The role of renewable energy in climate stabilization: results from the EMF27 scenarios     

Gunnar Luderer  Volker Krey  Katherine Calvin  James Merrick  Silvana Mima  Robert Pietzcker  Jasper Van Vliet  Kenichi Wada 《Climatic change》2014,123(3-4):427-441

This paper uses the EMF27 scenarios to explore the role of renewable energy (RE) in climate change mitigation. Currently RE supplies almost 20 % of global electricity demand. Almost all EMF27 mitigation scenarios show a strong increase in renewable power production, with a substantial ramp-up of wind and solar power deployment. In many scenarios, renewables are the most important long-term mitigation option for power supply. Wind energy is competitive even without climate policy, whereas the prospects of solar photovoltaics (PV) are highly contingent on the ambitiousness of climate policy. Bioenergy is an important and versatile energy carrier; however—with the exception of low temperature heat—there is less scope for renewables other than biomass for non-electric energy supply. Despite the important role of wind and solar power in climate change mitigation scenarios with full technology availability, limiting their deployment has a relatively small effect on mitigation costs, if nuclear and carbon capture and storage (CCS)—which can serve as substitutes in low-carbon power supply—are available. Limited bioenergy availability in combination with limited wind and solar power by contrast, results in a more substantial increase in mitigation costs. While a number of robust insights emerge, the results on renewable energy deployment levels vary considerably across the models. An in-depth analysis of a subset of EMF27 reveals substantial differences in modeling approaches and parameter assumptions. To a certain degree, differences in model results can be attributed to different assumptions about technology costs, resource potentials and systems integration.  相似文献   

Land-use transition for bioenergy and climate stabilization: model comparison of drivers,impacts and interactions with other land use based mitigation options   总被引：1，自引：0，他引：1  

Alexander Popp  Steven K. Rose  Katherine Calvin  Detlef P. Van Vuuren  Jan Phillip Dietrich  Marshall Wise  Elke Stehfest  Florian Humpenöder  Page Kyle  Jasper Van Vliet  Nico Bauer  Hermann Lotze-Campen  David Klein  Elmar Kriegler 《Climatic change》2014,123(3-4):495-509

In this article, we evaluate and compare results from three integrated assessment models (GCAM, IMAGE, and ReMIND/MAgPIE) regarding the drivers and impacts of bioenergy production on the global land system. The considered model frameworks employ linked energy, economy, climate and land use modules. By the help of these linkages the direct competition of bioenergy with other energy technology options for greenhouse gas (GHG) mitigation, based on economic costs and GHG emissions from bioenergy production, has been taken into account. Our results indicate that dedicated bioenergy crops and biomass residues form a potentially important and cost-effective input into the energy system. At the same time, however, the results differ strongly in terms of deployment rates, feedstock composition and land-use and greenhouse gas implications. The current paper adds to earlier work by specific looking into model differences with respect to the land-use component that could contribute to the noted differences in results, including land cover allocation, land use constraints, energy crop yields, and non-bioenergy land mitigation options modeled. In scenarios without climate change mitigation, bioenergy cropland represents 10–18 % of total cropland by 2100 across the different models, and boosts cropland expansion at the expense of carbon richer ecosystems. Therefore, associated emissions from land-use change and agricultural intensification as a result of bio-energy use range from 14 and 113 Gt CO2-eq cumulatively through 2100. Under climate policy, bioenergy cropland increases to 24–36 % of total cropland by 2100.  相似文献   

Vegetation geo-climatic zonation in the rocky mountains,Northern Utah,USA     

Antonin Kusbach  Helga Van Miegroet  Janis L. Boettinger  James N. Long 《山地科学学报》2014,11(3):656-673

We developed a vegetation geo-climatic zonation incorporating the zonal concept, gradient and discriminant analysis in Wasatch Range, northern Utah, USA. Mountainous forest ecosystems were sampled and described by vegetation, physiographic features and soil properties. The Snowpack Telemetry and National Weather Service Cooperative Observer Program weather station networks were used to approximate the climate of sample plots. We analysed vegetation and environmental data using clustering, ordination, classification, and ANOVA techniques to reveal environmental gradients affecting a broad vegetation pattern and discriminate these gradients. The specific objective was to assess and classify the response of the complex vegetation to those environmental factors operating at a coarse-scale climatic level. Ordination revealed the dominant role of regional, altitude-based climate in the area. Based on vegetation physiognomy, represented by five tree species, climatic data and taxonomic classification of zonal soils, we identified two vegetation geo-climatic zones： （1） a montane zone, with Rocky Mountain juniper and Douglas-fir; and （2） a subalpine zone, with Engelmann spruce and subalpine fir as climatic climax species. Aspen was excluded from the zonation due to its great ecological amplitude. We found significant differences between the zones in regional climate and landformgeomorphology/soils. Regional climate was represented by elevation, precipitation, and air and soil temperatures; and geomorphology by soil types. This coarsescale vegetation geo-climatic zonation provides a framework for a comprehensive ecosystem survey, which is missing in the central Rocky Mountains of the United States. The vegetationgeoclimatic zonation represents a conceptual improvement on earlier classifications. This framework explicitly accounts for the influence of the physical environment on the distribution of vegetation within a complex landscape typical of the central Rocky Mountains and in mountain ranges elsewhere.  相似文献   

Assessing the Accuracy of Volunteered Geographic Information arising from Multiple Contributors to an Internet Based Collaborative Project   总被引：2，自引：1，他引：1  

G. M. Foody  L. See  S. Fritz  M. Van der Velde  C. Perger  C. Schill  D. S. Boyd 《Transactions in GIS》2013,17(6):847-860

The recent rise of neogeography and citizen sensing has increased the opportunities for the use of crowdsourcing as a means to acquire data to support geographical research. The value of the resulting volunteered geographic information is, however, often limited by concerns associated with its quality and the degree to which the contributing data sources may be trusted. Here, information on the quality of sources of volunteered geographic information was derived using a latent class analysis. The volunteered information was on land cover interpreted visually from satellite sensor images and the main focus was on the labeling of 299 sites by seven of the 65 volunteers who contributed to an Internet‐based collaborative project. Using the information on land cover acquired by the multiple volunteers it was shown that the relative, but not absolute, quality of the data from different volunteers could be characterized accurately. Additionally, class‐specific variations in the quality of the information provided by a single volunteer could be characterized by the analysis. The latent class analysis, therefore, was able to provide information on the quality of information provided on an inter‐ and intra‐volunteer basis.  相似文献   

Securing the city: neoliberalism,space, and insecurity in postwar Guatemala,by Kevin Lewis O’Neill and Kedron Thomas     

Jared Van Ramshorst 《Urban geography》2013,34(2):313-314

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Testing Stokes-Helmert geoid model computation on a synthetic gravity field: experiences and shortcomings     

Petr Vaníček  Robert Kingdon  Michael Kuhn  Artu Ellmann  Will E. Featherstone  Marcelo C. Santos  Zdeněk Martinec  Christian Hirt  David Avalos-Naranjo 《Studia Geophysica et Geodaetica》2013,57(3):369-400

We report on testing the UNB (University of New Brunswick) software suite for accurate regional geoid model determination by use of Stokes-Helmert’s method against an Australian Synthetic Field (ASF) as “ground truth”. This testing has taken several years and has led to discoveries of several significant errors (larger than 5mm in the resulting geoid models) both in the UNB software as well as the ASF. It was our hope that, after correcting the errors in UNB software, we would be able to come up with some definite numbers as far as the achievable accuracy for a geoid model computed by the UNB software. Unfortunately, it turned out that the ASF contained errors, some of as yet unknown origin, that will have to be removed before that ultimate goal can be reached. Regardless, the testing has taught us some valuable lessons, which we describe in this paper. As matters stand now, it seems that given errorless gravity data on 1′ by 1′ grid, a digital elevation model of a reasonable accuracy and no topographical density variations, the Stokes-Helmert approach as realised in the UNB software suite is capable of delivering an accuracy of the geoid model of no constant bias, standard deviation of about 25 mm and a maximum range of about 200 mm. We note that the UNB software suite does not use any corrective measures, such as biases and tilts or surface fitting, so the resulting errors reflect only the errors in modelling the geoid.  相似文献   

Instrumental method for reducing error in compression-derived measurements of rainfall interception for individual trees     

John T. Van Stan II 《水文科学杂志》2013,58(6):1061-1066

Abstract

This technical note presents an instrumental method for the precise and timely installation of mechanical displacement sensors to investigate stem compression and relaxation associated with whole-tree rainwater loading and evaporation, respectively. We developed this procedure in response to the conclusions of Friesen et al. (2008 Friesen, J. 2008. Tree rainfall interception measured by stem compression. Water Resources Research, 44 doi:doi:10.1029/2008 WR007074. [Google Scholar]), which called for the development of a precision mounting method for strain sensors on inherently-irregular trunk cross-sections so that rainfall interception, storage and evaporation may be distinguished from other strain-related phenomena. To supply precise sensor installation locations, high-resolution trunk profiles are generated using the LaserBark^TM automated tree measurement system. These scans are utilized to approximate the location of neutral bending axes. A routine then instructs a mobile rangefinder along the cross-section to optically indicate exact positioning for strain sensors over the bending axes. As imprecise sensor placement linearly increases error and diminishes signal-to-noise ratio, this automated installation routine is designed to remove significant distortions created by wind throw, off-centre loading within unevenly-distributed canopies, and human error that can lead to erroneous measurements of rainfall interception.

Citation Van Stan, J. T. II, Jarvis, M. T., Levia, D. F. Jr & Friesen, J. (2011) Instrumental method for reducing error in compressionderived measurements of rainfall interception for individual trees. Hydrol. Sci. J. 56(6), 1061–1066.  相似文献   

A GIS toolkit for measuring and mapping space–time accessibility from a place-based perspective     

Matthias Delafontaine  Tijs Neutens  Nico Van de Weghe 《International journal of geographical information science》2013,27(6):1131-1154

This article introduces a novel geographical information system toolkit for measuring and mapping the accessibility of individuals to services. The toolkit contributes to earlier implementations by combining aspects of both place-based and person-based accessibility measures. To this end, place-based accessibility measures are derived from a person-based framework by considering space–time prisms that are centred at service facilities rather than individual anchor points. The implementation is also innovative by explicitly accounting for the opening hours of service delivery in its accessibility measurement. In addition, the toolkit is aimed to be user-friendly and to generate insightful and comprehensible results for non-technically oriented users, which is illustrated in a brief case study about library accessibility in Ghent (Belgium).  相似文献   

A spatial temporal downscaling approach to development of IDF relations for Perth airport region in the context of climate change     

Sujeewa Malwila Herath  Priyantha Ranjan Sarukkalige  Van Thanh Van Nguyen 《水文科学杂志》2013,58(11):2061-2070

ABSTRACT

Downscaling of climate projections is the most adapted method to assess the impacts of climate change at regional and local scales. This study utilized both spatial and temporal downscaling approaches to develop intensity–duration–frequency (IDF) relations for sub-daily rainfall extremes in the Perth airport area. A multiple regression-based statistical downscaling model tool was used for spatial downscaling of daily rainfall using general circulation models (GCMs) (Hadley Centre’s GCM and Canadian Global Climate Model) climate variables. A simple scaling regime was identified for 30 minutes to 24 hours duration of observed annual maximum (AM) rainfall. Then, statistical properties of sub-daily AM rainfall were estimated by scaling an invariant model based on the generalized extreme value distribution. RMSE, Nash-Sutcliffe efficiency coefficient and percentage bias values were estimated to check the accuracy of downscaled sub-daily rainfall. This proved the capability of the proposed approach in developing a linkage between large-scale GCM daily variables and extreme sub-daily rainfall events at a given location. Finally IDF curves were developed for future periods, which show similar extreme rainfall decreasing trends for the 2020s, 2050s and 2080s for both GCMs.