Geostatistical inversion of coupled problems: dealing with computational burden and different types of data

Practical application of geostatistical inversion to coupled problems is hampered by a number of difficulties. In this paper, we address two of them: first, the computational cost of sensitivity (Jacobian) matrices and, second, the evaluation of the relative weights of different types of data. Regarding the first, we revise the adjoint state equations to propose a form whose cost is independent of the number of unknown parameters and only grows with the number of observation wells. Regarding the second, we derive expressions for the relative weights of different types of data. These expressions are based on minimizing the expected likelihood, rather than the likelihood itself. The efficiency of both improvements is tested on a synthetic example. The example analyzes a wide range of groundwater flow and solute transport conditions. Yet, the expected likelihood consistently yields the optimal weights. The proposed form of the adjoint state equations leads to one order of magnitude reduction in CPU time with respect to the conventional sensitivity equations.     

The Contribution of Ecdysis to the Fate of Copper, Zinc and Cadmium in Grass Shrimp, Palaemonetes pugio Holthius

Depuration through ecdysis by grass shrimp, Palaemonetes pugio, was examined by exposure to a sublethal mixture of copper, zinc and cadmium for 72 h, followed by placement in uncontaminated water to molt. Percent eliminated with the exuviae varied for each metal; of the total intermolt body burden, 11% Cu, 18% Zn and 26% Cd was associated with the exuviae. Cu concentrations of intermolt exoskeletons were significantly higher than of the exuviae of post-ecdysis shrimp suggesting that Cu contained in the exoskeleton was reabsorbed before molting. Exuvial Cd concentration was not significantly different than the concentration of the intermolt exoskeleton, suggesting that most Cd in the exoskeleton was depurated with the exuviae. Although Zn whole-body burdens were lower after a molt, Zn losses were most likely due to excretion because exuvial concentrations were significantly lower than in the intermolt exoskeleton. Cu, Cd and Zn concentrations in exuviae shed in metal-enriched water were significantly higher due to adsorption than exuviae produced in uncontaminated water.     

Results based management in fisheries: Delegating responsibility to resource users

While the notion of results based management has been devoted recent attention in the context of reforming European fisheries management, it remains unclear what it entails. A conceptual model of results based management in fisheries is proposed as a way for public authorities to delegate specific management and documentation responsibilities to resource users. The model comprises three defining features: (1) That authorities define measurable objectives for the utilization of fisheries resources; (2) that resource users are made responsible for achieving these objectives and for (3) providing documentation that allows for an audit of the extent to which they are met. Selected cases are used to illustrate these features. Rationales and prospects of introducing results based management as an alternative in a European fisheries management context are discussed, giving consideration to how it may be pursued under the reformed common fisheries policy.     

Regional GHG reduction targets based on effort sharing: a comparison of studies

Over 40 studies that analyse future GHG emissions allowances or reduction targets for different regions based on a wide range of effort-sharing approaches and long-term concentration stabilization levels are compared. This updates previous work undertaken for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Regional reduction targets differ significantly for each effort-sharing approach. For example, in the Organisation for Economic Co-operation and Development (OECD) 1990 region, new proposals that emphasize the equity principles of responsibility, capability, and need, and those based on equal cumulative per capita emissions (carbon budgets), lead to relatively stringent emissions reduction targets. In order to reach a low concentration stabilization level of 450?ppm CO₂e, the allowances under all effort sharing approaches in OECD1990 for 2030 would be approximately half of the emissions of 2010 with a large range, roughly two-thirds in the Economies in Transition (EIT), roughly at the 2010 emissions level or slightly below in Asia, slightly above the 2010 level in the Middle East and Africa and well below the 2010 level in Latin America. For 2050, allowances in OECD1990 and EIT would be a fraction of today's emissions, approximately half of 2010 emission levels in Asia, and possibly less than half of the 2010 level in Latin America.

Policy relevance

The concept of equity and the stringency of future national GHG reduction targets are at the heart of the current debate on the new international climate change agreement to be adopted in 2015. Policy insights gained from an analysis of over 40 studies, which have quantitatively analysed the proposed GHG reduction targets, are presented. It is found that the outcome of effort-sharing approaches is often largely determined by the way the equity principle is implemented and that the distributional impacts of such approaches can be significantly different depending on the criteria used, the stabilization level and shape of the global emissions pathway. However, the current literature only covers a small proportion of the possible allocation approaches. There should thus be an in-depth modelling comparison to ensure consistency and comparability of results and inform decision making regarding the reduction of GHG emissions.     

中国黑碳气溶胶分布特征与辐射强迫的模拟研究

利用区域气候模式RegCM3模拟2000年我国黑碳气溶胶的分布特征和辐射强迫。结果表明,黑碳气溶胶主要分布在我国黄河以南、青藏高原以东的广大区域,柱含量由南向北递减;柱含量最大值在0.6mg／m^2以上,出现在中南、四川盆地、湖南、贵州、广西、广东西部和云南南部等地区;青藏高原南侧黑碳气溶胶次高值区的存在,反映了气溶胶的跨国界输送并影响区域气候的特点。黑碳气溶胶的大气顶辐射强迫介于0.1—0.8w／m^2之间,地表辐射强迫介于-0.1— -2.0W／m^2之间,两者分布特征与柱含量分布特征基本一致。同柱含量相似,黑碳气溶胶大气顸辐射强迫和地表辐射强迫也有明显的季节性变化,春季最大,秋、冬季次之,夏季最小。     

Radiative forcing and temperature response of dust aerosols over East Asia in the latest decade

A regional climate model, RegCM3, coupled with an online dust module, is used to simulate the radiative forcing (RF) and temperature response of dust aerosols over East Asia in the latest decade (2000–2009). The simulation results show that the geographical and seasonal differences of dust aerosols distribution over East Asia are obvious. There exist two extremes of dust aerosols with column burden (CB) greater than 1,000 mg/m²; one is in the Taklimakan Desert of the Xinjiang Uigur Autonomous Region, China, and the other is in the Badain Jaran Desert of the Inner Mongolian Autonomous Region, China. The maximum value of CB appears in spring, the secondary maximum in winter, and the minimum in autumn. The RF of dust aerosols has distribution characteristics similar to CB. The regional averaged RF over East Asia at the top of atmosphere (TOARF) is ?1.72 W/m² in spring and ?1.17 W/m² in autumn, and that at the surface (SURRF) is ?4.34 W/m² in spring and ?2.33 W/m² in autumn. The temperature at the surface is decreased by dust aerosols; the regional averaged temperature decrease over East Asia is 0.154 °C in spring and 0.085 °C in autumn. There are different impacts of dust aerosols on air temperature at different heights. The air temperature is decreased by dust aerosols in the lower troposphere, but the extent of the decrease diminishes with increasing height. The air temperature is in fact increased by dust aerosols at the height of 300–400 hPa in spring, which is greatly different from that in autumn.     

城市住房负担对上海流动人口居留意愿的影响

居留意愿被认为是影响流动人口居留决策的重要因素,而大城市不断增加的住房负担,日益成为制约流动人口居留意愿和行为的关键因素。鉴于既有研究中关于住房负担对流动人口居留意愿影响及其群体差异性考虑的不足,论文以上海为例,基于2012年和2017年流动人口动态监测调查问卷数据,采用二元Logistic回归模型,分析流动人口居留意愿的影响因素及其变化,并探讨住房负担对流动人口居留意愿与决策行为的影响。研究发现：① 房租收入比增加对于流动人口的居留意愿具有明显抑制作用,特别是低教育程度和低技术职业群体更加敏感;② 房价/房租的快速增长加重流动人口的住房负担,增加其实际居留难度,流动人口“想留不能留”将可能迫使其产生居留意愿的改变;③ 城市住房负担持续增加率先对较低劳动技能群体产生“驱离”效应,而压力进一步加剧则将导致更多流动人口迁出或被迫降低生活质量。建议城市政府为流动人口尽量提供更具包容性、可支付和多元化的住房。     

Breaking the impasse: towards a new regime for international climate governance

The reality of the current international order makes it imperative that a just and effective climate regime should balance the historical responsibility of developed countries with the increasing absolute emissions from many developing nations. The key pillars are briefly proposed for a new international climate architecture that envisions replacing the current annex system with two new annexes: Annex α, for countries with high current emissions and historically high emissions, and Annex β, for countries with high current emissions and historically low emissions. Countries in both annexes would implement legally binding targets under this framework. Additionally, this proposal includes alterations and revisions to funding and technology transfer mechanisms to correct for weaknesses and inequities under the current Kyoto architecture. The proposed framework stems from a belief that a top-down, international approach to climate policy remains the most effective for ensuring environmental integrity. Given the slow rate of institutional learning, the reform and improvement of the current system is held as a more efficient course of action than abandoning the progress already achieved. It is argued that the proposed framework could effectively accommodate key equity, environmental integrity, and political feasibility concerns.     

The Regensburg Model: reference values for the (I)NDCs based on converging per capita emissions†

A core question still remains after the Paris Agreement: who receives how much of the remaining CO₂ budget (resource/burden/effort sharing), so that the increase in the global average temperature is kept to well below 2°C above pre-industrial levels? If converging per capita emissions serve as a possible answer to this question, the discussion focuses primarily on the approach ‘Contraction and Convergence’ (C&C). The Regensburg Model now offers a further option for the mathematical implementation of converging per capita emissions. The authors identify features common to C&C and differences from C&C. They show that, of the convergence models they examined, the Regensburg Model is the most favourable option for industrialized countries.

Policy relevance

In politics, the concept of converging per capita emissions is often accepted at the abstract level. Civil society in particular can then take politicians at their word wherever they take values calculated using the Regensburg Model as points of reference; then prosperous developed countries in particular whose nationally determined contributions do not come up even to these reference values will find it difficult to justify their contributions.     

Agreement,significance, and understandings of historical responsibility in climate change negotiations

For over 20 years, Parties to the UN Framework Convention on Climate Change have struggled with the normative significance of history for the differentiation of responsibilities. Negotiations on ‘historical responsibility’ have been marked by considerable conflict between developed and developing countries. However, in 2010, the Parties acknowledged the concept in a consensus decision. This article analyses UN Climate Change Conference delegates' agreement with the decision, whether it reconciled conflict between interpretations of historical responsibility, and the significance that delegates ascribe to the decision for future agreements. The decision has not eliminated conflict between different interpretations. Delegates who understand historical responsibility as linking countries' historical contributions to climate change to their responsibilities to act agree more with the decision and foresee it having a stronger influence on future agreements than do those viewing the concept in more conceptual terms. The decision marks the start of negotiations concerning how rather than whether historical responsibility should guide operative text. This article demonstrates that (1) the divergent interpretations pose clear challenges for a necessary but demanding agreement on operationalization, and (2) focusing on an ambiguous version of proportionality between contribution to change and responsibility can become a first step for convergence between divergent positions.