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Global Sustainability Domino Effects in the Earth System – The

cambridge.org/ potential role of wanted tipping points

Marc Wiedermann1∗, Ricarda Winkelmann1,2∗, Jonathan F. Donges1,3, Christina Eder4, Jobst Heitzig1, Alexia Katsanidou4,5, E. Keith Smith4 Intelligence briefing 1Potsdam Institute for Climate Impact Research, Member of the Leibniz Association, Telegrafenberg Key words: social tipping, climate action, climate A31, 14473 Potsdam, Germany concern, climate impacts 2Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany 3 Author for correspondence: Stockholm Resilience Centre, Stockholm University, Kräftriket 2B, 114 19 Stockholm, Sweden Ricarda Winkelmann, Email: 4GESIS – Leibniz Institute for the Social Sciences, Unter Sachsenhausen 6-8, 50667 Cologne, Germany [email protected] and 5Institute of Sociology and Social Psychology, University of Cologne, Cologne, Germany Marc Wiedermann, Email: *shared first authorship [email protected]

Abstract Vital parts of the climate system, such as the West Antarctic Ice Sheet, are at risk even within the aspired aims of the Paris Agreement to limit global temperature rise to 1.5 – 2◦C. These so- called natural tipping elements are characterized by rapid qualitative shifts in their states once a critical threshold, e.g., of global mean temperature, is transgressed. We argue that the prevention of such unwanted tipping through effective climate policies may critically depend on cascading Domino effects from (anticipated) climate impacts to emission reductions via wanted social tipping in attitudes, behaviors and policies. Specifically, the latter has recently been noted as a key aspect in addressing contemporary global challenges, such as climate change, via self- amplifying positive feedbacks similar to the processes observable in climate tipping elements. Our discussion is supported with data on commonly observed linkages between (subjective) climate change knowledge, concern and consequential potential action and we argue that the presence of such interrelations serves as a necessary condition for the possibility of rapid climate action. arXiv:1911.10063v2 [physics.soc-ph] 18 Dec 2019

© Cambridge University Press and the European Microwave Association 2019

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How climate tipping became real -or- The unwanted warming (Schellnhuber et al., 2016). Interactions between these tipping point climate tipping elements (Kriegler et al., 2009) could trigger cas- cading effects and positive feedbacks that would further amplify There may have been a turning point in our thinking about cli- global warming (Steffen et al., 2018; Lenton et al., 2019) (see mate change: In 2014, several research groups suggested that the potential feedbacks in Fig. 1). Amundsen region of West Antarctica had entered a new dynamic With the recent observations from the Amundsen basin (Rignot regime, with glacier retreat controlled by the marine ice-sheet et al., 2014), the rather theoretical notion of climate tipping has instability, which could lead to its collapse in the long-term (e.g., become a reality. Declared a “holy shit moment of global warm- Rignot et al., 2014). Changes in the surrounding ocean circula- ing” by public media (Mooney, 2014), the implications are being tion have initiated internal ice dynamics that essentially cannot be widely discussed in science and the public (Lenton et al., 2019). reversed. They will likely lead to a destabilization of this entire ice basin and subsequently to global sea-level rise (Joughin et al., 2014; Feldmann and Levermann, 2015). A lot is at stake: this part of West Antarctica alone holds enough ice to raise global The need for social tipping -or- The wanted tipping point sea level by more than one meter (Bamber et al., 2009), while all of the marine ice basins in Antarctica together have a sea-level Without a rapid reduction in anthropogenic greenhouse gas emis- equivalent of almost 20 meters (DeConto and Pollard, 2016). sions, sea-level rise from the ice-sheets’ mass loss will continue The Antarctic Ice Sheet is only one of several crucial parts of for centuries or even millennia, changing the face of our planet as the climate system which – though massive in size – are so frag- we know it (Clark et al., 2016). In order to keep global warming ◦ ile that they can be severely disrupted by human activity. For these to “well below 2 C” compared to preindustrial levels and thereby so-called tipping elements, a small perturbation can suffice to push avoid some of the most severe climate change impacts on the long- them into a qualitatively different mode of operation (Schellnhu- term, swift action is required: net-zero greenhouse gas emissions ber, 2009). Several such large-scale tipping elements have been have to be achieved around mid-century, and the peak in emis- identified in the climate system (Lenton et al., 2008; Levermann sions as early as 2020 (Figueres et al., 2017). This translates into et al., 2012). Among the candidates with the most severe and far- roughly halving CO2 emissions each decade until 2050 in order to reaching consequences for the entire planet are the Thermohaline meet the Paris climate target with a 75% chance (Rockström et al., Ocean Circulation (Caesar et al., 2018) and the Greenland (Robin- 2017). However, in reality, global emissions have generally been son et al., 2012) and Antarctic ice sheets (Winkelmann et al., rising over the past decades (Figueres et al., 2017). 2015) (left part of Fig. 1). The risk of transgressing their criti- We are thus facing a severe clash of time-scales, with the cal thresholds increases with continued greenhouse gas emissions need to reverse the current trend in emissions in just a few years, and global warming (Church et al., 2013). The ice-sheets, along while climate impacts will continue to manifest well beyond the with coral reefs, mountain glaciers and the Arctic summer sea- end of this century. In order to overcome this dilemma and to ice, might in fact reach their tipping point even within the Paris meet the ambitious goals of the Paris Agreement, the amplifying Agreement’s target temperature range of 1.5 to 2◦ C of global feedbacks between climate tipping elements need to be matched with self-reinforcing effects within social systems bringing about

Greenland Ice Sheet Attitudes freshwater input + reduced - warming

Thermohaline Ocean Circulation salinity advection + Other tipping Policy elements

sea-level + Southern Ocean heat accumulation + Antarctic Behaviour (Consumption, production, Ice Sheet land-use,…)

Fig. 1. Domino effects in the Earth System. The knowledge of (anticipated or already observable) impacts caused by climate tipping elements (in green) such as the Antarctic Ice Sheet, Greenland Ice Sheet and the Thermohaline Ocean Circulation could lead to social tipping (in blue) via changes in attitudes, policies and – ultimately – behavior (for instance changes in consumption, production or land-use). In turn, processes within the social sphere can strongly affect the climate system through changes in greenhouse gas emissions. Green arrows denote possible feedbacks between the climate tipping elements. Plus (minus) signs indicate that the tipping of one element is likely to enhance (decrease) the possibility of another. Blue arrows indicate possible interactions in the social sphere.

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Domino Effects in the Earth System – The potential role of wanted tipping points 3

How concerned are you about polar ice loss?

0.50 0.25 fairly not very not at all

concerned concerned concerned very concerned 0.00

very informed A B

somewhat informed 0.7

somewhat 0.6 uninformed How well are you the polar regions? 0.5

nomdaotcagsin informed about changes very uninformed 0.4

very concerned C 0.3

direct link Conditional probabilities fairly concerned 0.2

not very 0.1 concerned

about polar ice loss? 0.0 How concerned are you not at all concerned

indirect link 0.0 0.5

direct link I already drive less willing be willing I don't drive Yes I would be No I would not

Are you willing to actively reduce your emission by, e.g., driving your car less?

Fig. 2. Climate knowledge leads to action via concern. Results of a social survey from Germany consisting of three questions regarding the loss of polar ice (see blue shaded ellipses). The exact questions (in German, with translation into English) are given in the Supplementary Information. The wording given in the labels presents a synthesis of the original introductory and question texts. Colors in A,B,C indicate conditional probabilities for answers on the horizontal axis given an answer on the vertical axis. The bar-charts indicate the relative frequency of each given answer.

rapid societal changes, or social tipping. This notion of social tip- It remains to note that, in contrast to most natural tipping ping, where a relatively small perturbation shifts a social system elements, social tipping elements can have positive or negative into a qualitatively different state via self-amplifying effects, has consequences for the coupled socio-ecological Earth system. As received recent scholarly interest (Milkoreit et al., 2018; Farmer such, their classification, much more than for natural tipping ele- et al., 2019; Tàbara et al., 2018). As such, this definition of social ments, is often based on normative judgement (Tàbara et al., 2018; tipping by means of positive feedback effects closely aligns with Farmer et al., 2019). the proposed definitions of climate tipping elements (Lenton et al., 2008; Levermann et al., 2012). Anticipated climate impacts as potential drivers of Societal transformation, where a system shifts from one state social change to a qualitatively different one has often been a key marking of historical transformations. These shifts can be sudden, such as It has been well established that meeting the aims of the Paris the “Velvet Revolution” in communist Czechoslovakia, where the Agreement is not only necessary but also still physically feasible ruling party fell within a matter of a few days, consequently lead- in the climate system (e.g., Schellnhuber et al., 2016). However, ing to an end of the command economy and the establishing of a the questions remains as to what such feasibility entails in the parliamentary republic. On the other hand, such shifts can also social sphere. occur on comparably slower time-scale, like the decades-long Effective mitigation of climate change requires behavioral “civil rights movement” in the United States, culminating in the change on the individual level, but, importantly, also the imple- 1960’s with a series of legislation banning formalized discrim- mentation of coordinated climate policies. Climate action on both inatory practices, guaranteeing equal access to education, labor, levels requires a sufficiently high level of awareness and cli- housing and voting rights. In addition rapid societal change can mate change concern to allow spreading of individual behavioral even be caused by unanticipated forces, such as the Fukushima change on social networks and the support of global climate Disaster in Japan affecting rapid shifts away from nuclear energy policies through democratic institutions. A number of factors production in Germany. including values, attitudes and political orientations, as well as other indicators, such as demographic characteristics, knowledge,

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risk perception and trust, have all been linked to climate change and potential action are a necessary condition for behavioral and awareness and concern (Hornsey et al., 2016). More importantly, social transformation, i.e., social tipping to occur. In other words subjective climate change knowledge, or climate literacy, has been if either a direct link between knowledge and concern or con- shown to be a strong positive predictor of such climate change cern and behavior would be absent such transformations or tipping concern (Kahan et al., 2012). At the same time, climate change would possibly be far less likely to occur. The present analysis concern has been shown to be strongly related to engagement in mainly intends to show that changes in behavior may come about environmentally friendly actions, albeit less strongly than with as the result of transformations along such a chain of processes. climate policy support (Hornsey et al., 2016). We show that the (German) public seems to recognize and antici- Given the need for rapid social changes, we question whether pate changes in the polar region which they consequently see as a it is possible that anticipated impacts of climate change can affect potential threat to future generations. Assessing whether this state behaviors and/or increase the likelihood of climate change ame- ultimately leads to environmental action may be determined by liorative policies. Generally, the perceptions of risks have been a multitude of additional variables that require further in-depth broadly noted as key drivers of behavior, such that the more an analysis. individual perceives a certain risk, the more likely they are to act Hence, further research needs to engage in understanding the in ways that aim to minimize these risks. The role of such antic- possible mechanisms and potential drivers behind the relatin- ipated risks has been discussed with respect to a broad range of ship between knowledge, concerns and behaviors. As noted by behaviors and aspects, such as health (Brewer et al., 2007; Floyd Kollmuss and Agyeman (2002), several barriers limit the possi- et al., 2000), financial decision making (Weber, 2004; Weber et al., bility for behavioral changes, such as higher costs of engaging 2012), or sexual behaviors (Benthin et al., 1993). Specifically with in new behaviors (Diekmann and Preisendörfer, 2003), or lim- respect to climate change, increased risk perceptions have been iting cultural, economic or political factors. We also note that found to motivate individuals to engage in more climate friendly knowledge may be further fostered by novel foci in education or behaviors (O’Connor et al., 1999; Semenza et al., 2008) as well increased media coverage. In addition, behavioral change can cer- as support climate policies (Leiserowitz et al., 2013; Smith and tainly also result from processes other than subjective knowledge Mayer, 2018). and concern, e.g., new technologies or changing socio-economic Drawing from environmental psychology, Kollmuss and Agye- conditions. Ultimately, individual actions themselves may be fol- man (2002) establish a theoretical framework noting the interplay lowed by emergent collective action as well as consequential between internal (e.g. motivation, values, attitudes) and external environmental regulations and climate policies. factors (e.g. institutional, economic, cultural) driving individual likelihood to engage in environmentally friendly behaviors. Inter- nal motivations, such as concerns, can drive pro-environmental Domino effects in the Earth System actions, most effectively when they are in synergy with other inter- In summary, we ask, somewhat provocatively, whether changes nal and external factors. And while knowledge of climate change in perceptions of natural dynamics in the Polar regions can raise is related to concerns, the relationship between knowledge and concerns about climate change enough to tip behaviors and cli- behavioral change is often indirect, filtered via external (institu- mate policies for achieving substantive reductions in greenhouse tional, economic, cultural) and internal (motivation) factors. Previ- gas emissions (Shi et al., 2015; Kahan et al., 2012). ous research also noted positive relationships between knowledge The answer seems to be two-fold: A priori, it may come as and concerns for the polar regions (Hamilton, 2008, 2012), but a surprise that people are concerned about ongoing or future as of current, there is limited empirical research on the drivers changes in Antarctica at all, since sea-level rise through ice loss – of environmental actions in relation to the such aforementioned compared to typical individual and political time horizons – is a changes. very slow process. The most severe impacts will most likely only To illustrate the potential of anticipated climate impacts to manifest beyond the lifetime of even our grandchildren’s genera- induce a change in people’s attitude we present an exploratory tion (Clark et al., 2016). Therefore, it is all the more remarkable analysis of the relationship between knowledge, concern and will- that knowledge about the dynamics in polar regions still corre- ingness to engage in behavioral ameliorative action in response to lates with an increased concern about climate change in general, observations in the polar regions, Fig. 2. Specifically we utilize a as indicated by the survey data. Ultimately, this concern can (as novel survey of 2904 Germany respondents in the German GESIS suggested by our data as well as earlier studies in, e.g., Hornsey Panel (August to October 2017) (GESIS, 2018), a nationally rep- et al. (2016)) have a positive impact on attitudes towards climate resentative, probability-based, mixed mode access panel, utilizing change and the associated willingness to engage in environmen- online and mail-in responses (Bosnjak et al., 2018). tally friendly actions. This clearly shows a potential for societal Broadly this data suggests that knowledge about changes in the change as a response to anticipated climate tipping. polar regions is directly linked to concerns for this area, and fur- Further, increased concerns towards the environment have the ther, concerns are positively related to the willingness to engage potential to effect policy changes. Changes to public opinion can in ameliorative actions (in this case driving one’s car less). Hence, punctuate previously stable and ‘sticky’ institutions, leading to we find the expected indirect link between (subjective) knowledge policy change (Baumgartner and Jones, 2010). Also, broad social and one’s willingness to change certain behaviors that appears activism can spur generation new political coalitions, or effect to be via the corresponding concerns. As such, there is prelimi- a change shift in the priorities of existing ones (Sabatier, 1988; nary evidence that concerns for the changes in the polar region Weible and Sabatier, 2017). may effect change in people’s behaviors. These observed links However, it would take a number of steps, i.e., policy and/or between subjective knowledge and concern, as well as concern economic changes to have a direct impact on emissions that in turn

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reduce the risk for a tipping of, e.g, the Antarctic Ice Sheet. This Association (project DOMINOES), the European Research Coun- implies that social tipping as a whole is more than the change in a cil project Earth Resilience in the Anthropocene (743080 ERA), single observable, but rather a possible cascading domino effect of the Stordalen Foundation via the Planetary Boundary Research intertwined processes, e.g., through social, political and financial Network (PB.net) and the Earth League’s EarthDoc programme. networks. Future work should thoroughly address several issues that so far hinder an in-depth analysis of social tipping elements in the References Earth System. First, a concise definition of social tipping should Jonathan L. Bamber, Riccardo E. M. Riva, Bert L. A. Vermeersen, and be developed as the basis for community-driven efforts to classify Anne M. LeBrocq. 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