Annual Review of Environment and Resources - Volume 43, 2018

China has emerged as a global economic powerhouse after four decades of unprecedented growth. Such growth has generated many environmental challenges with enormous ecological, socioeconomic, and health consequences in China and beyond. Although the overall quality of air and water is starting to improve, both are still below national and international standards. Water shortages are widespread. Biodiversity continues to decline. China is the world's top CO2 emitter, although per capita emissions are much lower than those of developed counties. On the positive side, large national conservation programs have been implemented, including the Natural Forest Conservation Program, the Grain-to-Green Program, Ecosystem Functional Conservation Areas, and Ecological Protection Redlines. More than 2,750 nature reserves have been established and a new national park system is being constructed. Some endangered and threatened species, such as the giant panda, are showing signs of recovery, and forest cover and some ecosystem services have increased. These mixed environmental outcomes result from human-nature interactions within China as well as between China and adjacent and distant countries. These include increasing rapid economic growth, resource consumption, land use change, trade and investment, and conservation and development policies. We suggest systems approaches such as nexus approaches and flow-centered governance to help China achieve ecological civilization and become an environmental leader on a metacoupled planet.

Weather and climate extremes impose serious impacts on natural and human systems. In its fifth assessment report (AR5) and a special report [Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX)], the Intergovernmental Panel on Climate Change provided a thorough assessment of observed and projected changes in extremes in a warming climate, with evidenced scientific gaps in the understanding of these responsive changes being reported. Reviewing post-AR5 literature, this article synthesizes recent advances regarding these previous gaps with respect to detection, attribution, and projection of extremes. We focus on constraints for the assessment confidence, overlooked types and characteristics of extremes, and changes in their thermodynamic-dynamic drivers. We also stress potential misinterpretations of existing results, propose an update of earlier key findings, and identify burgeoning topics.

Rising inequalities and accelerating global environmental change pose two of the most pressing challenges of the twenty-first century. To explore how these phenomena are linked, we apply a social-ecological systems perspective and review the literature to identify six different types of interactions (or “pathways”) between inequality and the biosphere. We find that most of the research so far has only considered one-directional effects of inequality on the biosphere, or vice versa. However, given the potential for complex dynamics between socioeconomic and environmental factors within social-ecological systems, we highlight examples from the literature that illustrate the importance of cross-scale interactions and feedback loops between inequality and the biosphere. This review draws on diverse disciplines to advance a systemic understanding of the linkages between inequality and the biosphere, specifically recognizing cross-scale feedbacks and the multidimensional nature of inequality.

Understanding the cultural dimensions of climate change requires understanding its religious aspects. Insofar as climate change is entangled with humans, it is also entangled with all the ways in which religion attends human ways of being. Scholarship on the connections between religion and climate change includes social science research into how religious identity figures in attitudes toward climate change, confessional and constructive engagements of religious thought with climate change from various communities and traditions, historical and anthropological analyses of how climate affects religion and religion interprets climate, and theories by which climate change may itself be interpreted as a religious event. Responses to climate change by indigenous peoples challenge the categories of religion and of climate change in ways that illuminate reflexive stresses between the two cultural concepts.

As populations become more affluent and urbanized, diets are shifting such that they are becoming higher in calories and include more highly processed foods and animal products. These dietary shifts are driving increases in diet-related diseases and are also causing environmental degradation. These linked impacts pose a new key issue for global society—a diet, health, and environment trilemma. Recent dietary shifts have contributed to increasing diet-related health and environmental impacts, including an 80% increase in global diabetes prevalence and an 860% increase in global nitrogen fertilizer use. Furthermore, if current dietary trajectories were to continue for the next several decades, diet-related diseases would account for three-quarters of the global burden of disease and would also lead to large increases in diet-related environmental impacts. We discuss how shifts to healthier diets—such as some Mediterranean, pescetarian, vegetarian, and vegan diets—could reduce incidence of diet-related diseases and improve environmental outcomes. In addition, we detail how other interventions to food systems that use known technologies and management techniques would improve environmental outcomes.

Differentiating the impacts of climate change between 1.5°C and 2°C requires a regional and sector-specific perspective. Whereas for some regions and sectors the difference in climate variables might be indistinguishable from natural variability, other areas especially in the tropics and subtropics will experience significant shifts. In addition to region-specific changes in climatic conditions, vulnerability and exposure also differ substantially across the world. Even small differences in climate hazards can translate into sizeable impact differences for particularly vulnerable regions or sectors. Here, we review scientific evidence of regional differences in climate hazards at 1.5°C and 2°C and provide an assessment of selected hotspots of climate change, including small islands as well as rural, urban, and coastal areas in sub-Saharan Africa and South Asia, that are particularly affected by the additional 0.5°C global mean temperature increase. We interlink these with a review of the vulnerability and exposure literature related to these hotspots to provide an integrated perspective on the differences in climate impacts between 1.5°C and 2°C.

Global atmospheric methane concentrations have continued to rise in recent years, having already more than doubled since the Industrial Revolution. Further environmental change, especially climate change, in the twenty-first century has the potential to radically alter global methane fluxes. Importantly, changes in temperature, precipitation, and net primary production may induce positive climate feedback effects in dominant natural methane sources such as wetlands, soils, and aquatic ecosystems. Anthropogenic methane sources may also be impacted, with a risk of enhanced emissions from the energy, agriculture, and waste sectors. Here, we review the global sources of methane, the trends in fluxes by source and sector, and their possible evolution in response to future environmental change. We discuss ongoing uncertainties in flux estimation and projection, and highlight the great potential for multisector methane mitigation as part of wider global climate change policy.

Vegetation modifies land-surface properties, mediating the exchange of energy, moisture, trace gases, and aerosols between the land and the atmosphere. These exchanges influence the atmosphere on local, regional, and global scales. Through altering surface properties, vegetation change can impact on weather and climate. We review current understanding of the processes through which tropical land-cover change (LCC) affects rainfall. Tropical deforestation leads to reduced evapotranspiration, increasing surface temperatures by 1–3 K and causing boundary layer circulations, which in turn increase rainfall over some regions and reduce it elsewhere. On larger scales, deforestation leads to reductions in moisture recycling, reducing regional rainfall by up to 40%. Impacts of future tropical LCC on rainfall are uncertain but could be of similar magnitude to those caused by climate change. Climate and sustainable development policies need to account for the impacts of tropical LCC on local and regional rainfall.

Life on Earth comes in many forms, but all life-forms share a common element in carbon. It is the basic building block of biology, and by trapping radiation it also plays an important role in maintaining the Earth's atmosphere at a temperature hospitable to life. Like all matter, carbon can neither be created nor destroyed, but instead is continuously exchanged between ecosystems and the environment through a complex combination of physics and biology. In recent decades, these exchanges have led to an increased accumulation of carbon on the land surface: the terrestrial carbon sink. Over the past 10 years (2007–2016) the sink has removed an estimated 3.61 Pg C year⁻¹ from the atmosphere, which amounts to 33.7% of total anthropogenic emissions from industrial activity and land-use change. This sink constitutes a valuable ecosystem service, which has significantly slowed the rate of climate change. Here, we review current understanding of the underlying biological processes that govern the terrestrial carbon sink and their dependence on climate, atmospheric composition, and human interventions.

Research on environmental change has often focused on changes in population as a significant driver of unsustainability and environmental degradation. Demographic pessimism and limited engagement with demographic realities underpin many arguments concerning limits to growth, environmental refugees, and environment-related conflicts. Re-engagement between demographic and environmental sciences has led to greater understanding of the interactions between the size, composition, and distribution of populations and exposure to environmental risks and contributions to environmental burdens. We review the results of this renewed and far more nuanced research frontier, focusing in particular on the way demographic trends affect exposure, sensitivity, and adaptation to environmental change. New research has explained how migration systems interact with environmental challenges in individual decisions and in globally aggregate flows. Here we integrate analysis on demographic and environmental risks that often share a root cause in limited social freedoms and opportunities. We argue for a capabilities approach to promoting sustainable solutions for a more mobile world.

Social-ecological systems (SES) research offers new theory and evidence to transform sustainable development to better contend with the challenges of the Anthropocene. Four insights from contemporary SES literature on (a) intertwined SES, (b) cross-scale dynamics, (c) systemic tipping points, and (d) transformational change are explored. Based on these insights, shifts in sustainable development practice are suggested to recognize and govern the complex and codeveloping social and ecological aspects of development challenges. The potential susceptibility of SES to nonlinear systemic reconfigurations is highlighted, as well as the opportunities, agency, and capacities required to foster reconfigurative transformations for sustainable development. SES research proposes the need for diverse values and beliefs that are more in tune with the deep, dynamic connections between social and ecological systems to transform development practice and to support capacities to deal with shocks and surprises. From these perspectives, SES research offers new outlooks, practices, and novel opportunity spaces from which to address the challenges of the Anthropocene.

Scholars and activists mobilize increasingly the term degrowth when producing knowledge critical of the ideology and costs of growth-based development. Degrowth signals a radical political and economic reorganization leading to reduced resource and energy use. The degrowth hypothesis posits that such a trajectory of social transformation is necessary, desirable, and possible; the conditions of its realization require additional study. Research on degrowth has reinvigorated the limits to growth debate with critical examination of the historical, cultural, social, and political forces that have made economic growth a dominant objective. Here we review studies of economic stability in the absence of growth and of societies that have managed well without growth. We reflect on forms of technology and democracy com-patible with degrowth and discuss plausible openings for a degrowth transition. This dynamic and productive research agenda asks inconvenient questions that sustainability sciences can no longer afford to ignore.

Climate action has two pillars: mitigation and adaptation. Mitigation faces collective action issues because its costs are focused on specific locations/actors but benefits are global and nonexcludable. Adaptation, in contrast, creates local benefits, and therefore should face fewer collective action issues. However, governance units vary in the types of adaptation policies they adopt. To explain this variation, we suggest conceptualizing adaptation-as-politics because adaptation speaks to the issues of power, conflicting policy preferences, resource allocation, and administrative tensions. In examining who develops and implements adaptation, we explore whether adaptation is the old wine of disaster management in the new bottle of climate policy, and the tensions between national and local policy making. In exploring what adaptation policies are adopted, we discuss maladaptation and the distinction between hard and soft infrastructure. Finally, we examine why politicians favor visible, hard adaptation over soft adaptation, and how international influences shape local policy.

This article takes stock of the evolution of the United Nations Framework Convention on Climate Change (UNFCCC) through the prism of three recent shifts: the move away from targeting industrial country emissions in a legally binding manner under the Kyoto Protocol to mandating voluntary contributions from all countries under the Paris Agreement; the shift from the top-down Kyoto architecture to the hybrid Paris outcome; and the broadening out from a mitigation focus under Kyoto to a triple goal comprising mitigation, adaptation, and finance under Paris. This review discusses the implications of these processes for the effectiveness, efficiency, and equity of the UNFCCC's institutional and operational settings for meeting the convention's objectives. It ends by sketching three potential scenarios facing the UNFCCC as it seeks to coordinate the Paris Agreement and its relationship to the wider landscape of global climate action.

New partnerships between governments, private companies, and nongovernmental organizations (NGOs) are reshaping global environmental governance. In particular, there has been a rise of voluntary sustainability standards in an attempt to manage social and environmental impacts of global supply chains. We analyze the large spectrum of interactions between private, public, and civil society actors around voluntary sustainability standards, primarily for tropical agriculture and forestry. This review uncovers a policy ecosystem dominated by a proliferation of standards that complement, substitute, or compete against each other, with coordination mechanisms beginning to arise. Contrary to widely held views, interactions between governments, NGOs, and private companies surrounding the adoption of sustainable practices are not generally antagonistic, and public and private environmental governance regimes rarely operate independently. The influence of these interactions on the effectiveness of sustainability standards needs more attention. Better understanding how private regulations interact with the policy ecosystem will help design more effective interventions.

India is a significant player in climate policy and politics. It has been vocal in international climate negotiations, but its role in these negotiations has changed over time. In an interactive relationship between domestic policy and international positions, India has increasingly become a testing ground for policies that internalize climate considerations into development. This article critically reviews the arc of climate policy and politics in India over time. It begins by examining changes in knowledge and ideas around climate change in India, particularly in the areas of ethics, climate impacts, India's energy transition, linkages with sustainability, and sequestration. The next section examines changes in politics, policy, and governance at both international and national scales. The article argues that shifts in ideas and knowledge of impacts, costs, and benefits of climate action and shifts in the global context are reflected and refracted through discourses in India's domestic and international policies.

This review focuses on transnational governance in the minerals and mining sector. Although several initiatives have emerged to address specific governance challenges in this sector, knowledge of these efforts is piecemeal and little is known about patterns in transnational governance development across this issue area. We address these gaps by reviewing the extant research literature and analyzing empirical examples of transnational minerals and mining governance, using the gold sector as an illustrative case. We identify the social, humanitarian, security, and environmental problems manifest along the mineral lifecycle and consider the extent to which existing transnational governance initiatives address these issues. We call for future scholarship that addresses the diversity of transnational governance practices in the minerals and mining sector and explains emergent patterns in the particular forms of governance that dominate this issue area, as well the types of problems that have (and have not) received attention.

The economic case for limiting warming to 1.5°C is unclear, due to manifold uncertainties. However, it cannot be ruled out that the 1.5°C target passes a cost-benefit test. Costs are almost certainly high: The median global carbon price in 1.5°C scenarios implemented by various energy models is more than US$100 per metric ton of CO2 in 2020, for example. Benefits estimates range from much lower than this to much higher. Some of these uncertainties may reduce in the future, raising the question of how to hedge in the near term. Maintaining an option on limiting warming to 1.5°C means targeting it now. Setting off with higher emissions will make 1.5°C unattainable quickly without recourse to expensive large-scale carbon dioxide removal (CDR), or solar radiation management (SRM), which can be cheap but poses ambiguous risks society seems unwilling to take. Carbon pricing could reduce mitigation costs substantially compared with ramping up the current patchwork of regulatory instruments. Nonetheless, a mix of policies is justified and technology-specific approaches may be required. It is particularly important to step up mitigation finance to developing countries, where emissions abatement is relatively cheap.

Future sea-level rise generates hazards for coastal populations, economies, infrastructure, and ecosystems around the world. The projection of future sea-level rise relies on an accurate understanding of the mechanisms driving its complex spatio-temporal evolution, which must be founded on an understanding of its history. We review the current methodologies and data sources used to reconstruct the history of sea-level change over geological (Pliocene, Last Interglacial, and Holocene) and instrumental (tide-gauge and satellite alimetry) eras, and the tools used to project the future spatial and temporal evolution of sea level. We summarize the understanding of the future evolution of sea level over the near (through 2050), medium (2100), and long (post-2100) terms. Using case studies from Singapore and New Jersey, we illustrate the ways in which current methodologies and data sources can constrain future projections, and how accurate projections can motivate the development of new sea-level research questions across relevant timescales.