Positive tipping points in a rapidly warming world

The challenge of meeting the UNFCCC CoP21 goal of keeping global warming ‘well below 2 (cid:1) C and to pursue efforts towards 1.5 (cid:1) C’ (‘the 2–1.5 (cid:1) C target’) calls for research efforts to better understand the opportunities and constraints for fundamental transformations in global systems dynamics which currently drive the unsustainable and inequitable use of the Earth’s resources. To this end, this research reviews and introduces the notion of positive tipping points as emergent properties of systems–including both human capacities and structural conditions — which would allow the fast deployment of evolutionary-like transformative solutions to successfully tackle the present socio-climate quandary. Our research provides a simple procedural synthesis to help identify and coordinate the required agents’ capacities to implement transformative solutions aligned with such climate goal in different contexts. Our research shows how to identify the required capacities, conditions and potential policy interventions which could eventually lead to the emergence of positive tipping points in various social–ecological systems to address the 2–1.5 (cid:1) C policy target. Our insights are based on the participatory downscaling of global Shared Socio-economic Pathways (SSPs) to Europe, the formulation of pathways of solutions within these scenarios and the results from an agent-based economic modelling.


Introduction
The challenge of meeting the UNFCCC CoP21 goal of keeping global warming 'well below 2 C and to pursue efforts towards 1.5 C' ('the 2-1.5 C Paris target') calls for the accelerated development of human capacities to implement transformative solutions in multiple contexts of action [1,2 ,3].In the present situation, it is essential not just to consider command-and-control policies for a 'rapid decarbonisation' [4] which would likely keep the root social causes, individual motives and incentive structures of excessive GHG emissions intact, but more importantly, and in terms of societal transformations, to identify the systemic conditions for a 'rapid sustainabilisation'.This quest involves first of all, finding out more about which are the key dynamics that would eventually allow a fundamentally reversion of the current unsustainable and inequitable trends in the use of the Earth's resources [5,6] and second, to explore the possibilities for individual and collective interventions in such dynamics given the limitations of existing governance arrangements.This research has two main goals.On the one hand, it reviews the literature on tipping points from a sustainability science perspective and calls for research efforts to better characterize their use in policy making.Given our research focus, we concentrate on the notion of positive tipping points, understood as emergent properties derived from complex systems dynamics that allow rapid transformations in individual and collective practices so as to reach evolutionary-like solutions to the present socioclimate quandary.In this regard, we provide a simple operational synthesis and framework aimed at identifying and supporting the building of agent capacities and system conditions conducive to such positive transformations [7 ].Our approach is based on the acknowledgement of the structural uncertainty about when, where, how or even if such new fundamentally new system conditions, or positive tipping points, will emerge.It also recognizes that social-ecological dynamics are subject to multiple non-linear, irreversible and cumulative processes that cannot be anticipated.However, it is also based on the assumption that social-ecological systems can somehow be navigated intentionally to achieve certain desirable goals, targets or more broadly visions.

Assessing positive tipping points in a highend climate World
Positive tipping points in social-ecological systems Most research in sustainability science and integrated assessment has focused on examining the catastrophic, abrupt nature of tipping points in biophysical systems or the implications of the realization of such crises or of crossing such negative thresholds for policy and action [8-10,11 ,12 ,13,14].However, and with few exceptions [15 ,16], little attention has been paid so far to trying to identify and characterize the possible emergence of positive tipping points in social-ecological systems dynamics.In the context of climate change 'beneficial social tipping points' have been already referred to those which 'increase societal resilience and reduce climate change damages via mitigation or adaptation, whereas harmful social tipping points are more likely to occur where there are low levels of societal resilience, under which societal risks increase because of failure to effectively adapt or mitigate' [17 ].Such beneficial systemic changes may be derived from the synergetic, multiplicative learning feedback effects of deliberate implementation of transformative solutions developed in multiple contexts of action [18].In this way, the articulation of learning feedbacks between multiple deliberate transformations at small system scales may be needed to achieve the long-term resilience at higher levels [19].Addressing the question on how to achieve the Paris target precisely falls under these concerns [20].It is neither possible to predict the exact moment, shape, dynamics or consequences of such required far-reaching changes in the configuration of global social-ecological systems nor if they will ever happen.However, and using an integrated research perspective, it may be possible to provide an operational framework to recognize the various conditions, capacities and concrete pathways of solutions, as well as the incentives [21], which could eventually lead in concrete contexts of action or subsystems to the emergence of positive tipping points.The later would increase our likelihood of successfully meeting the 2-1.5 C Paris target.
Tipping points fundamentally and irreversibly change the structure and the intrinsic functioning of a given system of reference.Some authors argue that early warnings and exceeding a threshold of concern about the acceptability of imminent occurrence of a tipping point may lead to 'adaptation turning points' in climate action [22] although this may be hard to put in practice.Some tipping points in certain systems may be unintentional and unexpected, others the result of deliberate actions.Trying deliberate or active transformations to achieve a fundamentally different kinds of systems may be necessary when the present institutions or systems' goals become unattainable [19,23,24].However, global social-ecological systemsfor which global warming is but only a symptom and amplifier of its unsustainable dynamics, are constituted by many 'systems of systems' [25] each of which being determined by its own logics, complex dynamics and effects on other systems.For instance, a tipping point in the way that global communication systems operated occurred with the introduction of the internet, rather suddenly and unexpectedly and the ultimate effects of this transformation cannot yet be forecast; governance systems also follow their own rationales, mainly still under the nation-state interests and constraints and thus are largely resistant to change; the structure and the functioning of global energy and resource property systems are determined by price and market competition rules which in turn may be in conflict with other more traditional or local cultural systems in the use of natural resources; the building of institutional systems has also undergone tipping points in history, for example, when certain civil rights have been achieved, including the end of slavery, the end of child labour, the right of women to vote or to have access to education.The consolidation of the IPPC can be also seen as a tipping point in the development of science for policy to address the climate quandary, albeit with limited effects on global transformation [26].Hence, both collective and individual social actions operate in multiple sociocultural, technological, governance, bio-physical and knowledge systems which interact with many other systems at the same time and at many levels.Therefore, it is hard to think of the existence of a single transformative solution or a single tipping point in one single system that would lead to the achievement of the 2-1.5 C target.Instead, multiple positive tipping points in multiple systems of action will be needed to achieve this aim.
There is little knowledge about which kinds of specific changes or transformative solutions are to be needed.Ultimately, such transformative solutions should be able to create new kinds of systemic conditions that eliminate the ultimate causes of the persistent problems.For this reason, we understand positive tipping points as emergent properties of systems that would allow the reaching of evolutionary-like transformative solutions to successfully tackle the present socio-climate quandary.
However, we admit that on the one hand, agents will only be able to act upon and apply transformative solutions to a limited, albeit crucial, number of systems in which they operate -for example, recycling materials, preventing food waste, mobility, civic and political representation, etc. [27].While on the other, particular transformative solutions that work in one context may not work in other contexts.A more nuanced narrative and interpretation of how different kinds of solutions can be linked or even supported through deliberate action-research to create multiplicative synergies and potentially induce positive tipping points to address the climate quandary is needed.

A procedural synthesis
Given the large complexity and non-linearity in the dynamics of social-ecological systems, it is simply not possible to forecast the whole array of potentially transformative solutions that need to be implemented globally and which may contribute to the achievement of the 2-1.5 C policy target.Instead, a more pragmatic approach can be formulated which focuses on identifying and characterizing the kinds of concrete and distributed capacities to implement these solutions.Required capacities will vary according to different people, needs and interests in their own contexts of action.
In this regard, a simple procedural framework can be developed linking desirable visions of the world, the building of agent capacities and systems of transformative solutions.Our perspective is based on the premise that transformations in social-ecological systems may be accelerated and purposefully brought about by social action.We make the case that in policy making a vision is a main driver of transformation [28][29][30]31 ], rather than the impending awareness of a catastrophe [32], and that positive tipping points may be induced by the cascading, feedback and cumulative effects of multiple interlinked actions -or interlinked systems of transformative solutions -which eventually push a system towards a new desired configuration (Figure 1).10A positive tipping point occurs when the original conditions of a system of reference are substantially and irreversibly transformed in a way that matches or exceeds a particular desired (normative), better-off configuration or vision (Figure 2).This moment is likely to happen fast only once agents have been able to build the required capacities to implement transformative solutions to do so.In this sense, tipping points will appear as emergent properties derived from the existing capacities which have been acquired when agents engage in applying their own systems of solutions to solve their problems according their own needs and priorities (often in trial-and-error and learning mode) [33].The implementation of transformative solutions may also lead to shifts in perception, the reconfiguration of social networks and of institutional arrangements [19].Visions serve as a cognitive, emotional and normative reference for orienting and qualifying radical system changes as positive developments in a given system of reference.They also help to introduce the intersubjective nature of agents' motivations in collective action which lies at the base of social transformations [34], transformative science [35,36]; and in this way, visions play an important role in identifying the potential agency capacities to implement transformative solutions.However, visions are not static, and therefore they ought to be reframed as new conditions and ambitions change.A vision does not provide a single 'end-point' in systems trajectories, but only an open-ended desirable state that demands continuous improvement and reframing.

Co-producing pathways of transformative solutions in socio-economic scenarios
It is becoming increasingly common to co-produce in a participatory way pathways of solutions using exploratory scenarios to determine the opportunity spaces for systems' transformations [37][38][39].Pathways are progressive courses of action for achieving strategic objectives, or more broadly to attain transformative visions, where short-term actions can pave the way for more medium and long-term actions.The pathways approach aids making sense of patterns of change and thinking of strategies and solutions to complex problems from an integrated and systemic perspective.Formulating pathways in concrete contexts helps to unveil climate actions that not only link adaptation and mitigation but also embrace broader to transformative change [40][41][42][43].
The co-production of pathways can therefore help to identify and articulate integrated solutions and how they may unroll over time, for instance, in the context of Challenges, but exclude Transformation as societal challenge independent from climate, which may be needed to address both mitigation and adaptation [36].SSPs offer sets of baseline conditions and how they evolve differently over time, but since SSPs are exploratory they do not provide solutions to particular problems.They only describe the contexts from which the opportunity spaces for the development of different pathways of solutions may unfold.
However, there is still little research specifically aimed as downscaling these global scenarios and turn them into actionable strategies in particular contexts of action using participatory procedures.Within the EU project IMPRESSIONS 12 , such an endeavour has been carried out at different spatial scales: from two municipalities in A positive tipping point (PTP) may be induced by boosting agents' capacities to implement pathways of solutions to achieve a transformative vision of the world.
Hungary to case studies in Scotland, Iberia, EU and Central Asia.The ultimate aim being to identify and assess potential pathways of solutions that could eventually be able to achieve a desired transformative vision of the world; or following the framework presented above, to 'flip' current system structures and dynamics into configurations attuned with the current climate and sustainability challenges.
In the European case study, four SSPs were co-developed based online and workshops interaction with stakeholders. 13SSP2 was excluded from the participatory process given that the focus of the project was to identify the potential opportunities for transformation in a highend climate change world (beyond 2 C of global warming at the end of the century).In addition, the main discriminatory axes of 'challenges to mitigation/adaptation' were substituted by the axes of 'degree of social inequality/ carbon intensity', with the aim of better capturing the essence of the key required changes in the socio-economic system while maintaining the link with greenhouse gas emissions.The newly adapted SSPs in IMPRES-SIONS offered ways to think about transformations in various systems including energy, governance, socio-cultural, technological and economic systems and in this way to explore which structural conditions and capacities, could lead to positive fundamental systemic changes according to a normative vision of the future.While different SSPs tended to promote different kinds of solutions and pathways which emerged from the different available structural conditions, it was possible to identify some cross-scenario robust actions across all scenarios including concrete transformative solutions which participants believed to be 'game-changers' for moving towards the vision.In particular, and according to the stakeholders consulted the potential emergence of new systems' configurations or positive tipping points will be dependent on deploying transformative capacities of agents in systems such as: Energy systems: full switch to renewable energies and a move towards energy self-sufficient Europe in a way that makes full use of its context-dependent potential (e.g.solar energy in Southern Europe).
Governance: civic participation if fully developed, with fair multi-level coordination and international cooperation in line with shared, integrated and long-term sustainability orientation.Socio-cultural: the European society widely adopts and normalises sustainability behaviours and is engaged in continuous learning and reflexivity.
Technological systems: Green high-tech and low-tech infrastructure systems are fully integrated in Europe (e.g.household rainwater collection, integrated water sensitive infrastructure, green biodiversity corridors).
Resource systems: full move towards a circular economy and towards organic agriculture.
Economy: integrating ecosystem services, and a focus on quality of life and social wellbeing is integrated into the core economic activity.
In short, trying to deliberately achieve positive tipping points aligned with the 2-1.5 C target and sustainability challenges would require the fast deployment of a mix of different types of transformative capacities to induce the synergetic, non-linear and cumulative effects which could be derived from the implementation of fundamental changes in the above systems.In addition, the articulation of learning feedbacks derived from the implementation of different actions and solutions is likely to be a core part of the required dynamics to build agents' capacities that would lead to a positive tipping point.This list, however, is not exhaustive and is only for illustrative purposes.Different contexts may yield alternative proposals or even consider other kinds of systems categorisation. 14In the scenario exercise, negative events and constraints for solution pathways were also identified, which included mostly the growing inequality, political de-stabilization matched with rampant environmental degradation which could make such positive transformation (in some systems) unattainable.Hence our results here only serve as an example of how the devising of a broad strategy, based on identifying feasible transformative solutions in concrete places could ultimately lead to a positive tipping point aligned with the pressing climate and sustainability goals.

Tipping points in the economy
A good part of the most promising and recent developments in the analysis of tipping points comes from economics [17 ,49] -although markedly concentrated on negative tipping points which damage socio-economic and/or environmental conditions and general equilibrium effects (e.g.[50]) under single rational agent assumptions.Furthermore, standard cost-and-benefit analysis is likely to fail when uncertain regime-switches drive the behaviour of the system [51].The effects and implications of negative tipping points are substantial when explored through models that do not endogenously account for threshold effects and tend to underestimate climaterelated damages [52].
Instead, a relatively novel strand work focuses on modelling the economy, the environment, the climate and their multiple interactions as a large complex system [53,54], where both negative and positive tipping points are found as emergent properties [55,56].This allows exploring agents' capacities to reach evolutionary-like solutions to the 1.5 C challenge.Agent-based computational economics abandons dictates of agents' rationality and market equilibrium in favour of more realistic, yet computationally intense, representations of human behaviours and interactions [57] based on heterogeneous and bounded rational agents and networks.In such a context, both negative and positive tipping points emerge endogenously [58].In IMPRESSIONS, Lamperti et al. [59] introduced the first agent-based integrated assessment DSK model and analyzed the impact of heterogeneous, individual-level climate damages on economic dynamics in line with the recent climate econometrics literature [60].In a nutshell, the model is composed of two industrial sectors exchanging capital goods, an energy sector endowed with different energy technologies, a financial system providing credit to the economy and households that consume and provide labour force.Further, a dedicated climate module is added to the picture in order to track the dynamics of climate and environmental variables.A remarkable feature of the model is that it accounts for an ecosystem of heterogeneous agents (firms, households, energy plants and banks) that interact and realistically behave according to evolutionary routines.The model is calibrated in its baseline to a RCP 8.5 scenario relying on data from the World Bank and the RCP Database (version 2.0.5).
Large scale computational experiments show that cumulative climate damages might shift the system dynamics and trap the economy in a stagnant state characterized by absent economic growth and high unemployment, which cannot be exited even when emissions are dramatically reduced (Figure 3).The result emerges from the percolation of climate shocks in the network of agents that, at a certain point, are not able to react.In particular, firms' innovation-driven productivity gains are more than compensated by negative shocks, which increase defaults and exacerbate lack demand due to increased unemployment.Overall, these effects prevent economic recovery and switches of the engine of growth.Positive tipping points are also found: technological change and competition among different energy technologies produces different equilibria, characterized by energy mixes.Even though the system starts from a relatively high share of fossil-fuelrelated energy production, a rapid transition towards a greener growth pattern, producing substantially higher growth and employment, is possible and synergetic with the effects of a large green Keynesian multiplier [61], derived from an active policy intervention.This may be exploited to construct pathways of solutions leading to positive tipping points (Figure 4).In our perspective, an endogenous and rapid transition to renewable energy sources constitute an example of positive tipping points, where economic agents autonomously moves away from carbon-intense technologies and self-organize in sustainable production systems.In particular, research and development (R&D) efforts are found to fast move away from fossil-fuel shocks due to increasing profitability of renewable technologies, whose development allows to slow emission growth and reduces future climate damage; such an effect further increases aggregate demand and sustain investment in green energy technologies thanks to the relatively lower unitary costs of production.The tipping element consists here in the relative competiveness of green technologies, which self-sustain its growth pattern thanks to the aforementioned process, and help the economy rapidly abandon fossil-fuel-related R&D.However, our modelling results find that the likelihood of such tipping points is remarkably low and suggests that, timely and strong policy interventions are needed to increase the, otherwise extremely low, likelihood of crossing such positive thresholds [62].
Last but not least, multiple tipping points cannot be treated in isolation, as they are not independent: crossing one point deeply affects the likelihood of crossing another, creating either catastrophic or beneficial cascades.Regime shifts changing the trajectory of the economy also modify the selection of statistical equilibria the system might be attracted to in the future.This opens a wide range of risks, as the route from one regime to the other might not be smooth as mainstream neoclassical economics predicts.Coping with these risks also calls, at the very least, for timely and sharp policy interventions [63][64][65] and actions at multiple scales involving a variety of state and non-state actors, whose non-trivial governance requires appropriate tools accounting for the multilayer networks linking different institutions.

Conclusion
The UNFCCC Paris goal of keeping global warming 'well below 2 C and to pursue efforts towards 1.5 C' cannot be considered a positive tipping point.Nor does it necessarily contain a transformative vision that could trigger the building of the necessary capacities to fundamentally change the current unsustainable dynamics of global systems accordingly [66].Only when: (1) such a policy target can be aligned with a series of multiple visions, knowledge networks and sustainable practices already being developed around the World, and (2) the required capacities of agents have been effectively boosted so as to apply transformative solutions that meet their needs in concrete and many different contexts, may we have a better chance of moving closer to a positive tipping point in collective action whereby present global dynamics are fundamentally modified and address the climate challenge in an equitable and sustainable way.
Certainly, in a world constituted by a closely interconnected 'systems of systems', multiple positive tipping points are needed to address the 2-1.5 C target.At present, and given their non-linear, cumulative and complex dynamics it is not possible to anticipate when, how, where or even if such positive tipping points will occur.
However, what is possible, at least from an integrated assessment perspective, is to identify and appraise the kinds of specific capacities which could help to implement concrete transformative solutions in many different systems of action and to do so according to the needs and priorities of different kinds of groups and people.
In particular, the required capacities that would lead to positive tipping points in system dynamics will vary according to future social-ecological conditions in which humans will live in the future.Such conditions, and the potential policy interventions to alter them, can be represented and assessed using various tools and methods.In this research, we used the results of the downscaling of the Shared Socio-economic Pathways (SSPs) and the coproduction of strategic pathways in Europe together with the outputs from an agent-based modelling exercise.These results showed that some pathways of transformative solutions which may occur at certain moments in time may drive certain systems closer (or further away) from their desired positive systemic transformation.That is, there is not one single solution or pathway of solutions to the 2-1.5 C target: but thousands of them of very 126 Sustainability governance and transformation different kinds.The ultimate shape and content of these solutions will depend on the many systems of reference in which agents operate around the world; and if these are aligned with their own transformative visions for a better life, there may be a greater chance to develop multiplicative synergies and multiple learning feedbacks amongst them, ultimately leading to global positive tipping point in way global systems operate.
Figure 1 Figure 2 Figure 3 McGowan KA, Antadze N, Blacklock J, Tjornbo O: How game changers catalyzed, disrupted, and incentivized social innovation: three historical cases of nature conservation, assimilation, and women's rights.Ecol Soc 2016, 21:13.This paper positions game changes as macro-phenomena in relation to social innovation.Three examples of game changers are analysed to Positive tipping points in a rapidly warming world David Ta `bara et al. 127

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