Spatial variations in CO2 fluxes in a subtropical coastal reservoir of Southeast China were related to urbanization and land-use types

Carbon dioxide (CO2) emissions from aquatic ecosystems are important components of the global carbon cycle, yet the CO2 emissions from coastal reservoirs, especially in developing countries where urbanization and rapid land use change occur, are still poorly understood. In this study, the spatiotemporal variations in CO2 concentrations and fluxes were investigated in Wenwusha Reservoir located in the southeast coast of China. Overall, the mean CO2 concentration and flux across the whole reservoir were 41.85 ± 2.03 µmol/L and 2.87 ± 0.29 mmol/m2/h, respectively, and the reservoir was a consistent net CO2 source over the entire year. The land use types and urbanization levels in the reservoir catchment significantly affected the input of exogenous carbon to water. The mean CO2 flux was much higher from waters adjacent to the urban land (5.05 ± 0.87 mmol/m2/hr) than other land use types. Sites with larger input of exogenous substance via sewage discharge and upstream runoff were often the hotspots of CO2 emission in the reservoir. Our results suggested that urbanization process, agricultural activities, and large input of exogenous carbon could result in large spatial heterogeneity of CO2 emissions and alter the CO2 biogeochemical cycling in coastal reservoirs. Further studies should characterize the diurnal variations, microbial mechanisms, and impact of meteorological conditions on reservoir CO2 emissions to expand our understanding of the carbon cycle in aquatic ecosystems.     

Forgotten carbon: indirect CO2 in greenhouse gas emission inventories

National governments that are Parties to the United Nations Framework Convention on Climate Change (UNFCCC) are required to submit greenhouse gas (GHG) inventories accounting for the emissions and removals occurring within their geographic territories. The Intergovernmental Panel on Climate Change (IPCC) provides inventory methodology guidance to the Parties of the UNFCCC. This methodology guidance, and national inventories based on it, omits carbon dioxide (CO₂) from the atmospheric oxidation of methane, carbon monoxide, and non-methane volatile organic compounds emissions that result from several source categories. The inclusion of this category of “indirect” CO₂ in GHG inventories increases global anthropogenic emissions (excluding land use and forestry) between 0.5 and 0.7%. However, the effect of inclusion on aggregate UNFCCC Annex I Party GHG emissions would be to reduce the growth of total emissions, from 1990 to 2004, by 0.2% points. The effect on the GHG emissions and emission trends of individual countries varies. The paper includes a methodology for calculating these emissions and discusses uncertainties. Indirect CO₂ is equally relevant for GHG inventories at other scales, such as global, regional, organizational, and facility. Similarly, project-based methodologies, such as those used under the Clean Development Mechanism, may need revising to account for indirect CO₂.     

Capital assets and institutional constraints to implementation of greenhouse gas mitigation options in agriculture

Agriculture is one of the major sources of greenhouse gas (GHG) emission. It accounts for approximately 15% of the total global anthropogenic emissions of GHGs. Emissions could be twice as much if indirect emissions are also taken into the consideration. However, unlike other high emitting sectors such as transport or energy, agriculture is potentially a significant carbon “sink”. It has high technical potential as a carbon sink and if tapped, can substantially enhance global sequestration efforts. The technical potential, however, may not translate into actual GHG reduction because of the capital assets and institutional constraints faced by the smallholder farmers in the developing countries. In this paper we develop a capital assets based framework of physical, financial, social, human and natural barriers to agricultural carbon mitigation initiatives and through analysis of current initiatives, we set out policy based options to reduce each of these barriers. Fundamentally, barrier removal will entail designing agricultural carbon mitigation initiatives in collaboration with farmer communities, through strengthening local institutions, understanding land tenure and natural resource cultures, ensuring legitimacy and equity in payments and fast tracking training and information. We provide a framework that simultaneously aids the dual objectives of alleviating poverty in the poor farming communities of developing countries and lowering global greenhouse gas emissions.     

国际贸易“碳中和”研究热点领域及其动向

碳中和是世界各国面临的共同问题。经济全球化与贸易自由化背景下国际贸易总量快速增长,伴随着深度国际分工与产业转移,贸易产品的生产者与消费者在陆表形成严重的空间位移。利用文献计量软件CiteSpace分析国际贸易主题下碳中和相关文献,揭示国际贸易“碳中和”研究动向。研究发现：（1）温室气体在全球范围时空演变,使跨区域、多尺度的全球碳治理变得更加复杂,发达国家将高污染与低价值链产业转移至各发展中国家,以生产者责任划分的碳核算原则不再适用于国际贸易合作。（2）进出口贸易逐渐成为新兴经济体经济发展动力,全球碳治理应转向新兴经济体与区域一体化,全球气候政策设计应遵守国际碳市场公平性底线,不断优化碳排放量核算体系,完善碳会计方法,模拟全球碳减排预期效果。重点提高产业部门碳减排意识和产业清洁技术及能源利用效率,利用多种手段改变生态系统的增汇减碳能力。新兴经济体在承接发达国家技术援助同时,应重点关注本国能源产业,发展可再生能源产业,提高能源的利用效率,并运用经济政策与金融工具促进本国的气候变化投融资产业发展。全球碳治理应更加注重公平性与国家间的经济发展、环境资源差异,利用多样的碳治理工具与协商合作方式,促使更多国家参与全球化或区域一体化的碳治理模式。（3）中国亟待通过国内多产业、多部门的增汇减排与国际碳减排、碳中和实践,健全碳市场机制,提高碳治理水平,为国际碳治理合作提供“最大公约数”。     

城市碳排放的评估方法——影响要素和过程研究

城市碳排放对全球碳循环和气候变化产生了深远的影响。论文在国内外城市碳排放研究基础上,从城市化的碳排放效应、城市碳排放估算和影响要素、碳排放观测、碳循环和碳代谢过程等方面系统归纳总结了碳排放评估方法、要素和过程。评述了Kaya恒等式、LMDI方法、CGE模型、混合分析法、清单编制法、UE模型、FFDAS模型、STIRPAT模型、格网模型、综合分析法(Four-part Methodology)、建筑碳排放模型、物质代谢法、EC碳通量观测等代表性碳排放估算和观测方法。研究焦点正在从宏观模式转向微观机理,从自然、人文单一过程转向人文-自然耦合过程,热点区域从发达国家城市转向发展中国家城市,从单一数据源转向遥感、实验观测等多源数据。基于上述特点,当前研究应从城市公平发展和低碳城市出发,建立城市公共利益能源研究框架,根据城市职能类型和发展水平,综合涡度通量观测、计量模型、生态模型、遥感和GIS技术,构建高精度城市碳排放账户,建立城市代谢存量和流量标准分类系统,发展和完善碳排放估算模型,提高城市碳排放计算结果精度和城市间的可比性。     

陕西省土地利用碳排放演变与影响因素分析研究

以陕西省统计数据为基础,利用土地利用碳排放模型和STIRPAT模型,分析了陕西省1999年-2013年土地利用碳排放演变与影响因素,结果表明:陕西省碳排放量呈增加趋势,增加了4.07倍,其中建设用地碳排量增加起主导作用.碳排放经历了减少(1999-2000年)、稳步增加(2001-2006年)和快速增加(2007-2013年)3个阶段.人口数量和GDP是陕西省土地利用碳排放变化的影响因素,其中人口数量对碳排放变化的贡献高于GDP.经济集约式发展和个人集约式低碳消费是碳减排的重要方向.     

中国大陆足迹家族的环境库兹涅茨曲线分析

论文选取我国1987—2013年土地利用、温室气体排放和用水量数据,运用投入产出法计算足迹家族中的土地足迹、碳足迹和水足迹,采用纵横向拉开档次法进行足迹整合,将整合得到的足迹综合指数与足迹家族各项指标取对数后进行环境库兹涅茨曲线分析。计算结果表明：足迹综合指数从1987年的2.274 2增长到2013年的3.816 9,与人均GDP呈平缓型曲线协同增长关系,说明生态占用持续增加,呈现资源利用的不可持续性;土地足迹、碳足迹与水足迹的环境库兹涅茨曲线分别呈∽型、协同增长型以及平稳型,说明我国城镇化正在进入转型期,碳排放仍处于上升阶段,水资源可持续性不乐观,指标的选取影响环境库兹涅茨曲线形态。     

江西省土地利用碳排放空间格局及碳平衡分区

二氧化碳浓度升高,导致全球气候变暖,生态环境问题逐渐凸显. 为此,绿色、低碳和循环发展成为我国当前工作重点. 江西省作为长江经济带生态文明建设的重要节点,大规模的城镇化建设导致碳排放量增加. 鉴于此,基于土地利用和能源消费数据构建碳排放量计算模型,探究江西省2000—2018年的碳排放空间格局特征,通过基尼系数、经济贡献系数和生态承载系数等多种分析方法探讨区域内的碳排放空间差异以及碳收支情况,同时从经济和生态的角度进行碳平衡分区并提出针对性的策略. 结果表明:①江西省2000—2018年土地利用碳排放总量逐年上升,从1 215.687×104 t增至4 907.425×104 t,总体表现为净碳源,碳减排压力较大. ②江西省碳排放空间格局呈现北高南低、西高东低的特征,北部和西部地区的碳排放总量明显大于南部和东部地区,其碳排放总量与各区域内的土地利用结构以及能源消费结构密切相关. ③江西省历年的碳补偿率均低于34%且逐年递减,碳补偿率、经济贡献系数和生态承载系数三者均空间差异明显,其中北部地区的碳补偿率低于南部地区,南部地区、东北地区的经济贡献率和生态承载系数高于西部地区. ④基于碳平衡分析,根据净碳排放量、生态承载系数等指标将江西省各地级市划分为4个碳排放发展功能区域,即碳汇功能区、低碳经济区、碳强度控制区、高碳优化区. 研究期内碳汇功能区数量变化较大,逐渐转为低碳经济区;碳强度控制区和高碳优化区数量基本无变化. 研究显示,江西省土地利用碳排放空间差异显著,协同减排的困难较大,为此根据碳平衡分区调整土地利用结构,有利于促进区域协同减排,推动全省低碳经济的发展,缓解因碳排放引起的全球气候变化问题.      

安徽省会经济圈土地利用变化的碳排放效益

土地利用变化是影响碳排放的重要因素。利用1997和2007年土地利用类型数据,采用碳排放评价模型,对安徽省会经济圈碳排放效益进行评价,并估算碳排放生态补偿标准。研究结果显示:①1997-2007年间碳排放总量增加1 049.92×10⁴ t,年均增长14.4%;②2007年经济圈内地均建设用地碳排放强度和地均碳排放强度分别为1997年的2.41倍、 2.18倍,1997和2007年,碳排放强度指数值都是合肥市>巢湖市>六安市;③经济圈内各县(区)地均碳排放强度差异显著,建设用地平均碳排放强度前3位的是合肥市区、 霍山县、 金寨县;④据中国造林成本的价格估算,合肥、 巢湖、 六安3市的碳汇补偿增加量分别为:21.83×10⁸、 4.31×10⁸、 2.48×10⁸元,县域生态补偿额差异显著;⑤土地利用结构、 产业结构与碳排放量存在一定的关系。从碳排放效益和生态补偿的角度,提出减少碳排放的途径。     

适应气候变化是当务之急

地球气候变化既有自然因素又有人为因素,全球变暖主要原因是人类活动温室气体排放过度。因此,在应对气候变化问题上,人们对减排温室气高度重视是理所当然,而长期以来对＂适应气候变化＂却有所忽视。其实,对发展中国家《适应气候变化》才是当务之急。本文在＂发展低碳经济,应对全球变暖＂减排二氧化碳温室气体的基础上,论述适应气候变化的迫切性和基本途径。     

Achieving forest carbon information with higher certainty: A five-part plan

International negotiations on the inclusion of land use activities into an emissions reduction system for the UN Framework Convention on Climate Change (UNFCCC) have been partially hindered by the technical challenges of measuring, reporting, and verifying greenhouse gas (GHG) emissions and the policy issues of leakage, additionality, and permanence. This paper outlines a five-part plan for estimating forest carbon stocks and emissions with the accuracy and certainty needed to support a policy for Reducing Emissions from Deforestation and forest Degradation, forest conservation, sustainable management of forests, and enhancement of forest carbon stocks (the REDD-plus framework considered at the UNFCCC COP-15) in developing countries. The plan is aimed at UNFCCC non-Annex 1 developing countries, but the principles outlined are also applicable to developed (Annex 1) countries. The parts of the plan are: (1) Expand the number of national forest carbon Measuring, Reporting, and Verification (MRV) systems with a priority on tropical developing countries; (2) Implement continuous global forest carbon assessments through the network of national systems; (3) Achieve commitments from national space agencies for the necessary satellite data; (4) Establish agreed-on standards and independent verification processes to ensure robust reporting; and (5) Enhance coordination among international and multilateral organizations.     

Application of the ‘Climafor’ Approach to Estimate Baseline Carbon Emissions of a Forest Conservation Project in the Selva Lacandona,Chiapas, Mexico

We present a methodology for testing and applying a regional baseline for carbon (C) emissions from land-use change, using a spatial modelling approach (hereafter called the Climafor approach). The methodology is based on an analysis of causal factors of previous land-use change (Castillo et al. 2005). Carbon risk matrices constructed from the spatial correlation analysis between observed deforestation and driving factors (Castillo et al. 2005), are used to estimate future carbonemissions within acceptable limits for a forest conservation project. The performance of two risk matrices were tested by estimating carbon emissions between 1975 and 1996 from randomly selected sample plots of sizes varying from 1,600 to 10,000 ha and comparing the results of the observed emissions from these sample plots with the model estimations. Expected emissions from continued land-use change was estimated for the community applying the risk matrices to the current land cover. The methodology provides an objective means of constructing baseline scenarios including confidence intervals, using the sum of variances of the various data sources, such as measured carbon densities, classification errors, errors in the risk matrices, and differences between the model prediction and observed emissions of sample plots due to sample size. The procedures applied in this study also give an indication of the impact of the variance in the various data sources on the size of the confidence intervals, which allows project developers to decide what data sources are essential to improve his baseline. The modelling approach to estimate the deforestation pattern is based on readily available cartographic and census data, whereas data on carbon densities are required to assess the potential for forest conservation projects to offset carbon emissions.     

安徽省近15年建设用地变化对碳排放效应测度及趋势预测——基于STIRPAT模型

建设用地变化的碳排放效应是现阶段土地利用变化研究热点之一.因此,本文运用安徽省统计年鉴数据,采用建设用地动态度模型及IPCC碳排放计算方法,对安徽省1997-2011年建设用地与碳排放动态变化特征进行了分析.同时,基于STIRPAT模型,采用偏最小二乘回归方法,揭示了建设用地对碳排放的边际效应,并运用SPSS软件对未来碳排放进行了预测.结果表明:研究时序内,建设用地与碳排放均呈增长态势,建设用地年均扩展速率为16.91％,碳排放年均增长6.61％,建设用地与碳排放正向效应显著;建设用地对碳排放的边际弹性系数为0.1194;惯性情景模式下,2015年、2020年安徽省建设用地扩展导致的碳排放将分别增至14472.42万t、19930.37万t;通过政策规制控制建设用地扩展趋势有利于抑制或减缓碳排放.本研究对了解安徽省碳排放变化趋势和指导土地利用规划有重要的现实意义,也可为省域尺度的建设用地碳排放效应研究提供范式借鉴.     

不同生计方式农户的碳足迹研究——以黑河流域中游张掖市为例

大气中二氧化碳浓度的增加导致全球变暖,已经是不争的事实。虽然碳排放量大部分来自发达城市,但是由于中国农村人口占全国的一半以上,因此农户的碳排放对全球气候变化的影响也不容忽视。论文将二氧化碳的质量作为碳足迹的单位,以黑河流域中游张掖市为例,基于入户调查资料,测算了当地农户碳足迹,运用单因素分析法和Gini 系数分析了不同生计方式农户碳足迹的结构特点,并且运用最小二乘法分析了影响农户碳足迹的因素。得出以下结论：①张掖市农户碳足迹总量为1.63×10⁹ kgCO₂,人均碳足迹为2.14×10³ kgCO₂;②从碳足迹类型来看,农户的碳足迹主要来自于能源消费,其次是房屋建设,食物生产加工和交通运输所占比例最小;③从碳足迹内部结构来看,张掖市不同生计方式农户的碳足迹有较大差异,非农户的碳足迹最大,其次是兼业户,纯农户的最小;④从碳足迹占有量的公平性看,碳足迹占有量偏差最大的为交通运输,Gini系数为0.51,其次是能源利用,Gini系数为0.41,食物生产加工碳足迹占有量比较合理,Gini系数为0.35,房屋建设的碳足迹占有量高度平均,Gini系数仅为0.12;⑤人口数量、收入水平和非农化是影响碳足迹的主要因素,随着人口数量增大、收入水平的提高和非农化程度的加深,农户碳足迹在不断增加。     

中国碳排放及影响因素的市域尺度分析

评估区域碳排放及其与社会经济状况的关系对于制定碳减排措施至关重要.以中国339个地级及以上城市(不含新疆部分城市和港澳台地区)为研究对象,探究了非化石能源占比、土地开发度、常住人口城镇化率、第二产业占比、人均GDP和人均建设用地面积对人均CO₂排放量的影响.通过构建模拟人均CO₂排放量的贝叶斯信念网络,识别各因素对人均CO₂排放量的全局影响;采用多尺度地理加权回归模型,分析各因素对人均CO₂排放量的局部影响.结果表明：(1)2020年,中国地级及以上城市人均CO₂排放量呈现出由南向北递增,东部沿海向内陆递减的格局.(2)从全局来看,人均CO₂排放量对各因素的敏感性从高到低依次为：人均建设用地面积>人均GDP>常住人口城镇化率>土地开发度>第二产业占比>非化石能源占比.(3)从局部来看,各因素与人均CO₂排放量的空间关系方向与全局关系一致,关系强度上存在空间异质性.(4)清洁能源、脱碳技术、土地节约集约利用...     

Contribution of industrial and developing countries to the atmospheric CO2 concentrations: — impact of the Kyoto protocol

The UN Framework Convention on Climate Change and the Kyoto protocol made under the Convention, aim at controlling the greenhouse gas emissions and their concentrations in the atmosphere. The contributions of fossil fuel use in industrial and developing countries to the atmospheric CO₂ concentration are calculated using estimates for emission developments and a simple carbon cycle model. The contribution of the industrial countries to the CO₂ concentration increase, above the preindustrial level, is estimated to be about 50 ppm in 1990 if only the emissions from fossil fuels are considered. The contribution from developing countries is about 15 ppm. The contribution from industrial countries would increase by about 20 ppm between 1990 and 2010 if no emission reductions were assumed and by about 15 ppm in the considered rather strict reduction scenario. According to the Kyoto protocol the emissions from industrial countries should be reduced by 5.2% from the 1990 level in about 20 years. This development of the emissions would cause a concentration increase of 18 ppm. The concentration increase due to developing countries between 1990 and 2010 would be about 15 ppm. In order that the present global increase rate of CO₂ concentration 1.5 ppm/a would not be exceeded, steeper reductions than those made in Kyoto should be agreed. Increasing global emissions and slow removal of CO₂ from the atmosphere makes it difficult to reach the ultimate objective of the Climate Convention, the stabilisation of the atmospheric concentration.     

Dynamic equity carbon permit allocation scheme to limit global warming to two degrees

Significant international collaboration is required to limit global temperature increase to below 2 °C above pre-industrial levels. Equity is the foundation of cooperation, and therefore, this study proposed a new dynamic carbon permit allocation scheme based on four principles: equality, historical responsibility, capability, and future development opportunities. Decision makers could have different preferences for allocating carbon permits, therefore, four equity rules or indicators (equality, responsibility, capacity, and sovereignty) were assigned different weights. Based on the global carbon budget of the 2 °C target, emission permits were calculated and relevant economic implications analyzed using the Global Change Assessment Model. Results indicated that developed countries should reduce emissions immediately, while allowances for developing regions could permit an initial increase in emissions until peaking. Applying different weights to the indicators resulted in multifarious regional allowances. Developed regions would benefit from the “preferring sovereignty” scenario and most developing countries would benefit under the “preferring responsibility” and “preferring capacity” scenarios. Compared with the Intended Nationally Determined Contributions submitted to the United Nations Framework Convention on Climate Change, this study found that in the short term, developed countries might insist on sovereignty as the preferred indicator. However, preferring sovereignty would place substantial mitigation pressures on developing countries in the long term. Therefore, in addressing global climate change, a dynamic choice in the weighting distribution for different indicators might be conducive to international agreement. Furthermore, a market-based trading instrument could help all participants both mitigate global climate change by reducing regional and global costs and facilitate mitigation capital flow from developed to less developed regions.     

基于函数极值条件下的中国碳达峰碳中和情景分析

基于函数极值条件提出了碳达峰出现时间和需要满足的理论条件,并对主要发达国家作了验证,同时对中国现状做了分析,最后采用了基准和强化两种情景分析了中国实现2030年碳达峰后进入2060年碳中和时期的二氧化碳排放量。研究结果显示：（1）根据IPAT恒等式将碳排放函数分解成人口、人均GDP和碳强度三个因素时,碳峰值出现时间为三个因素年增长率之和由正转负的正数值年度,发达国家的历史数据证实了这一条件。（2）中国三个因素年增长率之和自2003年起已经开始降低,最近几年一直在0.01~0.02徘徊,表明总体上朝着有利于碳达峰的方向发展,同时按照三个因素的预期发展目标计算得出中国2030年碳排放峰值的上限为112.2亿t,若2021—2035年保持相同的人均GDP年均复合增长率,碳强度年均复合增长率的绝对值需要比人均GDP年均复合增长率高0.14个百分点。（3）在能源消费总量逐渐回落的前提条件下,2060年基准情景下非化石能源占比约为65%,产生的二氧化碳量约为31.4亿t,强化情景下非化石能源占比约为70%,二氧化碳排放约为26.6亿t,而碳汇和CCUS等固碳技术还存在不确定性,碳中和任务依然艰巨。实现碳达峰碳中和最终需要控制能源消费,践行低碳消费行为。     

全球主要国家环境可持续性综合评估——基于碳、水、土地的足迹-边界整合分析

随着地球生态系统的交互性、复杂性与整体性特征日益显现,综合分析和比较各类人为环境影响及其最大安全阈值,对于从整体上判断人类活动的可持续性、揭示承载力的超载程度具有重要意义.基于环境足迹和行星边界两项新概念,运用极差法和目标距离法对全球30 个主要国家的碳、水和土地赤字数据进行了标准化与权重化处理,得到一个复合的国家环境可持续性压力指数,并结合3 项环境赤字的实际分布状况,将所有国家划分为4 类:环境强可持续性(3 国)、环境弱可持续性(8 国)、环境弱不可持续性(9 国)、环境强不可持续性(10 国).总体上,环境可持续性压力呈现南美洲国家低、亚洲和非洲国家居中、欧美发达国家高的地域格局,亚洲是4 类国家并存的唯一大洲.全球的碳、水和土地足迹-边界比分别为3.0、0.6、0.7,表明就全球尺度而言,温室气体排放已处于严重超载状态,水资源消费和土地利用尚处于盈余状态,这与现有文献结果相吻合,从而在一定程度上验证了本研究结论的可靠性.     

浙江省都市区碳排放时空演变及其影响因素

都市区建设促进城镇协同发展,对碳排放产生了影响,因此研究都市区建设与碳排放的关系,有助于探索减排的有效途径。基于浙江省各县市区2010—2018年间土地利用、能源消费等数据,测算碳排放量;利用空间自相关方法和空间计量回归模型,探讨四大都市区碳排放的时空演变特征及其影响因素。结果表明：（1）杭州都市区是浙江省最大的碳排放都市区,其次是宁波、温州和金义都市区。（2）碳排放在空间上具有明显的集聚特征。不同都市区碳排放的时空演变特征具有显著的差异性。（3）都市区建设有助于各城镇的协同作用,促进资源的高效配置和利用,进而降低碳排放。（4）都市区碳排放的影响因素和驱动机制受到都市区发展阶段和特色影响,形成不同的空间特征。（5）都市区低碳建设任务和方案是由其独特的碳排放驱动机制和时空演变特征决定的。