联合国千年生态评估及其启示

从“牧童经济”到可持续发展人类经历了漫长的历程。在可持续发展提出后的十几年内,经济与社会的进步对生态系统变化所起的作用仍难以估量,但全球生态系统及其供应能力并没有因此而得到理想的好转,全球环境恶化的趋势尚没有得到根本的改变,人类要有一个艰难的历程。但在可持续发展战略的指引下,最终会达到人与自然和谐共处的目标。     

单体经济模型下市场均衡状态利润成本变动规律浅析

微观经济学研究单体经济模型中经济活动个体的经济行为 ,核心是价格决定理论。商品的价格是由市场中对这种商品的供给和需求决定的。供给和需求相反的作用力 ,使商品达到市场均衡状态。当商品的生产成本发生变化时 ,供给函数发生变化 ,达到新的市场均衡。但均衡利润呈现出与生产成本变动相反的变化趋势。本文试图对其变化规律做出探讨。     

Adaptation to climate change in Africa: Challenges and opportunities identified from Ethiopia

Africa is widely held to be highly vulnerable to future climate change and Ethiopia is often cited as one of the most extreme examples. With this in mind we seek to identify entry points to integrate short- to medium-term climate risk reduction within development activities in Africa, drawing from experiences in Ethiopia. To achieve this we employ a range of data and methods. We examine the changing nature of climate risks using analysis of recent climate variability, future climate scenarios and their secondary impacts. We assess the effects of climate variability on agricultural production and national GDP. Entry points and knowledge gaps in relation to mainstreaming climate risks in Ethiopia are identified using the Government's plan for poverty reduction. We end with a case study incorporating climate risks through drought insurance within the current social protection programme in Ethiopia, which provides support to 8.3 million people.Rainfall behaviour in Ethiopia shows no marked emergent changes and future climate projections show continued warming but very mixed patterns of rainfall change. Economic analysis highlights sensitivities within the economy to large-scale drought, however, while the effects are clear in major drought years in other years the relationship is weak. For social protection fairly small positive and negative effects on the number of recipients and frequency of cash payments during drought occur under the extreme range of climate model rainfall projections (2020s).Our analysis highlights several important challenges and opportunities for addressing climate risks. Challenges primarily relate to the large uncertainties in climate projections for parts of Africa, a weak evidence base of complex, often non-deterministic, climate-society interactions and institutional issues. Opportunities relate to the potential for low-regrets measures to reduce vulnerability to current climate variability which can be integrated with relatively modest effort within a shift in Africa from a disaster-focused view of climate to a long-term perspective that emphasises livelihood security and vulnerability reduction.     

Modelling innovation and the macroeconomics of low-carbon transitions: theory,perspectives and practical use

Energy and climate policies may have significant economy-wide impacts, which are regularly assessed based on quantitative energy-environment-economy models. These tend to vary in their conclusions on the scale and direction of the likely macroeconomic impacts of a low-carbon transition. This paper traces the characteristic discrepancies in models’ outcomes to their origins in different macro-economic theories, most importantly their treatment of technological innovation and finance. We comprehensively analyse the relevant branches of macro-innovation theory and group them into two classes: ‘Equilibrium’ and ‘Non-equilibrium’. While both approaches are rigorous and self-consistent, they frequently yield opposite conclusions for the economic impacts of low-carbon policies. We show that model outcomes are mainly determined by their representations of monetary and finance dimensions, and their interactions with investment, innovation and technological change. Improving these in all modelling approaches is crucial for strengthening the evidence base for policy making and gaining a more consistent picture of the macroeconomic impacts of achieving emissions reductions objectives. The paper contributes towards the ongoing effort of enhancing the transparency and understanding of sophisticated model mechanisms applied to energy and climate policy analysis. It helps tackle the overall ‘black box’ critique, much-cited in policy circles and elsewhere.

Key policy insights

• Quantitative models commissioned by policy-makers to assess the macroeconomic impacts of climate policy generate contradictory outcomes and interpretations.

• The source of the differences in model outcomes originates primarily from assumptions on the workings of the financial sector and the nature of money, and of how these interact with processes of low-carbon energy innovation and technological change.

• Representations of innovation and technological change are incomplete in energy-economy-environment models, leading to limitations in the assessment of the impacts of climate-related policies.

• All modelling studies should state clearly their underpinning theoretical school and their treatment of finance and innovation.

• A strong recommendation is given for modellers of energy-economy systems to improve their representations of money and finance.

     

Hydrogen from coal gasification: An economical pathway to a sustainable energy future

Although hydrogen is the most abundant element in the universe, it does not occur naturally in large quantities or high concentrations on Earth. Hydrogen must be produced from other compounds such as fossil fuels, biomass, or water and is therefore considered an energy carrier like electricity. Gasification of carbonaceous, hydrogen-containing fuels is an effective method of thermal hydrogen production and is considered to be a key technology in the transition to a hydrogen economy. However, for gasification to play a major role during the transition period, capital and operating cost must be reduced and reliability and performance must be improved.Analyses show that hydrogen produced from coal-based gasification can be competitive with production from natural gas provided the cost of natural gas remains above $4/10⁶ Btu and the high reliability of gasification-based processes can be demonstrated. But for coal to be considered in a carbon-constrained environment, the cost of natural gas would have to be greater than $5.50/10⁶ Btu. The development of advanced technologies, however, offers the potential for significant reductions in capital costs, improved thermal efficiencies, and increased reliability. If these advanced technologies are capable of achieving their goals, the cost of producing hydrogen from coal could be reduced by 25–50%, even with the capture and sequestration of CO₂. With these reductions, the cost of natural gas would have to be less than $2.50/10⁶ Btu to compete, a scenario that is very unlikely to occur in the future. This potential cost reduction provides considerable impetus for continuing research and development in the production of hydrogen from coal.     

Deep-sea mining of seafloor massive sulfides

The potential emergence of an ocean mining industry to exploit seafloor massive sulfides could present opportunities for oceanographic science to facilitate seafloor mineral development in ways that lessen environmental harms.     

Maritime piracy confrontations across the globe: Can crew action shape the outcomes?

The recent tightening of military budget constraints has called into question the feasibility of costly multilateral naval intervention used to combat maritime piracy off the eastern coast of Africa. Though past studies agree that the transformation of the Somali economy and government is crucial for a long-term solution to piracy in this part of the world, short to medium-run solutions are needed to bridge the gap. Such solutions should be fiscally sensible and serve as effective deterrents, as well as be applicable in addressing the problem of piracy and maritime armed robbery in other parts of the globe. This paper builds upon the foundations laid in Mejia et al. [12] and Mileski et al. [13] by examining the following question: given that a ship is engaged by pirates, what factors help shape the outcome of the confrontation? This study finds that observable action taken on the part of a ship's crew is extremely effective in decreasing the risk of a ship being successfully robbed or hijacked. There has yet (as of May 2014) to be a reported incident where pirates successfully hijacked a vessel that had a security team on board, and so though the effectiveness of security in this matter can be inferred, it cannot be empirically tested (the same is true – in this study's dataset – of the effect of onboard security on deterring robberies). This may provide some guidance for policymakers; if naval intervention is to be scaled back, the encouragement and oversight of shipping companies’ crew response procedures (and perhaps of onboard security measures) by international governments could pose a valid alternative.     

Exploiting autoregressive properties to develop prospective urban arson forecasts by target

Municipal fire departments responded to approximately 53,000 intentionally-set fires annually from 2003 to 2007, according to National Fire Protection Association figures. A disproportionate amount of these fires occur in spatio-temporal clusters, making them predictable and, perhaps, preventable. The objective of this research is to evaluate how the aggregation of data across space and target types (residential, non-residential, vehicle, outdoor and other) affects daily arson forecast accuracy for several target types of arson, and the ability to leverage information quantifying the autoregressive nature of intentional firesetting. To do this, we estimate, for the city of Detroit, Michigan, competing statistical models that differ in their ability to recognize potential temporal autoregressivity in the daily count of arson fires. Spatial units vary from Census tracts, police precincts, to citywide. We find that (1) the out-of-sample performance of prospective hotspot models for arson cannot usefully exploit the autoregressive properties of arson at fine spatial scales, even though autoregression is significant in-sample, hinting at a possible bias-variance tradeoff; (2) aggregation of arson across reported targets can yield a model that differs from by-target models; (3) spatial aggregation of data tends to increase forecast accuracy of arson due partly to the ability to account for temporally dynamic firesetting; and (4) arson forecast models that recognize temporal autoregression can be used to forecast daily arson fire activity at the Citywide scale in Detroit. These results suggest a tradeoff between the collection of high resolution spatial data and the use of more sophisticated modeling techniques that explicitly account for temporal correlation.