Advancing the development and use of climate-change scenarios : A multi-scale analysis to explore socio-economic European futures

Climate change is one of the greatest challenges of our time and requires unprecedented changes to mitigate greenhouse gas emissions and adapt to climate-change impacts. Different viewpoints and definitions are used by scientists, decision makers and stakeholders to meaning of this challenge. The complexity of this diversity is amplified by the lack of a clear goal and methodology for the exploration of alternative futures in the form of future climate-change scenarios. Such scenarios need, at the same time, to be scientifically credible (credibility) and to reflect different viewpoints (legitimacy) in order to be generalised enough while representing contextual diversity (consistency) to be relevant for decision-making (salience). This thesis develops and analyse European and Central Asian socio-economic scenarios based on the global Shared Socio-economic Pathways (SSPs) to evaluate their credibility, legitimacy, consistency and relevance, with novel analytical methodologies. State-of-the-art scenario methodologies are framed on grounds of the objectives (exploratory and normative) and their links across scales (tight and loose links) and types (qualitative and quantitative). The first methodology is based on a fuzzy-set methodology to link qualitative (narratives) and quantitative (input variables to integrated assessment modelling) scenarios by assessing the different uncertainties resulting from their inherent complexities. In the second and third methodologies, a quantitative pan-European urbanisation model, stakeholder-led narratives and a qualitative concept of archetype are used discuss both the quantitative and qualitative scalability of the scenarios in a multi-scale approach. The fourth methodology combines a capital-capacities framework to link the goal of exploratory scenarios in relation to their relevance to decision-making by assessing their potential to achieve a (normative) desirable future. Overall, results suggest that linking directly the uncertainties contributes to more transparent qualitative and quantitative conversion and therefore yield more credible scenarios. When analysed across scales, global and European scenarios are consistent with both downscaled scenarios and local stakeholder-led narratives contribute to the creation of holistic and more legitimate scenarios. However, important divergences have emerged too. For instance, the scenario with high challenges to mitigation and low challenges to adaptation (SSP5) varies hugely across the European continent. The local versions of SSP5 tend to diverge from the global archetype more than the other SSPs. This divergence reflects different worldviews that challenge state-of-the-art knowledge and can ultimately question the role of global scenarios in guiding local scenario versions with a nested approach. I recommend the role of both narratives and quantifications to be equally important in capturing different uncertainties, stakes and worldviews, as well as a reframing of SSP uncertainty space as one of challenges to societal transformation, rather than one of challenges to mitigation and adaptation.</p

New European socio-economic scenarios for climate change research: operationalising concepts to extend the shared socio-economic pathways

Scenarios have been recognised as a useful tool for planning, which have resulted in a strong increase in the number of (multi-scale) scenarios in climate change research. This paper addresses the need for methodological progress and testing of conceptual considerations, by extending the global shared socio-economic pathways (SSPs). We present a set of four European SSPs until 2100 and a novel method to develop qualitative stories for Europe equivalent to the global SSPs starting from an existing set of European scenarios. Similar to the global SSPs, the set includes a sustainable future with global cooperation and less intensive lifestyles (We are the World; Eur-SSP1); a future in which countries struggle to maintain living standards in a high-carbon intensive Europe (Icarus; Eur-SSP3); a world in which power becomes concentrated in a small elite and where Europe becomes an important player (Riders on the Storm; Eur-SSP4); and one where a lack of environmental concern leads to the over-exploitation of fossil fuel resources addressed by technological solutions (Fossil-fuelled Development; Eur-SSP5). We conclude that the global SSPs are a good starting point for developing equivalent continental scale scenarios that, in turn, can serve multiple purposes. There are, however, methodological challenges related to the choice for equivalence and the exact methods by which scenarios are constructed that need to be tested further

Bridging uncertainty concepts across narratives and simulations in environmental scenarios

Uncertainties in our understanding of current and future climate change projections, impacts and vulnerabilities are structured by scientists using scenarios, which are generally in qualitative (narrative) and quantitative (numerical) forms. Although conceptually strong, qualitative and quantitative scenarios have limited complementarity due to the lack of a fundamental bridge between two different concepts of uncertainty: linguistic and epistemic. Epistemic uncertainty is represented by the range of scenarios and linguistic variables within them, while linguistic uncertainty is represented by the translation of those linguistic variables via the fuzzy set approach. Both are therefore incorporated in the models that utilise the final quantifications. The application of this method is demonstrated in a stakeholder-led development of socioeconomic scenarios. The socioeconomic scenarios include several vague elements due to heterogeneous linguistic interpretations of future change on the part of stakeholders. We apply the so-called ‘Centre of Gravity’ (CoG) operator to defuzzify the quantifications of linguistic values provided by stakeholders. The results suggest that, in these cases, uniform distributions provide a close fit to the membership functions derived from ranges of values provided by stakeholders. As a result, the 90 or 95% intervals of the probability density functions are similar to the 0.1 or 0.05 degrees of membership of the linguistic values of linguistic variables. By bridging different uncertainty concepts (linguistic and epistemic uncertainties), this study offers a substantial step towards linking qualitative and quantitative scenarios

Transition pathways to sustainability in greater than 2 C climate futures of Europe

The complex challenges arising from climate change that exceeds the +2 °C target (termed ‘high-end climate change’) in Europe require new integrative responses to support transformations to a more sustainable future. We present a novel methodology that combines transition management and high-end climate and socioeconomic change scenarios to identify pathways and move Europe closer to sustainability. Eighteen pathways have been co-created with stakeholders through a participatory process. The pathways support Europe in moving towards a desirable future vision, through top-down and bottom-up actions that lower greenhouse gas emissions, reduce impacts of and vulnerabilities to climate and socioeconomic changes and enhance well-being. Analysis shows that the pathways that are robust to future scenario uncertainty are those that shift Europe towards sustainable lifestyles, support and strengthen good governance for sustainability and promote adaptive resource management for water, agriculture and energy. The methodology can support the design of the urgent actions needed to meet the requirements of the Paris Agreement and to transform Europe, in preparation for an uncertain future

Archetyping shared socioeconomic pathways across scales: an application to central Asia and European case studies

The complex interactions of drivers represented in scenarios and climate change impacts across scales have led to the development of multiscale scenarios. Since the recent development of global shared socioeconomic pathways (SSPs), which have started being downscaled to lower scales, the potential of scenarios to be relevant for decision making and facilitate appreciation and inclusion of different perspectives has been increasing, compared with a single-scale global scenario set. However, in practice, quantitative downscaling of global scenarios results in narratives that are compressed from the global level to fit the local context to enhance consistency between global and local scales. We brought forward the concept of scenario archetypes to analyze multiscale SSP scenario narratives and highlight important diverging assumptions within the same archetype. Our methodology applied scenario archetypes both as typologies, to allocate specific cases of scenarios into existing scenario archetypes, and building blocks, conceptualized with worldviews from cultural theory. Although global SSPs generally match existing archetypes and tend to be well defined, the socially unequal SSPs at subglobal scales are more nuanced, and dominant worldviews are much less straighforward to interpret than in global scenarios. The closest match was the great transition–sustainability (SSP1) archetype, whereas the most divergent was the market forces–fossil fuel development (SSP5) archetype. Overall, our results highlight the need to improve uptake of bottom-up approaches in global scenarios to improve appreciation of different perspectives as sought after in multiscale scenarios

Differences between low-end and high-end climate change impacts in Europe across multiple sectors

The Paris Agreement established the 1.5 and 2 °C targets based on the recognition “that this would significantly reduce the risks and impacts of climate change”. We tested this assertion by comparing impacts at the regional scale between low-end ( 4 °C; RCP8.5) climate change scenarios accounting for interactions across six sectors (agriculture, forestry, biodiversity, water, coasts and urban) using an integrated assessment model. Results show that there are only minor differences in most impact indicators for the 2020s time slice, but impacts are considerably greater under high-end than low-end climate change in the 2050s and 2080s. For example, for the 2080s, mitigation consistent with the Paris Agreement would reduce aggregate Europe-wide impacts on the area of intensive agriculture by 21% (on average across climate models), on the area of managed forests by 34%, on water stress by 14%, on people flooded by 10% and on biodiversity vulnerability by 16%. Including socio-economic scenarios (SSPs 1, 3, 4, 5) results in considerably greater variation in the magnitude, range and direction of change of the majority of impact indicators than climate change alone. In particular, socio-economic factors much more strongly drive changes in land use and food production than changes in climate, sometimes overriding the differences due to low-end and high-end climate change. Such impacts pose significant challenges for adaptation and highlight the importance of searching for synergies between adaptation and mitigation and linking them to sustainable development goals

Integrated modelling of urban spatial development under uncertain climate futures: a case study in Hungary

To provide fundamental decision support information for climate risk assessment in Hungary, an urban spatial development model of land cover change and population age structure dynamics was developed and applied to local integrated scenarios of climate change and stakeholder-derived socio-economic change. The four integrated scenarios for Hungary produced contrasting projections for urban patterns to 2100, but peri-urbanisation around Budapest was estimated to occur under all scenarios, together with a decline in working age population in the centres of the capital and major towns. This suggests that future urban planning needs to take into consideration the potential for underutilised urban infrastructure in the centre of the capital and pressures for social service provisioning in its outskirt. The integrated scenarios and model developed can be used in future studies to test the effectiveness of inter-sectoral policy responses in adapting urban planning to multiple climate and socio-economic challenges