Mental and behavioral disorders account for approximately 7.4% of the global burden of disease, with depression now the world’s leading cause of disability. One in four people in the world will suffer from a mental health problem at some point in their life. City planning and design holds much promise for reducing this burden of disease, and for offering solutions that are affordable, accessible and equitable. Increasingly urban green space is recognized as an important social determinant of health, with the potential to protect mental health – for example, by buffering against life stressors - as well as relieving the symptom severity of specific psychiatric disorders. Pathways linking urban green space with mental wellbeing include the ability of natural stimuli – trees, water, light patterns – to promote ‘involuntary attention’ allowing the brain to disengage and recover from cognitive fatigue. This article brings together evidence of the positive effects of urban green space on common mental health problems (i.e. stress, anxiety, depression) together with evidence of its role in the symptom relief of specific psychiatric disorders, including schizophrenia and psychosis, post-traumatic stress disorder (PTSD), dementia, attention deficit/hyperactivity Disorder (ADHD) and autism. Urban green space is a potential force for building mental health: city planners, urban designers, policy makers and public health professionals need to maximize the opportunities in applying green space strategies for both health prevention and in supporting treatment of mental ill health.
Dominic Moran and Jorie Knook
Climate change is already having a significant impact on agriculture through greater weather variability and the increasing frequency of extreme events. International policy is rightly focused on adapting and transforming agricultural and food production systems to reduce vulnerability. But agriculture also has a role in terms of climate change mitigation. The agricultural sector accounts for approximately a third of global anthropogenic greenhouse gas emissions, including related emissions from land-use change and deforestation. Farmers and land managers have a significant role to play because emissions reduction measures can be taken to increase soil carbon sequestration, manage fertilizer application, and improve ruminant nutrition and waste. There is also potential to improve overall productivity in some systems, thereby reducing emissions per unit of product. The global significance of such actions should not be underestimated. Existing research shows that some of these measures are low cost relative to the costs of reducing emissions in other sectors such as energy or heavy industry. Some measures are apparently cost-negative or win–win, in that they have the potential to reduce emissions and save production costs. However, the mitigation potential is also hindered by the biophysical complexity of agricultural systems and institutional and behavioral barriers limiting the adoption of these measures in developed and developing countries. This includes formal agreement on how agricultural mitigation should be treated in national obligations, commitments or targets, and the nature of policy incentives that can be deployed in different farming systems and along food chains beyond the farm gate. These challenges also overlap growing concern about global food security, which highlights additional stressors, including demographic change, natural resource scarcity, and economic convergence in consumption preferences, particularly for livestock products. The focus on reducing emissions through modified food consumption and reduced waste is a recent agenda that is proving more controversial than dealing with emissions related to production.
Noa Kekuewa Lincoln and Peter Vitousek
Agriculture in Hawaiʻi was developed in response to the high spatial heterogeneity of climate and landscape of the archipelago, resulting in a broad range of agricultural strategies. Over time, highly intensive irrigated and rainfed systems emerged, supplemented by extensive use of more marginal lands that supported considerable populations. Due to the late colonization of the islands, the pathways of development are fairly well reconstructed in Hawaiʻi. The earliest agricultural developments took advantage of highly fertile areas with abundant freshwater, utilizing relatively simple techniques such as gardening and shifting cultivation. Over time, investments into land-based infrastructure led to the emergence of irrigated pondfield agriculture found elsewhere in Polynesia. This agricultural form was confined by climatic and geomorphological parameters, and typically occurred in wetter, older landscapes that had developed deep river valleys and alluvial plains. Once initiated, these wetland systems saw regular, continuous development and redevelopment. As populations expanded into areas unable to support irrigated agriculture, highly diverse rainfed agricultural systems emerged that were adapted to local environmental and climatic variables. Development of simple infrastructure over vast areas created intensive rainfed agricultural systems that were unique in Polynesia. Intensification of rainfed agriculture was confined to areas of naturally occurring soil fertility that typically occurred in drier and younger landscapes in the southern end of the archipelago. Both irrigated and rainfed agricultural areas applied supplementary agricultural strategies in surrounding areas such as agroforestry, home gardens, and built soils. Differences in yield, labor, surplus, and resilience of agricultural forms helped shape differentiated political economies, hierarchies, and motivations that played a key role in the development of sociopolitical complexity in the islands.
Matilda van den Bosch
Human beings are part of natural ecosystems and depend on them for their survival. In a rapidly changing environment and with increasing urbanization, this dependence is challenged. Natural environments affect human health and well-being both directly and indirectly. Urban green and blue areas provide opportunities for stress recovery and physical activity. They offer spaces for social interactions in the neighborhood and places for children’s play. Chronic stress, physical inactivity, and lack of social cohesion are three major risk factors for noncommunicable diseases, and therefore abundant urban greenery is an important asset for health promotion. Through numerous ecosystem services natural environments play a fundamental role in protecting health. Various populations depend on nature for basic material, such as fresh water, wood, fuel, and nutritious food. Biodiverse natural areas are also necessary for regulating the environment and for mitigating and adapting to climate change. For example, tree canopy cover can reduce the urban heat island effect substantially, preventing excess morbidity during heat waves. This natural heat-reducing effect also lessens the need for air conditioning systems and as a consequence decreases energy spending. Urban trees also support storm-water management, preventing flooding and related health issues. Air pollution is a major threat to population health. Urban trees sequester pollutants and, even though the effect may be relatively small, given the severity of the problem it may still have some public-health implications. The evidence around the effects of natural environments on health and well-being is steadily increasing. Several pathways and mechanisms are suggested, such as health services through functional ecosystems, early life exposure to biodiverse microbiota, which is important for the immune-system development, and sensory exposure, which has direct neurobiological impact supporting cognitive development and stress resilience. Support for several pathways is at hand that shows lower mortality rates and prevalence of cardiovascular and respiratory diseases, healthier pregnancy outcomes, reduced health inequalities, and improved mental health in urban areas with greater amounts of green and blue space. Altogether, the interactions between healthy natural environments and healthy people are multiple and complex, and require interdisciplinary attention and action for full understanding and resilient development of both nature and human beings.
Ortwin Renn and Andreas Klinke
Risk perception is an important component of risk governance, but it cannot and should not determine environmental policies. The reality is that people suffer and die as a result of false information or perception biases. It is particularly important to be aware of intuitive heuristics and common biases in making inferences from information in a situation where personal or institutional decisions have far-reaching consequences. The gap between risk assessment and risk perception is an important aspect of environmental policymaking. Communicators, risk managers, as well as representatives of the media, stakeholders, and the affected public should be well informed about the results of risk perception and risk response studies. They should be aware of typical patterns of information processing and reasoning when they engage in designing communication programs and risk management measures. At the same time, the potential recipients of information should be cognizant of the major psychological and social mechanisms of perception as a means to avoid painful errors. To reach this goal of mutual enlightenment, it is crucial to understand the mechanisms and processes of how people perceive risks (with emphasis on environmental risks) and how they behave on the basis of their perceptions. Based on the insights from cognitive psychology, social psychology, micro-sociology, and behavioral studies, one can distill some basic lessons for risk governance that reflect universal characteristics of perception and that can be taken for granted in many different cultures and risk contexts. This task of mutual enlightenment on the basis of evidence-based research and investigations is constrained by complexity, uncertainty, and ambiguity in describing, assessing, and analyzing risks, in particular environmental risks. The idea that the “truth” needs to be framed in a way that the targeted audience understands the message is far too simple. In a stochastic and nonlinear understanding of (environmental) risk there are always several (scientifically) legitimate ways of representing scientific insights and causal inferences. Much knowledge in risk and disaster assessment is based on incomplete models, simplified simulations, and expert judgments with a high degree of uncertainty and ambiguity. The juxtaposition of scientific truth, on one hand, and erroneous risk perception, on the other hand, does not reflect the real situation and lends itself to a vision of expertocracy that is neither functionally correct nor democratically justified. The main challenge is to initiate a dialogue that incorporates the limits and uncertainties of scientific knowledge and also starts a learning process by which obvious misperceptions are corrected and the legitimate corridor of interpretation is jointly defined. In essence, expert opinion and lay perception need to be perceived as complementing, rather than competing with each other. The very essence of responsible action is to make viable and morally justified decisions in the face of uncertainty based on a range of scientifically legitimate expert assessments. These assessments have to be embedded into the context of criteria for acceptable risks, trade-offs between risks to humans and ecosystems, fair risk and benefit distribution, and precautionary measures. These criteria most precisely reflect the main points of lay perception. For a rational politics of risk, it is, therefore, imperative to collect both ethically justifiable evaluation criteria and standards and the best available systematic knowledge that inform us about the performance of each risk source or disaster-reduction option according to criteria that have been identified and approved in a legitimate due process. Ultimately, decisions on acceptable risks have to be based on a subjective mix of factual evidence, attitudes toward uncertainties, and moral standards.