive. The SSPs can be mapped not only to the challenges space in Figure
1, but also to spaces defined by assumptions about key input elements. For example, it is
possible to map the SSPs to the space defined for the SRES scenarios. The relatively optimistic
SSP1 that is oriented toward sustainability, and relatively pessimistic SSP3 in which geopolitical
regions fragment rather than globalize, share features with SRES B1 and A2 worlds, respectively
(Kriegler et al., 2012; O‘Neill et al., 2014; van Vuuren and Carter, 2014). Similarly, SSP5 – a
21
high economic growth pathway with a fossil-based energy system shares features of the SRES
A1F scenario (Kriegler et al., 2012; O‘Neill et al., 2014; van Vuuren and Carter, 2014). There
are also relationships with the storylines of other assessments (see for example Table 1 of van
Vuuren and Carter, 2014). The Millennum Ecosystem Assessment (MA) scenarios (Carpenter et
al., 2005) are interesting in this respect given their ample attention to narratives. For example,
the MA Order from Strength scenario provides insight into possible consequences of an SSP4-
type world (Van Vuuren and Carter, 2014).
In summary, existing sets of narratives were often characterized in terms of economic growth,
regional integration, societal sustainability (equity and governance) and environmental
sustainability (environmental awareness and lifestyles). The SSPs can also be mapped to spaces
defined by assumptions about these elements. As illustrated in Figure 4, such mappings indicate
that the SSPs not only cover the range of challenges to mitigation and adaptation, but also to a
large extent the space of low vs. high economic growth, low vs. high societal sustainability and
low vs. high environmental sustainability seen in other scenario sets. Exceptions are the case of
low economic growth combined with high societal and environmental sustainability, and the case
of medium to high economic growth coupled with low societal and environmental sustainability.
The first case (low growth, high societal and environmental sustainability) would require an
SSP1 variant with a more dramatic shift to lower consumption lifestyles, sharing some features
with existing scenarios such as the Great Transition (Raskin et al., 2002) and Sustainability First
Figure 4: Illustrative mapping of SSPs to a space defined by elements of the SSP narratives
as opposed to consequences of the narratives for challenges to mitigation and adaptation.
Economic Growth (per capita)
Societal Sustainability
SSP1
SSP2
SSP3 SSP4
SSP5
SSP1
variant
Environmental Sustainability
Economic Growth (per capita)
SSP1
SSP2
SSP3
SSP4 SSP5
SSP1
variant
SSP4
variant
22
(Rothman et al 2007). The second case (high growth, low societal and environmental
sustainability) could be captured in a variant of SSP4 in which an internationally well-connected
society has very limited environmental awareness and exposure.
The discussion shows that there exists a close link between socio-economic challenges to
mitigation and adaptation, and the dimensions of sustainability and development. As a result, the
SSPs not only cover the space of mitigation and adaptation challenges, but also a wide range of
development and sustainability outcomes (see Figure 4). Thus, they can also be a useful tool for
the analysis of broader sustainable development objectives.
5 Discussion and Conclusions
There are several open questions about the design and use of SSPs. First, a broad question
remains as to the effectiveness of pathways characterized by a global sense of the challenges to
mitigation or adaptation they present. If, for example, challenges to adaptation are dominated by
local considerations, and if many of these considerations have only weak connections to
development trends in other regions or at a larger scale, then a global starting point for scenario
development would seem to be a less effective approach. We believe that an initial global
framing can in fact be useful, partly because local challenges will depend to some degree on
factors at the regional, national, or international level (e.g., energy prices, trade possibilities,
international institutions, global competition, technology spill-overs, policies, etc.), and partly
because a global framing serves as a means of deciding which local assumptions to make, even
in those cases in which there are only weak connections to larger-scale factors (for example,
local assumptions might be made to reflect the same type and degree of challenges that are the
intention of the global pathway). However, it will be important for the lessons learned in
carrying out studies in more specific contexts to be communicated to and incorporated in any
revision process for global scale narrative development.
Second, it was already clear in the narrative design process that more than one type of narrative
could be located within a particular domain of the challenges space. Which type might be most
useful, or whether the development of more than one type per domain would be useful, remains
to be seen. For example, as discussed in section 4, an alternative SSP1 storyline could be
envisioned that involves a substantially larger shift in values toward lower consumption
lifestyles, leading to a version of the narrative with much lower economic growth and energy
23
demand. Such a low growth, sustainable development pathway has some precedent in the
literature (Raskin et al., 2002; Rothman et al., 2007) and offers an alternative to the higher
growth sustainability pathway described here (which reflects more the B1/Technogarden
scenarios from SRES/Millennium Ecosystem Assessment). Similarly, an alternative version of
SSP2 could be developed in which challenges to mitigation and adaptation were moderate on
average across regions, but varied widely from region to region, rather than being more
uniformly middle-of-the-road as assumed in the SSP2 narrative presented here. These regional
differences could arise from, for example, current trends in water security without considering
any potential impacts of climate change (which are outside the SSPs). The storylines presented in
this paper are canonical, but the canon is not exclusive. To make a broadly useful framework for
climate scenario development, it will benefit the research community if alternative storylines that
can be located within a particular domain of the challenges space be explicitly identified as such.
Third, it may also be useful to consider narratives describing development pathways that move
through more than one domain of the challenges space over time. The approach taken by the
narratives presented here is to describe development pathways that move from current conditions
toward futures in which the challenges to mitigation and adaptation are progressively more and
more consistent with the intended outcome for the SSP. However it is possible that a
development pathway could move toward one combination of challenges before changing
direction and moving toward another. For example, surprises may drive such a change. In a
world developing along the pessimistic SSP3 narrative, a surprise breakthrough in mitigation
technology may quickly lower the challenges to mitigation and move society into the SSP4
domain. Exploring development pathways that move through more than one domain may be an
especially effective way to consider how fast societal trends may change, whether path
dependency may limit the long-term futures that could follow from trends over the next few
decades, and ultimately how these factors may influence challenges to mitigation and adaptation.
In addition to these open questions, it is also important to keep in mind that the narratives
presented here are qualitative components of basic SSPs. Extensions to these narratives will in
many cases be required to support more detailed analyses of climate response options and
impacts in particular sectors or locations (van Ruijven et al., 2014) and risk and vulnerability
assessments at different scales. Examples of extensions are already beginning to appear. In order
to produce the SSP-based integrated assessment model scenarios that appear in this special issue,
24
SSPs had to be extended to provide more detailed assumptions about future energy systems and
land use in order to specify required inputs to IAMs. Ebi (2014) has elaborated on the public
health-related aspects of the narratives, Birkmann et al. (2013) elaborated on the risk and
vulnerability aspects in the context of climate change and natural hazards, and extensions known
as ―representative agricultural pathways‖ to support agricultural impact assessment are under
development for the Agricultural Model Intercomparison and Improvement Project (AgMIP).
Moreover, extensions with respect to the pollution and health dimension of the SSPs are
discussed in several other papers in this Special Issue.
Capturing lessons from experience gained in applying the SSPs to integrated climate change
research, as well as in extending them to particular sectors and geographic scales, should be a
high priority. In that way future revisions of the narratives, or the development of additional
narratives, will most effectively support integrated climate change research.
25
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31
Tables
Table 1: Summary of assumptions regarding Demographic and Human Development elements of SSPs. Country groupings referred to in table entries for Human
Development are based on the World Bank definition of low-income (LIC), medium-income (MIC) and high-income (HIC) countries.
SSP element
SSP1
SSP2
SSP3
SSP4
SSP5
Country Fertility Groupings for demographic elements
High
Fert.
Low
Fert.
Rich-
OECD
High
Fert.
Low
Fert.
Rich-
OECD
High
Fert.
Low
Fert.
Rich-
OECD
High
Fert.
Low
Fert.
Rich-
OECD
High
Fert.
Low
Fert.
Rich-
OECD
Demographics
Population
Growth
Relatively low
Medium
High
Low
Relatively high
Low
Relatively low
Fertility
Low
Low
Med
Medium
High
High
Low
High
Low
Low
Low
Low
High
Mortality
Low
Medium
High
High
Med
Med
Low
Migration
Medium
Medium
Medium
High
Urbanization
Level
High
Medium
Low
High
High
Med
High
Type
Well managed
Continuation of historical
patterns
Poorly managed
Mixed across and within
cities
Better mgmt. over time,
some sprawl
Human
development
Education
High
Medium
Low
V.low/
uneq.
Low/
uneq.
Med/
uneq.
High
Health
investments
High
Medium
Low
Unequal within regions,
lower in LICs, medium in
HICs
High
Access to health
facilities, water,
sanitation
High
Medium
Low
Unequal within regions,
lower in LICs, medium in
HICs
High
Gender equality
High
Medium
Low
Unequal within regions,
lower in LICs, medium in
HICs
High
Equity
High
Medium
Low
Medium
High
Social cohesion
High
Medium
Low
Low, stratified
High
Societal
participation
High
Medium
Low
Low
High
32
Table 2: Summary of assumptions regarding Economy & Lifestyle and Policies & Institutions elements of SSPs. Country groupings referred to in table entries are based on
the World Bank definition of low-income (LIC), medium-income (MIC) and high-income (HIC) countries.
SSP element
SSP1
SSP2
SSP3
SSP4
SSP5
Economy &
Lifestyle
Growth (pc)
High in LICs, MICs;
medium in HICs
Medium, uneven
Slow
Low in LICs, medium in
other countries
High
Inequality
Reduced across and
within countries
Uneven moderate
reductions across and
within countries
High, especially across
countries
High, especially within
countries
Strongly reduced, especially
across countries
International
trade
Moderate
Moderate
Strongly constrained
Moderate
High, with regional
specialization in production
Globalization
Connected markets,
regional production
Semi-open globalized
economy
De-globalizing, regional
security
Globally connected elites
Strongly globalized,
increasingly connected
Consumption
& Diet
Low growth in material
consumption, low-meat
diets, first in HICs
Material-intensive
consumption, medium
meat consumption
Material-intensive
consumption
Elites: high consumption
lifestyles; Rest: low
consumption, low mobility
Materialism, status
consumption, tourism,
mobility, meat-rich diets
Policies &
Institutions
International
Cooperation
Effective
Relatively weak
Weak, uneven
Effective for globally
connected economy, not
for vulnerable populations
Effective in pursuit of
development goals, more
limited for envt. goals
Environmental
Policy
Improved management
of local and global
issues; tighter regulation
of pollutants
Concern for local
pollutants but only
moderate success in
implementation
Low priority for
environmental issues
Focus on local
environment in MICs, HICs;
little attention to
vulnerable areas or global
issues
Focus on local environment
with obvious benefits to
well-being, little concern
with global problems
Policy
orientation
Toward sustainable
development
Weak focus on
sustainability
Oriented toward security
Toward the benefit of the
political and business elite
Toward development, free
markets, human capital
Institutions
Effective at national and
international levels
Uneven, modest
effectiveness
Weak global institutions/
natl. govts. dominate
societal decision-making
Effective for political and
business elite, not for rest
of society
Increasingly effective,
oriented toward fostering
competitive markets
33
Table 3: Summary of assumptions regarding Technology and Environment & Resources elements of SSPs. Country groupings referred to in table entries are based on the
World Bank definition of low-income (LIC), medium-income (MIC) and high-income (HIC) countries.
SSP element
SSP1
SSP2
SSP3
SSP4
SSP5
Technology
Development
Rapid
Medium, uneven
Slow
Rapid in high-tech economies
and sectors; slow in others
Rapid
Transfer
Rapid
Slow
Slow
Little transfer within countries
to poorer populations
Rapid
Energy tech
change
Directed away from
fossil fuels, toward
efficiency and
renewables
Some investment in
renewables but continued
reliance on fossil fuels
Slow tech change,
directed toward
domestic energy
sources
Diversified investments
including efficiency and low-
carbon sources
Directed toward fossil
fuels; alternative sources
not actively pursued
Carbon
intensity
Low
Medium
High in regions with
large domestic fossil fuel
resources
Low/Medium
High
Energy
intensity
Low
Uneven, higher in LICs
High
Low/Medium
High
Environment &
Natural resources
Fossil
constraints
Preferences shift
away from fossil fuels
No reluctance to use
unconventional resources
Unconventional
resources for domestic
supply
Anticipation of constraints
drives up prices with high
volatility
None
Environment
Improving conditions
over time
Continued degradation
Serious degradation
Highly managed and improved
near high/middle-income
living areas, degraded
otherwise
Highly engineered
approaches, successful
management of local issues
Land Use
Strong regulations to
avoid environmental
tradeoffs
Medium regulations lead
to slow decline in the rate
of deforestation
Hardly any regulation;
continued deforestation
due to competition over
land and rapid
expansion of agriculture
Highly regulated in MICs, HICs;
largely unmanaged in LICs
leading to tropical
deforestation
Medium regulations lead to
slow decline in the rate of
deforestation
Agriculture
Improvements in ag
productivity; rapid
diffusion of best
practices
Medium pace of tech
change in ag sector; entry
barriers to ag markets
reduced slowly
Low technology
development, restricted
trade
Ag productivity high for large
scale industrial farming, low
for small-scale farming
Highly managed, resource-
intensive; rapid increase in
productivity.
34
Appendix (i.e. Supporting Information)
SSP1: Sustainability The Green Road
Sketch
The world shifts gradually, but pervasively, toward a more sustainable path,
emphasizing more inclusive development that respects perceived environmental
boundaries. Increasing evidence of and accounting for the social, cultural, and
economic costs of environmental degradation and inequality drive this shift.
Management of the global commons slowly improves, facilitated by increasingly
effective and persistent cooperation and collaboration of local, national, and
international organizations and institutions, the private sector, and civil society.
Educational and health investments accelerate the demographic transition,
leading to a relatively low population. Beginning with current high-income
countries,the emphasis on economic growth shifts toward a broader emphasis on
human well-being, even at the expense of somewhat slower economic growth over
the longer term. Driven by an increasing commitment to achieving development
goals, inequality is reduced both across and within countries. Investment in
environmental technology and changes in tax structures lead to improved
resource efficiency, reducing overall energy and resource use and improving
environmental conditions over the longer term. Increased investment, financial
incentives and changing perceptions make renewable energy more attractive.
Consumption is oriented toward low material growth and lower resource and
energy intensity. The combination of directed development of environmentally
friendly technologies, a favorable outlook for renewable energy, institutions that
can facilitate international cooperation, and relatively low energy demand results
in relatively low challenges to mitigation. At the same time, the improvements in
human well-being, along with strong and flexible global, regional, and national
institutions imply low challenges to adaptation.
Additional Information
Motivating forces: Growing evidence of and accounting for the social, cultural, and economic
costs of inequality and environmental degradation moves the world gradually, but pervasively, to
prioritize progress towards achieving global and national development and sustainability goals,
while reducing inequality (across and within economies). The shift is more pronounced in
developed countries, which increasingly prioritize improvements in well-being over economic
growth per se. Even in developing countries, where there is a continued focus on economic
growth, goals are tempered by increased attention to ensuring this growth is broad-based and
does not come at the expense of long-term degradation of local environments
35
This shift evolves over time and is not uniform. The gradual accumulation of evidence of the
costs of inequality and environmental degradation is punctuated by periodic tragedies that bring
these costs into stark relief. These events stimulate growing constituencies supporting change at
the local, national, regional, and international levels. Over time, the initially disparate
constituencies are mutually reinforcing, ultimately leading to effective and persistent cooperation
and collaboration across these scales and between public organizations, the private sector, and
civil society within and across all scales of governance, including local, regional, national, and
international.
These trends open the door to formal and informal actions that, over time, help to fundamentally
restructure the relationships within and between societies, and between humans and the
environment. Policies shift to align incentives with development and sustainability goals,
including measures such as the adoption and use of standardized measures of well-being to
complement GDP; a shift in taxes and subsidies towards a stronger recognition of environmental
considerations; a tightening of environmental regulation on the national and regional level;
optimizing resource use efficiencies associated with urbanizing lifestyles; and improving the
access of developing countries to international markets, including the opening of agricultural
markets. As a result of these changing incentives, as well as evolving norms, there are further
shifts in public and private behavior reflected in changing consumption and investment patterns.
Many of these developments are slow to take hold broadly, and face some resistance and
experience setbacks along the way. However, over time they become increasingly self-
reinforcing. It is a bumpy road, but one that eventually moves most of the world in a more
sustainable direction.
Policies, institutions and social conditions: Relatively effective and persistent cooperation and
collaboration of national and international organizations and institutions, the private sector, and
civil society help drive the transition from increased environmental degradation in the short-term
to improved management of the local environment and the global commons over the longer term.
For example, tighter controls on air pollution improve health in developing countries.
Improvements in agricultural productivity through rapid diffusion of best practices and
development of new cultivars and other technologies decrease challenges to food security.
Research and technology development reduce the challenges of access to safe water.
New global institutions evolve to support cooperation on sustainable development, with flexible
roles played by other actors. Reductions in corruption levels, policies calling for greater
transparency in all sectors of society, and strengthening of the rule of law gradually lead to
greater effectiveness of development policies.
Human development: A large emphasis is placed on education and providing access to health
care. Policies aim at achieving universal access and promoting higher education levels and
gender equality. Relatively high economic growth in low-income countries reduces poverty, and
a global focus on increasing equity also increases social cohesion, while maintaining high levels
of social and cultural diversity within and across countries. Increasing access to health care and
36
to safe water and improved sanitation in low-income countries reduces the burden of preventable
diseases.
Economy and lifestyles: This development pathway implies that economic growth is relatively
high in developing countries, although growth rates are moderated over time by a shift in
emphasis from growth per se to well-being, equity, and sustainability. Inequality is reduced
across and within countries. Markets are globally connected, but an emphasis on regional
production reduces the incentives for specialization and limits the increase in trade volumes.
Investment in environmental technology and changes in tax structures, including phase out of
subsidies on fossil fuels, particularly coal and oil, lead to higher levels of resource efficiency,
moderating overall energy and resource use over the longer term. Increased investment, lower
taxes, and changing perceptions make renewables more attractive. The service sector grows
relatively quickly. Consumption is oriented towards low material growth and lower resource and
energy intensity, with a relatively low level of consumption of animal products.
Population and urbanization: Investments in human capital and rapid technological change
accelerate the demographic transition in currently high fertility countries, leading to a relatively
low population. Economic optimism sustains or increases fertility levels toward the replacement
rate in currently low fertility countries. Urbanization, while still rapid in many developing
regions of the world, increasingly is directed via growth of civil society, governance capacity and
engaged decision-making to promote environmental benefits, and limit negatives associated with
urban growth and cities, reducing the incentives promoting urban sprawl and urban population
deconcentration. Cities become more consistent incubators and promoters of sustainability
practices. Migration is at intermediate levels. Although increasing integration of labor markets
allows people to move around more freely, improved regional livelihoods and the renewed
emphasis on regional production reduce migration incentives.
Environment and resources: The value shift toward prioritizing environmental sustainabiliy and
associated policy focus on environmental protection and technology development implies that air
and water pollution is likely to be low and results in improvements in environmental conditions
and enhanced protection for vulnerable ecosystems and regions. Depletion of non-renewable
resources is relatively low given the focus on environmentally friendly technology. Still, there
are challenges with respect to the trade-offs between various resources (such as the use of bio-
energy). Food security increases with attention paid to reducing the underlying drivers and
increased investment in research and development. Land use is strongly regulated to avoid
environmental tradeoffs.
Technology: Relatively rapid technological change is directed toward environmentally friendly
processes, including energy efficiency, clean energy technologies, and yield-enhancing
technologies for land. Strong investment in new technologies and research improves energy
access and advances alternative energy technologies. Technology transfer is facilitated by
international agreements on intellectual property rights and other issues.
37
Challenges: Challenges to mitigation are low because of high mitigative capacity brought about
by rapid technological change as well as effective institutions and willingness to cooperate,
facilitated by a broad orientation toward environmental sustainability in an urban-dominated
economy. Challenges to adaptation are low because of reductions in vulnerability at the
individual and societal levels, and the increased effectiveness of governance and institutions re-
oriented toward cooperation and sustainability principles. Better-educated populations and high
overall standards of living confer resilience to societal and environmental changes with enhanced
access to safe water, improved sanitation, and medical care. Other factors that reduce
vulnerability include, for example, the successful implementation of stringent policies to control
air pollutants and reductions in energy, food, and water insecurity. If and when severe climate
impacts do occur, coordination structures, e.g. integrated early warning systems, security
alliances, disaster relief services, and risk reduction and resiliency promotion strategies are in
place to assist those most at risk.
SSP 2: Middle of the Road
Sketch
The world follows a path in which social, economic, and technological trends do
not shift markedly from historical patterns. Development and income growth
proceeds unevenly, with some countries making relatively good progress while
others fall short of expectations. Most economies are politically stable. Globally
connected markets function imperfectly. Global and national institutions work
toward but make slow progress in achieving sustainable development goals,
including improved living conditions and access to education, safe water, and
health care. Technological development proceeds apace, but without fundamental
breakthroughs. Environmental systems experience degradation, although there
are some improvements and overall the intensity of resource and energy use
declines. Even though fossil fuel dependency decreases slowly, there is no
reluctance to use unconventional fossil resources. Global population growth is
moderate and levels off in the second half of the century as a consequence of
completion of the demographic transition. However, education investments are
not high enough to accelerate the transition to low fertility rates in low-income
countries and to rapidly slow population growth. This growth, along with income
inequality that persists or improves only slowly, continuing societal stratification,
and limited social cohesion, maintain challenges to reducing vulnerability to
societal and environmental changes and constrain significant advances in
sustainable development. These moderate development trends leave the world, on
average, facing moderate challenges to mitigation and adaptation, but with
significant heterogeneities across and within countries.
38
Additional Information
Motivating forces: In this world, socio-economic development occurs at moderate rates on
average, but with substantial differences on a regional level. Development of low-income
countries proceeds unevenly, with some countries making relatively good progress while others
do less well. Moderate corruption levels and limited access to the rule of law slows the
effectiveness of development policies.
Policies, institutions and social conditions: There is moderate awareness of the environmental
consequences of choices when using natural resources. There is relatively weak coordination and
cooperation among national and international institutions, the private sector, and civil society for
addressing environmental concerns. While local environmental concerns, such as air quality,
rank high on the agenda of many countries, implementation lags behind the ambitions. Globally
this leads to an intermediate pathway for pollutant emissions.
Human development: There is some progress towards universal education, but education
investments are not high enough to rapidly slow population growth, particularly in low-income
countries. Access to health care and safe water and improved sanitation in low-income countries
makes unsteady progress, with some countries benefiting from the resulting improvements to
population health and productivity. Gender equality and equity slowly improve, particularly in
countries with more sustainable development.
Economy and lifestyles: Moderate rates of development are reflected in economic growth
patterns, with high growth for some low-income countries. Emerging economies continue their
rapid development for an initial period, but experience a slowdown in growth rates as their
economies mature. High-income countries continue to grow at moderate rates. As a result, per-
capita income levels grow at a medium pace on the global average, with slow convergence of
relative income levels between the bulk of developing and industrialized countries. Most
countries are politically stable and associated globally connected markets function imperfectly.
The flow of information and global access to markets are rather well established in most
countries, although entry barriers to agricultural markets are reduced only slowly. Consumption
is oriented towards material growth, with growing consumption of animal products.
Income distributions within regions improve with increasing national income, but inequities
remain high in some regions. Poverty is a challenge for many disadvantaged populations
conditions of extreme poverty particularly so. Tensions within and between countries
periodically threaten to boil over, but do so only rarely, and never catastrophically. Conflicts over
environmental resources flare where and when there are high levels of food and/or water
insecurity coupled with political and economic instability
Population and urbanization: Population growth is moderate, with higher growth in low-income
countries, slowing population growth in middle-income countries, and limited to negative
population growth in most industrialized countries. Migration between countries continues at
intermediate levels owing to the restriction of labor markets, but there are intermittent periods of
39
greater international migration when populations are challenged by food insecurity, conflict, and
other factors. Urbanization proceeds at rates and in patterns consistent with historical experience
in different world regions. Urbanization is particularly transformative in East and South Asia and
sub-Saharan Africa. The transformation of cities resulting from the introduction of sustainable
energy technologies and associated design proceeds at differing rates, with the highest rates in
developed or rapidly developing urban contexts.
Environment and resources: Fossil fuel dependency slowly decreases, but access to global oil
and gas markets continues to play a large role in international relations. Growing energy demand
and no reluctance to use unconventional fossil sources lead to continuing environmental
degradation even with reductions in resource and energy intensity. There is less progress in low-
income countries. Moderate regulation of land use leads to a slow decline in the rate of
deforestation.
Technology: There is some international cooperation and investment in research and technology
on providing access to modern energy and promoting sustainable development. However, new
energy and agricultural technologies developed in industrialized countries are only slowly shared
with middle- and low-income countries, in part because of challenges to resolving intellectual
property rights, legal rights, and other issues with technology transfer.
Challenges: Mitigation challenges are moderate in this pathway with a semi-open globalized
economy and only moderate transformation toward environmentally friendly processes. Limits to
mitigative capacity include the continued reliance on fossil fuels, including unconventional oil
and gas resources, limited progress toward a urban sustainability transition, the moderate pace of
technological change in the energy and agricultural sectors, and challenges in global cooperation
on environmental issues.
Challenges to adaptation are moderate as global population growth, along with persisting income
inequality (globally and within economies), societal stratification, urban growth in exposed and
vulnerable locations, and limited social cohesion, maintain challenges to reducing vulnerability
to societal and environmental changes. Food and water insecurity continue to be problems in
disadvantaged areas of low-income countries. There is only intermediate success in addressing
air pollution or improving energy access for the poor as well as other factors that reduce
vulnerability to climate and other global changes.
SSP 3: Regional Rivalry A Rocky Road
Sketch
A resurgent nationalism, concerns about competitiveness and security, and
regional conflicts push countries to increasingly focus on domestic or, at most,
regional issues. This trend is reinforced by the limited number of comparatively
weak global institutions, with uneven coordination and cooperation for
40
addressing environmental and other global concerns. Policies shift over time to
become increasingly oriented toward national and regional security issues,
including barriers to trade, particularly in the energy resource and agricultural
markets. Countries focus on achieving energy and food security goals within their
own regions at the expense of broader-based development, and in several regions
move toward more authoritarian forms of government with highly regulated
economies. Investments in education and technological development decline.
Economic development is slow, consumption is material-intensive, and
inequalities persist or worsen over time, especially in developing countries. There
are pockets of extreme poverty alongside pockets of moderate wealth, with many
countries struggling to maintain living standards and provide access to safe
water, improved sanitation, and health care for disadvantaged populations. A low
international priority for addressing environmental concerns leads to strong
environmental degradation in some regions. The combination of impeded
development and limited environmental concern results in poor progress toward
sustainability. Population growth is low in industrialized and high in developing
countries. Growing resource intensity and fossil fuel dependency along with
difficulty in achieving international cooperation and slow technological change
imply high challenges to mitigation. The limited progress on human development,
slow income growth, and lack of effective institutions, especially those that can
act across regions, implies high challenges to adaptation for many groups in all
regions.
Additional Information
Motivating forces: Growing concerns with respect to international competitiveness and national
security, aided by renewed interest in regional identity and culture, push societies to become
more skeptical about globalization and increasingly focus on domestic or, at most, regional
issues and interests. These developments lead step by step and over time to a world that is
separated into regional blocks of countries with little interaction between them, resembling the
Cold War period from 1945-1990, but with multiple poles. Competition, including periodic direct
and proxy occurrences of conflict between regional blocs, results in weak progress in achieving
sustainable development goals.
Policies, institutions and social conditions: Due to the focus on national security and
sovereignty, government institutions dominate societal decision-making. Authoritarian regimes
emerge or are strengthened in many parts of the world, leading on balance to diminished
effectiveness of institutions. The remaining participatory societies are increasingly bound by a
strong ethic of supporting national priorities. A considerable level of corruption results from the
entanglement of the private and public sectors. Environmental policies have a very low priority
in this world.
41
Global governance and institutions are weak, with a lack of cooperation and consensus; effective
global leadership and capacities for problem solving are largely absent.
Human development: Investments in education are low and access to health care, safe water, and
improved sanitation is limited, leading to large and poor populations in low-income countries
with increasing burdens of preventable diseases, with limited opportunities for improving the
situation. Gender equality and equity change little over the century.
Economy and lifestyles: Slow economic growth in all regions results from, among other factors,
little international cooperation and low investments in education and in technology for
development. Development proceeds slowly, with high inequalities across countries and
persistent inequality within countries. There are pockets of extreme poverty alongside pockets of
moderate wealth, with many countries struggling to maintain living standards. Trends work
against the reduction of social stratification, with little improvement for disadvantaged
population groups. Inequities are especially prevalent in cities. Consumption is material
intensive. The world has de-globalized, and international trade, including energy resource and
agricultural markets, is restricted because of security concerns.
Population and urbanization: Overall, global population growth is high as a result of the low
education trends, slow economic development, and stalled demographic transitions, particularly
in developing countries. At the same time, mortality rates are high in developing countries, with
many children dying from preventable diseases (malnutrition, diarrheal disease, malaria). In
high-income countries, economic uncertainty leads to low fertility. Combined with low levels of
international migration, this leads to rapid aging in industrialized countries.
Urbanization is slow in all regions, due to slow economic growth that limits employment
opportunities in urban areas, low international migration, and development patterns that make
urban areas unattractive destinations for rural populations. However, disadvantaged populations
continue to move to poorly planned settlements around large urban areas, particularly in low-
income countries, often in places that are particularly vulnerable to extreme weather and climate
events.
Technology: In general, technology development is very slow due to low investment levels and
with very limited transfer of new technologies to other regions. Energy technology change is also
slow and mostly directed to the exploitation of domestic fossil resources to improve energy
security. Agricultural technology development is slow, especially with very limited transfer to
developing countries.
Environment and resources: A low priority for addressing environmental concerns leads to
serious degradation of the environment in some regions. Countries focus on achieving energy
and food security goals within their own region. There is a push to maintain domestic energy
supplies and develop unconventional fossil fuel resources. Domestic markets are highly
regulated and uncompetitive. With little regulation in place, there is continued deforestation due
to competition over land and rapid expansion of agriculture.
42
Challenges: Challenges to mitigation are high because of continued energy demand driven in
part by high population growth and little progress in efficiency. Use of domestic energy
resources results in some regions relying heavily on fossil fuels. More importantly, the absence
of institutions to facilitate global cooperative action and limited governance resources, low
technological capacity, and little investment in research and development lead to low mitigative
capacity.
Challenges to adaptation are high because of highly vulnerable human and natural systems;
because global governance, institutions, and leadership are relatively weak in addressing the
multiple dimensions of vulnerability; and because institutional effectiveness within regions and
countries is mixed at best. Low investments in human capital contribute to high vulnerability.
Meager progress on development goals results in poorly educated populations in some regions,
with many disadvantaged populations without access to safe water, improved sanitation, polluted
air, health care, and other factors that increase vulnerability. These factors lead to low adaptive
capacity in many parts of the world.
SSP 4: Inequality A Road Divided
Sketch
Highly unequal investments in human capital, combined with increasing
disparities in economic opportunity and political power, lead to increasing
inequalities and stratification both across and within countries. Over time, a gap
widens between an internationally-connected society that is well educated and
contributes to knowledge- and capital-intensive sectors of the global economy,
and a fragmented collection of lower-income, poorly educated societies that work
in a labor intensive, low-tech economy. Power becomes more concentrated in a
relatively small political and business elite, even in democratic societies, while
vulnerable groups have little representation in national and global institutions.
Economic growth is moderate in industrialized and middle-income countries,
while low income countries lag behind, in many cases struggling to provide
adequate access to water, sanitation and health care for the poor. Social cohesion
degrades and conflict and unrest become increasingly common. Technology
development is high in the high-tech economy and sectors. Uncertainty in the
fossil fuel markets lead to underinvestment in new resources in many regions of
the world. Energy companies hedge against price fluctuations partly through
diversifying their energy sources, with investments in both carbon-intensive fuels
like coal and unconventional oil, but also low-carbon energy sources.
Environmental policies focus on local issues around middle and high income
areas. The combination of some development of low carbon supply options and
expertise, and a well-integrated international political and business class capable
of acting quickly and decisively, implies low challenges to mitigation. Challenges
43
to adaptation are high for the substantial proportions of populations at low levels
of development and with limited access to effective institutions for coping with
economic or environmental stresses.
Additional Information
Motivating forces: In this world inequalities increase, both between and within countries, driven
mainly by a combination of skill-biased technology development and reduced access to higher
education. The technological development is rapid, favors entrepreneurial individuals and those
with post-secondary education, and leads to less demand for unskilled labor. This enables
economic growth to be supported by a relatively small proportion of the population with high
education, reinforcing the trend toward inequality.
On a large scale, this is seen as increasing socioeconomic fragmentationbetween world
regions, between nations within regions, and between sub-national regions and groups
continuing and accelerating trends that could be seen at the start of the 21st Century. The fall in
inequality that was seen in some regions halts and the rise of an extremely wealthy few among
the merely wealthy that began at the turn of the century continues, with wealth and income
increasingly concentrated.
Policies, institutions and social conditions: A large share of the population has limited access to
national institutions, which focus on the globally connected high-tech economy and operate
mainly in the interests of top earners and businesses. International institutions and power
structures increasingly focus on and serve the needs of the globally connected economy. This
concentration of power favors effective cooperation between nations and businesses to agree on
and implement action if it is in their interest to do so. Vulnerable groups have little
representation in these organizations and lack the capacity and resources to organize themselves.
Human development: Weak political power for less-affluent groups is compounded by fewer
economic opportunities, as they face limited access to credit. Among other effects, this limits
opportunities for low-educated households to pursue a better education, reducing social mobility.
In developing countries with less well-educated populations, public expenditures on education
focus on producing a small, highly educated elite at the expense of broader-based investments in
education, leading to much slower growth of the middle class than would otherwise be expected
and in many cases worsening income inequality.
Economy and lifestyles: The most distinctive aspect of the economy is its divergence both within
and across countries into a high-tech, knowledge- and capital-intensive economy to which the
relatively well off and highly educated parts of the population belong, and a low-tech, labor-
intensive economy in which the substantial fraction of the population that is less well off
participates. The high-tech economy globalizes with highly connected international businesses
and workers and open trade, but many people are left outside this system. In general the absolute
income of all or most people increases, but the relative position of manyin some countries, the
44
majorityworsens. At the national level, economic growth tends to be medium in industrialized
and middle-income countries, while low-income countries lag, with slow economic growth. As a
consequence, most middle-income countries see their per capita incomes gradually converge
toward those of the high-income countries, while most low-income countries (and some middle
income countries) are left behind. However, there are distinct leading and lagging economies
even within each of these groups and in nearly all countries income inequality increases. The
global middle class, which was expanding rapidly at the turn of the century, still expands, but
sluggishly, as economic gains at the low end of the global income distribution begin to slow.
Support for those in the middle classes falters, with weakening social security measures and
poorly regulated labor markets. The high and middle income groups have fairly high
consumption lifestyles, but the low income groups are limited to low consumption levels and
very limited mobility.
Population and urbanization: In industrialized countries, economic uncertainty for most of the
population leads to relatively low fertility and low population growth, and in some cases decline
with a medium pace of urbanization but with accelerated population deconcentration. In low- and
middle-income countries, urbanization rates remains high. In low-income countries this is
induced by the large cohorts of young people in rural areas that result from high fertility rates as
well as by a lack of promising employment opportunities and increasing security concern in rural
areas. In all countries, the richer group physically separates itself from the poorer population,
moving to enclaves within cities with a high demand for skilled labor and (mainly in the
wealthier countries) smaller towns with highly specialized job markets. In low and middle-
income countries, physical separation is partly reflected in large and growing peri-urban slums.
Rural areas and less-favored urban areas are largely, although not entirely, left behind by these
developments. Migration is high for richer groups, but difficult for low-income groups. Due to
the lack of access to health care and other services, mortality is relatively high for poorer groups,
especially in low-income countries, but also for those poorer groups in medium and high income
countries.
Technology: Within the high-tech economy, technology development and diffusion are rapid,
with high transfer rates between countries and firms. However, outside this main economic
system, technology diffusion is slow and people rely more on local resources. Social instability
of cities including increasing economic inequities and diminished governance capacity result in
limited ability to experiment with and implement new sustainability energy technology on a
widespread basis. Informal energy economies and procurement strategies in urban areas further
limit the progression toward energy sustainability.
Environment and resources: Environmental awareness is mainly limited to the direct living areas
of middle and high-earning groups, while little attention paid to global environmental problems
and their implications for poorer groups in society. As a consequence, there is a stark division in
environmental conditions. On the one hand, there are areas that the world cares about, close to
living areas of middle and high-earning groups and where these groups spend their vacations,
45
which are well-managed and environmentally clean. On the other hand, resource and production
areas and many other places that are out of sight do not get much attention and become
deteriorate.
Energy resources are strongly affected by oligopolistic structures in the fossil fuel market, which
lead to underinvestment in opening up new resources in many regions of the world, causing oil
and gas prices to rise and volatility to increase due to changes in demand and disruptions of
supply. In this uncertain environment, companies diversify into carbon-intensive fuels like coal
and unconventional oil, but also low-carbon energy sources. Renewable technologies benefit
from the high technology development, bringing them to competitive cost levels with fossil
energy sources. The low-carbon energy projects that succeed are typically those that provide
large private returns. These well-funded risk-mitigation strategies drive a new era of innovation
that provides effective and well-tested energy technologies, but are often pursued without
adequate protection of affected groups. Those groups lose assets and livelihoods, which increases
their vulnerability to climate change.
For agriculture, the productive areas of the world are dominated by industrialized agriculture and
monocultural production. Crop yields would be typically high in large-scale industrial farming,
but low for small-scale farming. Food trade is global, but access to markets is limited, increasing
vulnerability for non-connected population groups. Land use is highly regulated in high and
middle income countries, but largely unmanaged in low-income coutries leading to tropical
deforestation.
Challenges to mitigation are low in this world due to the pool of expertise and technologies that
can be rapidly brought to bear if there is a strong push towards lower emissions. The
concentration of power, especially to global businesses, enables them to develop and apply
effective climate policies, once it is in their interest to act. Challenges to adaptation are high,
given the relatively high inequality and substantial proportions of populations at low levels of
development and with limited access to effective institutions for coping with economic or
environmental stresses.
SSP5: Fossil-fueled Development Taking the Highway
Sketch
Driven by the economic success of industrialized and emerging economies, this
world places increasing faith in competitive markets, innovation and
participatory societies to produce rapid technological progress and development
of human capital as the path to sustainable development. Global markets are
increasingly integrated, with interventions focused on maintaining competition
and removing institutional barriers to the participation of disadvantaged
population groups. There are also strong investments in health, education, and
institutions to enhance human and social capital. At the same time, the push for
46
economic and social development is coupled with the exploitation of abundant
fossil fuel resources and the adoption of resource and energy intensive lifestyles
around the world. All these factors lead to rapid growth of the global economy.
There is faith in the ability to effectively manage social and ecological systems,
including by geo-engineering if necessary. While local environmental impacts are
addressed effectively by technological solutions, there is relatively little effort to
avoid potential global environmental impacts due to a perceived tradeoff with
progress on economic development. Global population peaks and declines in the
21st century. Though fertility declines rapidly in developing countries, fertility
levels in high income countries are relatively high (at or above replacement level)
due to optimistic economic outlooks. International mobility is increased by
gradually opening up labor markets as income disparities decrease. The strong
reliance on fossil fuels and the lack of global environmental concern result in
potentially high challenges to mitigation. The attainment of human development
goals, robust economic growth, and highly engineered infrastructure results in
relatively low challenges to adaptation to any potential climate change for all but
a few.
Additional Information
Motivating forces: Two major factors enable a break with historical patterns that showed a lack
of regional convergence in institutional arrangements and economic growth. First, the economic
success of emerging economies and more recently least developed countries gives rise to an
emergent global middle class that has been lacking in most regions of the world. The new middle
class stabilizes global economic development by promoting robust growth in demand for
services and goods especially in cities. The new middle class also fosters the more widespread
adoption of world views oriented towards market solutions and participatory societies in many
world regions. In particular, developing countries aim to follow the fossil- and resource-intensive
development model of the industrialized countries. Second, the digital revolution enables a
global discourse of a significant and increasing share of the population for the first time in
human history leading to a rapid rise in global institutions and promoting the ability for global
coordination.
Policies, institutions and social conditions: On a national and regional level, institutional
changes are initiated to foster competitive markets, leading by and large to more effective
institutions with lower levels of corruption, strong rule of law, and the removal of market entry
barriers for disadvantaged population groups. Social cohesion, gender equality, and political
participation are strengthened in most world regions. As a consequence, social conflicts are
gradually decreased, although the more pervasive adoption of participatory and market oriented
world views creates significant tension with traditional views during a transition phase.
On the international level, countries pursue a global ―development first‖ agenda and increasingly
47
cooperate on economic, development, and security policies. Regional conflicts are met with
assertive international action, and decline with rapid development and decreasing levels of social
conflict. Institutions that further market penetration and lower trade barriers are strengthened,
leading to accelerated globalization and high levels of international trade. International
cooperation on environmental policies is much more limited due to a perceived trade-off
between development and environmental goals for global, long-term issues.
Human development: Development policies emphasizing education and health are put in place to
accelerate human capital development. These policies, aided by rapid economic development,
lead to a strong reduction of extreme poverty and significantly improved access to education,
safe drinking water and modern energy in the medium term.
Economy and lifestyles: Economies become increasingly globalized over time with high levels of
international trade. The gross world product at the end of the century is very high. Per capita
incomes in developing countries increase rapidly, leading to strong convergence of interregional
income distributions and a measurable decline of income inequality within regions. At the same
time industrialized countries continue their focus on economic growth, driven in part by
consumerism and resource-intensive status consumption, including a preference for individual
mobility, meat-rich diets, and tourism and recreation. Developing countries rapidly adopt these
consumption patterns.
Population and urbanization: Global population peaks and declines in the 21st century, a result
of rapid fertility declines in developing countries driven by improving education, health, and
economic conditions. In high income countries, fertility is above replacement due to optimistic
outlooks for economic conditions. International mobility is increased by gradually opening up
labor markets as income disparities decrease. Migration from poorer to wealthier countries
buffers the effect of aging populations in industrialized countries. All regions reach high levels
of urbanization. Urban planning and land use management play crucial roles, but struggle to keep
up with the rapid migration of rural population into cities in the first few decades of the century.
While urbanization rates converge over time, urban structure and form develop in different world
regions to reflect historic patterns and prevailing local and national policies. This includes dense
mega-cities in densely populated countries, and large metropolitan areas with significant urban
sprawl in other regions of the world.
Technology: Technological progress is seen as a major driver of development and economic
growth. Fostered by widespread technology optimism, investments in technological innovation
are very high, with a focus on increasing labor productivity, fossil energy supply, and managing
the natural environment. In continuation of the current shale revolution, fossil resource extraction
is maximized at low cost, and local externalities of fossil energy production (e.g. health effects)
are well controlled by continued technological advancements in the fossil energy sector. Due to
the strong reliance on fossil energy, alternative energy sources are not actively pursued.
Environment and resources: Environmental consciousness exists on the local scale, and is
focused on end-of-pipe engineering solutions for local environmental problems that have
48
obvious impacts on well-being, such as air and water pollution particularly in urban settings. On
the other hand, individualistic lifestyles give rise to local opposition against engineering
solutions that affect local environments (NIMBY). Agro-ecosystems become more and more
managed in all world regions, facilitated by productivity improvements and the diffusion of
resource-intensive management practices in the agricultural sector. The resulting large increases
in agricultural productivity and a peaking and declining world population can support high per
capita food consumption and meat-rich diets globally. However, some deforestation continues
due to incomplete regulations. In the long run, land and environmental systems are highly
managed across the world, and there is a general tendency to decouple human-engineered
systems from natural systems as much as possible.
Challenges: The strong reliance on fossil fuels and the lack of global environmental concern
result in potentially high challenges to mitigation. The attainment of human development goals,
robust economic growth, and highly engineered infrastructures results in relatively low
challenges to adaptation for all but a few.
... In a next step, we calculate the expected effect of climate warming on GDPc, following two alternative methods from the recent climate-economic literature. GDPc projections from the Shared Socio-economic Pathways (SSPs; [20,21]) serve as a baseline, from which climate changeinduced perturbations are calculated. Finally, a global migration model is used to calculate migration flows for both the baseline and the perturbed GDPc scenarios, under different assumptions. ...
... Our baseline projections of future GDPc are taken from the projections produced by the OECD [21] under the five SSP narratives [20]. These narratives employ different assumptions on how our societies will evolve in the future, including changes in economic and political spheres. ...
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