Environmental policy: regional commitment to reducing emissions

The non-participation of the United States in the recently ratified Kyoto Protocol is a matter for global concern because it is estimated that the country produces 24% of all greenhouse-gas emissions worldwide. Here we analyse the commitment of individual states and municipalities to addressing this problem and find that, despite the federal policy, between 24 and 35% of the US population are currently (or soon will be) engaged in policies directed towards significantly reducing anthropogenic climate change. The importance of this sub-national effort, which we estimate corresponds to 27-49% of the gross domestic product, will depend--like the targets adopted in Kyoto--on the real reductions achieved in greenhouse-gas emissions.     

Origins and estimates of uncertainty in predictions of twenty-first century temperature rise

Predictions of temperature rise over the twenty-first century are necessarily uncertain, both because the sensitivity of the climate system to changing atmospheric greenhouse-gas concentrations, as well as the rate of ocean heat uptake, is poorly quantified and because future influences on climate-of anthropogenic as well as natural origin-are difficult to predict. Past observations have been used to help constrain the range of uncertainties in future warming rates, but under the assumption of a particular scenario of future emissions. Here we investigate the relative importance of the uncertainty in climate response to a particular emissions scenario versus the uncertainty caused by the differences between future emissions scenarios for our estimates of future change. We present probabilistic forecasts of global-mean temperatures for four representative scenarios for future emissions, obtained with a comprehensive climate model. We find that, in the absence of policies to mitigate climate change, global-mean temperature rise is insensitive to the differences in the emissions scenarios over the next four decades. We also show that in the future, as the signal of climate change emerges further, the predictions will become better constrained.     

Increased soil emissions of potent greenhouse gases under increased atmospheric CO2

Increasing concentrations of atmospheric carbon dioxide (CO(2)) can affect biotic and abiotic conditions in soil, such as microbial activity and water content. In turn, these changes might be expected to alter the production and consumption of the important greenhouse gases nitrous oxide (N(2)O) and methane (CH(4)) (refs 2, 3). However, studies on fluxes of N(2)O and CH(4) from soil under increased atmospheric CO(2) have not been quantitatively synthesized. Here we show, using meta-analysis, that increased CO(2) (ranging from 463 to 780 parts per million by volume) stimulates both N(2)O emissions from upland soils and CH(4) emissions from rice paddies and natural wetlands. Because enhanced greenhouse-gas emissions add to the radiative forcing of terrestrial ecosystems, these emissions are expected to negate at least 16.6 per cent of the climate change mitigation potential previously predicted from an increase in the terrestrial carbon sink under increased atmospheric CO(2) concentrations. Our results therefore suggest that the capacity of land ecosystems to slow climate warming has been overestimated.     

Removal of chlorofluorocarbons by increased mass exchange between the stratosphere and troposphere in a changing climate

Chlorofluorocarbons (CFCs), along with bromine compounds, have been unequivocally identified as being responsible for most of the anthropogenic destruction of stratospheric ozone. With curbs on emissions of these substances, the recovery of the ozone layer will depend on their removal from the atmosphere. As CFCs have no significant tropospheric removal process, but are rapidly photolysed above the lower stratosphere, the timescale for their removal is set mainly by the rate at which air is transported from the troposphere into the stratosphere. Using a global climate model we predict that, in response to the projected changes in greenhouse-gas concentrations during the first half of the twenty-first century, this rate of mass exchange will increase by 3% per decade. This increase is due to more vigorous extra-tropical planetary waves emanating from the troposphere. We estimate that this increase in mass exchange will accelerate the removal of CFCs to an extent that recovery to levels currently predicted for 2050 and 2080 will occur 5 and 10 years earlier, respectively.     

Reverse microemulsion synthesis of nanostructured complex oxides for catalytic combustion

Catalysts play an important role in many industrial processes, but their use in high-temperature applications-such as energy generation through natural gas combustion, steam reforming and the partial oxidation of hydrocarbons to produce feedstock chemicals--is problematic. The need for catalytic materials that remain stable and active over long periods at high operation temperatures, often in the presence of deactivating or even poisoning compounds, presents a challenge. For example, catalytic methane combustion, which generates power with reduced greenhouse-gas and nitrogen-oxide emissions, is limited by the availability of catalysts that are sufficiently active at low temperatures for start-up and are then able to sustain activity and mechanical integrity at flame temperatures as high as 1,300 degrees C. Here we use sol-gel processing in reverse microemulsions to produce discrete barium hexa-aluminate nanoparticles that display excellent methane combustion activity, owing to their high surface area, high thermal stability and the ultrahigh dispersion of cerium oxide on the their surfaces. Our synthesis method provides a general route to the production of a wide range of thermally stable nanostructured composite materials with large surface-to-volume ratios and an ultrahigh component dispersion that gives rise to synergistic chemical and electronic effects, thus paving the way to the development of catalysts suitable for high-temperature industrial applications.     

碳排放交易机制下随机性库存控制模型研究

为避免全球变暖造成灾难性的影响,碳排放交易机制已成为一种人们普遍接受的控制碳排放手段。建立了碳排放交易机制下随机性库存控制模型,分析了不同条件下最优订购量与期望成本的变化,得出当碳交易价格增加时,最优订购量会减少;碳排放配额增加时,期望成本会减少,而最优订购量保持不变。最后用算例说明碳排放交易机制使政府更重视企业微观层面的节能减排,引导企业更倾向减少碳排放量。     

考虑成本-碳排放量双目标的快递包装回收设施选址研究

2014年我国快递业务量成为世界第一,这标志着我国快递行业进入快速发展阶段。但是与此同时,快递包装带来的资源浪费和环境污染日益凸显。建立快递包装回收逆向物流网络,对快递包装进行回收是解决上述问题的有效途径。同时,在“双碳”战略要求下,决策者在进行规划时不仅要考虑成本因素,还要考虑碳排放量对环境的影响,以及在实施过程中对成本和碳排放量目标的权衡。针对上述问题,本研究建立考虑成本-碳排放量双目标的快递包装回收设施选址模型。为使模型更加贴近实际,本研究考虑了不同区域建设成本、不同处理技术成本和不同车辆类型对成本和碳排放量的影响。为求解模型,本研究利用NSGA-Ⅱ算法进行求解,得到了Pareto前沿解。本研究将Pareto前沿解根据成本和碳排放量的相对关系划分为3类,并分析每一类的特点,为决策者在实践中根据现实的经济发展水平和碳排放量要求进行决策提供了依据。     

中国未来国际海运CO2排放量预测

在充分调研国际海运CO2排放量计算方法及预测模型的基础上,建立了中国国际海运CO2排放量预测模型,并结合航运经济与物流研究所(ISL)等国际海运相关机构发布的数据以及政府间气候变化专门委员会(IPCC)排放情景特别报告(SRES)的基准情景,对中国2010—2050年国际海运CO2排放量进行了预测。并进一步分析了国际海事组织(IMO)意推的市场机制(碳税)对中国进出口贸易和国际海运运营成本的影响,为中国气候变化国际谈判、国际海运减排谈判和行业发展等提出相关政策建议。结果表明,未来20～30年,中国国际海运CO2排放量仍将快速增长。基准情景下2050年中国国际海运CO2排放量将达到2 337～5 790万t,为2010年的0.7～1.8倍。当碳税税率在15～45美元/t(以CO2为基准)时,将导致中国国际海运运营成本提高0.96%～9.76%。     

成本和时间约束下的集装箱运输的碳排放研究

随着中国集装箱吞吐量的不断增长,集装箱运输过程中产生的碳排放问题日益加剧。在对集装箱多种运输方式优化组合,建立加入多集装箱载货状态的成本,时间和碳排放的多目标规划模型,运用逐步法对模型进行求解。针对集装箱运输过程中差异需求,通过对成本和时间设置不同的约束,使得集装箱在运输过程中选择不同运输方式组合,从而达到碳排放量最少的目标。为实现集装箱运输企业不同需求下实施的碳排放控制策略提供科学依据。     

电厂中CO_2捕集技术的成本及效率

电厂中CO2捕集过程中成本过高和额外能耗问题是CO2捕集与封存(CCS)技术迄今没有大规模应用的重要障碍之一。针对电力部门,重点总结并比较各种CO2捕集技术成本,分析影响成本的重要因素,量化捕集过程中的效率损失、能源需求以及相关资源消耗。结合中国未来发展趋势,分析实行CO2捕集技术对中国能源和经济的影响。结果表明,超超临界煤粉电厂和IGCC电厂是未来CO2捕集技术发展的首选电厂类型。中国应积极进行CO2捕集技术的研发,使得成本和效率损失大幅度下降,使带有捕集的电厂成为中国温室气体减排方面重要的技术储备。     

排污权交易成本动因分析

排污权交易制度作为控制污染超量排放的方法之一,其有效实施必须以降低市场交易成本为前提.从国内外交易成本理论出发,分别从外部环境和企业内部分析排污权交易成本的形成机理和影响因素,提出降低排污权交易成本、提高交易效率的方法,为构建排污权交易市场提供理论指导和支持.     

基于学习曲线的CO2捕集和可再生能源发电成本

为研究CO2捕集与封存技术(CCS,carbon captureand storage)和风电、太阳能发电技术未来成本变化,该文利用年限平均法计算了不同技术的发电成本及构成;在对不同发电技术未来装机容量合理假设的基础上,利用学习曲线模型分析了中国光伏和风电技术的学习率,并分析了其未来发电成本的变化以及达到商业化所需要的社会投入成本;在分析CCS电站时,利用自下而上的方法,将捕集电站分解为不同的子系统,考察了其未来的发展。研究结果表明:风电技术为近期首选的减排技术,而光伏发电技术在长期具备竞争力;如果EOR(enhanced oil recovery)技术能够大规模推广,CCS技术也将具备充分的竞争力。     

碳约束下延时补货库存控制模型研究

构建了碳排放市场交易机制下考虑碳排放的延时补货库存控制模型,并与不考虑碳排放的情况进行对比,得出两者最优订购量和总成本在不同环境下发生的变化．碳排放市场交易机制有效地引导企业减少碳排放量,同时最优订购量取决于临界值的大小,碳配额影响总成本,企业可将多余的碳配额在市场上出售获得收益,最后通过算例分析证明了模型的有效性以及对企业生产库存最优化决策的影响．     

Contribution of anthropogenic and natural sources to atmospheric methane variability

Methane is an important greenhouse gas, and its atmospheric concentration has nearly tripled since pre-industrial times. The growth rate of atmospheric methane is determined by the balance between surface emissions and photochemical destruction by the hydroxyl radical, the major atmospheric oxidant. Remarkably, this growth rate has decreased markedly since the early 1990s, and the level of methane has remained relatively constant since 1999, leading to a downward revision of its projected influence on global temperatures. Large fluctuations in the growth rate of atmospheric methane are also observed from one year to the next, but their causes remain uncertain. Here we quantify the processes that controlled variations in methane emissions between 1984 and 2003 using an inversion model of atmospheric transport and chemistry. Our results indicate that wetland emissions dominated the inter-annual variability of methane sources, whereas fire emissions played a smaller role, except during the 1997-1998 El Ni?o event. These top-down estimates of changes in wetland and fire emissions are in good agreement with independent estimates based on remote sensing information and biogeochemical models. On longer timescales, our results show that the decrease in atmospheric methane growth during the 1990s was caused by a decline in anthropogenic emissions. Since 1999, however, they indicate that anthropogenic emissions of methane have risen again. The effect of this increase on the growth rate of atmospheric methane has been masked by a coincident decrease in wetland emissions, but atmospheric methane levels may increase in the near future if wetland emissions return to their mean 1990s levels.     

An Earth-like correspondence between Saturn's auroral features and radio emission

Saturn is a source of intense kilometre-wavelength radio emissions that are believed to be associated with its polar aurorae, and which provide an important remote diagnostic of its magnetospheric activity. Previous observations implied that the radio emission originated in the polar regions, and indicated a strong correlation with solar wind dynamic pressure. The radio source also appeared to be fixed near local noon and at the latitude of the ultraviolet aurora. There have, however, been no observations relating the radio emissions to detailed auroral structures. Here we report measurements of the radio emissions, which, along with high-resolution images of Saturn's ultraviolet auroral emissions, suggest that although there are differences in the global morphology of the aurorae, Saturn's radio emissions exhibit an Earth-like correspondence between bright auroral features and the radio emissions. This demonstrates the universality of the mechanism that results in emissions near the electron cyclotron frequency narrowly beamed at large angles to the magnetic field.     

The role of increasing temperature variability in European summer heatwaves

Instrumental observations and reconstructions of global and hemispheric temperature evolution reveal a pronounced warming during the past approximately 150 years. One expression of this warming is the observed increase in the occurrence of heatwaves. Conceptually this increase is understood as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small. Here we show that this framework fails to explain the record-breaking central European summer temperatures in 2003, although it is consistent with observations from previous years. We find that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account. We propose that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003. To test this proposal, we simulate possible future European climate with a regional climate model in a scenario with increased atmospheric greenhouse-gas concentrations, and find that temperature variability increases by up to 100%, with maximum changes in central and eastern Europe.     

基于不同面积比例的屋顶光伏光热系统设计

为降低高校建筑的能耗,设计了一种空气源热泵辅助式屋顶太阳能光伏光热系统。光伏组件和集热器的安装面积不仅会对电力侧产生影响,还会影响热力侧。首先建立系统的基本架构,然后以日运行费用为优化目标,使用改进的鲸鱼算法对系统进行优化,最后以乌鲁木齐某高校一宿舍楼为例,对光伏光热系统的环境及经济效益进行分析。算例结果表明,宿舍楼屋顶在安装满足最优比例的光伏光热系统的情况下,系统在环境保护和投资回收期方面都具有显著效益,切实达到了节约能源、减少二氧化碳排放和保护环境的目的。     

基于异质性假设的我国二氧化碳排放影响因素分析

比较准确地测算了我国29个省份的二氧化碳排放总量和人均排放量,并根据人均排放和收入,构建省级二氧化碳排放异质型面板,利用动态面板数据模型研究我国二氧化碳排放EKC曲线及影响因素.实证结果显示,高收入和低排放低收入地区的经济发展水平与二氧化碳排放量存在倒"U"型关系,环境库兹涅兹曲线假说成立.经济和产业结构、能源消费、国际贸易和城市化水平等是我国二氧化碳排放的重要影响因素.另外,我国二氧化碳排放表现出明显的路径依赖现象.     

考虑碳排放的农产品多级冷链物流网络均衡模型研究

构建由农业合作社、批发商以及零售商构成的三级农产品冷链物流网络,分别研究不考虑碳排放、考虑碳排放两种情形下农产品物流网络系统的均衡问题.并在考虑碳排放的情形下,对零售商订货次数、碳排放成本进行参数分析.研究表明:考虑碳排放后,系统销售给外部需求市场的农产品数量上升,价格也上升,从而系统整体利润也明显增长;当零售商增加订货批次时,应该设法增加对外部需求市场产品交易量而非提高产品价格来维持系统整体利润,而若碳排放成本增加,则应该提高产品价格.     

基于碳排放-位置分配模型的公共中心规划支持系统设计与应用研究

设计了基于碳排放-位置分配模型的公共中心规划支持系统（CELA-PCPSS），该系统可分为支撑层、数据层、模型层、功能层和表示层．其中，基于小汽车出行碳排放的位置分配模型是模型层乃至整个CELA-PCPSS的核心．CELA-PCPSS的主要功能是基于低碳视角计算出公共中心布局选址的最优位置，定量、可视化地模拟出不同公共中心布局形式下的小汽车出行碳排放空间格局与碳排放总量．以广州市为例，将CELA-PCPSS应用于其假设的公共中心规划选址中，模拟与计算出规划1~6个公共中心的最优选址位置及其相应的小汽车出行碳排放空间格局与碳排放总量．发现新增公共中心能减少小汽车出行碳排放总量，具有边际效应．因此，需综合考虑经济社会成本和人文因素来确定规划公共中心的数量和调整其选址位置，以使社会、经济和环境效益最大化．