Uncertainty and economic analysis of climate change: A survey of approaches and findings

The analysis of climate change is confronted with large uncertainties that need to be taken into account to arrive at meaningful policy recommendations. The main contribution of economics to this interdisciplinary task is to provide formal frameworks and techniques for analyzing climate policy in the context of uncertainty. This paper will give an overview of existing approaches and findings to provide a broad picture of what economics can contribute to the debate.     

global climate change: processes and products – an overview

Our knowledge of global climate change has many uncertainties.Whether global air temperature will increase, by how much, and when,are subject to debate, but there is little doubt that troposphericconcentrations of several trace gases are increasing. While possibleincreases in the average air temperature is a product of these changes,the increases in the trace gases alone will have an effect on agriculture.Increases in the ambient concentrations of carbon dioxide are expectedto have a positive net effect on crop production. In contrast, anyincreases in the penetration of surface-level ultraviolet-B (280–320 nm)radiation, and known increases in surface ozone concentrations, areconsidered to have adverse effects on certain crops. Our presentknowledge of the joint effects on crops of elevated levels of carbondioxide, ultraviolet-B radiation and ozone, and possible alterations in airtemperature and precipitation patterns, is virtually zero. Therefore, anypredictions of the effects of global climate change on agriculture aresubject to significant uncertainties. In contrast, coupling of climatechange (only temperature and precipitation) models to crop productionhas led to a number of future scenarios. In spite of theirpresent limitations, results from these efforts can be useful in planningfor future agriculture.     

Carrots and sticks for new technology: Abating greenhouse gas emissions in a heterogeneous and uncertain world

Many governments use technology incentives as an important component of their greenhouse gas abatement strategies. These carrots are intended to encourage the initial diffusion of new, greenhouse-gas-emissions-reducing technologies, in contrast to carbon taxes and emissions trading which provide a stick designed to reduce emissions by increasing the price of high-emitting technologies for all users. Technology incentives appear attractive, but their record in practice is mixed and economic theory suggests that in the absence of market failures, they are inefficient compared to taxes and trading. This study uses an agent-based model of technology diffusion and exploratory modeling, a new technique for decision-making under conditions of extreme uncertainty, to examine the conditions under which technology incentives should be a key building block of robust climate change policies. We find that a combined strategy of carbon taxes and technology incentives, as opposed to carbon taxes alone, is the best approach to greenhouse gas emissions reductions if the social benefits of early adoption sufficiently exceed the private benefits. Such social benefits can occur when economic actors have a wide variety of cost/performance preferences for new technologies and either new technologies have increasing returns to scale or potential adopters can reduce their uncertainty about the performance of new technologies by querying the experience of other adopters. We find that if decision-makers hold even modest expectations that such social benefits are significant or that the impacts of climate change will turn out to be serious then technology incentive programs may be a promising hedge against the threat of climate change.     

塔里木南缘孤立绿洲近50年气候变化特征分析

通过分析塔里木盆地孤立绿洲民丰县气温、降水2个气象要素的相关资料得出，从20世纪50年代至90年代，气温呈上升趋势，而夏秋两季降水量随温度上升而上升。从气象要素的历史变化和季节分布特征看，塔里木盆地的孤立绿洲整体环境状况仍处于比较差的阶段。此分析结论对合理利用本地气候资源具有实际意义，并且能够为研究干旱区气候变化提供一定的帮助。     

The personal CO2 calculator: A modeling tool for Participatory Integrated Assessment methods

Participatory Integrated Assessment (PIA) is an approach which aims at developing methods which allow to combine evaluations of experts and lay people in the field of Integrated Assessment. Thus, policy recommendations derived from PIA exercises are informed by scientific judgments and by valuations of “non-scientists”. For any PIA methodology the provision of insights, facts and figures about the policy problem at hand is crucial. In this paper we describe a PIA methodology which combines the social science research instrument “focus group” with a specific computer information tool, the “Personal CO₂ Calculator” (PCC). The tool supports citizens in discussing and recommending measures on climate change policy. Based on our experiences, we plead for information instruments that are tuned to and assist concrete target groups with their specific interests. This helps that policy recommendations derived from PIA exercises are based on both scientific knowledge as well as citizens' and stakeholders' policy preferences. This revised version was published online in July 2006 with corrections to the Cover Date.     

Rural poverty driven soil degradation under climate change: the sensitivity of the disposition towards the Sahel Syndrome with respect to climate

Starting from the basic assumption of the syndrome concept that essentially all of the present problematic civilization–nature interactions on the global scale can be subdivided into a limited number of typical patterns, the analysis of the response of these patterns (syndromes) to climate change can make a major contribution to climate impact research, surmounting the difficulties of more common sectoral ceteris paribus impact studies with respect to their systemic integration. In this paper we investigate in particular the influence of climate on the regional proneness or disposition towards one of the most important syndromes with respect to famines and malnutrition, the Sahel Syndrome. It describes the closely interlinked natural and socioeconomic aspects of rural poverty driven degradation of soil and vegetation on marginal sites. Two strategies of global climate impact assessment on a spatial 0.5°×0.5° grid were pursued: (a) As a measure for the climate sensitivity of the regional proneness, the absolute value of the gradient of the disposition with respect to the global field of 3} 12 monthy normals of temperature, irradiation and precipitation is calculated. (b) The disposition was evaluated for two different climate forecasts under doubled atmospheric CO₂ concentration. For both strategies two new quantitative global models were incorporated in a fuzzy-logic-based algorithm for determining the disposition towards the Sahel Syndrome: a neural-net-based model for plant productivity and a waterbalance model which calculates surface runoff considering vertical and lateral fluxes, both driven by the set of 36 monthly climatological normals and designed to allow very fast global numerical evaluation.Calculation (b) shows that the change in disposition towards the Sahel Syndrome crucially depends on the chosen climate forecast, indicating that the disagreement of climate forecasts is propagated to the impact assessment of the investigated socio-economic pattern. On the other hand the regions with a significant increase in disposition in at least one of the climate scenario-based model runs form a subset of the regions which are indicated by the local climate sensitivity study (a) as highly sensitive – illustrating that the gradient measure applied here provides a resonable way to calculate an upper limit or worst case of negative climate impact. This method is particularly valuable in the case of uncertain climate predictions as, e.g., for the change in precipitation patterns.     

全球变暖 夏季变凉

气候变化历来为人类所重视。近几十年来频繁而强烈的气候异常 ,已使人们认识到超极限地使用自然资源和气候资源、无所顾忌地排放各种污染物给人类带来的灾难。文章在总结、分析前人对未来气候变化的各种理论的基础上 ,根据影响气候的各因子及反馈关系的研究 ,提出未来世界气候变化的总体趋势是 :全球变暖 ,夏季变凉 ,气候异常将更加剧烈和频繁     

A Method for Integrated Assessment of Vulnerability to Climate Change in Siberian Forests: Example of Larch Area

The conceptual scheme of integrated assessment of vulnerability to climate change in Siberian forests is elaborated and applied to the extensive area in Siberia covered by Larch forests. Forest stakeholders on the provincial level are identified to be the most relevant for an integrated impact assessment. Organisation of the assessment study as a combination of 'top-down' and 'bottom-up' approaches is suggested. Major biophysical vulnerability indexes and regional syndromes are identified as the growing stock and current increment averaged by administrative unit. Models and data suitability and quality for an analysis of biophysical vulnerability in conditions of climate change are studied for Siberian forests and future development trends are identified. An application of the elaborated conceptual scheme, which employs two models of different type and forest inventory data, is presented for the Larch area.     

太湖流域水灾演变与环境变迁的相关分析

新石器时期以来,太湖地区的水灾发生机制和表现形式严格受控于海、地、气系统的能量均衡和转换过程,具有明显的阶段性特征,遵循由海洋优势性向海面控制基准下陆源洪水的演变过程.愈接近现代,成灾和干扰因素愈趋复杂,逐渐呈现出水灾与环境相互反馈使水灾加深(岗身体系形成并完善,太湖形成并扩张以来),以及人类活动、水灾与环境三者间相互反馈使水灾频度加大等趋势(尤其自南宋以来).提出了相对高海面的水灾控制基面效应和太湖水灾扩张效应等观点.     

温室效应对我国长江中下游地区气候的影响--数值模拟

利用RegCM2区域气候模式嵌套一个全球模式,进行了CO2加倍情况下对中国区域气候影响的数值试验,对长江中下游地区的情况进行了重点分析.结果表明,在CO2加倍的情况下,长江中下游地区的气温将明显升高,升高值一般在2.3～2.5℃以上,但低于全国平均值.同时,其大部分区域的降水也将增加,特别是在冬季和夏季,但年平均的增加率仅为7%,也低于全国平均值.温室效应会使该地区的日平均最高和最低气温升高,降水日数增多.夏季降水的增多可能会导致这一地区夏季更多的洪涝灾害.