The interactions between human population dynamics and the environment have often been viewed mechanistically. This review elucidates the complexities and contextual specificities of population-environment relationships in a number of domains. It explores the ways in which demographers and other social scientists have sought to understand the relationships among a full range of population dynamics (e.g., population size, growth, density, age and sex composition, migration, urbanization, vital rates) and environmental changes. The chapter briefly reviews a number of the theories for understanding population and the environment and then proceeds to provide a state-of-the-art review of studies that have examined population dynamics and their relationship to five environmental issue areas. The review concludes by relating population-environment research to emerging work on human-environment systems.
Carbon capture and storage (CCS) technologies remove carbon dioxide from flue gases for storage in geologic formations or the ocean. We find that CCS is technically feasible and economically attractive within the range of carbon policies discussed domestically and internationally. Current costs are about $200 to $250 per ton of carbon, although costs are sensitive to fuel prices and other assumptions and could be reduced significantly through technical improvements. Near-term prospects favor CCS for certain industrial sources and electric power plants, with storage in depleted oil and gas reservoirs. Deep aquifers may provide an attractive longer-term storage option, whereas ocean storage poses greater technical and environmental uncertainty. Vast quantities of economically recoverable fossil fuels, sizable political obstacles to their abandonment, and inherent delay associated with developing alternative energy sources suggest that CCS should be seriously considered in the portfolio of options for addressing climate change, alongside energy efficiency and carbon-free energy.
What is the social purpose of the firm? Is the sole or predominant purpose to make profits for the shareholders, as Milton Friedman famously noted, or should firms adopt policies that enhance social welfare, not necessarily increase profits? Should firms as legal "persons" act beyond their usual functions as agents of the shareholders? Should firms pursue political projects that might reduce profits, or should firms return profits back to shareholders and let shareholders decide what politics they wish to support? Do corporate social responsibility (CSR) policies represent agency conflicts whereby managers use shareholders' wealth to pursue their political and personal agendas, and, if so, should such managers face legal sanctions or at least be sanctioned by the stock market, an institution dedicated to enhancing shareholders' wealth?
The theoretical and normative aspects of the CSR debate are fascinating. While the commitment to pursuing CSR policies varies across firms, sectors, and countries, the salience of these policies is particularly striking in the realm of environmental management. While some firms have adopted CSR policies (or corporate environmentalism) unilaterally, others have sought to pursue CSR under the aegis of a formal program or club. Indeed, scholars are trying to examine conditions under which voluntary clubs might have a greater payoff for firms in relation to unilateral CSR actions.
To begin thinking about policy payoffs, one needs to examine how external stakeholders perceive CSR policies. What are their preferences? Do they have the capabilities to sanction or signal appreciation for CSR, thereby shaping firms' commitment to CSR? Scholars such as Michael Porter find win-win scenarios to be pervasive (specifically in the environmental arena) while others such as David Vogel are skeptical about the "market for virtue."
How do various institutions in which a firm is embedded influence its incentives to pursue CSR? One can argue that CSR is not likely to be viewed as managerial malfeasance: one seldom finds the United Sates Securities and Exchange Commission or shareholders suing firms for pursuing CSR. There is mixed evidence about the reaction of stock markets to CSR. The stock market seems to punish firms for not pursuing CSR in certain circumstances: research suggests that when the Toxics Release Inventory data were released, firms identified as major polluters saw declines in their share prices although their emissions were legal. There is no evidence, however, that the stock market will reward firms for pursuing CSR policies in every context. The message from the stock market seems to be: if CSR can avoid bad publicity for the firm, then it is acceptable; by itself, CSR does not constitute "good" news. And a similar story seems to hold for consumers' response to CSR. By and large, the market demand for socially responsive products has remained small. Furthermore, the current surge in the market for organics arguably reflects consumers' private interests in their own health, rather than their willingness to pay more to save the environment.
The debate about corporate social responsibility boils down to two questions: under what conditions will firms adopt CSR policies, and under what conditions will CSR policies enhance firms' social/environmental and financial performance? The debates on these issues have been particular intense in the context of corporate environmentalism—adoption of policies that are beyond firms' legal requirements with the explicit purpose of generating social externalities. For those favoring corporate environmentalism, the key challenge is to persuade firms to adopt such policies given that firms often cannot monetize and internalize the economic benefits of doing so, and have to incur non-trivial costs. Thus, while CSR might enhance firms' social/environmental performance and generate (non-tangible) goodwill benefits, these benefits might not be captured in the traditional measures of financial performance, at least not in the short run.
It is fair to say the assumption in the policy literature has been that firms will be reluctant to incur private costs to create positive social externalities, such as a cleaner environment. To persuade them to do so, coercion is required. Because governments are specialists in the production of coercion, they are perhaps in the best position to supply such policies. Thus emerged the rationale for the command and control approach to environmental governance. The idea is that...
For years economists have urged policymakers to use market-based approaches such as cap-and-trade programs or emission taxes to control pollution. The SO2 allowance market created by Title IV of the 1990 U.S. Clean Air Act Amendments represents the first real test of the wisdom of economists’ advice. Subsequent urban and regional applications of NOx emission allowance trading took shape in the 1990s in the United States, culminating in a second large experiment in emission trading in the eastern United States that began in 2003. This paper provides an overview of the economic rationale for emission trading and a description of the major U.S. programs for sulfur dioxide (SO2) and nitrogen oxides (NOx). We evaluate these programs along measures of performance including cost savings, environmental integrity, and incentives for technological innovation. We offer lessons for the design of future programs including, most importantly, those reducing carbon dioxide.
Throughout most of human history the constraints imposed by local environmental conditions and their natural variability were
powerful determinants of the security of individuals and societies: animals, droughts, floods, frosts, pathogens, storms,
and other environmental perturbations were significant causes of mortality, morbidity and social disruption. In today’s most
modern societies, technology, trade, industrialization, the use of fossil fuels, occupational specialization, and higher levels
of social organization have all weakened many of the constraints that the local environment places on people’s needs, rights,
and values (human security). Since the Industrial Revolution and the consolidation of the modern trading nation state, there
have been thousand-fold increases in the production of goods and the use of energy, and hundred-fold increases in international
trade in goods and services. Over the same period, the global population has increased from I billion to over 6 billion people,
and most people now live longer, consume more, and are better educated than in previous generations.
This review surveys five major efforts to identify and declare values essential to global sustainability; describes empirical trends (as measured by multinational and global-scale surveys) in values, attitudes, and behaviors related to human and economic development, the environment, and driving forces (population, affluence, technology, and entitlements); and describes empirical trends in attitudes toward contextual values that condition sustainable development (e.g., freedom and democracy, capitalism, globalization, and equality). Finally, the review identifies important barriers between attitudes and behavior; draws several conclusions regarding the value, attitudinal, and behavioral changes needed to achieve global sustainability; and suggests future research directions.
Species extinctions and the deterioration of other biodiversity features worldwide have led to the adoption of systematic conservation planning in many regions of the world. As a consequence, various software tools for conservation planning have been developed over the past twenty years. These tools implement algorithms designed to identify conservation area networks for the representation and persistence of biodiversity features. Budgetary, ethical, and other sociopolitical constraints dictate that the prioritized sites represent biodiversity with minimum impact on human interests. Planning tools are typically also used to satisfy these criteria. This chapter reviews both the concepts and technical choices that underlie the development of these tools. Conservation planning problems can be formulated as optimization problems, and we evaluate the suitability of different algorithms for their solution. Finally, we also review some key issues associated with the use of these tools, such as computational efficiency, the effectiveness of taxa and abiotic parameters at choosing surrogates for biodiversity, the process of setting explicit targets of representation for biodiversity surrogates, and dealing with multiple criteria. The review concludes by identifying areas for future research, including the scheduling of conservation action over extensive time periods and incorporating data about site vulnerability.
The pursuit of sustainability in particular places and sectors often unravels at the edges. Efforts to tackle environmental problems in one place shift them somewhere else or are overwhelmed by external changes in drivers. Gains in energy efficiency of appliances used in houses are offset by greater total numbers or compensating changes in patterns of use. Analytical perspectives and practical initiatives, which treat production and consumption jointly, are needed to complement experiences and efforts with sector-, place-, product- and consumer-oriented approaches.
There is now a growing body of scholarship exploring a diverse range of initiatives and experiments aimed at enabling sustainable production-consumption systems (PCSs). Different approaches make divergent assumptions about market institutions, government regulation, sociotechnical innovation, and actor partnerships. From this body of work flow useful insights for others who would engage, for example, in redesigning relationships around services rather than products or between third world producers and first world consumers in fair trade initiatives.
Energy-technology innovation (ETI) is the set of processes leading to new or improved energy technologies that can augment energy resources; enhance the quality of energy services; and reduce the economic, environmental, or political costs associated with energy supply and use. Advances achieved through ETI have made large contributions to the improvement of the human condition over the past 100 years. Still more will be required of ETI during the decades ahead if civilization is to succeed in meeting what we believe are the three greatest energy challenges still before it: reducing dependence on oil, drastically upgrading the energy services provided to the world's poor, and providing the energy required to increase and sustain prosperity everywhere without wrecking the global climate with the emissions from fossil-fuel burning. This will require significant enhancements to ETI through deeper analysis of ETI processes, greater investments in ETI, improved innovation policies, and better coordination and partnerships across sectors and countries.
The growth of CO-intensive transport, mobility and the impact of transport on the environment are reviewed. The recent global exponential growth in transport is unsustainable and must end unless the transport sector can decarbonize. The paper examines solutions for low-carbon transport systems; the behavioral options; possible demand reduction; the role of innovative technologies; and the means by which international agreements on pricing, standards, and regulations can be effectively used. Transport brings enormous benefits to society, and it has been instrumental in the globalization of the world economy, with substantial capital investments in its material infrastructure. Transport governance also needs rethinking to understand the major challenges, to implement major policy changes, and to address the problems of fragmented decision making. Holistic approaches, using ideas from transition management and niche development, are proposed as a framework within which both technological innovation and new patterns of travel and trade can be brought about.
Since prehistory, literature and the arts have been drawn to portrayals of physical environments and human-environment interactions. The modern environmentalist movement as it emerged first in the late-nineteenth century and, in its more recent incarnation, in the 1960s, gave rise to a rich array of fictional and nonfictional writings concerned with humans' changing relationship to the natural world. Only since the early 1990s, however, has the long-standing interest of literature studies in these matters generated the initiative most commonly known as “ecocriticism,” an eclectic and loosely coordinated movement whose contributions thus far have been most visible within its home discipline of literature but whose interests and alliances extend across various art forms and media. In such areas as the study of narrative and image, ecocriticism converges with its sister disciplines in the humanities: environmental anthropology, environmental history, and environmental philosophy. In the first two sections, we begin with a brief overview of the nature, significance, and evolution of literature-environment studies. We then summarize in more detail six specific centers of interest: (a) the imagination of place and place-attachment, (b) the enlistment and critique of models of scientific inquiry in the study of literature and the arts, (c) the examination of the significance of gender difference and environmental representation, (d) the cross-pollination of ecocritical and postcolonial scholarship as ecocriticism has extended its horizons beyond its original focus on Anglo-American imagination, (e) ecocriticism's evolving interest in indigenous art and thought, and (f) ecocri-ticism's no less keen and complex attentiveness to artistic representation and the ethics of relations between humans and animals.
Many aspects of Earth's climate system have changed abruptly in the past and are likely to change abruptly in the future. Although abrupt shifts in temperature are most dramatic in glacial climates, abrupt changes, resulting in an altered probability of drought, large floods, tropical storm landfall, and monsoon rainfall, are all important concerns even in the absence of significant anthropogenic climate forcing. Continued climate change will likely increase the probability of these types of abrupt change and also make abrupt changes in ocean circulation and sea level more likely. Although global warming may have already triggered abrupt change, current understanding and modeling capability is not sufficient to specify details of future abrupt climate change. Improved adaptation strategies are warranted, as well as efforts to avoid crossing climate change thresholds beyond which large abrupt changes in sea level, ocean circulation, and methane-clathrate release could greatly amplify the impacts of climate change.
As adaptation becomes more tightly integrated into the range of responses to climate change, understanding how knowledge of climate change impacts and vulnerabilities can be effectively used is essential both to direct research and to support action. This article reviews literature along an intellectual transect from knowledge of climate impacts on water systems to the influence of that knowledge on adaptation responses. We discuss scientific evidence for changing hydroclimatic regimes, methods for translating climatic information into results relevant to adaptation, uncertainties in these results, methods for addressing uncertainty via adaptation processes, challenges and opportunities for knowledge development and transfer, and sociopolitical factors that enable or hinder the use of knowledge. Challenges remain in developing and applying methods for identifying and reducing underlying vulnerabilities and reliably connecting technical knowledge of climate impacts with local needs remains an unsolved prob...
It is now commonplace to assert that actions toward sustainable development require a mix of scientific, economic, social and political knowledge, and judgments. The role of research-based knowledge in this complex setting is ambiguous and diverse, and it is undergoing rapid change both in theory and in practice. We review conventional views of the linkages between research-based knowledge and action, and the early response to concerns that these links could and should be improved, through efforts at translation and transfer. We then examine the range of critiques that challenge those conventional views by highlighting different aspects of the relationships between science and society, focusing on the implications for action toward sustainable development. We then review the theories and strategies that have emerged in the attempt to improve the linkages between research-based knowledge and action in the context of sustainability across four broad categories: participation, integration, learning, and negotiation. These form a hierarchy with respect to how deeply they engage with the various critiques. We propose that the relationships between research-based knowledge and action can be better understood as arenas of shared responsibility, embedded within larger systems of power and knowledge that evolve and change over time. The unique contribution of research-based knowledge needs to be understood in relation to actual or potential contributions from other forms of knowledge. We conclude with questions that may offer useful orientation to assessing or designing research-action arenas for sustainable development.
Adaptation is a process of deliberate change in anticipation of or in reaction to external stimuli and stress. The dominant research tradition on adaptation to environmental change primarily takes an actor-centered view, focusing on the agency of social actors to respond to specific environmental stimuli and emphasizing the reduction of vulnerabilities. The resilience approach is systems orientated, takes a more dynamic view, and sees adaptive capacity as a core feature of resilient social-ecological systems. The two approaches converge in identifying necessary components of adaptation. We argue that resilience provides a useful framework to analyze adaptation processes and to identify appropriate policy responses. We distinguish between incremental adjustments and transformative action and demonstrate that the sources of resilience for taking adaptive action are common across scales. These are the inherent system characteristics that absorb perturbations without losing function, networks and social capital that allow autonomous action, and resources that promote institutional learning.
Passenger transportation has evolved toward greater reliance on light-duty vehicles. The result, especially in the United States but increasingly elsewhere, is a car-centric transportation monoculture. Conventional cars provide a high level of personal freedom and convenience but are expensive, inefficient, and damaging to the global environment. This article reviews the literature and critically examines the debate about two fundamental challenges: (a) transforming vehicles to dramatically reduce oil use and greenhouse gas (GHG) emissions and (b) transforming the larger transportation system to expand personal mobility options and reduce their environmental and spatial footprints. The technologies and tools are at hand to achieve both. It will take a concerted effort from industry, government, and consumers to facilitate these transportation transformations.
This paper reviews the design approaches and technologies that have been used to reduce the energy requirements of new buildings by a factor of 2-4 compared to the energy use of otherwise comparable recent new buildings, or that have been used to achieve comparable savings in retrofits of existing buildings. This is followed by a critical discussion of documented studies of the energy performance of new and retrofitted buildings from around the world, along with cost information where-ever available. The additional costs of meeting the Passive Standard for heating loads in new buildings, which represents a factor of 5-10 reduction of heating load compared to current standard practice, has ranged from 0-16% of the construction costs of reference buildings. High-performance commercial buildings, with overall energy intensities of 25-50% that of recent conventional buildings, have been built at less cost, or only at a few percent more cost, than conventional buildings.
Aerosols are suspensions of solid and/or liquid particles in the atmosphere and modify atmospheric radiative fluxes and chemistry. Aerosols move mass from one part of the earth system to other parts of the earth system, thereby modifying biogeochemistry and the snow surface albedo. This paper reviews our understanding of the impacts of aerosols on climate through direct radiative changes, aerosol-cloud interactions (indirect effects), atmospheric chemistry, snow albedo, and land and ocean biogeochemistry. Aerosols play an important role in the preindustrial (natural) climate system and have been perturbed substantially over the anthropocene, often directly by human activity. The most important impacts of aerosols, in terms of climate forcing, are from the direct and indirect effects, with large uncertainties. Similarly large impacts of aerosols on land and ocean biogeochemistry have been estimated, but these have larger uncertainties.
Human agency is considered a key factor in determining how individuals and society respond to environmental change. This article synthesizes knowledge on agency, capacity, and resilience across human development, well-being, and disasters literature to provide insights to support more integrated and human-centered approaches to understanding environmental change. It draws out the key areas of agreement across these diverse fields and identifies the main points of contestation and uncertainty. This highlights the need to consider subjective and relational factors in addition to objective measures of capacity and to view these as reflexive and dynamic, as well as differentiated socially and temporally. These findings can help distinguish between coping, adaptation, and transformation as responses to environmental and other stressors.
Biological diversity of agriculture consists of several analytic levels and spatial management scales that are subject to complex interactions with global change. The complexity of interactions is related to the bidirectional impacts and influences of global land use and climate change in combination with social-environmental shifts (globalization of agricultural development; market integration; technological change; and regulation through global treaties, policies, and institutions). This article develops a conceptual framework of the complexity of interactions using four thematic nodes—biological diversity in agriculture; global change; management and scale; and social-environmental adaptation, vulnerability, and resilience. It argues for the increased relevance of this framework. Linking expanded scientific research and policy to this group of conceptual nodes yields insight into the impacts of global change on biological diversity in agriculture and into the design of conservation strategies, monitoring approaches, and sustainability policies. Future policy must anticipate interactions of biological diversity, agroecosystem complexity, and global change stemming from the acceleration and integration of region-scale land-use intensification and disintensification.
The consequences of the invention of DNA-based molecular techniques and their application to agriculture have been pervasive. This review examines the key consequences for farmers and the public. These include widespread commercial applications of agricultural biotechnology in a limited number of countries, a large private-sector investment in biotechnology research, significant economic contributions to farmers, continuing controversy over its environmental impacts, a proliferation of regulations (both national and international as a consequence of the technology and property rights), a wide range of changing public reaction, and relatively little contribution of the technology to increasing food production, nutrition, or farm incomes in less-developed countries.
Nitrogen (N) is central to living systems, and its addition to agricultural cropping systems is an essential facet of modern crop management and one of the major reasons that crop production has kept pace with human population growth. The benefits of N added to cropping systems come, however, at well-documented environmental costs: Increased coastal hypoxia, atmospheric nitrous oxide (NO), reactive N gases in the troposphere, and N deposition onto forests and other natural areas are some of the consequences of our inability to keep fertilizer N from leaving cropped ecosystems via unmanaged pathways. The N cycle is complex, and solutions require a thorough understanding of both the biogeochemical pathways of N in agricultural systems and the consequences of different management practices. Despite the complexity of this challenge, however, a number of technologies are available today to reduce N loss. These include adding rotational complexity to cropping systems to improve N capture by crops, providing farmers with decision support tools for better predicting crop fertilizer N requirements, improving methods for optimizing fertilizer timing and placement, and developing watershed-level strategies to recapture N lost from fields. Solutions to the problem of agricultural N loss will require a portfolio approach in which different technologies are used in different combinations to address site-specific challenges. Solutions will also require incentives that promote their adoption.
The relationships between energy use in food systems, food system productivity, and energy resource constraints are complex. Moreover, ongoing changes in food production and consumption norms concurrent with urbanization, globalization, and demographic changes underscore the importance of energy use in food systems as a food security concern. Here, we review the current state of knowledge with respect to the energy intensity of agriculture and food systems. We highlight key drivers and trends in food system energy use along with opportunities for and constraints on improved efficiencies. In particular, we point toward a current dearth of research with respect to the energy performance of food systems in developing countries and provide a cautionary note vis-à-vis increasing food system energy dependencies in the light of energy price volatility and concerns as to long-term fossil energy availabilities.
▪ Abstract Plant genetic resources provide the biological underpinning for agriculture and food production. No nation is independent in terms of these resources. Interdependence levels are high among countries. Policy impediments to access may subside, increasing already substantial germplasm flows. Serious questions exist, however, about the health and availability of the actual resources. Genebank collections contain many unintended duplicates, making aggregate numbers seem larger than they really are. Information about individual accessions, particularly those found in situ, is often poor, reducing frequency and efficiency of use and ultimate benefits. Although not firmly established today, the link between conservation and use must be strengthened.
Irrigated agriculture is the main source of water withdrawals, accounting for around 70% of all the world's freshwater withdrawals. The development of irrigated agriculture has boosted agricultural yields and contributed to price stability, making it possible to feed the world's growing population. Rapidly increasing nonagricultural demands for water, changing food preferences, global climate change, and new demands for biofuel production place increasing pressure on scarce water resources. Challenges of growing water scarcity for agriculture are heightened by the increasing costs of developing new water, soil degradation, groundwater depletion, increasing water pollution, the degradation of water-related ecosystems, and wasteful use of already developed water supplies. This article discusses the role of water for agriculture and food security, the challenges facing irrigated agriculture, and the range of policies, institutions, and investments needed to secure adequate access to water for food today and in the future.
This review by a multidisciplinary team maps key components and emerging connections within the intellectual landscape of agroecology. We attempt to extend and preview agroecology as a discipline in which agriculture can be conceptualized within the context of global change and studied as a coupled system involving a wide range of social and natural processes. This intrinsic coupling, combined with powerful emerging drivers of change, presents challenges for the practice of agroecology and agriculture itself, as well as providing the framework for some of the most innovative research areas and the greatest potential for innovation for a sustainable future in agriculture. The objective of this review is to identify forward-looking scientific questions to enhance the relevance of agroecology for the key challenges of mitigating environmental impacts of agriculture while dramatically increasing global food production, improving livelihoods, and thereby reducing chronic hunger and malnutrition over the coming decades.
▪ Abstract This review evaluates analyses that are or may be performed to estimate uncertainties associated with air quality modeling used in regulatory planning to meet National Ambient Air Quality Standards for ozone. The sources of uncertainties in photochemical air quality simulation models (PAQSMs) are described. Regulatory requirements for evaluating PAQSM performance and uncertainty concerns not addressed through standard performance evaluations are discussed. Available techniques for evaluating uncertainties are presented. Experiences with analyses conducted most commonly are reviewed, as are those that might be used in a cohesive model uncertainty evaluation. The review concludes with a call for renewed emphasis on applying current techniques complemented by heretofore sparsely used diagnostic, corroborative, and alternative approaches and enhanced observational databases.
▪ Abstract The regional nature of several important air pollutants, which include acids, ozone, particulate matter, mercury, and persistent organics (POPs), is widely recognized by researchers and decision makers. Such pollutants are transported regionally over scales from about 100 to a few 1000s of kilometers, large enough to cross state, provincial, national, and even continental boundaries. Managing these regional pollutants requires overcoming political, economic, and cultural differences to establish cooperation between multiple jurisdictions, and it requires recognition of the linkages between pollutants and of impacts at different geographic scales. Here, regional dynamics of the pollutants are discussed, addressing them individually and as a tightly linked physical and chemical system. Collaborative efforts to characterize and manage regional pollution are presented, along with potential directions for future efforts.
Ambient air pollution has significant impacts on global climate change in complex ways, involving both warming and cooling, and causes an estimated one million deaths every year. Modeling studies and observations from a suite of platforms, including those that are space based, have revealed that air pollution is a widespread global phenomenon. The net effect of air pollution is a global cooling that is masking 50% of the committed greenhouse gas (GHG) warming from the Industrial Revolution. Aggressive air pollution abatement and climate stabilization strategies that reduce cooling pollutants may lead to a short-term warming surge that is unsafe for ecosystems and the human population, imposing complex trade-offs in policy making. Conversely, selective reduction of warming air pollutants to mitigate near-term climate change may offer opportunities for synergistic policy development. Reducing and preventing the accumulation of fossil-fuel carbon dioxide (CO2) in the atmosphere is the only sustainable way to...
This review examines how neoliberal policies that include free trade and less government have altered environmental management of industry, forests, water, agricultural land, and fisheries in Latin America. We examine theories and case studies about the privatization and pricing of environmental services and common property resources, the environmental impacts of free trade, and the transfer of environmental management to local or nongovernmental institutions. We conclude that neoliberalism has had some profound influences on the environment and on environmental management in Latin America and that the implementation and impacts of neoliberal policies on local environments have varied greatly by nation and by place as a result of different political, institutional, economic, environmental, and social conditions. Although many studies of neoliberalism and environment paint a negative picture, there are places and people that have adapted well to and benefited from neoliberal policies. Unfortunately, judgments on the success of neoliberal policies are limited by data and by the lack of detailed and balanced case studies.
Traditional biomass remains the dominant contributor to the energy supply of a large number of developing countries, where it serves the household energy needs of over a third of humanity in traditional cookstoves or open fires. Efforts to reduce the enormous human health, socioeconomic, and environmental impacts by shifting to cleaner cookstoves and cleaner biomass-derived fuels have had some success, but much more needs to be done, possibly including the expanded use of fossil-derived fuels. Concurrently, biomass is rapidly expanding as a commercial energy source, especially for transport fuels. Bioenergy can positively contribute to climate goals and rural livelihoods; however, if not implemented carefully, it could exacerbate degradation of land, water bodies, and ecosystems; reduce food security; and increase greenhouse gas (GHG) emissions. For large-scale commercial biofuels to contribute to sustainable development will require agriculturally sustainable methods and markets that provide enhanced livelihood opportunities and equitable terms of trade. The challenge lies in translating the opportunity into reality.
Over a range of geological and historical timescales, warmer climate conditions are associated with higher atmospheric levels of CO 2, an important climate-modulating greenhouse gas. Coupled carbonclimate interactions have the potential to introduce both stabilizing and destabilizing feedback loops into Earth's system. Here we bring together evidence on the dominant climate, biogeochemical and geological processes organized by timescale, spanning interannual to centennial climate variability, Holocene millennial variations and Pleistocene glacial-interglacial cycles, and million-year and longer variations over the Precambrian and Phanerozoic. Our focus is on characterizing, and where possible quantifying, internal coupled carbon-climate system dynamics and responses to external forcing from tectonics, orbital dynamics, catastrophic events, and anthropogenic fossil-fuel emissions, One emergent property is clear across timescales: atmospheric CO 2 can increase quickly, but the return to lower levels through natural processes is much slower. The consequences of human carbon cycle perturbations will far outlive the emissions that caused them.
Restoration ecology provides the conceptual and practical frameworks to guide management interventions aimed at repairing environmental damage. Restoration activities range from local to regional and from volunteer efforts to large-scale multiagency activities. Interventions vary from a "do nothing" approach to a variety of abiotic and biotic interventions aimed at speeding up or altering the course of ecosystem recovery. Revised understanding of ecosystem dynamics, the place of humans in historic ecosystems, and changed environmental settings owing to rapid environmental change all impact on decisions concerning which interventions are appropriate. Key issues relating to ecosystem restoration in a rapidly changing world include understanding how potentially synergistic global change drivers interact to alter the dynamics and restoration of ecosystems and how novel ecosystems without a historic analogue should be managed.
Aquaculture is currently the fastest growing animal food production sector and will soon supply more than half of the world's seafood for human consumption. Continued growth in aquaculture production is likely to come from intensification of fish, shellfish, and algae production. Intensification is often accompanied by a range of resource and environmental problems. We review several potential solutions to these problems, including novel culture systems, alternative feed strategies, and species choices. We examine the problems addressed; the stage of adoption; and the benefits, costs, and constraints of each solution. Policies that provide incentives for innovation and environmental improvement are also explored. We end the review by identifying easily adoptable solutions and promising technologies worth further investment.
The Arctic is a key part of the global climate system because the net positive energy input to the tropics must ultimately be resolved through substantial energy losses in high latitude regions. The Arctic influences the global climate system through both positive and negative feedbacks that involve physical, ecological, and human systems of the Arctic. The balance of evidence suggests that positive feedbacks to global warming will likely dominate in the Arctic during the next fifty to one hundred years. However, the negative feedbacks associated with changing the freshwater balance of the Arctic Ocean might abruptly launch the planet into another glacial period on longer time scales. In light of uncertainties and the vulnerabilities of the climate system to responses in the Arctic, it is important that we improve our understanding of how integrated regional changes in the Arctic will likely influence the evolution of the global climate system.
To appreciate the beauty or the fragility of our environment and our cultural responses to it, we need to understand how artists have portrayed the environment in the past and how they are continuing to portray it in the present. Environmental art is presented in this paper as a new genre to describe works of art that are not only directly representational of the environment (e.g., Constable's Cloud Series or Monet's London Series) but also works of art that are clearly nonrepresentational and performative, such as Long's A Line Made by Walking or Turrell's Skyspaces. The need for an overarching new genre to describe nonrepresentational performative environmental art is more obvious because there has been a host of labels given to this type of art since the late 1960s, such as land art, earthworks, site-specific art, destination art, ecological art, eco-art, and environmental sculpture. The review is also concerned with the potential of environmental art for communicating climate change.
Voluntary environmental programs (VEPs) seek to improve the environment by encouraging, rather than mandating, businesses and other organizations to adopt environmentally protective measures. Since the 1990s, VEPs established by industry, government, and nongovernmental organizations have proliferated around the globe, raising the question of how effective these programs are in securing environmental protection, both on their own and in comparison to traditional mandatory regulations. This article reviews the emerging research literature on VEPs, describing the variation in their structures, providing a framework for assessing their impacts, and summarizing what is known about why organizations engage in voluntary environmental action and what effects these programs have on environmental quality.
In this review, we highlight new insights into the conceptualization of the vulnerability of social-environmental systems and identify critical points of convergence of what otherwise might be characterized as disparate fields of research. We argue that a diversity of approaches to studying vulnerability is necessary in order to address the full complexity of the concept and that the approaches are in large part complementary. An emerging consensus on the issues of critical importance to vulnerability reduction¿including concerns of equity and social justice¿and growing synergy among conceptual frameworks promise even greater relevancy and utility for decision makers in the near future. We synthesize the current literature with an outline of core assessment components and key questions to guide the trajectory of future research.
▪ Abstract The atmosphere is a chemically complex and dynamic system that interacts significantly with the land, oceans, and ecosystems. Most trace gases emitted into the atmosphere are removed by oxidizing chemical reactions involving ozone and the hydroxyl free radical. The rate of this self-cleansing process is often referred to as the oxidation capacity of the atmosphere. Without this process, atmospheric composition and climate would be very different from what we observe today. The fundamental chemistry involved and the influence of human activity on oxidation capacity are reviewed. Both the current measurements designed to determine rates of oxidation and evidence for changes in oxidizing capacity over recent decades are critically discussed.
This article describes the field of the detection and attribution of climate change and highlights recent progress, major issues, and future directions. The attribution of global temperature variations over the past century to a combination of anthropogenic and natural influences is now well established, with the anthropogenic factors dominating. Other aspects of the climate system, including regional quantities, are increasingly being found to also show a detectable signal of human influence. Of particular interest, though, is the attribution of changes in nonmeteorological quantities, such as hydrological and ecological measures, and of changes in the risk of extreme weather events to anthropogenic emissions. Methods are being developed for tackling these two problems but are still in the early stages. As the field gradually includes a service focus, the biggest challenges will become the integration of various approaches into an overall framework and the communication of the capabilities and limitations of that framework to the outside community.
We review the development of macroenvironmental indicators, an effort driven by a combination of improved understanding of the functioning of Earth's natural systems at large spatial and temporal scales and of increasing demands by an expanding human population for goods and services provided by ecosystems. To be credible, macroenvironmental indicators need to be based on established scientific concepts and supported by extensive data. To be adopted, they need to serve the interests of diverse stakeholders and be perceived as unbiased. The baselines against which they are evaluated must be clear. A modest number of macroindicators of abiotic natural capital, biotic natural capital, and ecological functioning are currently in use. Some of them are designed to report on trends in legislatively mandated goals and standards. Most environmental indicators, however, report on specific components of the environment at small scales. They are not readily aggregated to form synthetic macroenvironmental indicators.
Environmental cost-benefit analysis, or CBA, refers to the economic appraisal of policies and projects that have the deliberate aim of improving the provision of environmental services or actions that might affect (sometimes adversely) the environment as an indirect consequence. Vital advances have arisen in response to the challenges that environmental problems and environmental policy pose for CBA. In this article, we review a number of these developments. Perhaps most notably this includes continuing progress in techniques to value environmental changes. Growing experience of these methods has resulted in, on the one hand, ever greater sophistication in application and, on the other hand, scrutiny regarding their validity and reliability. Distributional concerns have led to a renewal of interest in how appraisals might throw light on questions about equity as well as efficiency, and there have been substantial new insights for discounting costs and benefits in the far-off future. Uncertainty about what is lost when environmental assets are degraded or depleted has resulted in a number of distinct proposals although precaution is the watchword in each. Just as importantly, there is a need to understand when CBA is used in practice and why environmental decisions are often made in a manner apparently inconsistent with cost-benefit thinking.
▪ Abstract Marine biodiversity encompasses all levels of complexity of life in the sea, from within species to across ecosystems. At all levels, marine biodiversity has naturally exhibited a general, slow trajectory of increase, punctuated by mass extinctions at the evolutionary scale and by disturbances at the ecological scale. In historical times, a synergy of human threats, including overfishing, global warming, biological introductions, and pollution, has caused a rapid decline in global marine biodiversity, as measured by species extinctions, population depletions, and community homogenization. The consequences of this biodiversity loss include changes in ecosystem function and a reduction in the provision of ecosystem services. Global biodiversity loss will continue and likely accelerate in the future, with potentially more frequent ecological collapses and community-wide shifts. However, the timing and magnitude of these catastrophic events are probably unpredictable.
Mercury pollution poses global human health and environmental risks. Although mercury is naturally present in the environment, human activities, such as coal burning, have increased the amount of mercury cycling among the land, atmosphere, and ocean by a factor of three to five. Emitted to the atmosphere in its elemental form, mercury travels worldwide before oxidizing to a form that deposits to ecosystems. In aquatic systems, mercury can convert into methylmercury, a potent neurotoxin. People and wildlife are exposed to methylmercury as it bioaccumulates up the food chain. Mercury continues to circulate in the atmosphere, oceans, and terrestrial system for centuries to millennia before it returns to deep-ocean sediments. Areas of uncertainty in the global biogeochemical cycle of mercury include oxidation processes in the atmosphere, land-atmosphere and ocean-atmosphere cycling, and methylation processes in the ocean. National and international policies have addressed direct mercury emissions, but further efforts to reduce risks face numerous political and technical challenges.
Here we review the fundamental interactions between hydrology and the cycling of carbon (C) and nitrogen (N) in terrestrial and stream ecosystems. We organize this review around five commonly studied environments: land-atmosphere interface, soil, groundwater, streams, and headwater catchments. Common among all environments is that hydrological transitions, either episodic changes in water availability or hydrologic transport of reactants, result in disproportionately high rates of C and N cycling. Two major research challenges in coupling hydrological and biogeochemical research are (a) effectively scaling reactions at these spatiotemporal transitions and (b) combining the progress made within each of the five environments listed above into an integrated understanding of hydrobiogeochemical cycles. Changes in local-to-regional hydrological cycling are likely to result in unexpected surprises at the landscape scale until progress in these research areas is made.
Surface freshwaters — lakes, reservoirs, and rivers — are among the most extensively altered ecosystems on Earth. Transformations include changes in the morphology of rivers and lakes, hydrology, biogeochemistry of nutrients and toxic substances, ecosystem metabolism and the storage of carbon (C), loss of native species, expansion of invasive species, and disease emergence. Drivers are climate change, hydrologic flow modification, land-use change, chemical inputs, aquatic invasive species, and harvest. Drivers and responses interact, and their relationships must be disentangled to understand the causes and consequences of change as well as the correctives for adverse change in any given watershed. Beyond its importance in terms of drinking water, freshwater supports human well-being in many ways related to food and fiber production, hydration of other ecosystems used by humans, dilution and degradation of pollutants, and cultural values. A natural capital framework can be used to assess freshwater ecosystem services, competing uses for freshwaters, and the processes that underpin the long-term maintenance of freshwaters. Upper limits for human consumption of freshwaters have been proposed, and consumptive use may approach these limits by the mid-century.
▪ Abstract A variety of transport processes operate within the biosphere at all temporal and spatial scales. Temporary events or chronic conditions, both scale-dependent, instigate the transport of entities having material, energetic, or informational properties via several different transport vectors. The fluxes and influences imparted by these transport phenomena shape the physical environment, underlie gene flow, facilitate animal communication, and constrain the nature of local systems. These transport phenomena have been highly altered in the last century as humankind has become an ever more potent force in the earth system. As a result, issues of environmental and earth system science are, to a considerable extent, aspects of transport phenomena. A general appreciation for transport phenomena, broadly defined, is vital to gaining an appropriate perspective on the fluid nature of the earth system and to defining system structure and function through present and past events.
Earth's surface will continue to warm for decades, and the sea level to rise for centuries, even if the atmospheric concentration of greenhouse gases (GHGs) is held fixed at current levels. This is referred to as “committed” climate change because it is essentially unavoidable. Committed climate change arises due to the large thermal inertia of the oceans and their consequent time lag in adjusting to altered GHG concentrations. This work describes the basic heat balance of the oceans, the physical reasons for the long time lag in ocean temperature and sea-level rise, and the observational evidence for human-induced ocean warming over the past 50 years.
We discuss the challenges confronting environmental governance caused by the increasing connectivity of resource-use systems and the growing functional interdependencies of ecological and social systems. We take as a point of departure the case of the Xingu Indigenous Park (PIX) in Brazil and its surrounding agro-industrial region. This case provides a basis for reviewing the literature on resource governance, including both points of consensus and contentious issues. We argue that no fixed spatial or temporal level is appropriate for governing ecosystems and their services sustainably, effectively, and equitably. We point to the need to recognize the multilevel nature of such problems and the role of institutions in facilitating cross-level environmental governance as an important form of social capital that is essential for the long-term protection of ecosystems and the well-being of different populations.
The three Kyoto flexible mechanisms—emissions trading, the clean development mechanism (CDM), and Joint Implementation (JI)—have always been controversial. Proponents saw the mechanisms as clever tools to ensure environmental outcomes were achieved at least cost. Reducing the costs of compliance, they argued, would make tighter environmental targets possible, and certainly more politically feasible. Detractors have argued that the flexible mechanisms commoditize Earth's atmosphere in a manner that will allow dubious projects and the exchange of “hot air” to substitute for serious engagement on climate change. This chapter reviews the Kyoto flexible mechanisms, which will become fully operative during the period 2008 to 2012. The review assesses their progress and success to date, examines the problems that have emerged, and considers suggestions for future developments in climate policy.