Probabilities in climate policy advice: a critical comment     

Gregor Betz 《Climatic change》2007,85(1-2):1-9

This essay explores as to whether probabilistic climate forecasting is consistent with the prerequisites of democratic scientific policy advice. It argues that, given the boundaries of our current knowledge, it is highly problematic to assign exact, unconditional probabilities to possible values of climate sensitivity. The range of possible–instead of probable–future climate scenarios is what climate policy should be based on.  相似文献   

A new linguistic quantifier knowledge-guided OWA approach for mineral prospectivity mapping: a case study of the Bavanat Region,Iran     

Reza Ghasemi  Behzad Tokhmechi  Gregor Borg 《Arabian Journal of Geosciences》2018,11(19):588

The main purpose of this study is to introduce a geographic information system (GIS)-based, multi-criteria decision analysis method for selection of favourable environments for Besshi-type volcanic-hosted massive sulphide (VHMS) deposits. The approach integrates two multi-criteria decision methods (analytical hierarchy process and ordered weighted averaging) and theory of fuzzy sets, within a GIS environment, to solve the problem of big suggested areas and missing known ore deposits in favourable environment maps for time and cost reduction. We doubled the fuzzy linguistic variables’ significance as a method to apply the arrange weights that the analytical hierarchy process (AHP)-ordered weighted averaging (OWA) hybrid procedure depends on. Another aim of this work is to assist mineral deposit exploration by modelling existing uncertainty in decision-making. Both AHP and fuzzy logic methods are knowledge-based, and they are affected by decision maker judgments. We used data-driven OWA approach in a hybrid method for solving this problem. We applied a new knowledge-guided OWA approach on data with changing linguistic variables according to the mineral system for VHMS deposits. Additionally, we used a vector-based method combination, which increased the precision of results. Results of knowledge-guided OWA showed that all of the mines and discovered deposits have been predicted with 100% accuracy in half of the size of the suggested area. To summarize, results improved the selection of possible target sites and increased the accuracy of results as well as reducing the time and cost, which will be used for field exploration. Finally, the hybrid methods with a knowledge-guided OWA approach have delivered more reliable results compared to exclusively knowledge-driven or data-driven methods. The study proved that expert knowledge and processed data (information) are critical important keys to exploration, and both of them should be applied in hybrid methods for reaching reliable results in mineral prospectivity mapping.  相似文献   

Centrifuge modelling of rainfall-induced slope failure in variably saturated soil     

Wang  Shun  Idinger  Gregor  Wu  Wei 《Acta Geotechnica》2021,16(9):2899-2916

Acta Geotechnica - This paper presents the results of centrifuge tests on rainfall-induced instabilities in variably saturated slopes. The roles of rainfall intensity and initial conditions, such...  相似文献   

Developing Africa’s energy mix     

Gregor Schwerhoff  Mouhamadou Sy 《Climate Policy》2019,19(1):108-124

Africa is growing rapidly both in terms of population size and economically. It is also becoming increasingly clear that fossil fuels impose a high price on society through local environmental pollution and Africa’s particular vulnerability to climate change. At the same time, Africa has an excellent renewable energy potential and prices for renewable energy are reaching the price range of fossil fuels. Comparing results from state-of-the-art Integrated Assessment Models we find different options for achieving a sustainable energy supply in Africa. They have in common, however, that strong economic development is considered compatible with the 2°C climate target. Taking both challenges and appropriate solutions into account, some models find that a complete switch to renewable energy in electricity production is possible in the medium term. The continental analysis identifies important synergy effects, in particular the exchange of electricity between neighbouring countries. The optimal energy mix varies considerably between African countries, but there is sufficient renewable energy for each country. The intermittency and higher capital intensity of renewable energy are important challenges, but proven solutions are available for them. In addition, we analyse the political economy of a sustainable energy transition in Africa.

Key policy insights

• An almost complete shift towards renewable energy (RE) is considered feasible and affordable in Africa.

• By 2050, electricity generation could be sourced largely from solar, wind and hydro power.

• Prices for RE in Africa are now within the price range of fossil fuels, partly due to the excellent RE potential.

• The optimal energy mix varies strongly between countries, but RE is sufficiently available everywhere.

• Addressing intermittency is possible, but requires investments and cooperation on the grid.

  相似文献   

The case for climate engineering research: an analysis of the “arm the future” argument     

Gregor Betz 《Climatic change》2012,111(2):473-485

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Formation of the Wiesloch Mississippi Valley-type Zn-Pb-Ag deposit in the extensional setting of the Upper Rhinegraben, SW Germany   总被引：2，自引：0，他引：2  

Katharina Pfaff  Ludwig H. Hildebrandt  David L. Leach  Dorrit E. Jacob  Gregor Markl 《Mineralium Deposita》2010,45(7):647-666

The Mississippi Valley-type (MVT) Zn–Pb–Ag deposit in the Wiesloch area, Southwest Germany, is controlled by graben-related faults of the Upper Rhinegraben. Mineralization occurs as vein fillings and irregular replacement ore bodies consisting of sphalerite, banded sphalerite, galena, pyrite, sulfosalts (jordanite and geocronite), barite, and calcite in the Middle Triassic carbonate host rock. Combining paragenetic information, fluid inclusion investigations, stable isotope and mineral chemistry with thermodynamic modeling, we have derived a model for the formation of the Wiesloch deposit. This model involves fluid mixing between ascending hot brines (originating in the crystalline basement) with sedimentary formation waters. The ascending brines originally had a near-neutral pH (around 6) and intermediate oxidation state, reflecting equilibrium with granites and gneisses in the basement. During fluid ascent and cooling, the pH of the brine shifted towards more acidic (around 4) and the oxidation state increased to conditions above the hematite-magnetite buffer. These chemical characteristics contrast strongly with those of the pore and fracture fluid residing in the limestone aquifer, which had a pH between 8 and 9 in equilibrium with calcite and was rather reduced due to the presence of organic matter in the limestone. Mixing between these two fluids resulted in a strong decrease in the solubility of silver-bearing sphalerite and galena, and calcite. Besides Wiesloch, several Pb–Zn deposits are known along the Upper Rhinegraben, including hydrothermal vein-type deposits like Badenweiler and the Michael mine near Lahr. They all share the same fluid origin and formation process and only differ in details of their host rock and fluid cooling paths. The mechanism of fluid mixing also seems to be responsible for the formation of other MVT deposits in Europe (e.g., Réocin, Northern Spain; Trèves, Southern France; and Cracow-Silesia, Poland), which show notable similarities in terms of their age, mineralogy. and mineral chemistry to the MVT deposit near Wiesloch.  相似文献   

Constraints on dissipation in the deep interiors of Ganymede and Europa from tidal phase-lags     

Hauke?HussmannEmail authorView author&#;s OrcID profile  Daigo?Shoji  Gregor?Steinbrügge  Alexander?Stark  Frank?Sohl 《Celestial Mechanics and Dynamical Astronomy》2016,126(1-3):131-144

Jupiter’s satellites are subject to strong tidal forces which result in variations of the gravitational potential and deformations of the satellites’ surfaces on the diurnal tidal cycle. Such variations are described by the Love numbers \(k_2\) and \(h_2\) for the tide-induced potential variation due to internal mass redistribution and the radial surface displacement, respectively. The phase-lags \( \phi _{k_2}\) and \( \phi _{h_2}\) of these complex numbers contain information about the rheological and dissipative states of the satellites. Starting from interior structure models and assuming a Maxwell rheology to compute the tidal deformation, we calculate the phase-lags in application to Ganymede and Europa. For both satellites we assume a decoupling of the outer ice-shell from the deep interior by a liquid subsurface water ocean. We show that, in this case, the phase-lag difference \(\varDelta \phi = \phi _{k_2}- \phi _{h_2}\) can provide information on the rheological and thermal state of the deep interiors if the viscosities of the deeper layers are small. In case of Ganymede, phase-lag differences can reach values of a few degrees for high-pressure ice viscosities \({<}10^{14}\) Pa s and would indicate a highly dissipative state of the deep interior. In this case \(\varDelta \phi \) is dominated by dissipation in the high-pressure ice layer rather than dissipation within the ice-I shell. These phase lags would be detectable from spacecraft in orbit around the satellite. For Europa \(\varDelta \phi \) could reach values exceeding \(20^\circ \) and phase-lag measurements could help distinguish between (1) a hot dissipative silicate mantle which would in thermal equilibrium correspond to a very thin outer ice-I shell and (2) a cold deep interior implying that dissipation would mainly occur in a thick (several tens of km) outer ice-I shell. These measurements are highly relevant for ESA’s Jupiter Icy Moons Explorer (JUICE) and NASA’s Europa Multiple Flyby Mission, both targeted for the Jupiter system.  相似文献   

Projections of global warming-induced impacts on winter storm losses in the German private household sector     

Hermann Held  Friedrich-Wilhelm Gerstengarbe  Tobias Pardowitz  Joaquim G. Pinto  Uwe Ulbrich  Kai Born  Markus G. Donat  Melanie K. Karremann  Gregor C. Leckebusch  Patrick Ludwig  Katrin M. Nissen  Hermann Österle  Boris F. Prahl  Peter C. Werner  Daniel J. Befort  Olaf Burghoff 《Climatic change》2013,121(2):195-207

We present projections of winter storm-induced insured losses in the German residential building sector for the 21st century. With this aim, two structurally most independent downscaling methods and one hybrid downscaling method are applied to a 3-member ensemble of ECHAM5/MPI-OM1 A1B scenario simulations. One method uses dynamical downscaling of intense winter storm events in the global model, and a transfer function to relate regional wind speeds to losses. The second method is based on a reshuffling of present day weather situations and sequences taking into account the change of their frequencies according to the linear temperature trends of the global runs. The third method uses statistical-dynamical downscaling, considering frequency changes of the occurrence of storm-prone weather patterns, and translation into loss by using empirical statistical distributions. The A1B scenario ensemble was downscaled by all three methods until 2070, and by the (statistical-) dynamical methods until 2100. Furthermore, all methods assume a constant statistical relationship between meteorology and insured losses and no developments other than climate change, such as in constructions or claims management. The study utilizes data provided by the German Insurance Association encompassing 24 years and with district-scale resolution. Compared to 1971–2000, the downscaling methods indicate an increase of 10-year return values (i.e. loss ratios per return period) of 6–35 % for 2011–2040, of 20–30 % for 2041–2070, and of 40–55 % for 2071–2100, respectively. Convolving various sources of uncertainty in one confidence statement (data-, loss model-, storm realization-, and Pareto fit-uncertainty), the return-level confidence interval for a return period of 15 years expands by more than a factor of two. Finally, we suggest how practitioners can deal with alternative scenarios or possible natural excursions of observed losses.  相似文献   

The reference frames of Mercury after the MESSENGER mission     

Alexander Stark  Jürgen Oberst  Frank Preusker  Steffi Burmeister  Gregor Steinbrügge  Hauke Hussmann 《Journal of Geodesy》2018,92(9):949-961

We report on recent refinements and the current status for the rotational state models and the reference frames of the planet Mercury. We summarize the performed measurements of Mercury rotation based on terrestrial radar observations as well as data from the Mariner 10 and the MESSENGER missions. Further, we describe the different available definitions of reference systems for Mercury and obtain the corresponding reference frame using data provided by instruments on board MESSENGER. In particular, we discuss the dynamical frame, the principal-axes frame, the ellipsoid frame, as well as the cartographic frame. We also describe the reference frame adopted by the MESSENGER science team for the release of their cartographic products, and we provide expressions for transformations from this frame to the other reference frames.  相似文献   

The evolution of spokes in Saturn's B ring     

Eberhard Grün  Gregor E. Morfill  Richard J. Terrile  Torrence V. Johnson  Gerhard Schwehm 《Icarus》1983,54(2):227-252

The optical appearance of spokes was studied in high resolution (?200 km/lp) images obtained by Voyager 2. Spokes are classified into three categories. (1) Extended spokes are seen in the distance interval of 100,000 to 112,000 km from Saturn's center. They have diffuse edges and are slightly wedge shaped. Their width at the base (towards Saturn) is about 20,000 km. Their active times (during which they increase in width) range from 4000 to 12,000 sec. (2) Narrow spokes are found in the distance range 104,000 to 116,000 km, have sharply defined edges, and are narrowest at the corotation distance (112, 300 km). Their typical radial extension and width is 6000 and 2,000 km, respectively. (3) Filamentary spokes are found outside 110,000 km mostly joined with a wider spoke further in. They are typically 3000 km in length and 500 km in width. Their active time is less than 1000 sec. Several narrow spokes were observed during formation along radial lines in the sunlit portion of the ring. The formation time is typically ?5 min for a 6000-km-long spoke. The rate of spoke formation is highest at the morning ansa outside Saturn's shadow. Several spokes have been found where one edge revolves with Keplerian speed whereas the other edge stays radial. Recurrent spoke patterns have been observed at the period of Saturn's rotation. From edge-on views of the ring system, an upper limit for the height of spokes of 80 km is derived.  相似文献