排序方式： 共有57条查询结果，搜索用时 218 毫秒
31.
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
32.
Stefanie Seubert Sonia Fernández-Montes Andreas Philipp Elke Hertig Jucundus Jacobeit Gernot Vogt Andreas Paxian Heiko Paeth 《Theoretical and Applied Climatology》2014,117(1-2):257-275
The behaviour of precipitation and maximum temperature extremes in the Mediterranean area under climate change conditions is analysed in the present study. In this context, the ability of synoptic downscaling techniques in combination with extreme value statistics for dealing with extremes is investigated. Analyses are based upon a set of long-term station time series in the whole Mediterranean area. At first, a station-specific ensemble approach for model validation was developed which includes (1) the downscaling of daily precipitation and maximum temperature values from the large-scale atmospheric circulation via analogue method and (2) the fitting of extremes by generalized Pareto distribution (GPD). Model uncertainties are quantified as confidence intervals derived from the ensemble distributions of GPD-related return values and described by a new metric called “ratio of overlapping”. Model performance for extreme precipitation is highest in winter, whereas the best models for maximum temperature extremes are set up in autumn. Valid models are applied to a 30-year period at the end of the twenty-first century (2070–2099) by means of ECHAM5/MPI-OM general circulation model data for IPCC SRES B1 scenario. The most distinctive future changes are observed in autumn in terms of a strong reduction of precipitation extremes in Northwest Iberia and the Northern Central Mediterranean area as well as a simultaneous distinct increase of maximum temperature extremes in Southwestern Iberia and the Central and Southeastern Mediterranean regions. These signals are checked for changes in the underlying dynamical processes using extreme-related circulation classifications. The most important finding connected to future changes of precipitation extremes in the Northwestern Mediterranean area is a reduction of southerly displaced deep North Atlantic cyclones in 2070–2099 as associated with a strengthened North Atlantic Oscillation. Thus, the here estimated future changes of extreme precipitation are in line with the discourse about the influence of North Atlantic circulation variability on the changing climate in Europe. 相似文献
33.
Ditte Strebel Bo Elberling Elke Morgner Heike E. Knicker & Elisabeth J. Cooper 《Polar research》2010,29(1):46-57
The influence of goose grazing intensity and open-topped chambers (OTCs) on near-surface quantities and qualities of soil organic carbon (SOC) was evaluated in wet and mesic ecosystems in Svalbard. This study followed up a field experiment carried out in 2003–05 (part of the project Fragility of Arctic Goose Habitat: Impacts of Land Use, Conservation and Elevated Temperatures). New measurements of soil CO2 effluxes, temperatures and water contents were regularly made from July to November 2007. SOC stocks were quantified, and the reactivity and composition measured by basal soil respiration (BSR) and solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy. Results reveal variations in soil carbon cycling, with significant seasonal trends controlled by temperature, water content and snow. Experimental warming (OTCs) increased near-surface temperatures in the growing season, resulting in significantly higher CO2 effluxes. Different grazing intensities had no significant effects on observed soil respiration, but BSR rates at the mesic site (13–23 µg CO2 g soil-C−1 h−1 ) were highest with moderate grazing and lowest in the absence of grazing. A limited effect of grazing on microbial respiration is consistent with a lack of significant differences in SOC quantity and quality. NMR data show that the composition of A-horizon SOC is dominated by O-N-alkyl C and alkyl C groups, and less by carboxyl C and aromatic C groups: but again no marked variation in response to grazing was evident. It can be concluded that two years after a goose grazing experiment, SOC cycling was less than the natural variation within contrasting vegetation types. 相似文献
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35.
Sebastian Menke Anne Sennhenn Jörg‐H. Sachse Elke Majewski Bernhard Huchzermeyer Thomas Rath 《洁净——土壤、空气、水》2012,40(12):1401-1407
Ten algae species were analyzed by comparing their growth in specific hypersaline industrial wastewater. It was a by‐product of fertilizer production which was released by K + S Aktiengesellschaft, Germany. Due to processing, brine water contains a high amount of salts ( 200 g L?1). A successful algal biotechnology mainly depends on choosing and screening the adequate algae for a specific application along with the design of optimal culture conditions with comparable photo bioreactor technologies. Therefore, a high throughput screening technology was developed. In comparison to glass flasks or flat panel reactors this system was eligible for screening applications because of disposable characteristics and the equability of each culture tube. Dunaliella salina, Tetraselmis tetrathele, and Nannochloropsis salina grew in the presence of hypersaline wastewater where T. tetrathele grew best to a wastewater concentration of 75% by salt shock experiments. D. salina tolerates a wastewater level up to 80% by gradual increase. Intracellular ion contents of lyophilized algae samples were measured. They feature special transporter to either exclude ions, i.e., sodium from the cell, or to include ions like potassium and magnesium in order to secure functionality of sensitive enzymes. Under saline stress conditions these transport systems as well as metabolic pathways leading to the production of compatible osmolytes could be induced. Stress tolerance mechanisms developed in initially unstressed culture either by stepwise adaptation or by shock exposure to harsh salt condition. For this reason a feasible mass production in industrial hypersaline wastewater was possible. 相似文献
36.
David Letson Carlos E. Laciana Federico E. Bert Elke U. Weber Richard W. Katz Xavier I. Gonzalez Guillermo P. Podestá 《Climatic change》2009,97(1-2):145-170
In many places, predictions of regional climate variability associated with the El Niño–Southern Oscillation phenomenon offer the potential to improve farmers’ decision outcomes, by mitigating the negative impacts of adverse conditions or by taking advantage of favorable conditions. While the notion that climate forecasts are potentially valuable has been established, questions of when they may be more or less valuable have proven harder to resolve. Using simulations, we estimate the expected value of seasonal climate information under alternative assumptions about (a) land tenure (ownership vs. short-term leases) and (b) the decision maker’s objective function (expected utility vs. prospect theory value function maximization), employing a full range of plausible parameter values for each objective function. This allows us to show the extent to which the value of information depends on risk preferences, loss aversion, wealth levels and expectations, as well as situational constraints. Our results demonstrate in a non-laboratory decision context that, in some cases, psychologically plausible deviations from expected utility maximization can lead to substantial differences in estimates of the expected value of climate forecasts. Efforts to foster effective use of climate information and forecasts in agriculture must be grounded in a firm understanding of the goals, objectives and constraints of decision makers. 相似文献
37.
Field relations, mineralogy, major- and trace-element contents (including REE analyses of whole-rock samples and minerals) of three Proterozoic granites and their associated molybdenite mineralized aplites have been studied at Allebuoda, Munka and Kåtaberget in northern Sweden. The granites crystallized from melts that were not saturated with water. The mineralized potassic aplites formed by quenching of residual melts caused by sudden pressure drop, H2O saturation and vapour escape during tectonic rupturing. Leucogranites with higher Na2O/K2O ratios from Allebuoda and Munka crystallized during H2O-saturated equilibrium conditions in which the exsolved vapour could continuously migrate away. The pressure was probably 3 kbar at Munka, and somewhat lower at Allebuoda.
The granites have REE patterns characterized by LREE enrichments and negative Eu anomalies. In comparison, the potassic aplites and the more sodic leucogranites are depleted in LREE, enriched in HREE and have larger negative Eu anomalies. Allanite and monazite are the most important REE carriers in the granites. These minerals are strongly enriched in LREE, whereas fluorite and xenotime, which are more abundant in the aplites, are most enriched in HREE. Due to the strong control of accessory minerals on the REE balance, REE are of limited use in petrogenetic modelling of highly evolved granitic systems. 相似文献
38.
From 1992 to 1994, trace metal concentrations of bog water, Sphagnum mosses and peat cores of the bog “Georgenfelder Hochmoor” at Zinnwald-Georgenfeld in the Eastern Ore Mountains (Germany) were investigated. A sampling campaign in September 2019 allows the comparison of the older measurements with today's trace metal concentrations. No changes were found in the bog waters, while the trace metal concentrations of the Sphagnum mosses have decreased significantly. Due to the low growth rate of the peat and despite certain heterogeneity between the peat cores, the investigated elemental data for the peat sampled in the 1990s and in 2019 are in the same concentration range. The maximum concentrations are measured in the upper samples of all peat cores for the analysed elements (except sulphur). Compared to upper crustal data, a different behaviour of the elements is observed: Cr, Sc, Ti, and V, rare earth elements show crustal ratios, while Al and Si are also influenced by crust-air fractionation. Cd, Cu, Ni, Pb, and Zn are additionally enriched by anthropogenic atmospheric inputs from industry and transport. These results confirm the assumption that peat cores record past atmospheric deposition. 相似文献
39.
Ren Verburg Elke Stehfest Geert Woltjer Bas Eickhout 《Global Environmental Change》2009,19(4):434-446
This study explores the effects of agricultural trade liberalisation and concomitant changes in agricultural areas and livestock production on greenhouse gas emissions using the coupled LEITAP–IMAGE modelling system. The results indicate that liberalisation leads to an increase in total greenhouse gas emissions by about 6% compared to the reference scenario value in 2015. The increase in CO2 emissions are caused by vegetation clearance due to a rapid expansion of agricultural area; mainly in South America and Southeast Asia. Increased methane emissions in the case of full liberalisation are caused by less intensive cattle farming in regions such as South America and Southeast Asia. This pattern is observed up to 2050. Total global production of milk, dairy and beef do not change with full liberalisation, but production shifts were observed from North America and Europe to South America and Southeast Asia. Results are less pronounced in variants where trade liberalisation is only implemented partially. Remarkably, our study shows in the trade barrier removal scenario larger numbers of dairy cows in Australia and New Zealand (ANZ) then with full liberalisation scenario or a variant in which only milk quota are abolished. This illustrates that different types of liberalisation need to be analysed regionally and per commodity before general conclusions on the impact of trade liberalisation can be drawn. Our study contributes new information on greenhouse gas emissions to a vast number of trade liberalisation studies that focus on economic impacts. The combined economic-environmental impacts need to be assessed in detail before general conclusions on trade liberalisation can be given. 相似文献
40.
Holger Göttel Jörn Alexander Elke Keup-Thiel Diana Rechid Stefan Hagemann Tanja Blome Annett Wolf Daniela Jacob 《Climatic change》2008,87(1-2):35-50
In the context of the EU-Project BALANCE () the regional climate model REMO was used for extensive calculations of the Barents Sea climate to investigate the vulnerability
of this region to climate change. The regional climate model REMO simulated the climate change of the Barents Sea Region between
1961 and 2100 (Control and Climate Change run, CCC-Run). REMO on ~50 km horizontal resolution was driven by the transient
ECHAM4/OPYC3 IPCC SRES B2 scenario. The output of the CCC-Run was applied to drive the dynamic vegetation model LPJ-GUESS.
The results of the vegetation model were used to repeat the CCC-Run with dynamic vegetation fields. The feedback effect of
the modified vegetation on the climate change signal is investigated and discussed with focus on precipitation, temperature
and snow cover. The effect of the offline coupled vegetation feedback run is much lower than the greenhouse gas effect. 相似文献