Forest carbon accounting methods and the consequences of forest bioenergy for national greenhouse gas emissions inventories

While bioenergy plays a key role in strategies for increasing renewable energy deployment, studies assessing greenhouse gas (GHG) emissions from forest bioenergy systems have identified a potential trade-off of the system with forest carbon stocks. Of particular importance to national GHG inventories is how trade-offs between forest carbon stocks and bioenergy production are accounted for within the Agriculture, Forestry and Other Land Use (AFOLU) sector under current and future international climate change mitigation agreements. Through a case study of electricity produced using wood pellets from harvested forest stands in Ontario, Canada, this study assesses the implications of forest carbon accounting approaches on net emissions attributable to pellets produced for domestic use or export. Particular emphasis is placed on the forest management reference level (FMRL) method, as it will be employed by most Annex I nations in the next Kyoto Protocol Commitment Period. While bioenergy production is found to reduce forest carbon sequestration, under the FMRL approach this trade-off may not be accounted for and thus not incur an accountable AFOLU-related emission, provided that total forest harvest remains at or below that defined under the FMRL baseline. In contrast, accounting for forest carbon trade-offs associated with harvest for bioenergy results in an increase in net GHG emissions (AFOLU and life cycle emissions) lasting 37 or 90 years (if displacing coal or natural gas combined cycle generation, respectively). AFOLU emissions calculated using the Gross-Net approach are dominated by legacy effects of past management and natural disturbance, indicating near-term net forest carbon increase but longer-term reduction in forest carbon stocks. Export of wood pellets to EU markets does not greatly affect the total life cycle GHG emissions of wood pellets. However, pellet exporting countries risk creating a considerable GHG emissions burden, as they are responsible for AFOLU and bioenergy production emissions but do not receive credit for pellets displacing fossil fuel-related GHG emissions. Countries producing bioenergy from forest biomass, whether for domestic use or for export, should carefully consider potential implications of alternate forest carbon accounting methods to ensure that potential bioenergy pathways can contribute to GHG emissions reduction targets.     

全球二氧化碳浓度非均匀分布条件下碳排放与升温关系的统计分析

为定量评估全球二氧化碳浓度非均匀分布条件下碳排放与升温的关系,采用空间自相关分析与空间联立方程组模型,基于1度、2度与3度空间分辨率的全球二氧化碳浓度,碳排放与近地面气温等格点数据,揭示了2003—2015年全球二氧化碳浓度的空间分布聚集特征并估计了碳排放对升温的影响系数。结果发现：二氧化碳浓度在空间上表现为北半球高浓度值聚集与南半球低浓度值聚集的分布型。利用二氧化碳浓度非均匀分布的参数条件对碳排放与升温影响的估计结果表明,代入二氧化碳浓度非均匀分布这一参数会小幅拉低碳排放对升温影响的估计结果。研究表明,全球二氧化碳浓度非均匀分布是当前评估碳排放升温影响亟待引入的参数;同时由于估计结果的空间尺度效应的存在,相关参数的空间范围与分辨率的选择也需要关注。     

Importance of indirect nitrous oxide emissions at the field, farm and catchment scale

Direct and indirect nitrous oxide (N₂O) emissions and leaching losses from an intensively managed grazed pasture in the Ythan catchment, Aberdeenshire, UK, were measured and compared over a 17-month period. Simultaneous measurements of farm-wide leaching losses of N₂O were also made and catchment-wide fluxes were estimated from existing N leaching data. The relative importance of direct and indirect N₂O fluxes at the field, farm and catchment scale was then assessed. At the field scale we found that direct N₂O emissions were low (1.2 kg N ha⁻¹ year⁻¹, 0.6% of N input) with indirect N₂O emissions via drainage waters comprising a significant proportion (25%) of total N₂O emissions. At the whole-farm scale, the N₂O-N emission factor (0.003) for leached NO₃-N (EF_5-g) was in line with the IPCC's recent downward revision. At the catchment scale, a direct N₂O flux of 1.9 kg N ha⁻¹ year⁻¹ and an indirect flux of 0.06 kg N₂O-N ha⁻¹ year⁻¹ were estimated. This study lends further support to the recent downward revision of the IPCC emission factor for N₂O arising from leached N in surface and ground waters (EF_5-g) and highlights the need for multiple point sampling to ensure that the importance of indirect N₂O losses via drainage waters is not misrepresented at the farm and catchment scales.     

Analysis of differences between national inventories and an Emissions Database for Global Atmospheric Research (EDGAR)

A comparison is made of national greenhouse gas inventories for the Climate Convention, (including US country study results) and an emissions database for global atmospheric research (EDGAR). The comparison pointed to some gaps in reporting and some large differences within sectors. In most cases the differences can be traced down to the use of different emission factors or the use of national statistics that differed from the internationally available ones. Comparison of inventories may stimulate the scientific exchange of data and increase the consensus on emissions. This comparison of semi-independent databases may therefore reduce uncertainties in emissions estimates. The exercise illustrated the usefulness of standard reporting formats and the availability of background information other than the official National Communications to the Climate Convention. The comparison may lead to major revisions of officially reported methane emissions in several countries.     

资源型城市可持续发展对碳排放的影响研究——基于资源依赖的视角

基于2003~2018年285个地级市的面板数据,首先使用双重差分模型考察《全国资源型城市可持续发展规划(2013~2020年)》(以下简称《规划》)对碳排放的影响;其次,探究该政策通过资源依赖这一路径对碳排放的影响效果;进一步地,基于城市区域和城市规模两个视角分析该政策通过资源依赖影响碳排放的异质性效果;最后,探究《规划》的空间溢出效应.结果表明《规划》显著地降低了资源型城市的碳排放;机制分析表明,《规划》能够通过降低资源依赖进而减少碳排放,且产业结构升级和技术进步对《规划》的碳减排效应起到了正向调节作用;异质性分析表明,《规划》通过降低资源依赖进而促降碳排放的效果在东､中部地区以及大城市更为明显;《规划》对本地及周边地区均具有显著的碳减排效应.本研究对于在双碳目标下实现中国资源型城市的可持续发展具有重要的政策启示.     

Linking the EU emissions trading scheme: economic implications of allowance allocation and global carbon constraints

We investigate the role of domestic allowance allocation and global emissions constraints for the carbon-market impacts of linking the EU Emissions Trading Scheme (ETS) internationally. Employing a quantitative simulation model of the global carbon market, we find that the economic benefits from connecting the European ETS to emerging non-EU schemes strongly depend on the regional allowance allocation of the linking participants: In a world of moderate carbon constraints, an economically efficient regional allowance allocation induces a much stronger fall in total compliance costs than a sub-optimal (i.e. too high) domestic allocation of emissions permits. However, a more efficient (i.e. stricter) allocation shifts abatement efforts and compliance costs to energy-intensive industries which are covered by the domestic ETS. We further find that committing to ambitious global emissions reduction targets (compatible with stabilizing CO₂ concentrations at 450 ppm) induces much stronger regional abatement efforts and substantially higher compliance costs for the abating regions. In such an ambitious climate policy regime, an efficient domestic allocation of allowances is even more important from an economic perspective: Here, linking emissions trading schemes diminishes the associated compliance costs on the largest scale.

POC的结构参数对DMCC发动机排放影响的试验研究

在一台直列4缸增压中冷电控单体泵柴油机的进气道上增加甲醇喷射装置,实现柴油甲醇二元燃料燃烧(DMDF)模式.利用废气分析仪对其主要气体排放进行测量,研究在排气管上加装的柴油颗粒氧化催化转化器结构参数对尾气催化效率的影响,试验结果表明:POC长度越长,对碳烟、THC、和未燃甲醇的转化效果越好,甲醇替代率为30%、POC长度为100 mm时,对碳烟、CO、THC和未燃甲醇的平均净化效率分别为15.00%、91.61%、75.56%、66.96%,长度增加至200 mm后,上述效率明显提高,分别提高到30.37%、99.29%、67.55%、95.44%;POC孔密度增加,POC对碳烟、CO及未燃甲醇的转化效率有小幅增加,甲醇替代率为30%时,孔密度从200目增加到300目,对碳烟、CO和未燃甲醇的催化效率分别从19.61%、94.66%、86.07%提高到23.06%、97.44%和88.56%;POC结构参数的改变对NO_x的转化效率影响不大.     

二氧化碳排放与经济增长关系的实证分析

在全球范围内为应对气候变化而达成二氧化碳减排共识的背景下,探求“经济增长”与“二氧化碳排放”间相互关系.运用协整,向量自回归模型,脉冲响应函数以及格兰杰因果检验等方法,对处在经济发展不同阶段区域的人均二氧化碳排放量与经济增长间关系进行因果检验.研究结果表明：区域经济发展与人均二氧化碳排放量存在长期均衡关系,但是由于区域间经济发展水平及发展方式的不同,人均二氧化碳排放量与经济增长间相互影响程度存在差异,且二氧化碳排放量的减少并不是经济增长的必然结果,必须通过产业结构调整,扶持第三产业,使用清洁能源,发展低碳经济的方式来实现,本文对我国碳减排政策的制定具有一定借鉴意义.     

Exploring the assumed invariance of implied emission factors for forest biomass in greenhouse gas inventories

Reviews of each nation's annual greenhouse gas inventory submissions including forestland are part of the ongoing reporting process of the United Nations Framework Convention on Climate Change. Goals of these reviews include improving quality and consistency within and among reports. One method of facilitating comparisons is the use of a standard index such as an implied emission factor (IEF), which for forest biomass indicates net rate of carbon emission or sequestration per area. Guidance on the use of IEFs in reviews is limited, but there is an expectation that values should be relatively constant both over time and across spatial scales. To address this hypothesis, we examine IEFs over time, derived from U.S. forests at plot-, state-, and national-levels. Results show that at increasingly aggregated levels, relative heterogeneity decreases but can still be substantial. A net increase in U.S. whole-forest IEFs over time is consistent with results from temperate forests of nations in the European Community. IEFs are better viewed as a distribution of values rather than one constant value principally because of sensitivities to productivity, disturbance, and land use change, which can all vary considerably across a nation's forest land.     

变尺度混沌-遗传算法在复杂河流水质模型参数优化中的应用

将变尺度混沌-遗传算法(MSCGA)应用于复杂河流水质模型参数优化.采用湘江衡阳段水质监测资料,以二维河流水质数学模型反演结果的均方误差为适应度函数,估计横向扩散系数Dx、纵向弥散系数Dy和污染物衰减系数κ.数值实验结果表明,MSCGA寻优过程具有明显的分级特征,级级收敛;在同样的条件下,MSCGA的收敛速度较快,为遗传算法(GA)的1.36倍;同时,MSCGA克服了GA早熟收敛的问题,其最优适应度函数值为7.6×10-4,而GA的最优适应度函数值9.6×10-4.将MSCGA应用于研究河段,求得Dx、Dy分别为0.1335、0.0011,BOD5、As、Cr的衰减系数κ分别为0.0229、0.0100、0.0107.     

On the relationship between PM2.5 concentrations and regional-scale primary PM emissions for the United Kingdom: an issue of subsidiarity

A site-specific particulate matter PM source apportionment model has been used to estimate the contributions from local primary PM emissions, regional primary PM emissions and the regional background to PM_2.5 concentrations at 102 monitoring site locations and to the centres of 1 km × 1 km grid squares across the United Kingdom. The local primary PM contributions have then been compared with Europe-wide urban PM_2.5 increments estimated at 50 km × 50 km in European-scale integrated assessment models. It is concluded that Europe-wide PM increments used in policy analyses grossly underestimate urban PM concentrations obtained from the site-specific PM source apportionment model for the United Kingdom. Europe-wide urban PM_2.5 increments estimated at 5 km × 5 km scale are significantly improved, particularly for London, but underestimate those for smaller towns and cities by factors of 2–3. These underestimations have important air quality policy ramifications. Although environmental policies may well be best formulated at the European scale, the underpinning air quality modelling may be best carried out at the local scale.     

A comparison of five high-resolution spatially-explicit,fossil-fuel,carbon dioxide emission inventories for the United States

The quantification of fossil-fuel-related emissions of carbon dioxide to the atmosphere is necessary in order to accurately represent carbon cycle fluxes and to understand and project the details of the global carbon cycle. In addition, the monitoring, reporting, and verification (MRV) of carbon dioxide emissions is necessary for the success of international agreements to reduce emissions. However, existing fossil-fuel carbon dioxide (FFCO₂) emissions inventories vary in terms of the data and methods used to estimate and distribute FFCO₂. This paper compares how the approaches used to create spatially explicit FFCO₂ emissions inventories affect the spatial distribution of emissions estimates and the magnitude of emissions estimates in specific locales. Five spatially explicit FFCO₂ emission inventories were compared: Carbon Dioxide Information and Analysis Center (CDIAC), Emission Database for Global Atmospheric Research (EDGAR), Fossil Fuel Data Assimilation System (FFDAS), Open-source Data Inventory for Anthropogenic CO₂ (ODIAC), and Vulcan. The effects of using specific data and approaches in the creation of spatially explicit FFCO₂ emissions inventories, and the effect of resolution on data representation are analyzed using graphical, numerical, and cartographic approaches. We examined the effect of using top-down versus bottom-up approaches, nightlights versus population proxies, and the inclusion of large point sources. The results indicate that the approach used to distribute emissions in space creates distinct patterns in the distribution of emissions estimates and hence in the estimates of emissions in specific locations. The different datasets serve different purposes but collectively show the key role of large point sources and urban centers and the strong relationship between scale and uncertainty.     

Managing the cost of emissions for durable,carbon-containing products

We recognize that carbon-containing products do not decay and release CO₂ to the atmosphere instantaneously, but release that carbon over extended periods of time. For an initial production of a stock of carbon-containing product, we can treat the release as a probability distribution covering the time over which that release occurs. The probability distribution that models the carbon release predicts the amount of carbon that is released as a function of time. The use of a probability distribution in accounting for the release of carbon to the atmosphere realizes a fundamental shift from the idea that all carbon-containing products contribute to a single pool that decays in proportion to the size of the stock. Viewing the release of carbon as a continuous probabilistic process introduces some theoretical opportunities not available in the former paradigm by taking advantage of other fields where the use of probability distributions has been prevalent for many decades. In particular, theories developed in the life insurance industry can guide the development of pricing and payment structures for dealing with the costs associated with the oxidation and release of carbon. These costs can arise from a number of proposed policies (cap and trade, carbon tax, social cost of carbon, etc), but in the end they all result in there being a cost to releasing carbon to the atmosphere. If there is a cost to the emitter for CO₂ emissions, payment for that cost will depend on both when the emissions actually occur and how payment is made. Here we outline some of the pricing and payment structures that are possible which result from analogous theories in the life insurance industry. This development not only provides useful constructs for valuing sequestered carbon, but highlights additional motivations for employing a probability distribution approach to unify accounting methodologies for stocks of carbon containing products.     

The sensitivity of the costs of reducing emissions from deforestation and degradation (REDD) to future socioeconomic drivers and its implications for mitigation policy design

Mitigation and Adaptation Strategies for Global Change - Climate change mitigation policies for the land use, land use change, and forestry (LULUCF) sector are commonly assessed based on marginal...     

On discrepancies between different laboratory measurements of kinetic parameters for the reaction of the hydroxyl radical with halocarbons

This paper discusses laboratory-measured rate coefficients for the reaction of hydroxyl radicals with halogenated organic compounds. A knowledge of such rate coefficients is vital in assessing the tropospheric lifetimes of the compounds. There appear to be significant differences between measurements from different laboratories. Possible sources of the discrepancies are discussed critically, and the possible influence of the technique employed (flash-photolysis or discharge-flow) is considered. Reactive impurities, secondary losses of OH and unanticipated heterogeneous processes might each invalidate the experimental measurements. The effects of these influences are analysed in turn. The conclusion is drawn that the most probable source of error derives from surface phenomena, and some experimental evidence is given that supports this idea. In these circumstances, it may turn out that the most reliable data are those obtained at high temperatures and that, contrary to received wisdom, it may be advantageous to extrapolate high-temperature data to calculate rate coefficients at tropospheric temperatures.     

基于证据权法的安徽东溪金矿大比例尺成矿预测与评价

应用GIS技术结合地质、地球物理、地球化学等资料进行综合信息成矿预测是目前找矿的趋势。以霍山县东溪金矿及外围1∶10 000大比例尺地区为研究对象,在野外地质调查的基础上,结合空间位置统计结果和矿区成矿特征,利用GIS平台提取地质、地球物理、地球化学等多元地质找矿信息,建立矿区找矿预测模型。选择符合条件的独立预测因子作为证据图层,以5m×5m为网格单元,分析各证据图层与矿体空间分布关系。运用证据权法对矿区及外围进行成矿预测,通过图形方式直观表达成矿高概率的空间分布,对圈定的找矿靶区进行综合评述。研究区找矿靶区内地质、物探、化探找矿信息良好,各靶区内均有较好的金矿化信息。