Marginal Abatement Cost Curves for UK Agricultural Greenhouse Gas Emissions

This article addresses the challenge of developing a ‘bottom‐up’ marginal abatement cost curve (MACC) for greenhouse gas (GHG) emissions from UK agriculture. An MACC illustrates the costs of specific crop, soil and livestock abatement measures against a ‘business as usual’ scenario. The results indicate that in 2022 under a specific policy scenario, around 5.38 Mt CO₂ equivalent (e) could be abated at negative or zero cost. A further 17% of agricultural GHG emissions (7.85 Mt CO₂e) could be abated at a lower unit cost than the UK Government’s 2022 shadow price of carbon [£34 (tCO₂e)^?1]. The article discusses a range of methodological hurdles that complicate cost‐effectiveness appraisal of abatement in agriculture relative to other sectors.     

Addressing Uncertainty in Efficient Mitigation of Agricultural Greenhouse Gas Emissions

The agricultural sector, as an important source of greenhouse gas (GHG) emissions, is under pressure to reduce its contribution to climate change. Decisions on financing and regulating agricultural GHG mitigation are often informed by cost‐effectiveness analysis of the potential GHG reduction in the sector. A commonly used tool for such analysis is the bottom‐up marginal abatement cost curve (MACC) which assesses mitigation options and calculates their cumulative cost‐effective mitigation potential. MACCs are largely deterministic, typically not reflecting uncertainties in underlying input variables. We analyse the uncertainty of GHG mitigation estimates in a bottom‐up MACC for agriculture, for those uncertainties capable of quantitative assessment. Our analysis identifies the sources and types of uncertainties in the cost‐effectiveness analysis and estimates the statistical uncertainty of the results by propagating uncertainty through the MACC via Monte Carlo analysis. For the case of Scottish agriculture, the uncertainty of the cost‐effective abatement potential from agricultural land, as expressed by the coefficient of variation, was between 9.6% and 107.3% across scenarios. This means that the probability of the actual abatement being less than half of the estimated abatement ranged from <1% (in the scenario with lowest uncertainty) to 32% (in the scenario with highest uncertainty). The main contributors to uncertainty are the adoption rate and abatement rate. While most mitigation options appear to be ‘win–win’ under some scenarios, many have a high probability of switching between being cost‐ineffective and cost‐effective.     

储备花生油氧化稳定性及品质研究

研究了储备花生油的氧化稳定性及品质变化。结果表明,氮气体系中花生油最稳定,适于推广。氧化变质的花生油中脂肪酸组成总体变化很小,SFA和MUFA的含量稍有增大,PUFA逐渐减少。而添加抗氧化剂有利于提高花生油的稳定性。合成抗氧化剂效果优于天然抗氧化剂,复合抗氧化剂效果优于单一抗氧化剂。     

Net Greenhouse Gas Emissions and the Economics of Annual Crop Management Systems

The aim of this study was to evaluate the relative economic profitability and net greenhouse gas (GHG) abatement potential of alternative tillage and cropping systems. A simulation model was parameterized using biophysical and economic data representing different crop rotations under conventional, minimum, and zero tillage cropping systems, in the Black soil zone of Saskatchewan. This model was used to estimate the relative potential of each of the management practices to sequester carbon and to emit GHG including, nitrous oxide and carbon dioxide. The model also provided estimates of the relative profitability of each of the management practices over time horizons of 30 years. These simulation results were used to develop trade-off functions reflecting net income and net GHG abatement for each cropping system. An income risk measure was incorporated to facilitate an analysis of the relative economic attractiveness of the simulated cropping systems. Furthermore, sensitivity analysis was performed on nitrous oxide emission coefficients (an area of significant uncertainty in the literature) and on weather patterns to reflect uncertain future climate change impacts. Results indicated that net GHG emissions were relatively lower for reduced tillage management, while conventional tillage may be relatively more attractive from an economic perspective. However, results also indicated that such economic factors as risk and economies of size may have a significant influence on this latter result.     

中国土地利用碳排放的研究误区和未来趋向

研究目的:分析当前中国土地利用碳排放研究中存在的误区,并提出基于土地科学视角的该领域整合研究的设想。研究方法:基于文献调查和回顾,对中国土地利用碳排放的研究进行了总结和回顾。研究结果:当前研究在碳收支研究参数的选择、研究尺度的匹配、土地利用空间布局方案、土地利用生命周期碳排放核算及综合研究等方面还存在一些误区,这制约了土地利用碳排放研究的进一步深化。研究结论:土地科学在区域碳排放研究中具有综合研究的优势和特色,应考虑从土地科学学科体系的角度构建土地利用碳排放研究的整体框架和方法体系,并开展区域示范研究;并进一步加强基于地块尺度的"自然-社会"二元碳收支的综合集成及土地利用全生命周期过程的碳排放效率研究。     

土地利用控制与土地用途分区管制浅析

从土地利用分散决策和土地管理集中决策即土地利用控制及土地用途分区管制机制的角度,分析了土地用途分区管制的必要性、可行性;借鉴国外经验,提出了完善我国的土地用途分区管制制度.     

土地利用规划的碳排放评价和预测与调控——以安徽省滁州市南谯区为例

为了促进低碳土地利用方式的形成,结合滁州市南谯区土地利用总体规划修编开展了碳排放评估。结果表明,南谯区碳排放总体成负排放,通过对1991-2005年主要土地利用方式和总碳排放分析,全区碳排放呈不断减少趋势,从1991年的-1644510.1 t发展到2005年的-1614135.9 t。将现行土地利用规划(1996-2010年)碳排放与2005年碳排放对比,耕地比规划减排90.07 t、林地比规划少吸收3391.80 t、草地比规划少吸收13.46t、建设用地比规划多排18280.54 t,总排放距规划预期有很大距离。对2010、2015、2020年碳排放做出预测,全区总碳排放量有不断增加的趋势。为了减少碳排放,主要从节能和合理管理耕地两方面着手,并将低碳经济提到规划中。     

把转变土地利用方式、集约用地置于土地利用战略的首位

研究目的:探讨缓解土地资源供需矛盾的战略重点。研究方法:对比分析法研究结果:改革开放前,中国采取依靠资源投入的增长方式,土地利用效率很低,土地资源浪费严重。改革开放后,人口快速增加,土地资源的稀缺性增强,中国实行了严格保护耕地、严格控制建设用地的战略,虽然降低了建设用地—GDP弹性系数,但是并没有解决上地资源的供需矛盾:研究结论:新时期,人口和资源环境刚性约束渐趋增强,上地资源供需矛盾日益尖锐,亟需把转变土地利用方式、集约用地置于土地利用战略首位,在此基础上保发展、保资源、保环境,推动实现经济社会全面协调可持续发展。     

Agriculture,Land Tenure and International Migration in Rural Guatemala

In this paper, we ask what the effects of migration and remittances are on land tenure, agriculture and forests, based on empirical evidence from four rural communities in Guatemala. Our results suggest that remittances improve migrant families' access to agricultural land which – depending on the context – fosters more equitable local land distribution patterns or land concentration by migrant families. Changes in the political economy of the country also combine to stimulate these patterns, while remittances contribute to secure land rights held by migrant households. But even though migrant households are acquiring more land, the trend does not change the traditional pattern of land distribution in the country. Regarding forests, significant changes were not observed in two of the communities, while in one we observed forest decline and in the last, forest recovery. A trend away from reliance on the land for survival results in forest recovery.     

湖北省农、林、牧、渔业动态关系研究

农业、林业、畜牧业和渔业的产出主要由投入决定,但是各业之间也是相互作用和相互影响的。湖北省农、林、牧、渔业各业脉冲响应函数表明,除渔业外,各业自身1个单位标准误差信息对产值的冲击最大。预测方差分解表明湖北省畜牧业的发展对农、林、渔业发展的扰动最大。     

浅谈农地制度创新

分析农地制度创新的必要性 ,探讨农村土地所有制改革的理论观点 ,提出增加承包权的长度和强度。     

黄河流域耕地利用碳排放时空特征及影响因素研究

研究目的：揭示黄河流域耕地利用碳排放时空演变特征，并探究其影响因素，为“双碳”目标下把握区域碳排放变化规律、制定农业碳减排策略提供参考。研究方法：以黄河流域78个市域单元为研究对象，运用耕地利用碳排放核算、空间热点分析和时空地理加权回归模型（GTWR）等方法进行定量分析。研究结果：（1）2005—2020年黄河流域耕地利用碳排放量及排放强度的变化趋势呈明显的“倒U型”特征，这基本符合经济发展水平与环境污染程度之间的变化规律；（2）黄河流域耕地利用碳排放强度空间差异性明显并表现出显著的空间集聚特征，碳排放强度低值区主要集中于黄河流域中游及上游地区，高值区则位于下游地区的河南、山东两省；（3）农地的规模化经营、农作物种植结构“趋粮化”对黄河流域大部分地区的耕地利用碳排放强度具有抑制作用，而农村居民收入水平、农业发展水平、农业机械投入、复种程度、农业财政支持则表现为正向驱动，且各因素的影响效应具有显著的空间异质性。研究结论：黄河流域各区域之间的耕地利用碳排放差异显著，且驱动因素亦不相同，应结合区域实际情况制定差异化的耕地利用策略和碳减排措施。     

开发区土地资源的利用与管理

研究目的:探讨完善开发区土地管理体制的途径与土地资源可持续利用的手段.研究方法:文献资料法和比较分析法.研究结果:尽管充裕的土地资源是开发区得以设立和发展的基础,但开发区土地资源的利用确实存在严重的闲置和浪费;开发区的过多过滥,以及开发区独立于所在行政地域之外的土地管理体制是导致乱占耕地与土地闲置的主要原因;开发区土地资源的产出效益有待进一步提高.研究结论:改变并完善开发区的土地管理体制,实行土地资源的可持续利用.     

不确定性与土地利用规划

研究目的:从不确定性的视角,审视中国土地利用规划的理论和思路,讨论土地利用规划编制和实施过程中客观上业已存在的不确定性及其所产生的负面影响和应对之策,以提高确定性规划的科学性和可操作性。研究方法:文献综合法、逻辑推理法和规范分析法。研究结果:确定性规划与不确定性未来之间不是非此即彼的关系,而是模糊关系。人类无法控制不确定性未来,但是可以借助规划人为干预和引导不确定性未来的走向。研究结论:不确定性孕育着规划的产生,规划是对未来不确定性的缓解和抵消;土地利用规划中最基本的不确定性是预测未来和为了适应未来而在现在对失误进行的调整;应对土地利用规划中的不确定性,目的在于增强对未来的预测能力和调控能力。     

违法用地对土地可持续集约利用的影响机制及效应研究

研究目的:研究土地违法对土地可持续集约利用的影响机制及效应。研究方法:基于2006—2015年中国省级面板数据,建立土地违法对土地可持续集约利用影响的理论分析框架,并进行实证检验和区域差异分析。研究结果:(1)违法用地对土地可持续集约利用具有正向影响,并且这种影响效应在东部地区最为显著;(2)引入土地市场化因素后,东部地区和中部地区违法用地对土地可持续集约利用的负向影响加剧,且中部地区高于东部地区,而西部地区的影响作用相反,加入土地市场化因素后违法用地对土地可持续集约利用的影响显著为正;(3)违法用地对土地可持续集约利用的影响在空间上具有溢出效应。研究结论:中国需进一步深化土地市场化改革,建立土地出让全过程的监督管理体系,抑制违法用地;创新土地出让方式,提高土地周转效率;实施分区域差异化管理的对策建议。