5,806 research outputs found

    Unintended Environmental Consequences of a Global Biofuels Program

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    Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).Biofuels are being promoted as an important part of the global energy mix to meet the climate change challenge. The environmental costs of biofuels produced with current technologies at small scales have been studied, but little research has been done on the consequences of an aggressive global biofuels program with advanced technologies using cellulosic feedstocks. Here, with simulation modeling, we explore two scenarios for cellulosic biofuels production and find that both could contribute substantially to future global-scale energy needs, but with significant unintended environmental consequences. As the land supply is squeezed to make way for vast areas of biofuels crops, the global landscape is defined by either the clearing of large swathes of natural forest, or the intensification of agricultural operations worldwide. The greenhouse gas implications of land-use conversion differ substantially between the two scenarios, but in both, numerous biodiversity hotspots suffer from serious habitat loss. Cellulosic biofuels may yet serve as a crucial wedge in the solution to the climate change problem, but must be deployed with caution so as not to jeopardize biodiversity, compromise ecosystems services, or undermine climate policy.This study received funding from the MIT Joint Program on the Science and Policy of Global Change, which is supported by a onsortium of government, industry and foundation sponsors

    A coupled terrestrial and aquatic biogeophysical model of the Upper Merrimack River watershed, New Hampshire, to inform ecosystem services evaluation and management under climate and land-cover change

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    Accurate quantification of ecosystem services (ES) at regional scales is increasingly important for making informed decisions in the face of environmental change. We linked terrestrial and aquatic ecosystem process models to simulate the spatial and temporal distribution of hydrological and water quality characteristics related to ecosystem services. The linked model integrates two existing models (a forest ecosystem model and a river network model) to establish consistent responses to changing drivers across climate, terrestrial, and aquatic domains. The linked model is spatially distributed, accounts for terrestrial–aquatic and upstream–downstream linkages, and operates on a daily time-step, all characteristics needed to understand regional responses. The model was applied to the diverse landscapes of the Upper Merrimack River watershed, New Hampshire, USA. Potential changes in future environmental functions were evaluated using statistically downscaled global climate model simulations (both a high and low emission scenario) coupled with scenarios of changing land cover (centralized vs. dispersed land development) for the time period of 1980–2099. Projections of climate, land cover, and water quality were translated into a suite of environmental indicators that represent conditions relevant to important ecosystem services and were designed to be readily understood by the public. Model projections show that climate will have a greater influence on future aquatic ecosystem services (flooding, drinking water, fish habitat, and nitrogen export) than plausible changes in land cover. Minimal changes in aquatic environmental indicators are predicted through 2050, after which the high emissions scenarios show intensifying impacts. The spatially distributed modeling approach indicates that heavily populated portions of the watershed will show the strongest responses. Management of land cover could attenuate some of the changes associated with climate change and should be considered in future planning for the region

    The Benefits to People of Expanding Marine Protected Areas

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    This study focuses on how the economic value of marine ecosystem services to people and communities is expected to change with the expansion of marine protected areas (MPAs). It is recognised, however, that instrumental economic value derived from ecosystem services is only one component of the overall value of the marine environment and that the intrinsic value of nature also provides an argument for the conservation of the marine habitats and biodiversity

    A blueprint for the estimation of seagrass carbon stock using remote sensing-enabled proxies

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    Seagrass ecosystems sequester carbon at disproportionately high rates compared to terrestrial ecosystems and represent a powerful potential contributor to climate change mitigation and adaptation projects. However, at a local scale, rich heterogeneity in seagrass ecosystems may lead to variability in carbon sequestration. Differences in carbon sequestration rates, both within and between seagrass meadows, are related to a wide range of interrelated biophysical and environmental variables that are difficult to measure holistically using traditional field surveys. Improved methods for producing robust, spatially explicit estimates of seagrass carbon storage across large areas would be highly valuable, but must capture complex biophysical heterogeneity and variability to be accurate and useful. Here, we review the current and emerging literature on biophysical processes which shape carbon storage in seagrass beds, alongside studies that map seagrass characteristics using satellite remote sensing data, to create a blueprint for the development of remote sensing-enabled proxies for seagrass carbon stock and sequestration. Applications of satellite remote sensing included measuring seagrass meadow extent, estimating above-ground biomass, mapping species composition, quantifying patchiness and patch connectivity, determining broader landscape environmental contexts, and characterising seagrass life cycles. All of these characteristics may contribute to variability in seagrass carbon storage. As such, remote sensing methods are uniquely placed to enable proxy-based estimates of seagrass carbon stock by capturing their biophysical characteristics, in addition to the spatiotemporal heterogeneity and variability of these characteristics. Though the outlined approach is complex, it is suitable for accurately and efficiently producing a full picture of seagrass carbon stock. This review has drawn links between the processes of seagrass carbon sequestration and the capabilities of remote sensing to detect and characterise these processes. These links will facilitate the development of remote sensing-enabled proxies and support spatially explicit estimates of carbon stock, ensuring climate change mitigation and adaptation projects involving seagrass are accounted for with increased accuracy and reliability

    MAESTRA2: A MODEL FOR SIMULATING SPATIALLY EXPLICIT CARBON DIOXIDE EXCHANGE RATES AMONG SPECIES\u27 WATER STRESS RESPONSE

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    MAESTRA2, a species specific mechanistic model, was parameterized to estimate water use, carbon accumulation and organ specific respiration of five deciduous tree species under both irrigated and water stressed conditions. The model was validated using temporally and spatially explicit ecophysiological data to account for seasonal changes in species physiology. The following tree species: Acer rubrum L. \u27Summer Red\u27 (A. rubrum), Betula nigra (B. nigra), Paulownia elongata (P. elongata), Quercus nuttallii (Q. nuttallii), and Quercus phellos (Q. phellos) were intensively measured and organ specific destructively harvested samples were compared to modeled estimates of carbon accumulation. Among species, we observed variability in carbon dioxide exchange rates under well watered and water stressed conditions. A. rubrum carbon sequestration under water deficit was 29% less than the well watered treatment. The species other than A. rubrum were similar to each other (56%-63% less carbon sequestered as compared to the well watered). A. rubrum root biomass was higher in the drought treatment as compared to the well watered control, possibly explaining its carbon sequestration characteristics. Modeling validation results indicated that the model does have the capability to down regulate photosynthetic capacity on a per species basis. Differences between measured values and modeled estimates were within 6% for A. rubrum, 12% for B. nigra, 8% for P. elongata, 2% for Q. nuttallii, and 7% for Q. phellos. Therefore, seasonal carbon accumulation estimates adequately represented field observations in both well watered and drought treatments. Moreover, sap flux measurements confirmed the models ability to estimate diurnal gas exchange under both well watered and water stressed conditions. The work provides evidence that MAESTRA2 is a process-based model capable of accurately quantifying spatially explicit carbon dioxide exchange rates at the species level and in response to water stress

    Literature review on the integration of ecosystem services in agricultural economic models

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    Most analytic tools used in assessing gains from investments in agricultural research either fail to take into consideration environmental impacts or, if they do, it is at a very limited level. The CGIAR Research Programs adopt a systems approach and require a fully integrated consideration of biodiversity and ecosystems services (ESS). This document therefore reviews existing methodologies and available data to identify how biodiversity and ESS can be integrated into analyses at multiple scales; households, farms, landscapes, agriculture sector and economy-wide. The literature review is also designed to identify possible synergies between models at different scales to enable a better understanding of trade-offs between agricultural systems, their environment and human well-being
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