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"Müller, Wolfgang"
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Delegation and accountability in parliamentary democracies
Parliamentary democracy is the most common way of organizing delegation and accountability in contemporary democracies. Yet knowledge of this type of regime has been incomplete and often unsystematic. Delegation and Accountability in Parliamentary Democracies offers new conceptual clarity on the topic. Taking principal-agent theory as its framework, the work illustrates how a variety of apparently unrelated representation issues can now be understood. This procedure allows scholarship to move well beyond what have previously been cloudy and confusing debates aimed at defining the virtues and perils of parliamentarism. This new empirical investigation includes all 17 West European parliamentary democracies. These countries are compared in a series of cross-national tables and figures, and 17 country chapters provide a wealth of information on four discrete stages in the delegation process: delegation from voters to parliamentary representatives, delegation from parliament to the prime minister and cabinet, delegation within the cabinet, and delegation from cabinet ministers to civil servants. Each chapter illustrates how political parties serve as bonding instruments, which align incentives and permit citizen control of the policy process. This is complemented by a consideration of external constraints, such as courts, central banks, corporatism, and the European Union, which can impinge on national-level democratic delegation. The concluding chapters go on to consider how well the problems of delegation and accountability are solved in these countries. Delegation and Accountability in Parliamentary Democracies provides an unprecedented guide to contemporary European parliamentary democracies. As democratic governance is transformed at the dawn of the twenty-first century, it illustrates the important challenges faced by the parliamentary democracies of Western Europe.
eBook
القلاع أيام الحروب الصليبية
عمل تاريخى يقدمه الكاتب الكبير فولفغانغ مولرفيز كبحث فى حقبة الحروب الصليبية عبر تاريخها، يتناول الكتاب تشييد القلاع والحصون فى الحروب الصليبية داخل البلدان التى دخلها الصليبيون. إليك كتاب القلاع أيام الحروب الصليبية. يحاول مؤلف هذا الكتاب، وهو ألماني الجنسية، إعطاء فكرة عامة عن القلاع التي وقع اختيار عليها من مصادر عديدة ورد ذكرها في نهاية الكتاب. وجعل من كتابه أقساما ثلاثة. تضمن أولها: المدخل، ويتناول فيه المؤلف تاريخ الحروب الصليبية بإبجاز شديد، مع إبراز أهم وقائعه، والدول الصليبية التي تأسست في بلاد الشام وآسيا الصغرى واليونان. وتضمن القسم الثاني : (القلاع)، وصف أهم القلاع التي ما تزال موجودة آثارها حتى يومنا هذا، من حيث موقعها وتخطيطها وأهميتها وتاريخها اعتبارا من بداية الحروب الصليبية، (وهو لا يحاول هنا الرجوع إلى تاريخ بناء القلعة الأول منذ أن شيدت). أما القسم الثالث : فيتضمن مجموعة من اللوحات المصورة لأهم المدن المحصنة والقلاع (160 لوحة)، مع شرح لمحتويات اللوحة. كما تضمن الكتاب أيضا لائحة بأسماء القلاع الرئيسية، والمكان الذي ورد إسمها فيه، وخريطة امة تبين مواقع المدن والقلاع المختلفة إبان الحروب الصليبية، وثبتا بالمراجع التي استند إليها في وصف كل قلعة، والمراجع العامة.
Book
Dynamical and thermodynamical drivers of variability in European summer heat extremes
We use the 100-member Max Planck Institute Grand Ensemble (MPI-GE) to disentangle the contributions from colocated dynamic atmospheric conditions and local thermodynamic effects of moisture limitation as drivers of variability in European summer heat extremes. Using a novel extreme event definition, we find that heat extremes with respect to the evolving mean climate increase by 70% under a moderate warming scenario during the twenty-first century. With a multiple regression approach, we find that the dynamical mechanisms representing blocking and anticyclonic conditions are the main driver of variability in extreme European summer temperatures, both in past and future climates. By contrast, local thermodynamic drivers play a secondary role in explaining the total variability in extreme temperatures. We also find that considering both dynamical and thermodynamical sources of variability simultaneously is crucial. Assessing only one type of drivers leads to an overestimation of their effect on extreme temperatures, particularly when considering only thermodynamical drivers. Lastly, we find that although most past and future heat extremes occur under favorable dynamical atmospheric conditions; this occurs 10–40% less frequently over Central Europe in the twenty-first century. By contrast, heat extremes over Central Europe occur 40% more frequently under concurrent extreme moisture limitation in the twenty-first Century. Our findings highlight a new type of neutral-atmosphere, moisture-driven heat extremes, and confirm that the increase in European heat extremes and associated variability increase are dominated by the local thermodynamic effect of moisture limitation.
Journal Article
Towards operational predictions of the near-term climate
Near-term climate predictions — which operate on annual to decadal timescales — offer benefits for climate adaptation and resilience, and are thus important for society. Although skilful near-term predictions are now possible, particularly when coupled models are initialized from the current climate state (most importantly from the ocean), several scientific challenges remain, including gaps in understanding and modelling the underlying physical mechanisms. This Perspective discusses how these challenges can be overcome, outlining concrete steps towards the provision of operational near-term climate predictions. Progress in this endeavour will bridge the gap between current seasonal forecasts and century-scale climate change projections, allowing a seamless climate service delivery chain to be established.Near-term climate predictions bridge the gap between seasonal forecasts and long-term projections. This Perspective outlines the challenges and opportunities for near-term climate prediction, highlighting the need for co-ordinated efforts to benefit society.
Journal Article
A systematic atmospheric parameter optimization method to improve ENSO simulation in the ICON XPP Earth system model
The El Niño–Southern Oscillation (ENSO) is a dominant mode of interannual climate variability, yet accurately simulating ENSO in climate models remains a major challenge due to its complex coupled dynamics. In this study, we present a linear optimization framework and systematically adjust atmospheric parameters to improve ENSO fidelity in the Icosahedral Nonhydrostatic eXtended Predictions and Projections (ICON XPP) Earth System Model of the Max-Planck-Institute for Meteorology. The optimization approach is based on the superposition of parameter sensitivities and a Nelder–Mead algorithm that reduces the ENSO cost function. The cost function accounts for ENSO-related tropical climatology, variability, and feedbacks, which are estimated with the ENSO metric package. We first assess the sensitivity of ENSO metrics to 21 atmospheric parameters in atmosphere-only simulations. The optimization approach reduces the ENSO cost function by 30 % in the optimized atmosphere-only runs. Key improvements include reduced precipitation bias and strengthened atmospheric feedbacks such as the Bjerknes and thermal damping feedbacks. These results demonstrate the effectiveness of our method in improving ENSO metrics within the atmosphere-only configuration. Six parameters identified as most impactful from atmosphere-only tuning experiments are subsequently tuned in fully coupled simulations. The optimized fully coupled run yields moderate improvements in ENSO amplitude, cold tongue SST bias, seasonal phase-locking, ocean-atmosphere coupling and teleconnection patterns. However, isolated ENSO tuning introduces unrealistic global warming, which is further corrected by adjusting turbulence-related parameters without degrading ENSO skill. These results demonstrate that systematic ENSO tuning can yield performance gains but must be balanced with broader climate stability constraints. Our method offers a scalable, physically grounded optimization strategy, with strong potential for tuning ENSO in climate model configurations.
Journal Article
Hotspots of extreme heat under global warming
We evaluate how hotspots of different types of extreme summertime heat change under global warming increase of up to
4
∘
C
; and which level of global warming allows us to avert the risk of these hotspots considering the irreducible range of possibilities defined by well-sampled internal variability. We use large samples of low-probability extremes simulated by the 100-member Max Planck Institute Grand Ensemble (MPI-GE) for five metrics of extreme heat: maximum absolute temperatures, return periods of extreme temperatures, maximum temperature variability, sustained tropical nights, and wet bulb temperatures. At
2
∘
C
of warming, MPI-GE projects maximum summer temperatures below
50
∘
C
over most of the world. Beyond
2
∘
C
, this threshold is overshot in all continents, with the maximum projected temperatures in hotspots over the Arabic Peninsula. Extreme 1-in-100-years pre-industrial temperatures occur every 10–25 years already at
1.5
∘
C
of warming. At
4
∘
C
, these 1-in-100-years extremes are projected to occur every 1 to 2 years over most of the world. The range of maximum temperature variability increases by 10–50% at
2
∘
C
of warming, and by 50–100% at
4
∘
C
. Beyond
2
∘
C
, heat stress is aggravated substantially over non-adapted areas by hot and humid conditions that occur rarely in a pre-industrial climate; while extreme pre-industrial tropical night conditions become common-pace already at
1.5
∘
C
. At
4
∘
C
of warming, tropical night hotspots spread polewards globally, and are sustained during more than 99% of all summer months in the tropics; whilst extreme monthly mean wet bulb temperatures beyond
26
∘
C
spread both over large tropical as well as mid-latitude regions.
Journal Article
Extreme heat and drought typical of an end-of-century climate could occur over Europe soon and repeatedly
Extreme heat and drought typical of an end-of-century climate could soon occur over Europe, and repeatedly. Despite the European climate being potentially prone to multi-year successive extremes due to the influence of the North Atlantic variability, it remains unclear how the likelihood of successive extremes changes under warming, how early they could reach end-of-century levels, and how this is affected by internal climate variability. Using the Max Planck Institute Grand Ensemble, we find that even under moderate warming, end-of-century heat and drought levels virtually impossible 20 years ago reach 1-in-10 likelihoods as early as the 2030s. By 2050–2074, two successive years of single or compound end-of-century extremes, unprecedented to date, exceed 1-in-10 likelihoods; while Europe-wide 5-year megadroughts become plausible. Whole decades of end-of-century heat stress could start by 2040, by 2020 for drought, and with a warm North Atlantic, end-of-century decades starting as early as 2030 become twice as likely.
Journal Article
Determination of metamaterial parameters by means of a homogenization approach based on asymptotic analysis
By using modern additive manufacturing techniques, a structure at the millimeter length scale (macroscale) can be produced showing a lattice substructure of micrometer dimensions (microscale). Such a system is called a metamaterial at the macroscale, because its mechanical characteristics deviate from the characteristics at the microscale. Consequently, a metamaterial is modeled by using additional parameters. These we intend to determine. A homogenization approach based on asymptotic analysis establishes a connection between these different characteristics at micro- and macroscales. A linear elastic first-order theory at the microscale is related to a linear elastic second-order theory at the macroscale. Small strains (and, correspondingly, small gradients) are assumed at both scales. A relation for the parameters at the macroscale is derived by using the equivalence of energy at macro- and microscales within a so-called representative volume element (RVE). The determination of the parameters becomes possible by solving a boundary value problem within the framework of the finite element method. The proposed approach guarantees that the additional parameters vanish if the material is purely homogeneous; in other words, it is fully compatible with conventional homogenization schemes based on spatial averaging techniques. Moreover, the proposed approach is reliable, because it ensures that the obtained additional parameters are insensitive to choices of the RVE consisting of a repetition of smaller RVEs depending upon the intrinsic size of the structure.
Journal Article