Confidence in the projected impacts of climate change on agricultural systems has increased substantially since the first Intergovernmental Panel on Climate Change (IPCC) reports. In Africa, much work has gone into downscaling global climate models to understand regional impacts, but there remains a dearth of local level understanding of impacts and communities’ capacity to adapt. It is well understood that Africa is vulnerable to climate change, not only because of its high exposure to climate change, but also because many African communities lack the capacity to respond or adapt to the impacts of climate change. Warming trends have already become evident across the continent, and it is likely that the continent’s 2000 mean annual temperature change will exceed +2°C by 2100. Added to this warming trend, changes in precipitation patterns are also of concern: Even if rainfall remains constant, due to increasing temperatures, existing water stress will be amplified, putting even more pressure on agricultural systems, especially in semiarid areas. In general, high temperatures and changes in rainfall patterns are likely to reduce cereal crop productivity, and new evidence is emerging that high-value perennial crops will also be negatively impacted by rising temperatures. Pressures from pests, weeds, and diseases are also expected to increase, with detrimental effects on crops and livestock. Much of African agriculture’s vulnerability to climate change lies in the fact that its agricultural systems remain largely rain-fed and underdeveloped, as the majority of Africa’s farmers are small-scale farmers with few financial resources, limited access to infrastructure, and disparate access to information. At the same time, as these systems are highly reliant on their environment, and farmers are dependent on farming for their livelihoods, their diversity, context specificity, and the existence of generations of traditional knowledge offer elements of resilience in the face of climate change. Overall, however, the combination of climatic and nonclimatic drivers and stressors will exacerbate the vulnerability of Africa’s agricultural systems to climate change, but the impacts will not be universally felt. Climate change will impact farmers and their agricultural systems in different ways, and adapting to these impacts will need to be context-specific. Current adaptation efforts on the continent are increasing across the continent, but it is expected that in the long term these will be insufficient in enabling communities to cope with the changes due to longer-term climate change. African famers are increasingly adopting a variety of conservation and agroecological practices such as agroforestry, contouring, terracing, mulching, and no-till. These practices have the twin benefits of lowering carbon emissions while adapting to climate change as well as broadening the sources of livelihoods for poor farmers, but there are constraints to their widespread adoption. These challenges vary from insecure land tenure to difficulties with knowledge-sharing. While African agriculture faces exposure to climate change as well as broader socioeconomic and political challenges, many of its diverse agricultural systems remain resilient. As the continent with the highest population growth rate, rapid urbanization trends, and rising GDP in many countries, Africa’s agricultural systems will need to become adaptive to more than just climate change as the uncertainties of the 21st century unfold.
Babatunde O. Abidoye
To view climate change adaptation from an economic perspective requires a definition of adaptation, an economic framework in which to view adaptation, and a review of the literature on specific adaptations (especially in agriculture). A focus on tools for applying adaptation to developing countries highlights the difference between mitigation and the adaptation decision-making process. Mitigation decisions take a long-term perspective because carbon dioxide lasts for a very long time in the atmosphere. Adaptation decisions typically last the lifespan of the investments, so the time frame depends on the specific adaptation investment, but it is invariably short compared to mitigation choices, which have implications for centuries. The short time frame means that adaptation decisions are not plagued by the same uncertainty that plagues mitigation choices. Finally, most adaptation decisions are local and private, whereas mitigation is a global public decision. Private adaptation will occur even without large government programs. Public adaptations that require government assistance can mainly be made by existing government agencies. Adaptation does not require a global agreement.
Sarah E. Scales, Julia Massi, and Jennifer A. Horney
Climate change is affecting every region of the world and is accelerating at an alarming rate. International efforts for mitigating climate change, like the Paris Agreement, through reductions in greenhouse gases are vital for slowing the global increase in temperatures. However, these mitigation measures will not have immediate impact, so urgent action is needed to address negative impacts currently posed by climate change. Adaptation measures are central to this response now, and will continue to be critical for protecting human health as temperatures rise and climate-related disasters increase in both frequency and severity. To maximize the effectiveness of adaptation measures, the health impacts of disasters should be well-characterized at the global, regional, national, and local levels. Surveillance and early warning systems are vital tools for early identification and warning of hazards and their potential impacts. Increasing global capacity to identify causes of morbidity and mortality directly and indirectly attributable to disasters are in line with the objectives of the Sustainable Development Goals and Bangkok Principles of the Sendai Framework for Disaster Risk Reduction. Both improving data collected in disaster settings and more effectively using that information in real time are central to reducing the human-health impacts of disasters. The human-health impacts of climate change and associated disasters are interrelated. Climate change and commensurate changes in environmental suitability, vector viability, and human migration strongly influence the prevalence and seasonality of infectious and communicable diseases. Both drought and flood contribute to food and water insecurity, leading to a higher prevalence of undernourishment and malnourishment, especially in children. Compromised nutritional status, in conjunction with resulting human migration, leave individuals immunocompromised and populations at a high risk for spread of infectious disease. Extreme heat exposure likewise compromises individuals’ ability to regulate their physiological response to external stressors. Disasters of all classifications can result in exposure to environmental hazards, decrease air quality, and negatively affect mental health. Accordingly, health adaptation measures to climate change must be equally interrelated, addressing needs across disciplines, at both individual and community levels, and incorporating the many facets of the health needs of affected populations.
Farnaz Pourzand and Ilan Noy
The effect of climate change on hydrology and water resources is possibly one of the most important current environmental challenges, and it will be important for the rest of the 21st century. Climate change is anticipated to intensify the hydrological cycle and to change the temporal and spatial distribution patterns of water resources. It is predicted to increase the frequency and intensity of extreme hydrological events, such as heavy rainfall and floods, but in some locations also droughts. Water-related hazards occur due to complex interactions between atmospheric and hydrological systems. These events can then cause economic disasters, societal disturbances, and environmental impacts, which can pose a major threat to lives and livelihoods if they happen in places that are exposed and vulnerable to them. The economic impacts of extreme hydrological events can be separated into direct damage and indirect losses. Direct damage includes the damages to fixed assets and capital; losses of raw materials, crops, and extractable natural resources; and, most importantly, mortality, morbidity, and population displacement. All can be a direct consequence of the extreme hydrological event. Indirect losses are reductions in economic activity, particularly the production of goods and services—which will be greatly decreased after the disaster and because of it. Possibly the most damaging hydro-meteorological hazard, drought, is also the one that is least understood and the most difficult to quantify—even its onset is often difficult to identify. Drought is recognized as being associated with some of the most high-profile humanitarian disasters of past years, threatening the lives and livelihoods of millions of people, particularly those living in semi-arid and arid regions. Drought impacts depend on a set of weather parameters—high temperatures, low humidity, the timing of rain, and the intensity and duration of precipitation, as well as its onset and termination—and they depend on the population and assets and their vulnerabilities. While drought has wide-ranging effects on many economic sectors, the agricultural sector bears much of the impact, as it is very dependent on precipitation and evapotranspiration. Approximately 1.3 billion people rely on agriculture as their main source of income. In developing countries, the agriculture sector absorbs up to 80% of all direct damages from droughts. Droughts may be the biggest threat to food security and rural livelihoods globally, and they can increase local poverty, displace large numbers of people, and hinder the already fragile progress that has been made toward the achievement of Sustainable Development Goals (SDGs). As such, understanding droughts’ impacts, identifying ways to prevent or ameliorate them, and preventing further deterioration in the climatic conditions and social vulnerabilities that are their root causes are all of utmost importance.
Juha Merilä and Ary A. Hoffmann
Changing climatic conditions have both direct and indirect influences on abiotic and biotic processes and represent a potent source of novel selection pressures for adaptive evolution. In addition, climate change can impact evolution by altering patterns of hybridization, changing population size, and altering patterns of gene flow in landscapes. Given that scientific evidence for rapid evolutionary adaptation to spatial variation in abiotic and biotic environmental conditions—analogous to that seen in changes brought by climate change—is ubiquitous, ongoing climate change is expected to have large and widespread evolutionary impacts on wild populations. However, phenotypic plasticity, migration, and various kinds of genetic and ecological constraints can preclude organisms from evolving much in response to climate change, and generalizations about the rate and magnitude of expected responses are difficult to make for a number of reasons. First, the study of microevolutionary responses to climate change is a young field of investigation. While interest in evolutionary impacts of climate change goes back to early macroevolutionary (paleontological) studies focused on prehistoric climate changes, microevolutionary studies started only in the late 1980s. The discipline gained real momentum in the 2000s after the concept of climate change became of interest to the general public and funding organizations. As such, no general conclusions have yet emerged. Second, the complexity of biotic changes triggered by novel climatic conditions renders predictions about patterns and strength of natural selection difficult. Third, predictions are complicated also because the expression of genetic variability in traits of ecological importance varies with environmental conditions, affecting expected responses to climate-mediated selection. There are now several examples where organisms have evolved in response to selection pressures associated with climate change, including changes in the timing of life history events and in the ability to tolerate abiotic and biotic stresses arising from climate change. However, there are also many examples where expected selection responses have not been detected. This may be partly explainable by methodological difficulties involved with detecting genetic changes, but also by various processes constraining evolution. There are concerns that the rates of environmental changes are too fast to allow many, especially large and long-lived, organisms to maintain adaptedness. Theoretical studies suggest that maximal sustainable rates of evolutionary change are on the order of 0.1 haldanes (i.e., phenotypic standard deviations per generation) or less, whereas the rates expected under current climate change projections will often require faster adaptation. Hence, widespread maladaptation and extinctions are expected. These concerns are compounded by the expectation that the amount of genetic variation harbored by populations and available for selection will be reduced by habitat destruction and fragmentation caused by human activities, although in some cases this may be countered by hybridization. Rates of adaptation will also depend on patterns of gene flow and the steepness of climatic gradients. Theoretical studies also suggest that phenotypic plasticity (i.e., nongenetic phenotypic changes) can affect evolutionary genetic changes, but relevant empirical evidence is still scarce. While all of these factors point to a high level of uncertainty around evolutionary changes, it is nevertheless important to consider evolutionary resilience in enhancing the ability of organisms to adapt to climate change.
Richard K. Norton
Coastal shorelands and communities are among the most beautiful, vital, remunerative, popular, inequitable, and hazardous of places to live, work, and play. Because of the varied and intensive uses of them combined with climate-related impacts to them, they increasingly experience threats from coastal hazards, suffer ecological degradation, and engender contentious conflicts. Although some coastal shorelands are publicly owned, many are privately owned. Coastal states and communities confront many challenges as they plan for and manage the use of privately owned coastal shorelands. Coastal shorelands encompass the near-shore beaches, dunes, wetlands, and other transitional areas within dynamic coastal zones, whether developed or natural. Sustainability suggests the ability of natural and social coastal systems to persist, whereas resilience speaks to the sustainability of those systems when subject to substantial disruptions such as flooding from extreme storms. In addition to promoting sustainable and resilient coastal shorelands in general, advocates also call for redressing the heightened risks and other inequities experienced by historically marginalized communities. Most of the challenges prompting calls for enhanced coastal resilience, sustainability, and equity are not unique to coastal settings, but coastal communities especially need to attend to them given the heightened risks and development pressures they face. Broadly, they include increasingly frequent and fierce storms, floods, drought, fires, and heatwaves. Coastal communities also face unique challenges, including accelerating rates of shoreline recession and increasing near-shore flooding. Further complicating these natural dynamics are complex and poorly adapted property right, public interest, and related legal/administrative institutional arrangements shaping both private and public expectations in coastal settings. Community planning, if well executed, offers the promise of facilitating and advancing the kinds of nuanced and adaptive resiliency and sustainability goals needed everywhere, especially in coastal settings. Toward that end, researchers and advocates promote a range of planning principles, such as recognizing that coastal economies are nested within and dependent upon coastal ecosystems; promoting culturally aware, place-based, and infrastructure-efficient development policies; adopting no- to low-regrets climate adaptation policies; and encouraging ongoing learning and adaptative management. They similarly promote a variety of planning methods to support those policies, such as land suitability, infrastructure capacity, hazard vulnerability, and social vulnerability analyses, best engaged through scenario-based planning given climate-related uncertainties. Coastal communities experiencing aggressive shoreline recession face difficult choices as well—such as whether to armor receding shores or withdraw—most of which will require acknowledging and working through unavoidable trade-offs. Finally, providing knowledge about natural coastal dynamics and management systems is necessary but not by itself sufficient. Also needed are enhanced local capacity to conduct the analyses required to identify policies and programs that will effectively and equitably advance coastal sustainability and the firm commitment of local residents and officials to adopt those policies—challenges that are daunting but not insurmountable.
W. J. Wouter Botzen
Increasing natural disaster losses in the past decades and expectations that this trend will accelerate under climate change motivated the development of a branch of literature on the economics of natural disaster insurance. A starting point for assessing the implications of climate change for insurance and developing risk management strategies is understanding the factors underlying historical loss trends and the way that future risks will develop. Most studies have pointed toward socioeconomic developments as the main cause of historical trends in natural disaster risks. Moreover, evidence reveals that climate change has been a contributing factor, which is expected to grow in importance in the future. Several supply and demand side obstacles may prevent natural disaster insurance from optimally fulfilling its desirable function of offering financial protection at affordable premiums. Climate change is expected to further hamper the insurability of natural disaster risks, unless insurers and governments proactively respond to climate change, for example by linking insurance coverage with risk reduction activities. A branch of literature has developed about how the functioning of insurance should be improved to cope with climate change. This includes industry-level responses, reforms of insurance market structures, such as public–private natural disaster insurance provision, and recommendations for addressing behavioral biases in insurance demand and for stimulating risk reduction. In view of the rising economic losses of natural disasters, this field of study is likely to remain an active one.
James B. London
Coastal zone management (CZM) has evolved since the enactment of the U.S. Coastal Zone Management Act of 1972, which was the first comprehensive program of its type. The newer iteration of Integrated Coastal Zone Management (ICZM), as applied to the European Union (2000, 2002), establishes priorities and a comprehensive strategy framework. While coastal management was established in large part to address issues of both development and resource protection in the coastal zone, conditions have changed. Accelerated rates of sea level rise (SLR) as well as continued rapid development along the coasts have increased vulnerability. The article examines changing conditions over time and the role of CZM and ICZM in addressing increased climate related vulnerabilities along the coast. The article argues that effective adaptation strategies will require a sound information base and an institutional framework that appropriately addresses the risk of development in the coastal zone. The information base has improved through recent advances in technology and geospatial data quality. Critical for decision-makers will be sound information to identify vulnerabilities, formulate options, and assess the viability of a set of adaptation alternatives. The institutional framework must include the political will to act decisively and send the right signals to encourage responsible development patterns. At the same time, as communities are likely to bear higher costs for adaptation, it is important that they are given appropriate tools to effectively weigh alternatives, including the cost avoidance associated with corrective action. Adaptation strategies must be pro-active and anticipatory. Failure to act strategically will be fiscally irresponsible.
Global environmental change amplifies and creates pressures that shape human migration. In the 21st century, there has been increasing focus on the complexities of migration and environmental change, including forecasts of the potential scale and pace of so-called environmental migration, identification of geographic sites of vulnerability, policy implications, and the intersections of environmental change with other drivers of human migration. Migration is increasingly viewed as an adaptive response to climatic and environmental change, particularly in terms of livelihood vulnerability and risk diversification. Yet the adaptive potential of migration will be defined in part by health outcomes for migrating populations. There has been limited examination, however, of the health consequences of migration related to environmental change. Migration related to environmental change includes diverse types of mobility, including internal migration to urban areas, cross-border migration, forced displacement following environmental disaster, and planned relocation—migration into sites of environmental vulnerability; much-debated links between environmental change, conflict, and migration; immobile or “trapped” populations; and displacement due to climate change mitigation and decarbonization action. Although health benefits of migration may accrue, such as increased access to health services or migration away from sites of physical risk, migration—particularly irregular (undocumented) migration and forced displacement—can amplify vulnerabilities and present risks to health and well-being. For diverse migratory pathways, there is the need to anticipate, respond to, and ameliorate population health burdens among migrants.