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171.
Aviation constitutes about 2.5% of all energy-related CO2 emissions and in addition there are non-CO2 effects. In 2016, the ICAO decided to implement a Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) and in 2017 the EU decided on faster emission reductions in its Emissions Trading System (EU ETS), which since 2012 includes the aviation sector. The effects of these policies on the expected development of air travel emissions from 2017 to 2030 have been analyzed. For the sample country Sweden, the analysis shows that when emissions reductions in other sectors are attributed to the aviation sector as a result of the EU ETS and CORSIA, carbon emissions are expected to reduce by ?0.8% per year (however if non-CO2 emissions are included in the analysis, then emissions will increase). This is much less than what is needed to achieve the 2°C target. Our analysis of potential national aviation policy instruments shows that there are legally feasible options that could mitigate emissions in addition to the EU ETS and CORSIA. Distance-based air passenger taxes are common among EU Member States and through increased ticket prices these taxes can reduce demand for air travel and thus reduce emissions. Tax on jet fuel is an option for domestic aviation and for international aviation if bilateral agreements are concluded. A quota obligation for biofuels is a third option.

Key policy insights
  • Existing international climate policies for aviation will not deliver any major emission reductions.

  • Policymakers who want to significantly push the aviation sector to contribute to meeting the 2°C target need to work towards putting in place tougher international policy instruments in the long term, and simultaneously implement temporary national policy instruments in the near-term.

  • Distance-based air passenger taxes, carbon taxes on jet fuel and quota obligations for biofuels are available national policy options; if they are gradually increased, and harmonized with other countries, they can help to significantly reduce emissions.

  相似文献   
172.
In principle, many climate policymakers have accepted that large-scale carbon dioxide removal (CDR) is necessary to meet the Paris Agreement’s mitigation targets, but they have avoided proposing by whom CDR might be delivered. Given its role in international climate policy, the European Union (EU) might be expected to lead the way. But among EU climate policymakers so far there is little talk on CDR, let alone action. Here we assess how best to ‘target’ CDR to motivate EU policymakers exploring which CDR target strategy may work best to start dealing with CDR on a meaningful scale. A comprehensive CDR approach would focus on delivering the CDR volumes required from the EU by 2100, approximately at least 50 Gigatonnes (Gt) CO2, according to global model simulations aiming to keep warming below 2°C. A limited CDR approach would focus on an intermediate target to deliver the CDR needed to reach ‘net zero emissions’ (i.e. the gross negative emissions needed to offset residual positive emissions that are too expensive or even impossible to mitigate). We argue that a comprehensive CDR approach may be too intimidating for EU policymakers. A limited CDR approach that only addresses the necessary steps to reach the (intermediate) target of ‘net zero emissions’ is arguably more achievable, since it is a better match to the existing policy paradigm and would allow for a pragmatic phase-in of CDR while avoiding outright resistance by environmental NGOs and the broader public.

Key policy insights

  • Making CDR an integral part of EU climate policy has the potential to significantly reshape the policy landscape.

  • Burden sharing considerations would probably play a major role, with comprehensive CDR prolonging the disparity and tensions between progressives and laggards.

  • Introducing limited CDR in the context of ‘net zero’ pathways would retain a visible primary focus on decarbonization but acknowledge the need for a significant enhancement of removals via ‘natural’ and/or ‘engineered’ sinks.

  • A decarbonization approach that intends to lead to a low level of ‘residual emissions’ (to be tackled by a pragmatic phase-in of CDR) should be the priority of EU climate policy.

  相似文献   
173.
塔里木盆地喀什凹陷克拉托天然气来源分析及聚气特征   总被引:2,自引:1,他引:1  
塔里木西南喀什凹陷的克拉托天然气主要表现为原油的溶解气或者湿气,甲烷含量为74.59%~85.58%,克4井和克30井天然气则为较干的湿气。克拉托天然气的δ13C1值为-41.2‰~-40.6‰,δ13C2值为-30.0‰~-27.4‰。气源对比表明克拉托天然气主要源自具有混源母质特征的中侏罗统湖相烃源岩,不同于源自石炭系烃源岩的阿克莫木天然气。喀什凹陷的中-下侏罗统烃源岩主要是由于新近系的巨厚沉积才从未成熟—低成熟阶段进入成熟—高成熟阶段,生成的油气在克拉托背斜圈闭中聚集,虽也属晚期成藏,却具有连续聚气的特征。上新世末期,喀什凹陷的周缘开始抬升,早期油气藏受到破坏,形成了现今的地表油气苗或油砂。  相似文献   
174.
Secular variations of carbon isotopic composition of organic carbon can be used in the study of global environmental variation, the carbon cycle, stratigraphic delimitation, and biological evolution, etc. Organic carbon isotopic analysis of the Nangao and Zhalagou sections in eastern Guizhou reveals a negative excursion near the Precambrian-Cambrian boundary that correlates with a distinct carbonate carbon isotopic negative excursion at this boundary globally. Our results also demonstrate that several alternating positive and negative shifts occur in the Meishucunian, and an obvious negative anomaly appears at the boundary between the Meishucunian and Qiongzhusian. The isotope values are stable in the middle and lower parts but became more positive in the upper part of the Qiongzhusian. Evolution of organic carbon isotopes from the two sections in the deepwater facies can be well correlated with that of the carbonate carbon isotopes from the section in the shallow water facies. Integrated with other stratigraphic tools, we can precisely establish a lower Cambrian stratigraphic framework from shallow shelf to deep basin of the Yangtze Platform.  相似文献   
175.
有机碳和无机碳的流域输出是湖泊碳埋藏的重要驱动因子,而喀斯特地区无机碳循环具有反应迅速且对人类活动影响敏感的特点.在流域开发持续增强的背景下,喀斯特地区湖泊有机碳和无机碳的来源、含量与埋藏通量可能会出现同步变化的协同模式.本文以云南省石林喀斯特地区流域土地利用类型不同的两个中型湖泊(长湖、月湖)开展对比分析,通过对沉积物钻孔的土壤侵蚀强度(磁化率)、流域外源输入(C:N比值)、水动力(粒度)、营养盐(总氮、总磷)、藻类生产力(叶绿素色素)等代用指标的分析,结合监测数据和历史资料重建了两个湖泊环境变化的近百年历史,并定量识别了有机碳和无机碳埋藏响应流域开发的变化特征与协同模式.沉积物磁化率和C:N比值结果揭示了流域地表侵蚀和外源输入的阶段性特征,同时总氮和总磷含量记录了长湖和月湖营养水平上升的长期模式.在流域森林覆被较高(33.43%)的长湖中,全岩和有机质C:N比值分别与磁化率信号呈显著正相关(r=0.95和0.89,P<0.001),且与无机碳和有机碳含量呈显著负相关(r=-0.94,P<0.001和r=-0.52,P=0.01),反映了森林植被退化时流域碳输出的减少对沉...  相似文献   
176.
Alluviation and sedimentation of the Yellow River are important factors influencing the surface soil structure and organic carbon content in its lower reaches. Selecting Kaifeng and Zhoukou as typical cases of the Yellow River flooding area, the field survey, soil sample collection, laboratory experiment and Geographic Information System(GIS) spatial analysis methods were applied to study the spatial distribution characteristics and change mechanism of organic carbon components at different soil depths. The results revealed that the soil total organic carbon(TOC), active organic carbon(AOC) and nonactive organic carbon(NOC) contents ranged from 0.05–30.03 g/kg, 0.01–8.86 g/kg and 0.02–23.36 g/kg, respectively. The TOC, AOC and NOC contents in the surface soil layer were obviously higher than those in the lower soil layer, and the sequence of the content and change range within a single layer was TOCNOCAOC. Geostatistical analysis indicated that the TOC, AOC and NOC contents were commonly influenced by structural and random factors, and the influence magnitudes of these two factors were similar. The overall spatial trends of TOC, AOC and NOC remained relatively consistent from the 0–20 cm layer to the 20–100 cm layer, and the transition between high-and low-value areas was obvious, while the spatial variance was high. The AOC and NOC contents and spatial distribution better reflected TOC spatial variation and carbon accumulation areas. The distribution and depth of the sediment, agricultural land-use type, cropping system, fertilization method, tillage process and cultivation history were the main factors impacting the spatial variation in the soil organic carbon(SOC) components. Therefore, increasing the organic matter content, straw return, applying organic manure, adding exogenous particulate matter and conservation tillage are effective measures to improve the soil quality and attain sustainable agricultural development in the alluvial/sedimentary zone of the Yellow River.  相似文献   
177.
The Canadian Model of Ocean Carbon (CMOC) has been developed as part of a global coupled climate carbon model. In a stand-alone integration to preindustrial equilibrium, the model ecosystem and global ocean carbon cycle are in general agreement with estimates based on observations. CMOC reproduces global mean estimates and spatial distributions of various indicators of the strength of the biological pump; the spatial distribution of the air-sea exchange of CO2 is consistent with present-day estimates. Agreement with the observed distribution of alkalinity is good, consistent with recent estimates of the mean rain ratio that are lower than historic estimates, and with calcification occurring primarily in the lower latitudes. With anthropogenic emissions and climate forcing from a 1850-2000 climate model simulation, anthropogenic CO2 accumulates at a similar rate and with a similar spatial distribution as estimated from observations. A hypothetical scenario for complete elimination of iron limitation generates maximal rates of uptake of atmospheric CO2 of less than 1 PgC y−1, or about 11% of 2004 industrial emissions. Even a ‘perfect’ future of sustained fertilization would have a minor impact on atmospheric CO2 growth. In the long term, the onset of fertilization causes the ocean to take up an additional 77 PgC after several thousand years, compared with about 84 PgC thought to have occurred during the transition into the last glacial maximum due to iron fertilization associated with increased dust deposition.  相似文献   
178.
大黄鱼病原副溶血弧菌拮抗菌的筛选   总被引:1,自引:1,他引:0  
用点种法从大黄鱼肠道优势菌群中筛选出104株病原性副溶血弧菌的拮抗菌,进一步研究拮抗效果最好的11株拮抗菌的抗菌谱和生长曲线,其中NAC平板上筛选的4株拮抗菌的抗菌范围较广,锰营养琼脂培养基上筛选的3株拮抗菌具有生长优势。用BIOLOG板测定了抗菌谱较广、有一定生长优势3株拮抗菌(R22,Y58和J312)的碳源利用情况,结果表明,3株拮抗菌的碳源谱都比较广,都能利用糖类、有机酸和氨基酸等,而且与鱼类营养的竞争较小。16S rRNA基因同源性分析的结果显示与R22,Y58,J312同源性达99%以上的菌株分别来自弧菌属、芽孢杆菌属和假单胞菌属。进一步对R22,J312和Y58三株拮抗菌进行生化鉴定,结果显示R22为溶藻弧菌,J312为荧光假单胞菌,但Y58的种属未能得到确认。所得到的3株拮抗菌R22,Y58,J312在拮抗病原菌、抗菌谱、生长特性和营养利用等方面都初步满足益生菌的筛选条件,有待进一步检测其安全性和实用效果以便能够成为能实用的益生菌。  相似文献   
179.
楚科奇海表层沉积物的生源组分及其对碳埋藏的指示意义   总被引:2,自引:2,他引:0  
工业革命以来大气中CO2浓度由280 ppm剧增至375 ppm,是导致全球气候变暖的主要原因[1]。海洋作为大气CO2的“汇”之一,每年可吸收人类释放CO2气体总量的30%,对全球碳循环的收支平衡有重要作用[2]。两极地区是CO2的主要汇区,也是全球变化的重要反馈窗口。因此,了解碳在北冰洋的生物地球化学循环过程是十分必要的[3-4]。海洋中的生源沉积物主要来自于海洋上层浮游生物碎屑的沉降,主要由蛋白石(以生物硅代替,BSi)、碳酸钙(CaCO3)和有机质(通常用有机碳替代,TOC)组成[5]。  相似文献   
180.
The temporal and spatial variability of dissolved inorganic phosphate (DIP), nitrogen (DIN), carbon (DIC) and dissolved organic carbon (DOC) were studied in order to determine the net ecosystem metabolism (NEM) of San Diego Bay (SDB), a Mediterranean-climate lagoon. A series of four sampling campaigns were carried out during the rainy (January 2000) and the dry (August 2000 and May and September 2001) seasons. During the dry season, temperature, salinity and DIP, DIC and DOC concentrations increased from oceanic values in the outer bay to higher values at the innermost end of the bay. DIP, DIC and DOC concentrations showed a clear offset from conservative mixing implying production of these dissolved materials inside the bay. During the rainy season, DIP and DOC increased to the head, whereas salinity decreased toward the mouth due to land runoff and river discharges. The distributions of DIP and DOC also showed a deviation from conservative mixing in this season, implying a net addition of these dissolved materials during estuarine mixing within the bay. Mass balance calculations showed that SDB consistently exported DIP (2.8–9.8 × 103 mol P d−1), DIC (263–352 × 103 mol C d−1) and DOC (198–1233 × 103 mol C d−1), whereas DIN (5.5–18.2 × 103 mol N d−1) was exported in all samplings except in May 2001 when it was imported (8.6 × 103 mol N d−1). The DIP, DIC and DOC export rates along with the strong relationship between DIP, DIC or DOC and salinity suggest that intense tidal mixing plays an important role in controlling their distributions and that SDB is a source of nutrients and DOC to the Southern California Bight. Furthermore, NEM ranged from −8.1 ± 1.8 mmol C m−2 d−1 in September to −13.5 ± 5.8 mmol C m−2 d−1 in January, highlighting the heterotrophic character of SDB. In order to explain the net heterotrophy of this system, we postulate that phytoplankton-derived particulate organic matter, stimulated by upwelling processes in the adjacent coastal waters, is transported into the bay, retained and then remineralized within the system. Our results were compared with those reported for the heterotrophic hypersaline coastal lagoons located in the semi-arid coast of California–Baja California, and with those autotrophic hypersaline systems found in the semi-arid areas of Australia. We point out that the balance between autotrophy and heterotrophy in inverse estuaries is dependent on net external inputs of either inorganic nutrients or organic matter as it has been indicated for positive estuaries.  相似文献   
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