Search

Climate change and socioeconomic developments are driving risks from natural hazards and thus determine the effectiveness and efficiency for disaster risk management strategies. With DAPP-MR, an approach to apply a decision-focused lens, and a longer-term planning perspective in multi-risk systems has been recently developed. DAPP-MR guides the exploration of disaster risk management pathways under uncertainty while explicitly accounting for trade-offs and synergies of policy measures across (interconnected) sectors, hazards, and time.This work provides a first insight into the utility of the DAPP-MR framework to support disaster risk management decision making in the complex context of multi-hazard, multi-stakeholder settings. We used an integrated impact assessment modelling environment to assess (multi-)hazard impacts in a synthetic river basin, capturing interests and dynamics of three sectors (agriculture, inland shipping, residential housing) exposed to interacting flood and drought-hazards. We showcase (interactive) methods and metrics for the analysis and evaluation of potential risk management pathways. They were selected to deal with the increasingly multi-objective set-up in multi-risk systems explicitly capturing and explore effects from integrating measures directed towards different hazards and sectors.

The key risks assessment developed in the context of the IPCC Working Group II AR6 Europe chapter pulled together multiple line of evidence across the published literature and used expert elicitation to identify those risks with the greatest potential to become severe or that are already severe now. Four key risks have been identified for Europe, namely: 1) heat stress to human and ecosystems; 2) loss of agriculture productivity due to heat and dry conditions and extreme weather; 3) water scarcity to multiple interconnected sectors; 4) coastal and inland flooding. Alongside the assessment of the key risks, an assessment of the effectiveness of discrete adaptation options was also performed following a protocol which defines adaptation effectiveness as the risk reduction potential of an adaptation option from a given baseline. More than 50 discrete options were assessed with the greatest majority showing medium effectiveness to reduce risks. These two assessments have brought forward some critical aspects in adaptation decision making which have inspired further analysis. These aspects are 1) the need for long term planning, 2) the diversity of contexts within which adaptation takes place, 3) the existence of multiple interacting risks and 4) the limited knowledge on the effectiveness of adaptation as opposed to the knowledge on adaptation limits. We explore here the use of warming sensitive adaptation pathways as a framework to address these critical aspects and present reflections on how illustrative adaptation pathways can support effective decision making that also reduces the implementation gap. For example, our pathways framework points at a dichotomous future to reduce coastal flooding in the long term and a future where all options will be needed to reduce the risks of water scarcity. The framework also shows that considering multiple risks together under different levels of warming can inform adaptation decision making about potential constraints, trade-offs, and lock-ins. In general, for the illustrative adaptation pathways to be useful planning tools certain preconditions must be in place such as legitimacy through monitoring and evaluation as well as human and financial capital towards multiple and diverse pathways.

Sea-level rise (SLR) causes the frequency of extreme sea levels to amplify. Projections of the frequency amplification of extremes are often computed for arbitrary future years and for the historical centennial event. Such projections may therefore not provide salient information to adaptation planners, as they do not indicate when certain flood risk thresholds will be crossed given the current degree of local coastal flood protection.To better support adaptation planning, we introduce a framework that extends the emerging timing perspective on sea-level rise to the frequency amplification of extreme sea levels. Moreover, by relating amplification factors to model estimates of local flood protection standards, we project the timing of a range of decreases in the local degree of protection. The projections are based on tide gauge observations (GESLA3) and relative sea-level projections of IPCC AR6 until 2150.Our central estimates indicate that the estimated degrees of protection will on average be exceeded 10 times more frequently within the next 30 years (the lead time that large adaptation measures may take) at 26 & 32% of the tide gauges considered, and annually at 4 & 8%, for respectively a low & high emissions scenario (SSP1-2.6 & SSP3-7.0). Furthermore, in scenarios in which sea-level rise will accelerate, the same decreases in the degree of coastal protection will occur substantially faster in the future. Our projection framework may help adaptation planners to assess the available lead time and useful lifetime of protective infrastructure, given unacceptable decreases in the degree of coastal protection., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Decision-making under uncertainty is important for managing human-natural systems in a changing world. A major source of uncertainty that challenges decisions is rooted in their multi-actor settings, i.e., the poorly understood societal actors with diverse values, complex relationships, and conflicting management approaches. Despite general agreement across disciplines on co-producing knowledge for viable and inclusive outcomes in multi-actor settings, there is still limited conceptual clarity and no systematic understanding on what co-production means in decision-making under uncertainty and how it can be achieved. Here, we use content analysis and clustering to systematically analyse 50 decision-making cases with multiple time and spatial scales across 26 countries and in 9 different sectors in the last decade to serve two aims. The first is to synthesise the key recurring approaches that underpin high quality decision co-production across many cases of diverse features. The second is to identify important deficits and opportunities to leverage existing approaches towards flourishing co-production in supporting decision-making. We find that four general approaches emerge centred around: promoting innovation for robust and equitable decisions; broadening the span of co-production across interacting systems; fostering social learning and inclusive participation; and improving pathways to impact. Additionally, five key areas that should be addressed to improve decision co-production are identified in relation to: participation diversity; social learning; power relationships; governance inclusivity; and transformative change. Characterising the emergent approaches and their key areas for improvement can help guide future works towards more pluralistic and integrated science and practice.

The shrinking solution space for adaptation calls for long-term dynamic planning starting now

To deal with large uncertainties about future climate and socio-economic developments, planners in deltas are adopting an integrative and adaptive planning approach referred to as Adaptive Delta Management (ADM). Bangladesh has used the ADM approach for the development of its adaptive plan; Bangladesh Delta Plan 2100 (BDP 2100). The success of policy strategies in an adaptive delta plan critically depends on a specific adaptation of livelihoods of local communities (Community Livelihood Adaptation; CLA), especially in an agriculture-oriented society like Bangladesh. For example, while triple rice cropping might be evaluated as a robust strategy in all futures considered, its success eventually depends on whether farmers’ will actually make that choice, which is deeply uncertain. In this paper, we use literature review, insights from interviews and field observations to examine how the uncertainty in CLA impacts (adaptive) delta management. We study two historical cases of livelihood adaptation of farmer communities confronted with salinization and waterlogging in the polders of southwest Bangladesh since the 1960s. We conclude that historically the uncertainty about CLA in polders has been ignored in the development of policy plans, leading to the failure of anticipated policy outcomes. We recommend planners in Bangladesh and other deltas worldwide to take account of CLA as uncertainty when developing long-term adaptive plans.

Global warming may cause abrupt and non-linear climate tipping points, with large impacts to established socio-economic systems [1]. The socio-economic system itself also exhibits many non-linear change processes, and therefore may experience manifold unintentional climate-change induced socio-economic tipping points (SETPs) that could already follow from relatively small changes in climatic conditions. Examples are the gentrification of vulnerable groups or abrupt unplanned retreat from areas of increasing climate risk, abrupt transitions in financial markets, large-scale systematic malfunction of critical infrastructure networks during weather extremes, sudden reconfigurations of insurance markets and house price collapses. Such SETPs are defined as ‘a climate change induced, abrupt change of a socio-economic system, into a new, fundamentally different state’ [2]. It is important for spatial-economic planners and capital investors to know if and under what conditions SETPs may happen, and what can be done to anticipate and manage their causes and effects.With three model-based case studies we demonstrate a stepwise approach to identify SETPs and to support adaptation and mitigation policy. The first is a house price collapse and radical transformation of long-term flood risk policy in a coastal city like Rotterdam, following rapid sea level rise due to Antarctic ice-sheet instability. Using a model that simulates flood risk, house prices and adaption integrally, we identify abrupt house price collapses in hundred-thousands possible futures spanning the uncertainty in sea level rise, storm surge and house market scenarios. We explicitly explore the long-term impacts of four dynamic adaptive strategies to anticipate flood risk and their successfulness in avoiding a SETP [3]. The second case is the financial collapse of the winter sports industry in the European Alps following a gradually retreating snowline [4]. The third is a large-scale systematic malfunction of national road networks of European countries due to increasing river flood hazards. The focus of our contribution is on showing how decision making can be supported despite the large uncertainties around SETPs. Finally, we discuss how the SETP-concept aligns with socio-ecological regime shifts [5] and deliberate positive social tipping points to achieve large mitigation and adaptation challenges [6,7].Types of tipping points along the cause-effect chain from increasing GHG, to biophysical changes, to socioeconomic impacts and transformative adaptation and mitigation response. Source [2], CC-BY3.0 license.Refs (doi): [1] 10.1073/pnas.2103081118; [2] 10.1088/1748-9326/ab6395; [3] 10.2139/ssrn.3935775; [4] 10.1016/j.envsci.2021.09.005; [5] 10.1088/1748-9326/aaaa75; [6] 10.1073/pnas.1900577117 [7] v10.1016/j.ecolecon.2021.107242

Adaptation to sea-level rise (SLR) will be necessary to protect people at risk from flooding due to a combination of tide, surge and SLR in the future. This adaptation commitment requires adequate time and resources to prepare for the impacts of SLR that are expected within this century and beyond (here until 2150). In this study, we address the question of “when” in addition to “how much” adaptation to SLR is needed. We use a scenario-neutral approach to assess the amount of people at risk from flooding under different SLR magnitudes. We combine this scenario neutral approach with SLR projections for the SSPs in AR6 and population growth scenarios in the coastal zone to identify the timing, in which the number of additional people affected by SLR alone or in combination with a 100-year storm event will exceed a set of thresholds. The comparison of the timing for different SSPs demonstrates that it is rather a question of “when” than “if” these thresholds will be exceeded. Some countries will need to adapt to SLR within the next few decades to prevent an additional 1–5 million people from becoming affected by flooding. Other countries have more time for adaption but will face a rapid increase in the number of people at risk from flooding beyond 2100. Combining SLR impacts with projected population change further increases the number of people at risk in the middle of this century for most SSPs. Considering low-confidence high-end SLR scenarios that include the possibility for a more rapid melting of the ice sheets may shift expected impacts approximately 50 years forward. This means that adaptation needs to be implemented faster and sooner than previously anticipated, which may have consequences for the available adaptation options. Ignoring the potential and long-term (including beyond 2100) commitment for adaptation may lead to an adaptation gap and subsequently expensive retrofitting of infrastructure, creation of stranded assets, and less time to adapt at greater cost. In contrast, acknowledging and acting upon the long-term adaptation commitment can encourage timely adaptation and its alignment with other societal ambitions.

While current adaptation planning approaches commonly focus on single hazards and individual sectors, a paradigm shift in decision-making is required to account for the increasingly interconnected world. Decision making support tools are needed to enable fair distribution of support and (increasingly) limited resources (i.e. space, financial means). No such integrated tools exist yet that account for dependencies, conflicts, and co-benefits between various stakeholders as well as the knowledge regarding dependencies and co-existence of various hazards and their joint impacts. This work provides a first conceptual framework of a decision-support tool in the context of adaptation planning in a multi-hazard, multi-stakeholder setting.Decision-making processes for adaptation planning need to follow dynamically robust plans instead of a static optimal strategy to account for the deeply uncertain future. In fact, a myriad of uncertain or even unknown factors (i.e. climate change, socio-economic developments, technology advancement) might lead to very different future developments. Dynamic Adaptation Policy Pathways (DAPP) is a widely used systematic and practical approach for decision-making over time and strategic planning under uncertain conditions to design dynamic, adaptive plans covering short-term no-regret actions, long-term options, and adaptation signals to take actions.A systematic literature review was undertaken to analyze adaptation planning concepts across various (multi-)sectors and (multi-)hazard contexts. This literature review was used to identify underlying paradigms and relevant concepts in the field of scenario analysis, pathway modelling, and multi-objective decision-making useful for advancing the existing DAPP approach. Using a simple, synthetic multi-hazard, multi-sector case study, the tailored adaptation planning framework was tested for its robustness.As a result, an advanced DAPP framework was developed. It accounts for several different physical processes playing a role in natural hazard impacts on human systems (i.e., different hazard types). Moreover, it accounts for spatial and temporal dependence of (different) hazards influencing coping capacities and the triggering space to take adaptation actions (compound, consecutive, aggregating impacts). Furthermore, the framework acknowledges 1) the diversity of stakeholders in an exposed system in terms of their vulnerability, objectives, coping capacities and contesting interests (e.g., limited resources or space), and 2) the diversity of driving actors of adaptation action within a system and the connectedness of decisions and implications on the system development. The framework uses information about the system and its boundaries, along with information about the available adaptation actions, information about the decision making process / motivation to take adaptation action, information about possible conflicts / dependencies within the decision space (with regards to objectives, adaptation actions, and other system elements) and implicit assumptions used to define the system (of systems). Using this framework, adaptation pathways – meaning sequence of adaptation actions – can be created and evaluated with regards to their robustness and performance in comparison to long-term visions.

The second volume in the Summary for Urban Policymakers (SUP) series, Climate Change in Cities and Urban Areas: Impacts, Adaptation and Vulnerability, offers a concise and accessible distillation of the IPCC Working Group II Report. Cities are places of high risks from climate change, resulting from the interaction of climate change hazards, the exposure of infrastructure, people and ecosystems, the vulnerability of exposed elements and communities, and the negative or unintended effects of responses to climate change to people and ecosystems. This report assesses the feasibility and effectiveness of different adaptation options but highlights that adaptation has limits and can even lead to maladaptation, triggering unintended effects which increase risk, emissions and lock-ins. It synthesises the latest evidence on the necessary urban-led transformation, as well as evidence on operationalizing the five simultaneous system transitions across land, coastal, ocean and freshwater ecosystems; cities, regions, and infrastructure; energy and industrial systems, accelerated by societal choices. Cities and urban areas have a critical role to play in the climate resilient development needed to meet goals of climate change, human wellbeing, and ecosystem health challenges.

The Summary for Urban Policymakers (SUP) initiative provides a distillation of the IPCC reports into accessible and targeted summaries that can help inform action at city and regional scales. This is a collection of the three volumes of the SUP series combined together.

Climate change threatens winter tourism in the Alps severely, and ski resorts are struggling to cope under uncertain climate change. We aim to identify under what conditions physical and economic tipping points for ski resorts may occur under changing climate in six Swiss ski resorts representing low, medium, and high elevation in the Alps. We use exploratory modeling (EMA) to assess climate change impacts on ski resorts under a range of futures adaptation options: (1) snowmaking and (2) diversifying the ski resorts' activities throughout the year. High-resolution climate projections (CH2018) were used to represent climate uncertainty. To improve the coverage of the uncertainty space and account for the climate models' intra-annual variability, we produced new climate realizations using resampling techniques. We demonstrate the importance of five factors, namely climate scenarios (RCPs), intra-annual climate variability, snow processes model, and two adaptation options, in ski resorts survival under a wide range of future scenarios. In six ski resorts, strong but highly variable decreases in the future number of days with good snow conditions for skiing (GSD) are projected. However, despite the different characteristics of the resorts, responses are similar and a shrunk of up to 31, 50, and 62 days in skiing season (Dec-April) is projected for the near-future (2020–2050), mid-future (2050–2080), and far-future (2070–2100), respectively. Similarly, in all cases, the number of days with good conditions for snowmaking (GDSM) will reduce up to 30, 50, and 74 days in the skiing season in the near-, mid-, and far-future horizons, respectively. We indicate that all ski resorts will face a reduction of up to 13%, 33%, and 51% of their reference period (1981–2010) revenue from winter skiing activities in the near-, mid-, and far-future horizons. Based on the outcomes of the EMA, we identify Dynamic Adaptive Policy Pathways (DAPP) and determine the adaptation options that ski resorts could implement to avoid tipping points in the future. We highlight the advantages of adaptive planning in a first of its kind application of DMDU techniques to winter tourism. We specify the possible adaptation options ranging from "low revenue diversification and moderate snowmaking" to "high revenue diversification and large snowmaking" and demonstrate when an adaptation action fails and a change to a new plan is needed. By the end of the century, we show that only ski resorts with ski lines above 1800–2000 m elevation will survive regardless of the climate scenarios. Our approach to decision-making is highly flexible and can easily be extended to other ski resorts and account for additional adaptation options.

This session will critically examine new and emerging approaches to adaptation using three contrasting themes to illustrate key issues. The session will comprise 3 panels on: Conservation/biodiversity, Coastal Systems and Urban Systems. Each panel will address the common themes of (a) co-benefits and transformation issues; (b) how to handle uncertainty; (c) justice dimensions; (d) links between systems; and (e) working across scales – national policy to local implementation.

The need for explicitly considering equity in climate change adaptation planning is increasingly being recognized. However, evaluations of adaptation often adopt an aggregated perspective, while disaggregation of results is important to learn about who benefits when and where. A typical example is adaptation of rice agriculture in the Vietnam Mekong Delta (VMD). Efforts focused on flood protection have mainly benefitted large‐scale farmers while harming small‐scale farmers. To investigate the distributional consequences of adaptation policies in the VMD, we assess both aggregate total output and equity indicators, as well as disaggregated impacts in terms of district‐level farming profitability. Doing so requires an adequate representation of the multisectoral dynamics between the human and biophysical systems which influence farming profitability. We develop a spatially explicit integrated assessment model that couples inundation, sedimentation, soil fertility and nutrient dynamics, and behavioral land‐use change and farming profitability calculation. We find that inter‐district inequality responds in a non‐linear way to climatic and socio‐economic changes and choices of adaptation policies. The patterns of who wins and who loses could change substantially when a different policy is implemented or if a slightly different uncertain future materializes. We also find that there is no simple ranking of alternative adaptation policies, so one should make trade‐offs based on agreed preferences. Accounting for equity implies exploring the distribution of outcomes over different groups over a range of uncertain futures. Only by accounting for multisectoral dynamics can planners anticipate the equity consequences of adaptation and prepare additional measures to aid the worse‐off actors.

The future of ski resorts in the Swiss Alps is highly uncertain. Being dependent on snow cover conditions, winter sport tourism is highly susceptible to changes in temperature and precipitation. With the observed warming of the European Alps being well above global average warming, snow cover in Switzerland is projected to shrink at a rapid pace. Climate uncertainty originates from greenhouse gas emission trajectories (RCPs) and differences between climate models. Beyond climate uncertainty, the snow conditions are strongly subject to intra-annual variability. Series of unfavorable years have already led to the financial collapse of several low-altitude ski resorts. Such abrupt collapses with a large impact on the regional economy can be referred to as climate change induced socio-economic tipping points. To some degree, tipping points may be avoided by adaptation measures such as artificial snowmaking, although these measures are also subject to physical and economical constraints. In this study, we use a variety of exploratory modeling techniques to identify tipping points in a coupled physical-economic model applied to six representative ski resorts in the Swiss Alps. New high-resolution climate projections (CH2018) are used to represent climate uncertainty. To improve the coverage of the uncertainty space and accounting for the intra-annual variability of the climate models, a resampling technique was used to produce new climate realizations. A snow process model is used to simulate daily snow-cover in each of the ski resorts. The likelihood of survival of each resort is evaluated from the number of days with good snow conditions for skiing compared to the minimum thresholds obtained from the literature. Economically, the good snow days are translated into the total profit of ski resorts per season of operation. Multiple unfavorable years of total profit may lead to a tipping point. We use scenario discovery to identify the conditions under which these tipping points occur, and reflect on their implications for the future of snow tourism in the Swiss Alps.

We present the first systematic, global stocktake of the academic literature on human adaptation. We screen 48,316 documents and identify 1,682 articles that present empirical research documenting human efforts to reduce risk from climate change and associated hazards. Coding and synthesizing this literature highlights that the overall extent of adaptation across global regions and sectors is low. Adaptations are largely local and incremental rather than transformative. Behavioural adjustments by individuals and households are more prevalent than any other type of response, largely motivated by drought and precipitation variability. Local governments and civil society are engaging in risk reduction across all sectors and regions, particularly in response to flooding. Urban technological and infrastructural adaptations to flood risk are prevalent in Europe, while shifts in farming practices dominate reporting from Africa and Asia. Despite increasing evidence of adaptation responses, evidence that these responses are reducing risks (observed and projected) remains limited.

Assessing global progress on human adaptation to climate change is an urgent priority. Although the literature on adaptation to climate change is rapidly expanding, little is known about the actual extent of implementation. We systematically screened >48,000 articles using machine learning methods and a global network of 126 researchers. Our synthesis of the resulting 1,682 articles presents a systematic and comprehensive global stocktake of implemented human adaptation to climate change. Documented adaptations were largely fragmented, local and incremental, with limited evidence of transformational adaptation and negligible evidence of risk reduction outcomes. We identify eight priorities for global adaptation research: assess the effectiveness of adaptation responses, enhance the understanding of limits to adaptation, enable individuals and civil society to adapt, include missing places, scholars and scholarship, understand private sector responses, improve methods for synthesizing different forms of evidence, assess the adaptation at different temperature thresholds, and improve the inclusion of timescale and the dynamics of responses. Determining progress in adaptation to climate change is challenging, yet critical as climate change impacts increase. A stocktake of the scientific literature on implemented adaptation now shows that adaptation is mostly fragmented and incremental, with evidence lacking for its impact on reducing risk.

Without adaptation, sea-level rise (SLR) will put more people at risk of flooding. This requires a timely and adequate commitment to adaptation. In this paper, we show how adaptation needs to unfold over time to manage climate-induced SLR. We use a novel scenario-neutral approach, applied globally and subsequently combined with SLR and population scenarios, to assess when, where, and how fast to adapt up to 2150. As rates of SLR accelerate, adaptation needs to occur at an increasing pace or at a larger scale. While it is certain that adaptation will be necessary, it is uncertain when and how fast. After only ∼ 0.15 m SLR relative to 2020, 1 million people need to adapt to permanent submergence and the amount of people at risk of a 100-year flood increases with 21% to 83 million people. This would occur in the next 30 (20–45) years for RCP4.5 and within 25 (18–36) years under RCP8.5, assuming no change in protection or population. The uncertainty in timing increases with higher SLR, albeit for some impacts it can still a matter of time. Population at risk of a 100-year flood doubles after 0.75 m SLR which could occur by ∼ 2080 (2068–2088), 2100 (2085–2130), or 2150 (2115-beyond 2150) under a high-end, RCP8.5, or RCP4.5 scenario respectively. The rate, at which the risk increases, differs strongly per country. In some countries an additional 1–5 million people of the present population will be at risk of a 100-year flood within the next two decades, while others have more time to adapt but will see rapid growth of risk past 2100. Combining SLR impacts with projected population change further increases the number of people at risk of a 100-year flood by ∼13% between 2040–2060 (under both RCP8.5-SSP5 and RCP4.5-SSP2). This can be managed through protecting, floodproofing or limiting developments in high-risk areas. A commitment to adaptation is inevitable to maintain risk at present levels. With increasing warnings of the potential for accelerated SLR due to rapid ice sheet melt, adaptation may need to happen faster and sooner than previously anticipated which can have consequences for how to adapt. Failure to acknowledge the potential and long-term (including beyond 2100) adaptation commitment in development and adaptation planning may lead to a commitment gap and subsequently expensive retrofitting of infrastructure, creation of stranded assets, and less time to adapt at greater cost. In contrast, considering the long-term adaptation commitment can support timely adaptation and alignment with other societal goals.

Sea level rise is one of the most indisputable effects of global warming with important consequences for current decisions concerning mitigation and adaptation. A few evolutions in the climate and decision making fields have recently increased the concerns of sea level information users about the potential impacts of future sea level. We identify four main evolutions:- Most countries are not on track to reach their Paris agreement emission pledges, making the goal of staying well bellow 2ºC less and less attainable.- New climate model simulations from the Coupled Model Inter-comparison Project 6 (CMIP6) have both a higher average climate sensitivity and a larger spread between models compared to CMIP5.- The Greenland and Antarctic ice sheets are melting faster than expected in previous IPCC reports and future projections from a recent structured expert judgment show larger expected melt and more uncertainty than both current numerical models and a previous expert judgment.- Decision makers are more and more interested in events with a large impact and a small probability to build robust infrastructure and design robust long term strategies concerning relocation of coastal communities.While these four evolutions are fundamentally deeply uncertain, to explore their combined effect we build a subjective probabilistic framework that allows to propagate the uncertainty through the different components and obtain sea level rise projections. In this presentation we present this framework, the results and their sensitivity to multiple hypothesis and we discuss implications for different uses and users of sea level rise information.

The concept of tipping points has received much attention in research on climate change. In the biophysical realm, climate tipping points describe critical thresholds at which large-scale elements of the Earth switch to a qualitatively different state; and ecological tipping points describe thresholds separating distinct dynamic regimes of ecosystems. The tipping point metaphor is also used to indicate transformative change in adaptation and mitigation strategies. However, there remains an underexplored field: climate change induced socio-economic tipping points (SETPs). We define an SETP as: a climate change induced, abrupt change of a socio-economic system, into a new, fundamentally different state. We make a distinction between SETPs in terms of transformational response to climate change and SETPs in terms of socio-economic impacts.SETPs are points where a gradual change in climatic conditions causes an abrupt, fundamental reconfiguration of the socio-economic system. Through a stakeholder consultation, we identified 22 candidate SETP examples with policy relevance for Europe. Three of these were investigated in more detail, with special attention for their tipping point characteristics (stable states at both sides of a critical threshold, abrupt transition between those states, and the mechanism explaining the non-linear and abrupt behaviour).The first example is the collapse of winter sports tourism in low-altitude ski resorts. In the face of climate change, this may occur abrupt, cause a fundamental reconfiguration of the local and regional economy, and is very hard to reverse. In some cases, it could be possible to achieve a fundamental shift towards summer tourism.The second example is the farmland abandonment in Southern Europe. Large parts of Spain have already seen widespread farmland abandonment and associated migration. Increasing heat and drought may worsen the conditions, with considerable social, and to a lesser extent, economic consequences. On the local scale, this manifests itself as a clear SETP: a lively agricultural area suddenly tips to the ‘Spanish Lapland’: deserted farms, villages with ageing population, little economic activity and underdeveloped infrastructure and facilities.The third example is sea-level rise induced reconfiguration of coastal zones. In the face of accelerating sea level rise (SLR), threatened communities may retreat from vulnerable coastal zones. This may be caused by migration (voluntary human mobility), displacement (involuntary movement following a disaster) or relocation (retreat managed by the government). The SETP of retreat from a certain area is usually triggered by a flood event. However, also the adaptation to increasing flood risk may be so transformative, that it can be considered a structural configuration of the system. This is currently seen in The Netherlands, where studies on extreme SLR have triggered a debate in which very transformative strategies are proposed, such as: constructing a dike in front of the entire coast, retreat from areas with economic stagnation and population decline, or elevating all new buildings above sea level.A key insight is that the rate of climate change may exceed the capacity of society to adapt in the traditional way, triggering a shift towards fundamentally different policies and a reconfiguration of the socio-economic system.

In the past decade, many different projections of global and regional sea-level rise as a result of climate change have been published (Garner et al, 2018, Horton et al, 2018). This wide range of projections illustrates the large uncertainty about future sea-level rise, which is complicated for coastal decision makers relying on these projections. Here, we aim to provide insights into the available projections, by identifying the main contributing sources in each of the sea-level projections, and sorting the projections into ‘families’ that have contributing sources or methodologies in common. Using these ‘families’, we discuss the main differences between projections in terms of rates and timing of certain levels of sea-level rise. Sea-level rise projections are often compared by showing amounts or rates at a certain future point in time, e.g., 2050 or 2100. For many areas, a sea-level rise exceeding 1 to 2 m will require truly transformative decisions. Such decisions have a long lead time (in the order of 30 years) for planning and implementation. Showing the timing of a particular rate or magnitude of sea-level rise may provide insight that it is not a matter of if and how to adapt, but when to adapt. This may help decision makers in dealing with the uncertainties and it may accelerate adaptation.We find that a sea-level rise of 25 cm (since 2000) is first reached for each of the RCP scenarios (the 95th percentile) within a decade of each other. This indicates that for a structure with a lifetime based on a sea-level rise of 25 cm, decisions are not conditional on the RCP scenario. The latest year for crossing the 25 cm threshold (the 5th percentile), however, does depend more on the RCP scenario: for the RCP2.6 scenario this is later than for the RCP8.5 scenario, because the acceleration is less strong. As the levels examined grow (0.25 m, 0.5 m, 0.75 m, etc.), the initial year of reaching that level starts to diverge more between the scenarios, and therefore the timing of decision points starts to be more and more conditional upon RCP scenario. However, for investments with a long envisioned lifetime such as coastal infrastructure, certain amounts of sea level rise may still be within the lifetime independent of the RCP scenario.

Tipping points have become a key concept in research on climate change, indicating points of abrupt transition in biophysical systems as well as transformative changes in adaptation and mitigation strategies. However, the potential existence of tipping points in socio-economic systems has remained underexplored, whereas they might be highly policy relevant. This paper describes characteristics of climate change induced socio-economic tipping points (SETPs) to guide future research on SETPS to inform climate policy. We review existing literature to create a tipping point typology and to derive the following SETP definition: a climate change induced, abrupt change of a socio-economic system, into a new, fundamentally different state. Through stakeholder consultation, we identify 22 candidate SETP examples with policy relevance for Europe. Three of these are described in higher detail to identify their tipping point characteristics (stable states, mechanisms and abrupt change): the collapse of winter sports tourism, farmland abandonment and sea-level rise-induced migration. We find that stakeholder perceptions play an important role in describing SETPs. The role of climate drivers is difficult to isolate from other drivers because of complex interplays with socio-economic factors. In some cases, the rate of change rather than the magnitude of change causes a tipping point. The clearest SETPs are found on small system scales. On a national to continental scale, SETPs are less obvious because they are difficult to separate from their associated economic substitution effects and policy response. Some proposed adaptation measures are so transformative that their implementations can be considered an SETP in terms of 'response to climate change'. Future research can focus on identification and impact analysis of tipping points using stylized models, on the exceedance of stakeholder-defined critical thresholds in the RCP/SSP space and on the macro-economic impacts of new system states. © 2020 The Author(s). Published by IOP Publishing Ltd. This paper has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776479 for the project CO-designing the Assessment of Climate CHange costs. https://www.coacch.eu/

Adaptation to coastal flood risk is hampered by high uncertainty in the rate and magnitude of sea-level rise. Subsequently, adaptation decisions carry strong risks of under- or over-investment, and could lead to costly retrofitting or unnecessary high margins. To better allocate resources timely and effectively, and achieve long-term sustainability, planners could utilise adaptation pathways, revealing the path-dependencies of adaptation options. This helps to identify low-regret short-term decisions that preserve options in an uncertain future, while monitoring to detect signals to adapt. A major barrier to the application of adaptation pathways is limited experience. To facilitate this, here we generalize this pathways approach for six common coastal archetypes, resulting in generic pathways suitable to be adjusted to local conditions. This provides a much richer analysis of coastal adaptation than provided by any previous analysis, by assessing the solution space and options over time for a variety of coastal regions. Based on this analysis, we find that the number of adaptation options declines while sea-level rises. For some archetypes, it becomes clear that long-term thinking is needed now, about if, how and when to move to transformative options, such as planned retreat, which may presently not be considered or acceptable. Our analysis further shows that coastal adaptation needs to start earlier than anticipated, especially given time required for local debate and choice and to implement measures. This paper has been partly supported by the EU research projects RISES-AM- (FP7-ENV-693396. The work of JAJ was also done in the framework of the M-CostAdapt (CTM2017-83655-C2-1-R, MINECO/AEI/FEDER, UE).

© 2016 The Authors Implementing climate-resilient pathways in conditions of uncertainty and change is a serious challenge. Approaches have been developed for this type of problem, one of which, Dynamic Adaptive Policy Pathways approach (DAPP), has been applied in practice in a limited number of circumstances, mainly for large infrastructure projects and at national scales. To better understand what it takes to catalyse uptake of DAPP to better address uncertainty and change than typical static planning approaches, we examined the role of a simulation game facilitated by a knowledge broker, in a real-life local decision setting on flood risk management in New Zealand. Four intervention phases over four years are described and their influence analysed: 1) creating interest through framing the science, 2) increasing awareness using the Game, 3) experimenting with DAPP, and 4) uptake of DAPP. We found that a knowledge broker introducing new framing of changing risk profiles, facilitating use of the Game and the DAPP approach in a real-life decision making setting, with contextual support from events and (inter)national reports, catalysed the uptake of adaptive pathways planning. We identified enabling requirements necessary for embedding adaptive planning into decision-making practice for addressing uncertainty and change.

A variety of model-based approaches for supporting decision-making under deep uncertainty have been suggested, but they are rarely compared and contrasted. In this paper, we compare Robust Decision-Making with Dynamic Adaptive Policy Pathways. We apply both to a hypothetical case inspired by a river reach in the Rhine Delta of the Netherlands, and compare them with respect to the required tooling, the resulting decision relevant insights, and the resulting plans. The results indicate that the two approaches are complementary. Robust Decision-Making offers insights into conditions under which problems occur, and makes trade-offs transparent. The Dynamic Adaptive Policy Pathways approach emphasizes dynamic adaptation over time, and thus offers a natural way for handling the vulnerabilities identified through Robust Decision-Making. The application also makes clear that the analytical process of Robust Decision-Making is path-dependent and open ended: an analyst has to make many choices, for which Robust Decision-Making offers no direct guidance. This paper compares Robust Decision-Making (RDM) and Dynamic Adaptive Policy Pathways (DAPP).RDM and DAPP have different merits, which highlight their complementarity.RDM has a clear analytical process and the application is reasonably straight forward.DAPP offers a convenient framework for designing plans for dynamic adaptation over time.

A wide variety of tools and approaches for supporting the making of decisions under deep uncertainty have been put forward, but we lack a comparative overview. This chapter presents a taxonomy of approaches and tools for supporting decisionmaking under deep uncertainty. The taxonomy is based on a decomposition of the tools and approaches into a set of common building blocks. Analysts can use the taxonomy for designing context-specific approaches to support DMDU.

Integrated assessment models often treat land-use change as an external driving force. In reality, land-use is influenced by environmental conditions. This paper explores the merits of endogenising land-use change, i.e. making land-use change an internal dynamic process in models used for supporting climate adaptation planning. For this purpose, we extend the Waas environmental impact assessment model, a hypothetical case study previously used for exploring new model-based climate adaptation approaches. We use a utility-based land-use change model for endogenising the land-use dynamics, evaluate its implications, and identify the conditions under which endogenising land-use change becomes important. We find that endogenising land-use dynamics changes the performance of the policies, allows for assessing policies that target land-use, and widens the outcomes of interest that can be considered. The relevance of endogenising land-use dynamics depends on (i) the expected degree of future climate change, (ii) the society’s sensitivity to climate events, and (iii) the types of policies that decision makers want to evaluate. Ignoring the interaction between the environment and the society (in this case the land-use) can result in both under- and overestimation of the impacts of adaptation and might limit the adaptation options that are considered.

Decision making by flood risk managers is challenged by uncertainty and changing climate risk profiles that have elements of deep uncertainty. Flood risk managers at a regional level in New Zealand requested better understanding and tools for decision making under conditions of uncertainty and changing conditions. A game was used to catalyze a process of new knowledge transfer and its uptake in technical assessments and decision making processes. The understanding enabled DAPP to be used to develop a long-term plan that can accommodate changes in flood frequency from climate change (as projected in three climate change scenarios) over at least 100 years. Use of “new” economic tools with DAPP facilitated decision making to consider the sensitivity of alternative policies to a range of climate change scenarios, to discount rate, decision review date, and costs and losses, thus addressing deep uncertainty by considering the long-term effects of initial decisions to changing conditions. The risk of path-dependent decisions and the role that current frameworks and practices play in blinding actors to the range of possible outcomes that could evolve in the future, was reduced. A series of interventions to raise and increase awareness through new information and its framing, experimentation, and leadership enabled the uptake of DAPP.

A highly uncertain future due to changes in climate, technology and socio-economics has led to the realisation that identification of "best-guess" future conditions might no longer be appropriate. Instead, multiple plausible futures need to be considered, which requires (i) uncertainties to be described with the aid of scenarios that represent coherent future pathways based on different sets of assumptions, (ii) system performance to be represented by metrics that measure insensitivity (i.e. robustness) to changes in future conditions, and (iii) adaptive strategies to be considered alongside their more commonly used static counterparts. However, while these factors have been considered in isolation previously, there has been a lack of discussion of the way they are connected. In order to address this shortcoming, this paper presents a multidisciplinary perspective on how the above factors fit together to facilitate the development of strategies that are best suited to dealing with a deeply uncertain future. Integrated view of concepts for dealing with a highly uncertain future in modelling.Role of multiple plausible futures amongst other paradigms for modelling the future.Relation of multiple plausible futures to deep, local/global uncertainty and VUCA.Overview of how different scenario approaches help to identify plausible futures.Factors affecting static and adaptive approaches to robustness to multiple futures.