In architecture, mitigation reduces the magnitude of climate change by reducing demand for resources; anticipatory adaptation improves performance against hazards; and planned adaptation creates policies and codes to support adaptation. Adaptation prepares for a future with intensifying climate conditions. The built environment must prepare for challenges that may be encountered during the service life of the building, and reduce human exposure to hazards. Structures are responsible for about 39% of the primary energy consumption worldwide and 24% of the greenhouse gas emissions, significantly contributing to the causes of climate change. Measures to reduce demand in the initial construction and over the life cycle of the building operation directly impact the climate. Improving performance against hazards requires a suite of modifications to counter specific threats. Adaptation measures may address higher temperatures, extreme precipitation, stormwater flooding, sea-level rise, hurricanes, drought, soil subsidence, wildfires, extended pest ranges, and multiple hazards. Because resources to meet every threat are inadequate, actions with low costs now which offer high benefits under a range of predicted future climates become high-priority solutions. Disaster risk is also reduced by aligning policies for planning and construction with anticipated hazards. Climate adaptation policies based on the local effects of climate change are a new tool to communicate risk and share resources. Building codes establish minimum standards for construction, so incorporating adaptation strategies into codes ensures that the resulting structures will survive a range of uncertain futures.
Adapting to Climate Sensitive Hazards through Architecture
Allison Hoadley Anderson
Agenda Setting and Natural Hazards
Rob A. DeLeo
Agenda setting describes the process through which issues are selected for consideration by a decision-making body. Among the myriad of issues policymakers can consider, few are more vexing than natural hazards. By aggregating (or threatening to aggregate) death, destruction, and economic loss, natural hazards represent a serious and persistent threat to public safety. While citizens rightfully expect policymakers to protect them, many of the policy challenges associated natural hazards fail to reach the crowded government agenda. This article reviews the literature on agenda setting and natural hazards, including the strain between preparing for emerging hazards, on the one hand, and responding to existing disasters, on the other hand. It considers the extent to which natural hazards pose distinctive difficulties during the agenda-setting process, focusing specifically on the dynamics of issue identification, problem definition, venue shopping, and interest group mobilization in natural hazard domains. It closes by suggesting a number of future avenues of agenda-setting research.
Assessment and Adaptation to Climate Change-Related Flood Risks
Brenden Jongman, Hessel C. Winsemius, Stuart A. Fraser, Sanne Muis, and Philip J. Ward
The flooding of rivers and coastlines is the most frequent and damaging of all natural hazards. Between 1980 and 2016, total direct damages exceeded $1.6 trillion, and at least 225,000 people lost their lives. Recent events causing major economic losses include the 2011 river flooding in Thailand ($40 billion) and the 2013 coastal floods in the United States caused by Hurricane Sandy (over $50 billion). Flooding also triggers great humanitarian challenges. The 2015 Malawi floods were the worst in the country’s history and were followed by food shortage across large parts of the country. Flood losses are increasing rapidly in some world regions, driven by economic development in floodplains and increases in the frequency of extreme precipitation events and global sea level due to climate change. The largest increase in flood losses is seen in low-income countries, where population growth is rapid and many cities are expanding quickly. At the same time, evidence shows that adaptation to flood risk is already happening, and a large proportion of losses can be contained successfully by effective risk management strategies. Such risk management strategies may include floodplain zoning, construction and maintenance of flood defenses, reforestation of land draining into rivers, and use of early warning systems. To reduce risk effectively, it is important to know the location and impact of potential floods under current and future social and environmental conditions. In a risk assessment, models can be used to map the flow of water over land after an intense rainfall event or storm surge (the hazard). Modeled for many different potential events, this provides estimates of potential inundation depth in flood-prone areas. Such maps can be constructed for various scenarios of climate change based on specific changes in rainfall, temperature, and sea level. To assess the impact of the modeled hazard (e.g., cost of damage or lives lost), the potential exposure (including buildings, population, and infrastructure) must be mapped using land-use and population density data and construction information. Population growth and urban expansion can be simulated by increasing the density or extent of the urban area in the model. The effects of floods on people and different types of buildings and infrastructure are determined using a vulnerability function. This indicates the damage expected to occur to a structure or group of people as a function of flood intensity (e.g., inundation depth and flow velocity). Potential adaptation measures such as land-use change or new flood defenses can be included in the model in order to understand how effective they may be in reducing flood risk. This way, risk assessments can demonstrate the possible approaches available to policymakers to build a less risky future.
Assessment Principles for Glacier and Permafrost Hazards in Mountain Regions
Simon Allen, Holger Frey, Wilfried Haeberli, Christian Huggel, Marta Chiarle, and Marten Geertsema
Glacier and permafrost hazards in cold mountain regions encompass various flood and mass movement processes that are strongly affected by rapid and cumulative climate-induced changes in the alpine cryosphere. These processes are characterized by a range of spatial and temporal dimensions, from small volume icefalls and rockfalls that present a frequent but localized danger to less frequent but large magnitude process chains that can threaten people and infrastructure located far downstream. Glacial lake outburst floods (GLOFs) have proven particularly devastating, accounting for the most far-reaching disasters in high mountain regions globally. Comprehensive assessments of glacier and permafrost hazards define two core components (or outcomes): 1. Susceptibility and stability assessment: Identifies likelihood and origin of an event based on analyses of wide-ranging triggering and conditioning factors driven by interlinking atmospheric, cryospheric, geological, geomorphological, and hydrological processes. 2. Hazard mapping: Identifies the potential impact on downslope and downstream areas through a combination of process modeling and field mapping that provides the scientific basis for decision making and planning. Glacier and permafrost hazards gained prominence around the mid-20th century, especially following a series of major disasters in the Peruvian Andes, Alaska, and the Swiss Alps. At that time, related hazard assessments were reactionary and event-focused, aiming to understand the causes of the disasters and to reduce ongoing threats to communities. These disasters and others that followed, such as Kolka Karmadon in 2002, established the fundamental need to consider complex geosystems and cascading processes with their cumulative downstream impacts as one of the distinguishing principles of integrative glacier and permafrost hazard assessment. The widespread availability of satellite imagery enables a preemptive approach to hazard assessment, beginning with regional scale first-order susceptibility and hazard assessment and modeling that provide a first indication of possible unstable slopes or dangerous lakes and related cascading processes. Detailed field investigations and scenario-based hazard mapping can then be targeted to high-priority areas. In view of the rapidly changing mountain environment, leading beyond historical precedence, there is a clear need for future-oriented scenarios to be integrated into the hazard assessment that consider, for example, the threat from new lakes that are projected to emerge in a deglaciating landscape. In particular, low-probability events with extreme magnitudes are a challenge for authorities to plan for, but such events can be appropriately considered as a worst-case scenario in a comprehensive, forward-looking, multiscenario hazard assessment.
Climate Change as a Transboundary Policymaking Natural Hazards Problem
Throughout the world, major climate-related catastrophic events have devastated lives and livelihoods. These events are predicted to increase in frequency and intensity across the globe, as greenhouse gas emissions continue to accumulate in our atmosphere. The causes and consequences of these disasters are not constrained to geographic and political boundaries, or even temporal scales, increasing the complexity of their management. Differences in cultures, governance and policy processes often occur among jurisdictions in a transboundary setting, whether adjacent nations that are exposed to the same transboundary hazard or across municipalities located within the same political jurisdiction. Political institutions and processes may vary across jurisdictions in a region, presenting challenges to cooperation and coordination of risk management. With shifting climates, risks from climate-related natural hazards are in constant flux, increasing the difficulty of making predictions about and governing these risks. Further, different groups of individuals may be exposed to the same climate hazard, but that exposure may affect these groups in unique ways. Managing climate change as a transboundary natural hazard may mandate a shift from a focus on individual climate risks to developing capacity to encourage learning from and adaptation to a diversity of climatic risks that span boundaries. Potential barriers to adaptation to climate risks must not be considered individually but rather as a part of a more dynamic system in which multiple barriers may interact, impeding effective management. Greater coordination horizontally, for example through networks linking cities, and vertically, across multiple levels of governance (e.g., local, regional, national, global), may aid in the development of increased capacity to deal with these transboundary risks. Greater public engagement in management of risks from climate change hazards, both in risk mitigation and post-hazard recovery, could increase local-level capacity to adapt to these hazards.
Community-Based Disaster Risk Reduction
Community-based approaches existed even before the existence of the state and its formal governance structure. People and communities used to help and take care of each other’s disaster needs. However, due to the evolution of state governance, new terminology of community-based disaster risk reduction (CBDRR) has been coined to help communities in an organized way. Different stakeholders are responsible for community-based actions; the two key players are the local governments and civil society, or nongovernment organizations. Private sector and academic and research institutions also play crucial roles in CBDRR. Many innovative CBDRR practices exist in the world, and it is important to analyze them and learn the common lessons. The key to community is its diversity, and this should be kept in mind for the CBDRR. There are different entry points and change agents based on the diverse community. It is important to identify the right change agent and entry point and to develop a sustainable mechanism to institutionalize CBDRR activities. Social networking needs to be incorporated for effective CBDRR.
Economics and Disaster Risk Management
Randrianalijaona Mahefasoa, Razanakoto Thierry, Salava Julien, Randriamanampisoa Holimalala, and Lazamanana Pierre
Economics is the science of wealth, the main objective of which is to satisfy human needs within the constraint of limited available resources. The production and consumption patterns of economic agents are examined in order to identify the most efficient and optimal ways of meeting needs. At the same time, redistribution problems have an important place in economic science, and they lead to questions of development and economic growth. Since the 1990s, officially declared by the United Nations as the International Decade for Natural Disaster Reduction (IDNDR), the relatively frequent occurrence of devastating disasters, induced mainly by natural hazards but also by human activities, development efforts and economic growth have been seriously threatened. Poverty alleviation efforts undertaken by nations in the Global South and supported by international donors, as well as development outcomes worldwide, are suffering from disasters. The international community has become more and more aware of the need to systematically mainstream disaster risk reduction in development policy and strategy. Therefore, disaster risk reduction economics is becoming a priority and part of economics as a science. For more than three decades, based on risk assessment, risk prevention and mitigation strategies, including structural and nonstructural measures, such as but not limited to, risk retention and transfer, preparedness as well as ex-post activities such as response, recovery and reconstruction are using economic variables and tools since mid-2000s to become more efficient. Furthermore, protecting economic growth and development benefits is possible only if enough attention is given to risk science. From this perspective, risk science is becoming part of economics, as evidenced by the new branch called risk reduction economics, which is essential to the attainment of sustainable development goals and resilient societies.
Evolution of Strategic Flood Risk Management in Support of Social Justice, Ecosystem Health, and Resilience
Throughout history, flood management practice has evolved in response to flood events. This heuristic approach has yielded some important incremental shifts in both policy and planning (from the need to plan at a catchment scale to the recognition that flooding arises from multiple sources and that defenses, no matter how reliable, fail). Progress, however, has been painfully slow and sporadic, but a new, more strategic, approach is now emerging. A strategic approach does not, however, simply sustain an acceptable level of flood defence. Strategic Flood Risk Management (SFRM) is an approach that relies upon an adaptable portfolio of measures and policies to deliver outcomes that are socially just (when assessed against egalitarian, utilitarian, and Rawlsian principles), contribute positively to ecosystem services, and promote resilience. In doing so, SFRM offers a practical policy and planning framework to transform our understanding of risk and move toward a flood-resilient society. A strategic approach to flood management involves much more than simply reducing the chance of damage through the provision of “strong” structures and recognizes adaptive management as much more than simply “wait and see.” SFRM is inherently risk based and implemented through a continuous process of review and adaptation that seeks to actively manage future uncertainty, a characteristic that sets it apart from the linear flood defense planning paradigm based upon a more certain view of the future. In doing so, SFRM accepts there is no silver bullet to flood issues and that people and economies cannot always be protected from flooding. It accepts flooding as an important ecosystem function and that a legitimate ecosystem service is its contribution to flood risk management. Perhaps most importantly, however, SFRM enables the inherent conflicts as well as opportunities that characterize flood management choices to be openly debated, priorities to be set, and difficult investment choices to be made.
Fatalism, Causal Reasoning, and Natural Hazards
Fatalism about natural disasters hinders action to prepare for those disasters, and overcoming this fatalism is one key element to preparing people for these disasters. Research by Bostrom and colleagues shows that failure to act often reflects gaps and misconceptions in citizen’s mental models of disasters. Research by McClure and colleagues shows that fatalistic attitudes reflect people’s attributing damage to uncontrollable natural causes rather than controllable human actions, such as preparation. Research shows which precise features of risk communications lead people to see damage as preventable and to attribute damage to controllable human actions. Messages that enhance the accuracy of mental models of disasters by including human factors recognized by experts lead to increased preparedness. Effective messages also communicate that major damage in disasters is often distinctive and reflects controllable causes. These messages underpin causal judgments that reduce fatalism and enhance preparation. Many of these messages are not only beneficial but also newsworthy. Messages that are logically equivalent but are differently framed have varying effects on risk judgments and preparedness. The causes of harm in disasters are often contested, because they often imply human responsibility for the outcomes and entail significant cost.
Gender Mainstreaming and Climate Change
Women and girls are disproportionately impacted by climate change, not because of innate characteristics but as a result of the social structures and cultural norms that shape gender inequalities. Feminist activists and transnational organizations continue to voice their concerns regarding the need for greater attention to gender inequalities in the context of climate change. Gender mainstreaming is a policy process designed to address the gendered consequences of any planned actions—the ultimate aim being to achieve gender equality. Gender mainstreaming emerged in the late 1990s at the Beijing Women’s Conference as a result of the frustrations of feminist activists and international nongovernmental organizations about the lack of attention to gender equality. Yet its implementation has been hampered both by a lack of vision as to its purpose and by ongoing tensions, particularly between those who espouse equality and those who support the mainstream. This has led to resistance to gender mainstreaming within departments and units that are charged with its implementation, and indeed a reluctance of key players to commit to gender equality. Yet there is still strong support for the original feminist intent from activists and researchers addressing the impacts of climate change. The transformational potential of gender mainstreaming is still viewed as a process that could address and challenge gender inequalities in the context of increasing climate challenges. However, there are barriers that must be overcome for the transformational potential of gender mainstreaming to be realized. These include equating climate justice with gender justice, ensuring that the radical feminist intent of gender mainstreaming is not co-opted by the neoliberal agenda of maximizing economic development over gender equality and women’s empowerment, and ensuring that organizations tasked with facilitating gender mainstreaming not only understand its intent but also address gender inequalities within their own organizational structures and practices.
Impact of Climate Change on Agriculture Adaptation in Coastal Zones of Bangladesh
Umma Habiba and Md. Anwarul Abedin
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Natural Hazard Science. Please check back later for the full article. Bangladesh scored seventh in a ranking of countries most affected by climatic calamities in the second decade of the 21st century. Climate change poses a great threat to Bangladesh’s economy due to its effect on the agricultural system. The agriculture sector employs about 40.6% of the country’s labor force and contributes 14.1% of the gross domestic product (GDP). Various climatic factors such as changes in precipitation, temperature, sea level rise, salinity intrusion, drought, and natural disasters (storm surges, cyclones, etc.) impact the agriculture sector. These factors ultimately affect crop production and increase food insecurity. The coastal zone frequently suffers the impacts of climate change through coastal flooding, cyclones, storm surges, drought, salinity intrusion, water-logging, and so forth. These crises not only affect agricultural productivity but also lead to degradation of soil productivity and lower agricultural production/yield. To cope with the impacts on coastal agriculture, government, nongovernmental organizations, and communities have practiced a number of adaptation measures. They have adopted several measures such as using stress-tolerant rice varieties; crops that consume less water; short-duration crops; crop diversification; crop rotation; mix cropping/intercropping; efficient use of irrigation, fertilizer, and pesticides; soil conservation; floating gardens; sorjan cultivation; homestead vegetable gardening; and the re-excavation of canals. However, these adaptive practices are responsive and timely immediately after the occurrence of the effects of climate change. Taking this into consideration, it is imperative to scale up these adaptation measures and to synchronize efforts at various levels for their successful implementation by coastal communities in order to cope with climate change in a sustainable manner.
Impact of Climate Change on Flood Factors and Extent of Damages in the Hindu Kush Region
Atta-ur Rahman, Shakeel Mahmood, Mohammad Dawood, Ghani Rahman, and Fang Chen
This chapter analyzes the impacts of climate change on flood factors and extent of associated damages in the Hindu Kush (HK) region. HK mountains system is located in the west of the Himalayas and Karakorum. It is the greatest watershed of the River Kabul, River Chitral, River Panjkora, and River Swat in the eastern Hindu Kush and River Amu in western Hindu Kush. The Hindu Kush system hosts numerous glaciers, snow-clad mountains, and fertile river valleys; it also supports large populations and provides year-round water to recharge streams and rivers. The study region is vulnerable to a wide range of hazards including floods, earthquakes, landslides, desertification, and drought. Flash floods and riverine floods are the deadliest extreme hydro-meteorological events. The upper reaches experience characteristics of flash flooding, whereas the lower reach is where river floods occur. Flash floods are more destructive and sudden. Almost every year in summer, monsoonal rainfall and high temperature join hands with heavy melting of glaciers and snow accelerating discharge in the river system. In the face of climate change, a significant correlation between rainfall patterns, trends in temperature, and resultant peaks in river discharge have been recorded. A rising trend was found in temperature, which leads to early and rapid melting of glaciers and snow in the headwater region. The analysis reveals that during the past three decades, radical changes in the behavior of numerous valley glaciers have been noted. In addition, the spatial and temporal scales of violent weather events have been growing, since the 1980s. Such changes in water regimes including the frequent but substantial increase in heavy precipitation events and rapid melting of snow in the headwater region, siltation in active channels, excessive deforestation, and human encroachments onto the active flood channel have further escalated the flooding events. The HK region is beyond the reach of existing weather RADAR network, and hence forecasting and early warning is ineffective. Here, almost every year, the floods cause damages to infrastructure, scarce farmland, and sources of livelihood.
Intersectionality as a Forward-Thinking Approach in Disaster Research
Cassandra Jean, Tilly E. Hall, and Jamie Vickery
Disaster researchers, policymakers, and practitioners are confronted with the pressing need to understand and address how and why certain individuals and groups of individuals experience inequities leading up to, during, and postdisaster. These efforts must consider how to address such inequities through collaborative efforts toward intentional and systemic change. The use of intersectional approaches supports better analyze and critique of discriminatory and oppressive practices that disproportionately impact historically marginalized peoples, especially in the face of hazards and disasters. Intersectionality calls for understanding how different forms of privilege, power, and oppression interact and compound to create unequal socioeconomic outcomes across individuals and groups of individuals based on their identities (e.g., age, race, sexuality, and gender) and conditions (e.g., housing composition, immigration, and marital status). A review of inter- and multidisciplinary terrains of disaster studies shows that there are multifaceted utilities, capabilities, and advantages of adopting an intersectional approach. By considering historical discriminatory practices and the root causes of vulnerability, intersectionality highlights the systemic and institutionalized patterns that create precarious situations for some people while simultaneously protecting others. Intersectionality is also well suited to support insight into individuals’ capacities that affect their ability to prepare for, respond to, and recover from disastrous events, as well as assist them in avoiding or reducing risks that make them susceptible to disaster in the first place. However, intersectional approaches within disaster studies remain underutilized and, sometimes, superficially applied. Simplistic representations, the unequal attention given to certain intersections, and the domination of Western epistemologies must be attended to in order to challenge, disrupt, and diligently undo the interactions of systematic privilege, power, and oppression that render unequal disaster experiences and outcomes.
Introduction to Socio-Ecological Resilience
Vincenzo Bollettino, Tilly Alcayna, Philip Dy, and Patrick Vinck
In recent years, the notion of resilience has grown into an important concept for both scholars and practitioners working on disasters. This evolution reflects a growing interest from diverse disciplines in a holistic understanding of complex systems, including how societies interact with their environment. This new lens offers an opportunity to focus on communities’ ability to prepare for and adapt to the challenges posed by natural hazards, and the mechanism they have developed to cope and adapt to threats. This is important because repeated stresses and shocks still cause serious damages to communities across the world, despite efforts to better prepare for disasters. Scholars from a variety of disciplines have developed resilience frameworks both to guide macro-level policy decisions about where to invest in preparedness and to measure which systems perform best in limiting losses from disasters and ensuring rapid recovery. Yet there are competing conceptions of what resilience encompasses and how best to measure it. While there is a significant amount of scholarship produced on resilience, the lack of a shared understanding of its conceptual boundaries and means of measurement make it difficult to demonstrate the results or impact of resilience programs. If resilience is to emerge as a concept capable of aiding decision-makers in identifying socio-geographical areas of vulnerability and improving preparedness, then scholars and practitioners need to adopt a common lexicon on the different elements of the concept and harmonize understandings of the relationships amongst them and means of measuring them. This article reviews the origins and evolution of resilience as an interdisciplinary, conceptual umbrella term for efforts by different disciplines to tackle complex problems arising from more frequent natural disasters. It concludes that resilience is a useful concept for bridging different academic disciplines focused on this complex problem set, while acknowledging that specific measures of resilience will differ as different units and levels of analysis are employed to measure disparate research questions.
Lessons on Risk Governance From the UNISDR Experience
In the context of this article, risk governance addresses the ways and means—or institutional framework—to lead and manage the issue of risk related to natural phenomena, events, or hazards, also referred to popularly, although incorrectly, as “natural disasters.” At the present time, risk related to natural phenomena includes a major focus on the issue of climate change with which it is intimately connected, climate change being a major source of risk. To lead involves mainly defining policies and proposing legislation, hence proposing goals, conducting, promoting, orienting, providing a vision—namely, reducing the loss of lives and livelihoods as part of sustainable development—also, raising awareness and educating on the topic and addressing the ethical perspective that motivates and facilitates engagement by citizens. To manage involves, among other things, proposing organizational and technical arrangements, as well as regulations allowing the implementation of policies and legislation. Also, it involves monitoring and supervising such implementation to draw further lessons to periodically enhance the policies, legislation, regulations, and organizational and technical arrangements. UNISDR (now known as UNDRR) was established in 2000 to promote and facilitate risk reduction, becoming in a few years one of the main promoters of risk governance in the world and the main global advocate from within the United Nations system. It was an honor to serve as the first director of the UNISDR (2001–2011). A first lesson to be drawn from this experience was the need to identify, understand, and address the obstacles not allowing the implementation of what seems to be obvious to the scientific community but of difficult implementation by governments, private sector, and civil society; and alternatively, the reasons for shortcomings and weaknesses in risk governance. A second lesson identified was that risk related to natural phenomena also provides lessons for governance related to other types of risk in society—environmental, financial, health, security, and so on, each a separate and specialized topic, sharing, however, common risk governance approaches. A third lesson was the relevance of understanding leadership and management as essential components in governance. Drawing lessons on one’s own experience is always risky as it involves some subjectivity in the analysis. In the article, the aim has, nonetheless, been at the utmost objectivity on the essential learnings in having conducted the United Nations International Strategy for Disaster Reduction—UNISDR—from 2001 to around 2009 when leading and managing was shared with another manager, as I prepared for retirement in 2011. Additional lessons are identified, including those related to risk governance as it is academically conceived, hence, what risk governance includes and how it has been implemented by different international, regional, national, and local authorities. Secondly, I identify those lessons related to the experience of leading and managing an organization focused on disaster risk at the international level and in the context of the United Nations system.
Megacity Disaster Risk Governance
James K. Mitchell
Megacity disaster risk governance is a burgeoning interdisciplinary field that seeks to encourage improved public decision-making about the safety and sustainability of the world’s largest urban centers in the face of environmental threats ranging from floods, storms, earthquakes, wildfires, and pandemics to the multihazard challenges posed by human-forced climate change. It is a youthful, lively, contested, ambitious and innovative endeavor that draws on research in three separate but overlapping areas of inquiry: disaster risks, megacities, and governance. Toward the end of the 20th century, each of these fields underwent major shifts in thinking that opened new possibilities for action. First, the human role in disaster risks came to the fore, giving increased attention to humans as agents of risk creation and providing increased scope for inputs from social sciences and humanities. Second, the scale, complexity, and political–economic salience of very large cities attained high visibility, leading to recognition that they are also sites of unprecedented risks, albeit with significant differences between rapidly growing poorer cities and slower growing affluent ones. Third, the concept of public decision-making expanded beyond its traditional association with actions of governments to include contributions from a wide range of nongovernmental groups that had not previously played prominent roles in public affairs. At least three new conceptions of megacity disaster risk governance emerged out of these developments. They include adaptive risk governance, smart city governance, and aesthetic governance. Adaptive risk governance focuses on capacities of at-risk communities to continuously adjust to dynamic uncertainties about future states of biophysical environments and human populations. It is learning-centered, collaborative, and nimble. Smart city governance seeks to harness the capabilities of new information and communication technologies, and their associated human institutions, to the increasingly automated tasks of risk anticipation and response. Aesthetic governance privileges the preferences of social, scientific, design, or political elites and power brokers in the formulation and execution of policies that bear on risks. No megacity has yet comprehensively or uniformly adopted any of these risk governance models, but many are experimenting with various permutations and hybrid variations that combine limited applications with more traditional administrative practices. Arrangements that are tailor-made to fit local circumstances are the norm. However, some version of adaptive risk governance seems to be the leading candidate for wider adoption, in large part because it recognizes the need to continuously accommodate new challenges as environments and societies change and interact in ways that are difficult to predict. Although inquiries are buoyant, there remain many unanswered questions and unaddressed topics. These include the differential vulnerability of societal functions that are served by megacities and appropriate responses thereto; the nature and biases of risk information transfers among different types of megacities; and appropriate ways of tackling ambiguities that attend decision-making in megacities. Institutions of megacity disaster risk governance will take time to evolve. Whether that process can be speeded up and applied in time to stave off the worst effects of the risks that lie ahead remains an open question.
Modeling Tropical Cyclones in a Changing Climate
Tropical cyclones (TCs) in their most intense expression (hurricanes or typhoons) are the main natural hazards known to humankind. The impressive socioeconomic consequences for countries dealing with TCs make our ability to model these organized convective structures a key issue to better understanding their nature and their interaction with the climate system. The destructive effects of TCs are mainly caused by three factors: strong wind, storm surge, and extreme precipitation. These TC-induced effects contribute to the annual worldwide damage of the order of billions of dollars and a death toll of thousands of people. Together with the development of tools able to simulate TCs, an accurate estimate of the impact of global warming on TC activity is thus not only of academic interest but also has important implications from a societal and economic point of view. The aim of this article is to provide a description of the TC modeling implementations available to investigate present and future climate scenarios. The two main approaches to dynamically model TCs under a climate perspective are through hurricane models and climate models. Both classes of models evaluate the numerical equations governing the climate system. A hurricane model is an objective tool, designed to simulate the behavior of a tropical cyclone representing the detailed time evolution of the vortex. Considering the global scale, a climate model can be an atmosphere (or ocean)-only general circulation model (GCM) or a fully coupled general circulation model (CGCM). To improve the ability of a climate model in representing small-scale features, instead of a general circulation model, a regional model (RM) can be used: this approach makes it possible to increase the spatial resolution, reducing the extension of the domain considered. In order to be able to represent the tropical cyclone structure, a climate model needs a sufficiently high horizontal resolution (of the order of tens of kilometers) leading to the usage of a great deal of computational power. Both tools can be used to evaluate TC behavior under different climate conditions. The added value of a climate model is its ability to represent the interplay of TCs with the climate system, namely two-way relationships with both atmosphere and ocean dynamics and thermodynamics. In particular, CGCMs are able to take into account the well-known feedback between atmosphere and ocean components induced by TC activity and also the TC–related remote impacts on large-scale atmospheric circulation. The science surrounding TCs has developed in parallel with the increasing complexity of the mentioned tools, both in terms of progress in explaining the physical processes involved and the increased availability of computational power. Many climate research groups around the world, dealing with such numerical models, continuously provide data sets to the scientific community, feeding this branch of climate change science.
Observation and Spatial Modeling of Snow- and Ice-Related Mass Movement Hazards
Snow- and ice-related hazardous processes threaten society in tropical to high-latitude mountain areas worldwide and at highly variable time scales. On the one hand, small snow avalanches are recorded in high numbers every winter. On the other hand, glacial lake outburst floods (GLOFs) or large-scale volcano–ice interactions occur less frequently but may evolve into destructive process chains resulting in major disasters. These extreme examples document the huge field of types, magnitudes, and frequencies of snow- and ice-related hazardous processes. Mountain societies have learned to cope with natural hazards for centuries, guided by personal experiences and oral and written tradition. Historical records are today still important as a basis to mitigate snow- and ice-related hazards. They are complemented by a broad array of observation and modeling techniques. These techniques differ among themselves with regard to (1) the type of process under investigation and (2) the scale and purpose of investigation. Multi-scale monitoring and warning systems for snow avalanches are in operation in densely populated mid-latitude mountain areas. They build on meteorological and snow profile data in combination with a large pool of expert knowledge. In contrast, ice-related processes such as ice- or rock-ice avalanches, GLOFs, or associated process chains cause damage less frequently in space and time, so that societies are less well adapted. Even though the hazard sources are often far from the society—making field observation challenging—flows travelling for tens of kilometers sometimes impact populated areas. These hazards are strongly influenced by climate change–induced glacier and permafrost dynamics. On the regional or national scale, the evolution of such hazards has to be monitored at short intervals through aerial and satellite imagery and terrain data, employing geographic information systems (GIS). Known hazardous situations have to be monitored in the field. Physical models—applied either in the laboratory or at real-world sites—are employed to explore the mobility of hazardous processes. Since the 1950s, however, computer models have increasingly gained importance in exploring possible travel distances, impact areas, velocities, and impact forces of events. While simple empirical-statistical approaches are used at broad scales in combination with GIS, advanced numeric models are applied to analyze specific case studies. However, the input parameters for these models are uncertain so that (1) the model results have to be validated with observations and (2) appropriate strategies to deal with the uncertainties have to be applied before using the model results for hazard zoning or dimensioning of protective structures. Due to rapid atmospheric warming and related changes in the cryosphere, hazard situations beyond historical experiences are expected to be increasingly relevant in the future. Scenario-based modeling of complex systems and process chains therefore represents an emerging research direction.
Permafrost-Related Geohazards and Infrastructure Construction in Mountainous Environments
Lukas U. Arenson and Matthias Jakob
Mountain environments, home to about 12% of the global population and covering nearly a quarter of the global land surface, create hazardous conditions for various infrastructures. The economic and ecologic importance of these environments for tourism, transportation, hydropower generation, or natural resource extraction requires that direct and indirect interactions between infrastructures and geohazards be evaluated. Construction of infrastructure in mountain permafrost environments can change the ground thermal regime, affect gravity-driven processes, impact the strength of ice-rich foundations, or result in permafrost aggradation via natural convection. The severity of impact, and whether permafrost will degrade or aggrade in response to the construction, is a function of numerous parameters including climate change, which needs to be considered when evaluating the changes in existing or formation of new geohazards. The main challenge relates to the uncertainties associated with the projections of medium- (decadal) and long-term (century-scale) climate change. A fundamental understanding of the various processes at play and a good knowledge of the foundation conditions is required to ascertain that infrastructure in permafrost environment functions as intended. Many of the tools required for identifying geohazards in the periglacial and appropriate risk management strategies are already available.
Permafrost-Related Geohazards in Cold Russian Regions
Permafrost, or perennially frozen ground, and the processes linked to the water phase change in ground-pore media are sources of specific dangers to infrastructure and economic activity in cold mountainous regions. Additionally, conventional natural hazards (such as earthquakes, floods, and landslides) assume special characteristics in permafrost territories. Permafrost hazards are created under two conditions. The first is a location with ice-bounded or water-saturated ground, in which the large amount of ice leads to potentially intensive processes of surface settlement or frost heaving. The second is linked with external, natural, and human-made disturbances that change the heat-exchange conditions. The places where ice-bounded ground meets areas that are subject to effective disturbances are the focus of hazard mapping and risk evaluation. The fundamentals of geohazard evaluation and geohazard mapping in permafrost regions were originally developed by Gunnar Beskow, Vladimir Kudryavtsev, Troy Péwé, Oscar Ferrians, Jerry Brown, and other American, European, and Soviet authors from 1940s to the 1980s. Modern knowledge of permafrost hazards was significantly enriched by the publication of Russian book called Permafrost Hazards, part of the six-volume series Natural Hazards in Russia (2000). The book describes, analyses, and evaluates permafrost-related hazards and includes methods for their modeling and mapping. Simultaneous work on permafrost hazard evaluation continued in different countries with the active support of the International Permafrost Association. Prominent contributions during the new period of investigation were published by Drozdov, Clarke, Kääb, Pavlov, Koff and several other thematic groups of researchers. The importance of common international works became evident. The international project RiskNat: A Cross-Border European Project Taking into Account Permafrost-Related Hazards was developed as a new phenomenon in scientific development. The intensive economic development in China presented new challenges for linear transportation routes and hydrologic infrastructures. A study of active fault lines and geological hazards along the Golmud–Lhasa Railway across the Tibetan plateau is a good example of the achievements by Chinese scientists. The method for evaluating the permafrost hazards was based on survey data, monitoring data, and modeling results. The survey data reflected the current environmental conditions, and they are usually shown on a permafrost map. The monitoring data are helpful in understanding the current tendencies of permafrost evolution in different landscapes and regions. The modeling data provided a permafrost forecast that takes climate change and its impact on humans into account. The International Conference on Permafrost in 2016, in Potsdam, Germany, demonstrated the new horizons of conventional and special permafrost mapping in offshore and continental areas. Permafrost hazards concern large and diverse aspects of human life. It is necessary to expand the approach to this problem from geology to also include geography, biology, social sciences, engineering, and other spheres of competencies in order to synthesize local and regional information. The relevance of this branch of science grows with taking into account climate change and the growing number of natural disasters.