Annual Review of Environment and Resources - Volume 36, 2011

Despite hazard mitigation efforts and scientific and technological advances, extreme weather events continue to cause substantial losses. The impacts of extreme weather result from complex interactions among physical and human systems across spatial and temporal scales. This article synthesizes current interdisciplinary knowledge about extreme weather, including temperature extremes (heat and cold waves), precipitation extremes (including floods and droughts), and storms and severe weather (including tropical cyclones). We discuss hydrometeorological aspects of extreme weather; projections of changes in extremes with anthropogenic climate change; and how social vulnerability, coping, and adaptation shape the societal impacts of extreme weather. We find four critical gaps where work is needed to improve outcomes of extreme weather: (a) reducing vulnerability; (b) enhancing adaptive capacity, including decision-making flexibility; (c) improving the usability of scientific information in decision making, and (d) understanding and addressing local causes of harm through participatory, community-based efforts formulated within the larger policy context.

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.

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.

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.

The demand for electricity—closely linked to human, social, and economic development—is expected to rise significantly in the coming decades, especially in developing countries. Coal power currently is, and is expected to remain, an important part of the global electric power mix with much of the future growth again in developing countries. At the same time, coal-based power generation results in multiple, significant externalities with human health and potential climate change impacts being particularly important. This has spurred much effort over the decades to better determine the range and value of the impacts. Although uncertainties still remain in many aspects, it has become quite clear that the existing health and potential climate impacts from coal-power use are considerable. More stringent regulations are already being enforced and planned in developed countries, and developing countries are beginning to follow suit. Improved coal-based power generation technologies (deployed often as a result of regulations) can play an important role in mitigating these impacts, but their further development and deployment is complicated by a number of interrelated factors: the urgency of the climate imperative, the lack of coherent policies, the scale and complexity of the transition to cleaner-coal power, and the level of technological effort being devoted to (or available for) such a transition. Looking ahead, even as the wait for more stringent climate policies continues, there is a need to catalyze the innovation cycle through research and development (R&D) efforts while facilitating uptake and appropriate international cooperation to ensure rapid technology adoption across the globe.

The energy poor (EP) encompass between 1.25 billion and 3 billion people who do not have access to beneficial energy for their cooking, illumination, or mechanical needs. Their lives are disfigured by ill health, poverty, lack of education, and underdevelopment. The universally accepted norm of sustainable development (SD) demands that the rest of the world, spearheaded by the rich nations, address the plight of the EP. In a welcome response, the United Nations (UN) has recently embraced the need for universal access to electricity and declared 2012 the “International Year of Sustainable Energy for All” with a focus on providing electricity. Although access to electricity must remain the ultimate objective, the daunting additional costs of electricity, and the time taken to do so—realistically 30 years—will shunt the EP into limbo unless interim measures are also taken. Beneficial energy based on appropriate sustainable energy technologies (ASETs) can provide such intermediate energy. ASETs bridge the gap between capital-intensive electricity and the traditional subsistence technologies of the EP. ASETs demand serious consideration.

Human habitations require energy and water, which are increasingly interdependent. Energy systems have changed from using water for mechanical energy to building dams to provide irrigation water for agriculture and hydroelectricity. Large volumes of water are required to cool thermal electricity-generating stations—whether coal, natural gas, nuclear, or solar powered. Changes in cooling technology are reducing water withdrawals while increasing water consumption. Water produced from fossil fuel production represents environmental challenges and supply opportunities. Some renewable energy sources, such as wind turbines and photovoltaics, have far lower water requirements. Increasing development of biofuels creates a direct connection between water and energy systems. Energy, mostly for pumps, is necessary for supplying potable water and treating wastewater. Pumping from deeper underground as well as removing more contaminants (e.g., medicines, agricultural chemicals) and salt requires more energy. Water and wastewater treatment can dominate electricity demand in municipalities. Water reuse requires energy for treatment and pumping. Life cycle assessments and integrated resource planning strive to account for the total impacts.

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.

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.

The growth of CO2-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.

Green chemistry and engineering seek to maximize efficiency and minimize health and environmental hazards throughout the chemical production process. This review demonstrates how green chemistry principles and metrics can influence the entire life cycle of a chemical from design through disposal. After reviewing essential metrics and recent advances in the field within this context, we consider the case of nanotechnology. As an emerging field, nanotechnology provides an instructive framework to consider the influence and application of green chemistry. Interdisciplinary innovation guides both fields, and both seek to transform the nature of technology. The applications and implications of emerging green technology are discussed, and future opportunities for interdisciplinary collaborations are highlighted.

Land degradation, as a threat to smallholders in the tropics, attracts less attention than other global challenges. In addition, gaps between scientific understandings of land degradation and international policy regimes are problematic. We identify the three most significant debates including their different policy implications: desertification in the Sahel, nutrient depletion in Africa, and rural reforms in China. Using a political ecology frame across disciplines, scales of inquiry, and regional experiences, we nuance the often polarized scientific debate while seeking to bridge the gap between science and policy. Three main findings emerge: State-led rural reforms in China represent an important approach to land degradation; a renewed focus on agriculture and sustainability in development discourses opens new ways for tackling nutrient depletion with combined sociotechnological reforms; and a policy void in Africa paves the way for market mechanisms, such as payment for environmental services, that are insufficiently understood and put fairness at risk.

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.

Although global rates of tropical deforestation remain alarmingly high, they have decreased over the period 2000–2010, and a handful of tropical developing countries have recently been through a forest transition—a shift from net deforestation to net reforestation. This review synthesizes existing knowledge on the occurrence, causes, and ecological impacts of forest transitions and examines the prospects and policy options for a global forest transition. The ecological quality of forest transitions depends on multiple factors, including the importance of natural forest regeneration versus plantations. Given an increased competition for productive land between different land uses, a global forest transition will require major technological and policy innovations to supply wood and agricultural products. In the globalization era, national strategies aimed at forest protection and sustainable use of forest resources may have unintended effects abroad owing to a displacement of land use across countries. Decisions by consumers combined with certification schemes and moratoriums have an increasing influence on the fate of forests.

Reducing emissions from deforestation and forest degradation (REDD+) policies, projects, and interventions are among the most prominent of recent attempts to mitigate climate change. Because REDD+ projects focus on forests, they simultaneously affect socioeconomic and ecological outcomes at local, subnational, national, regional, and global levels. This review assesses the promise of REDD+ for the continued ability of forests to provide multiple benefits to human societies at multiple scales. We survey REDD+ efforts at different levels, examining them through an actor-oriented approach. The article highlights the criticality of collaborative action to enhance desired outcomes of REDD+ efforts. In summarizing major REDD+ future trends, the paper emphasizes the need to learn from past forestry, agricultural, biodiversity, and development policies, and for adaptive policy making.

Tourism is a large, diffuse global industry. Environmental aspects are little studied, with ∼1,500 publications in total. Impacts range from global contributions to climate change and ocean pollution to localized effects on endangered plant and animal species in protected areas. Environmental management is limited more by lack of adoption than by lack of technology. Government regulation is more effective than industry-based ecocertification. In developing nations, tourism can contribute to conservation by providing political and financial support for public protected area agencies and for conservation on private and communally owned lands. This is important in building resilience to climate change. In developed nations, such effects are outweighed by the impacts of recreational use and by political pressures from tourism property developers. These interactions deserve research in both natural and social sciences. Research priorities include more sophisticated recreation ecology as well as legal and social frameworks for conservation tourism.

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.

Understanding the interaction of human and environmental systems requires understanding the religious dimensions to the integration of ecology and society. Research on the significance of religion to environmental problems and of ecological ideas to religion has emerged into a robust interdisciplinary field. One sign of its vitality lies in the methodological arguments over how to conceptualize and assess that significance. Another lies in the diversity of research projects, which appear within most religious traditions, from many geographical contexts, and in several different disciplines. This article introduces major approaches to the field and key questions raised, and then briefly assesses recent work in three broad areas of tradition.