Annual Review of Environment and Resources - Volume 41, 2016

The Central African forests, the planet's second largest rainforest block, are key to global environmental health. They influence climate change through their crucial role in carbon sinking and storage, affect weather patterns across Africa, and safeguard unique species and biodiverse communities. Their fate is important to everyone, not just today's inhabitants. The forests cover seven countries, and the differing socioeconomic histories and trajectories of these nations determine divergent fates for people, trees, and wildlife across the region. We review current knowledge of how the Central African forests have been shaped by climate and human activity within the region and assess how they may evolve under future climate change, population growth, and the Anthropocene race for wealth and energy. We highlight three different environmental trajectories for the countries of the region, identify key current regional issues that have an international dimension, and highlight five new points of future concern.

Peatlands are wetland ecosystems that accumulate dead organic matter (i.e., peat) when plant litter production outpaces peat decay, usually under conditions of frequent or continuous waterlogging. Collectively, global peatlands store vast amounts of carbon (C), equaling if not exceeding the amount of C in the Earth's vegetation; they also encompass a remarkable diversity of forms, from the frozen palsa mires of the northern subarctic to the lush swamp forests of the tropics, each with their own characteristic range of fauna and flora. In this review we explain what peatlands are, how they form, and the contribution that peatland science can make to our understanding of global change. We explore the variety in formation, shape, vegetation type, and chemistry of peatlands across the globe and stress the fundamental features that are common to all peat-forming ecosystems. We consider the impacts that past, present, and future environmental changes, including anthropogenic disturbances, have had and will have on peatland systems, particularly in terms of their important roles in C storage and the provision of ecosystem services. The most widespread uses of peatlands today are for forestry and agriculture, both of which require drainage that results in globally significant emissions of carbon dioxide (CO2), a greenhouse gas (GHG). Climatic drying and drainage also increase the risk of peat fires, which are a further source of GHG emissions [CO2 and methane (CH4)] to the atmosphere, as well as causing negative human health and socioeconomic impacts. We conclude our review by explaining the roles that paleoecological, experimental, and modeling studies can play in allowing us to build a more secure understanding of how peatlands function, how they will respond to future climate- and land-management-related disturbances, and how best we can improve their resilience in a changing world.

Carbon emissions in an industrialized world have created two problems for coral reefs: climate change and ocean acidification. Climate change drives ocean warming, which impacts biological and ecological reef processes, triggers large-scale coral bleaching events, and fuels tropical storms. Ocean acidification slows reef growth, alters competitive interactions, and impairs population replenishment. For managers and policymakers, ocean warming and acidification represent an almost paradoxical challenge by eroding reef resilience and simultaneously increasing the demand for reef resilience. Here, I address this problem in the context of challenges and potential solutions. Management efforts can compensate for reduced coral reef resilience in the face of global change, but to a limited extent and over a limited time frame. Critically, a realistic perspective on what sustainability measures can be achieved for coral reefs in the face of ocean warming and acidification is important to avoid setting unachievable goals for regional and local-scale management programs.

Here, we identify the extant species of marine megafauna (>45 kg maximum reported mass), provide a conceptual template for the ways in which these species influence the structure and function of ocean ecosystems, and review the published evidence for such influences. Ecological influences of more than 90% of the 338 known species of extant ocean megafauna are unstudied and thus unknown. The most widely known effect of those few species that have been studied is direct prey limitation, which occurs through consumption and risk avoidance behavior. Consumer-prey interactions result in indirect effects that extend through marine ecosystems to other species and ecological processes. Marine megafauna transport energy, nutrients, and other materials vertically and horizontally through the oceans, often over long distances. The functional relationships between these various ecological impacts and megafauna population densities, in the few well-studied cases, are characterized by phase shifts and hysteresis.

We review the major conceptual models of atmospheric moisture transport, which describe the link between evaporation from the ocean and precipitation over the continents. We begin by summarizing some of the basic aspects of the structure and geographical distribution of the two major mechanisms of atmospheric moisture transport, namely low-level jets (LLJs) and atmospheric rivers (ARs). We then focus on a regional analysis of the role of these mechanisms in extreme precipitation events with particular attention to the intensification (or reduction) of moisture transport and the outcome, in terms of precipitation anomalies and subsequent flooding (drought), and consider changes in the position and occurrence of LLJs and ARs with respect to any associated flooding or drought. We then conclude with a graphical summary of the impacts of precipitation extremes, highlighting the usefulness of this information to hydrologists and policymakers, and describe some future research challenges including the effects of possible changes to ARs and LLJs within the context of future warmer climates.

Human interactions with wildlife are a defining experience of human existence. These interactions can be positive or negative. People compete with wildlife for food and resources, and have eradicated dangerous species; co-opted and domesticated valuable species; and applied a wide range of social, behavioral, and technical approaches to reduce negative interactions with wildlife. This conflict has led to the extinction and reduction of numerous species and uncountable human deaths and economic losses. Recent advances in our understanding of conflict have led to a growing number of positive conservation and coexistence outcomes. I summarize and synthesize factors that contribute to conflict, approaches that mitigate conflict and encourage coexistence, and emerging trends and debates. Fertile areas for scholarship include scale and complexity, models and scenarios, understanding generalizable patterns, expanding boundaries of what is considered conflict, using new tools and technologies, information sharing and collaboration, and the implications of global change. The time may be ripe to identify a new field, anthrotherology, that brings together scholars and practitioners from different disciplinary perspectives to address human–wildlife conflict and coexistence.

The assessment literature on climate change solutions to date has emphasized technologies and options based on cost-effectiveness analysis. However, many solutions to climate change mitigation misalign with such analytical frameworks. Here, we examine demand-side solutions, a crucial class of mitigation options that go beyond technological specification and cost-benefit analysis. To do so, we synthesize demand-side mitigation options in the urban, building, transport, and agricultural sectors. We also highlight the specific nature of demand-side solutions in the context of development. We then discuss key analytical considerations to integrate demand-side options into overarching assessments on mitigation. Such a framework would include infrastructure solutions that interact with endogenous preference formation. Both hard infrastructures, such as the built environment, and soft infrastructures, such as habits and norms, shape behavior and as a consequence offer significant potential for reducing overall energy demand and greenhouse gas emissions. We conclude that systemic infrastructural and behavioral change will likely be a necessary component of a transition to a low-carbon society.

Rare earths, sometimes called the vitamins of modern materials, captured public attention when their prices increased more than tenfold in 2010 and 2011. As prices fell between 2011 and 2016, rare earths receded from public view, but less visibly, they became a major focus of innovative activity in companies, government laboratories, and universities. Geoscientists worked to better understand the resource base and improve our knowledge about mineral deposits that can be mines in the future. Process engineers carried out research that is making primary production and recycling more efficient. Materials scientists and engineers searched for substitutes that require fewer or no rare earths while providing properties comparable or superior to those of existing materials. As a result, even though global supply chains are not significantly different now than they were before the market disruption, the innovative activity motivated by the disruption will likely have far-reaching, if unpredictable, consequences for supply chains of rare earths in the future.

The electric power sector around the world is undergoing long-term technical, economic, and market transformations. Part of these transformations is the challenge of integrating high shares of renewable energy, particularly variable wind and solar. The concept of flexibility of a power system is key in terms of balancing these variable sources while keeping the lights on. On the supply side, flexibility arises from innovations in flexible coal and gas power plants, energy storage, and renewables. On the demand side, many distributed resources—generation, flexible demand, storage, and electric vehicles—can also contribute, and likewise transmission and distribution networks, grid operations, and market designs. Experience with measures and innovations for grid integration in all these categories is given, from several jurisdictions like Germany, Denmark, and California, where renewables already provide 20–40% shares of electricity and plans to reach 50% exist. Questions point to areas of technology, economics, planning, operations, business, and policy that need further understanding and learning from experience.

Climate change represents the most significant challenge of the twenty-first century and poses risks to water and sanitation services. Concerns for water supply include damage to infrastructure from flooding, loss of water sources due to declining rainfall and increasing demand, and changes in the water quality of water sources and within distribution of water. Sanitation concerns include damage and loss of services from floods and reduced carrying capacity of waters receiving wastewater. Key actions to reduce climate risks include the integration of measures of climate resilience into water safety plans, as well as improved accounting and management of water resources. Policy prescriptions on technologies for service delivery and changes in management models offer potential to reduce risks, particularly in low-income settings. Water and sanitation services contribute to greenhouse gas emissions. Choice of wastewater treatment technologies, improved pumping efficiency, use of renewable sources of energy, and within-system generation of energy offer potential for reducing emissions. Overall, greater attention and research are required to understand, plan for, and adapt to climate change in water and sanitation services. As with many other climate change adaptations, the likely benefits from no-regrets solutions are likely to outweigh the costs of investment.

Environmental problems can be reduced if people more consistently engage in proenvironmental actions. In this article, I discuss factors that motivate or inhibit individuals to act proenvironmentally. Many people are intrinsically motivated to engage in proenvironmental actions, because protecting the environment makes them feel good about themselves. People are more likely to be intrinsically motivated to act proenvironmentally over and again when they strongly endorse biospheric values. However, people may be less likely to act on their biospheric values when these values are not supported by the context, or when competing values are activated by factors in a choice context. Next, I discuss strategies to encourage proenvironmental actions by strengthening biospheric values, or by empowering and motivating people to act on their biospheric values. Moreover, I discuss factors influencing the acceptability of environmental policies that aim to encourage proenvironmental behavior.

This review examines the relationships between politics, sustainability, and development. Following an overview of sustainability thinking across different traditions, the politics of resources and the influence of scarcity narratives on research, policy and practice are explored. This highlights the politics of transformations and the way these play out under combinations of technology-led, market-led, state-led, and citizen-led processes. In particular, this review points to the politics of alliance building and collective action for sustainability and development. Transformations cannot be managed or controlled, but must draw on an unruly politics, involving diverse knowledges and multiple actors. This review highlights how politics are articulated through regimes of truth, rule, and accumulation, and how understanding such political processes has implications for institutional and governance responses. The conclusion reflects on future research priorities and the methodological stance required for an effective response to the political challenges of sustainability and development.

This article begins with a review and synthesis of some of the key theories, scholars, case examples, debates, methods, and (multiple) interpretations of environmental justice (EJ), as well as its expansion and globalization. We then look to some newly emerging themes, actions, and strategies for EJ and just sustainabilities. First, we look at the practices and materials of everyday life, illustrated by food and energy movements; second, the ongoing work on community and the importance of identity and attachment, informed by urban planning, food, and climate concerns; third, the growing interest in the relationship between human practices and communities and nonhuman nature. We also expand on the longstanding interest in just sustainabilities within this movement, illustrated by a wide range of concerns with food, energy, and climate justice. These new areas of work illustrate both recent developments and a set of paths forward for both the theory and practice of EJ.

Corporate environmentalism (CE) pertains to firm-level efforts to reduce pollution and resource use along with protecting natural habitats. Importantly, firms pledge to undertake these actions beyond the requirements of the law. Although historically CE efforts focused on resource conservation, their contemporary focus is on pollution reduction to reduce direct harm to humans and their communities and on the protection of environmental sinks. We review two broad categories of CE: direct CE and indirect CE. Direct CE, whether undertaken unilaterally or collectively, pertains to firms themselves adopting policies that reduce the environmental impact of their activities, or disclosing information about their environmental performance. Indirect CE refers to policies of actors (such as financial institutions) that encourage firms seeking their resources (through loans, venture capital, etc.) to commit to environmental stewardship policies. Three key lessons emerge. First, firm-level characteristics, particularly size and economic performance, encourage CE. Second, although pressure from external stakeholders, especially environmental nongovernmental organizations (NGOs), has played an important role in discouraging policies that harm the environment, its effect on encouraging proenvironmental activities remains unclear. Third, the literature is ripe with serious methodological issues. The endogeneity between firms’ economic and environmental record and their CE efforts poses difficulty in drawing causal inferences.

Social media is changing how people connect, create, and share content and is an integral force shaping modern society. Given the significant environmental challenges society faces, this review considers (a) how social media is currently contributing to the development of a more sustainable society and (b) directions for future work such that researchers and practitioners may more effectively utilize this technology. At present, case studies, anecdotal evidence, and research demonstrate that social media is contributing to sustainability in diverse ways including behavioral interventions utilizing social media elements; social and political activism; supporting/generating sustainable business practices and addressing corporate “greenwashing”; increasing access to, and the potential quality of, environmental education; and through citizen science projects. Although this work is promising, there is an urgent need for further and more methodologically rigorous research, which evaluates the specific impacts of social media technology on sustainability outcomes, i.e., proenvironmental knowledge, attitudes, and—in particular—behavior.

Transformative governance is an approach to environmental governance that has the capacity to respond to, manage, and trigger regime shifts in coupled social-ecological systems (SESs) at multiple scales. The goal of transformative governance is to actively shift degraded SESs to alternative, more desirable, or more functional regimes by altering the structures and processes that define the system. Transformative governance is rooted in ecological theories to explain cross-scale dynamics in complex systems, as well as social theories of change, innovation, and technological transformation. Similar to adaptive governance, transformative governance involves a broad set of governance components, but requires additional capacity to foster new social-ecological regimes including increased risk tolerance, significant systemic investment, and restructured economies and power relations. Transformative governance has the potential to actively respond to regime shifts triggered by climate change, and thus future research should focus on identifying system drivers and leading indicators associated with social-ecological thresholds.

Existing technologies, institutions, and behavioral norms together act to constrain the rate and magnitude of carbon emissions reductions in the coming decades. The inertia of carbon emissions due to such mutually reinforcing physical, economic, and social constraints is referred to as carbon lock-in. Carbon lock-in is a special case of path dependency, which is common in the evolution of complex systems. However, carbon lock-in is particularly prone to entrenchment given the large capital costs, long infrastructure lifetimes, and interrelationships between the socioeconomic and technical systems involved. Further, the urgency of efforts to avoid dangerous climate change exacerbates the liability of even small lock-in risks. Although carbon lock-in has been recognized for years, efforts to characterize the types and causes of carbon lock-in, or to quantitatively assess and evaluate its policy implications, have been limited and scattered across a number of different disciplines. This systematic review of the literature synthesizes what is known about the types and causes of carbon lock-in, including the scale, magnitude, and longevity of the effects, and policy implications. We identify three main types of carbon lock-in and describe how they coevolve: (a) infrastructural and technological, (b) institutional, and (c) behavioral. Although each type of lock-in has its own set of processes, all three are tightly intertwined and contribute to the inertia of carbon emissions. We outline the conditions, opportunities, and strategies for fostering transitions toward less-carbon-intensive emissions trajectories. We conclude by proposing a carbon lock-in research agenda that can help bridge the gaps between science, knowledge, and policy-making.

Risk analysis of species invasions links biology and economics, is increasingly mandated by international and national policies, and enables improved management of invasive species. Biological invasions proceed through a series of transition probabilities (i.e., introduction, establishment, spread, and impact), and each of these presents opportunities for management. Recent research advances have improved estimates of probability and associated uncertainty. Improvements have come from species-specific trait-based risk assessments (of estimates of introduction, establishment, spread, and impact probabilities, especially from pathways of commerce in living organisms), spatially explicit dispersal models (introduction and spread, especially from transportation pathways), and species distribution models (establishment, spread, and impact). Results of these forecasting models combined with improved and cheaper surveillance technologies and practices [e.g., environmental DNA (eDNA), drones, citizen science] enable more efficient management by focusing surveillance, prevention, eradication, and control efforts on the highest-risk species and locations. Bioeconomic models account for the interacting dynamics within and between ecological and economic systems, and allow decision makers to better understand the financial consequences of alternative management strategies. In general, recent research advances demonstrate that prevention is the policy with the greatest long-term net benefit.

Losses from natural hazards, including geophysical and hydrometeorological hazards, have been increasing worldwide. This review focuses on the process by which scientific evidence about natural hazards is applied to support decision making. Decision analysis typically involves estimating the probability of extreme events; assessing the potential impacts of those events from a variety of perspectives; and evaluating options to plan for, mitigate, or react to events. We consider issues that affect decisions made across a range of natural hazards, summarize decision methodologies, and provide examples of applications of decision analysis to the management of natural hazards. We conclude that there is potential for further exchange of ideas and experience between natural hazard research communities on decision analysis approaches. Broader application of decision methodologies to natural hazard management and evaluation of existing decision approaches can potentially lead to more efficient allocation of scarce resources and more efficient risk management.