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1.
G. Cornelis van Kooten 《Climatic change》2009,95(3-4):449-463
Biological activities that sequester carbon create CO2 offset credits that could obviate the need for reductions in fossil fuel use. Credits are earned by storing carbon in terrestrial ecosystems and wood products, although CO2 emissions are also mitigated by delaying deforestation, which accounts for one-quarter of anthropogenic CO2 emissions. However, non-permanent carbon offsets from biological activities are difficult to compare with each other and with emissions reduction because they differ in how long they prevent CO2 from entering the atmosphere. This is the duration problem. It results in uncertainty and makes it hard to determine the legitimacy of biological activities in mitigating climate change. Measuring, verifying and monitoring the carbon sequestered in sinks greatly increases transaction costs and leads to rent seeking by sellers of dubious sink credits. While biological sink activities undoubtedly help mitigate climate change and should not be neglected, it is shown that there are limits to the substitutability between temporary offset credits from these activities and emissions reduction, and that this has implications for carbon trading. A possible solution to inherent incommensurability between temporary and permanent credits is also suggested. 相似文献
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Alejandro Caparrós 《Climatic change》2009,96(3):421-441
We set out a dynamic model to investigate optimal time paths of emissions, carbon stocks and carbon sequestration by land
conversion, allowing for non-instantaneous carbon sequestration. Previous research in a dynamic general equilibrium framework,
assuming instantaneous carbon sequestration, has shown that land conversion should take place as soon as possible. On the
contrary, previous research within a partial equilibrium framework has shown that, with increasing carbon prices, it is optimal
to delay carbon sequestration through land conversion. We show that land use change alternatives, e.g. reforestation, have
to be used as soon as possible before the singular path is reached, i.e. the unique trajectory that brings the system to the
steady-state. We also show that faster increasing carbon prices can induce a reduction in the rate of reforestation, and that
this may take place after an initial phase of increased reforestations or even immediately, depending upon the shape of the
increase in carbon prices. Finally, we show that the type of species used is relevant and that the land conversion rate gets
smaller the longer it takes the trees to grow. We analyze four different carbon accounting methods, describing the conditions
that make them efficient and discussing the comparative advantages of each of them. 相似文献
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John M. DeCicco 《Climatic change》2012,111(3-4):627-640
Public policy supports biofuels for their benefits to agricultural economies, energy security and the environment. The environmental rationale is premised on greenhouse gas (GHG, “carbon”) emissions reduction, which is a matter of contention. This issue is challenging to resolve because of critical but difficult-to-verify assumptions in lifecycle analysis (LCA), limits of available data and disputes about system boundaries. Although LCA has been the presumptive basis of climate policy for fuels, careful consideration indicates that it is inappropriate for defining regulations. This paper proposes a method using annual basis carbon (ABC) accounting to track the stocks and flows of carbon and other relevant GHGs throughout fuel supply chains. Such an approach makes fuel and feedstock production facilities the focus of accounting while treating the CO2 emissions from fuel end-use at face value regardless of the origin of the fuel carbon (bio- or fossil). Integrated into cap-and-trade policy and including provisions for mitigating indirect land-use change impacts, also evaluated on an annual basis, an ABC approach would provide a sound carbon management framework for the transportation fuels sector. 相似文献
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Land-use, land-use change and forestry (LULUCF) activities will play an important role in global climate change mitigation. Many carbon schemes require the delivery of both climate and rural development benefits by mitigation activities conducted in developing countries. Agroforestry is a LULUCF activity that is gaining attention because of its potential to deliver climate benefits as well as rural development benefits to smallholders. There is hope that agroforestry can deliver co-benefits for climate and development; however experience with early projects suggests co-benefits are difficult to achieve in practice. We review the literature on agroforestry, participatory rural development, tree-based carbon projects and co-benefit carbon projects to look at how recommended project characteristics align when trying to generate different types of benefits. We conclude that there is considerable tension inherent in designing co-benefit smallholder agroforestry projects. We suggest that designing projects to seek ancillary benefits rather than co-benefits may help to reduce this tension. 相似文献
6.
Mechanisms controlling soil carbon turnover and their potential application for enhancing carbon sequestration 总被引：6，自引：0，他引：6
In addition to increasing plant C inputs, strategies for enhancing soil C sequestration include reducing C turnover and increasing
its residence time in soils. Two major mechanisms, (bio)chemical alteration and physicochemical protection, stabilize soil organic C (SOC) and thereby control its turnover. With (bio)chemical alteration, SOC is transformed by biotic
and abiotic processes to chemical forms that are more resistant to decomposition and, in some cases, more easily retained
by sorption to soil solids. With physicochemical protection, biochemical attack of SOC is inhibited by organomineral interactions
at molecular to millimeter scales. Stabilization of otherwise decomposable SOC can occur via sorption to mineral and organic
soil surfaces, occlusion within aggregates, and deposition in pores or other locations inaccessible to decomposers and extracellular
enzymes. Soil structure is a master integrating variable that both controls and indicates the SOC stabilization status of
a soil. One potential option for reducing SOC turnover and enhancing sequestration, is to modify the soil physicochemical
environment to favor the activities of fungi. Specific practices that could accomplish this include manipulating the quality
of plant C inputs, planting perennial species, minimizing tillage and other disturbances, maintaining a near-neutral soil
pH and adequate amounts of exchangeable base cations (particularly calcium), ensuring adequate drainage, and minimizing erosion.
In some soils, amendment with micro- and mesoporous sorbents that have a high specific surface – such as fly ash or charcoal
– can be beneficial.
All authors contributed equally to this article. 相似文献
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Tropical deforestation and atmospheric carbon dioxide 总被引：4，自引：0，他引：4
R. A. Houghton 《Climatic change》1991,19(1-2):99-118
Recent estimates of the net release of carbon to the atmosphere from deforestation in the tropics have ranged between 0.4 and 2.5 × 1015 g yr–1. Two things have happened to require a revision of these estimates. First, refinements of the methods used to estimate the stocks of carbon in the vegetation of tropical forests have produced new estimates that are intermediate between the previous high and low estimates of carbon stocks. When these revised estimates were used here to calculate the emissions of carbon from deforestation, the new range was 1.0–2.0 × 1015 g C.Second, the previous range of estimates of flux was based on rates of deforestation in 1980. Myers' recent estimate of the rates of tropical deforestation in 1989 is about 90% higher than the rates just 10 years ago. When these recent rates were used to calculate the current net flux of carbon to the atmosphere, the range was between 1.6 and 2.7 × 1015 g C.Other uncertainties expanded this range, however, to 1.1–3.6 × 1015 g C yr–1. Three factors contributed about equally to the expanded range: rates of deforestation, the fate of deforested lands (permanent or temporary clearing), and carbon stocks of forests, including anthropogenic reductions of carbon stocks within forests (thinning or degradation). 相似文献
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随着气候变化影响加剧,全球气候治理进程加速,实现碳达峰已经成为全球气候行动的核心,各国也相继制定碳中和目标并开展行动。中国在第75届联合国大会一般性辩论上提出了碳达峰碳中和目标,部分已实现碳达峰的发达经济体也提出了各自的碳中和承诺。文中从“整体-阶段”及“焦点-公平”视角分析了欧盟和美国等主要发达经济体碳达峰的历程和特点,以及其碳中和目标和规划。研究发现,发达经济体在碳达峰过程中普遍经历了较长的爬坡期（58~136年）和平台期（4~20年),在碳达峰时,发达经济体的能源结构以油气为主,油气占一次能源消费比重为57%~77%,其人均排放量、历史累计排放以及人均GDP也都处于较高水平,在碳达峰前后总体处于经济与碳排放脱钩状态。各发达经济体的碳中和路径均以能源转型为重点,采用了多元化的政策工具,并且注重低碳和负碳技术的革新。根据发达经济体的政策展望,在实现碳中和时,均难以将绝对排放量降为零,都需要通过碳移除手段进行抵消。通过对比分析,发现中国的碳达峰和碳中和目标是具有雄心的气候承诺,相较其他发达经济体需要付出更大努力。建议运用全面综合的政策工具支撑碳中和目标的有效落实,加快中国的气候立法,在兼顾公正转型的同时推动能源结构调整,注重可再生能源和能效方面的新技术开发应用。 相似文献
12.
Considering the influence of sequestration duration and carbon saturation on estimates of soil carbon capacity 总被引：10，自引：0，他引：10
Rates of soil C sequestration have previously been estimated for a number of different land management activities, and these
estimates continue to improve as more data become available. The time over which active sequestration occurs may be referred
to as the sequestration duration. Integrating soil C sequestration rates with durations provides estimates of potential change
in soil C capacity and more accurate estimates of the potential to sequester C. In agronomic systems, changing from conventional
plow tillage to no-till can increase soil C by an estimated 16±3%, whereas increasing rotation intensity can increase soil
C by an estimated 6±3%. The increase in soil C following a change in rotation intensity, however, may occur over a slightly
longer period (26 yr) than that for tillage cessation (21 yr). Sequestration strategies for grasslands have, on average, longer
sequestration durations (33 yr) than for croplands. Estimates for sequestration rates and durations are mean values and can
differ greatly between individual sites and management practices. As the annual sequestration rate declines over the sequestration
duration period, soil C approaches a new steady state. Sequestration duration is synonymous with the time to which soil C
steady state is reached. However, soils could potentially sequester additional C following additional changes in management
until the maximum soil C capacity, or soil C saturation, is achieved. Carbon saturation of the soil mineral fraction is not
well understood, nor is it readily evident. We provide evidence of soil C saturation and we discuss how the steady state C
level and the level of soil C saturation together influence the rate and duration of C sequestration associated with changes
in land management. 相似文献
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Soil carbon sequestration 总被引：1，自引：0，他引：1
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Much attention has been paid to the ways that people’s home energy use, travel, food choices and other routine activities affect their emissions of carbon dioxide and, ultimately, their contributions to global warming. However, the reproductive choices of an individual are rarely incorporated into calculations of his personal impact on the environment. Here we estimate the extra emissions of fossil carbon dioxide that an average individual causes when he or she chooses to have children. The summed emissions of a person’s descendants, weighted by their relatedness to him, may far exceed the lifetime emissions produced by the original parent. Under current conditions in the United States, for example, each child adds about 9441 metric tons of carbon dioxide to the carbon legacy of an average female, which is 5.7 times her lifetime emissions. A person’s reproductive choices must be considered along with his day-to-day activities when assessing his ultimate impact on the global environment. 相似文献
17.
Achieving a successful transition to a low carbon economy, in the UK and other countries, will require sufficient people with appropriate qualifications and skills to manufacture, install, and operate the low carbon technologies and approaches. The actual numbers and types of skills required are uncertain and will depend on the speed and direction of the transition pathways, but there are reasons to doubt that market mechanisms will deliver the necessary skilled workers in a timely manner. The range of market, government, and governance failures relating to the provision of low carbon skills are examined, particularly for their potential to cause a slower, costlier, and less employment-intensive transition. The potential policy responses to these failures are considered, including standardization of funding for training; formalization of transferable qualifications; legally binding targets for carbon emissions reductions and low carbon technology deployment; framework contracts and agreements between actors in key sectors; licensing and accreditation schemes for key technology sectors; government support for skills academies and training centres; support for first movers in niches; increasing mobility of workers; and providing a clear long-term cross-sectoral framework for a low carbon transition, including skills training. Policy relevance The article argues for the importance of skills issues for a successful transition to a low carbon economy. It outlines the potential causes of skills shortages, both generic and those specific to low carbon, as well as the probable impact of these types of shortages. By changing existing sectoral and occupational patterns, the transition will disrupt the existing market and government mechanisms to identify and remedy skills shortages in specific sectors. The nature and required pace of the low carbon transition also means that there are pressures that could induce greater skills shortages. These shortages, in turn, could critically delay elements of the transition and increase its cost and duration. The article outlines approaches taken to address these causes of skills shortages, drawing on examples from UK low carbon policy. The article ends with an argument that skills issues need to be more central to transitions debates. 相似文献
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We outline the theoretical and political background to the global carbon mechanisms and how they emerged in the form of the Kyoto Protocol??s Clean Development Mechanism, Joint Implementation, and Intergovernmental Emissions Trading. We present empirical data on the response to date and the variants that have arisen. Based on this, we analyse the issues and evidence on the main controversies around additionality, efficiency and effectiveness of the instruments. The final part of the paper considers some of the implications for future development. 相似文献
19.
Using a global carbon cycle model (GLOCO) that considers seven terrestrial biomes, surface and deep ocean layers based on the HILDA model and a single mixed atmosphere, we analyzed the response of atmospheric CO2 concentration and oceanic DIC and DOC depth profiles to additions of carbon to the atmosphere and ocean. The rate of transport of carbon to the deepest oceanic layers is rather insensitive to the atmosphereic-ocean surface gas exchange coefficient over a wide range, hence discrepancies between researchers on the precise global average value of this coefficient do not significantly affect predictions of atmospheric response to anthropogenic inputs. Upwelling velocity, on the other hand, amplifies oceanic response by increasing primary production in the upper ocean layers, resulting in a larger flux into DOC and sediments and increased carbon storage; experiments to reduce the uncertainty in this parameter would be valuable.The location of the carbon addition, whether it is released in the atmosphere or in the middle of the oceanic thermocline, has a significant impact on the maximum atmospheric CO2 concentration (pCO2) subsequently reached, suggesting that oceanic burial of a significant fraction of carbon emissions (e.g. via clathrate hydrides) may be an important management option for limiting pCO2 buildup. Our analysis indicates that the effectiveness of ocean burial decreases asymptotically below about 1000 m depth. With a constant emissions scenario (at 1990 levels), pCO2 at year 2100 is reduced from 501 ppmv considering all emissions go to the atmosphere, to 422 ppmv with ocean burial at a depth of 1000 m of 50% of the fossil fuel emissions. An alternative scenario looks at stabilizing pCO2 at 450 ppmv; with no ocean burial of fossil fuel emissions, the rate of emissions has to be cut drastically after the year 2010, whereas oceanic burial of 2 GtC/yr allows for a smoother transition to alternative energy sources. 相似文献
20.
Aerosol light absorption, black carbon, and elemental carbon at the Fresno Supersite, California 总被引：2，自引：0，他引：2
Judith C. Chow John G. Watson Prakash Doraiswamy Lung-Wen Antony Chen David A. Sodeman Douglas H. Lowenthal Kihong Park W. Patrick Arnott Nehzat Motallebi 《Atmospheric Research》2009,93(4):874-887
Particle light absorption (bap), black carbon (BC), and elemental carbon (EC) measurements at the Fresno Supersite during the summer of 2005 were compared to examine the equivalency of current techniques, evaluate filter-based bap correction methods, and determine the EC mass absorption efficiency (σap) and the spectral dependence of bap. The photoacoustic analyzer (PA) was used as a benchmark for in-situ bap. Most bap measurement techniques were well correlated (r ≥ 0.95). Unadjusted Aethalometer (AE) and Particle Soot Absorption Photometer (PSAP) bap were up to seven times higher than PA bap at similar wavelengths because of absorption enhancement by backscattering and multiple scattering. Applying published algorithms to correct for these effects reduced the differences to 24 and 17% for the AE and PSAP, respectively, at 532 nm. The Multi-Angle Absorption Photometer (MAAP), which accounts for backscattering effects, overestimated bap relative to the PA by 51%. BC concentrations determined by the AE, MAAP, and Sunset Laboratory semi-continuous carbon analyzer were also highly correlated (r ≥ 0.93) but differed by up to 57%. EC measured with the IMPROVE/STN thermal/optical protocols, and the French two-step thermal protocol agreed to within 29%. Absorption efficiencies determined from PA bap and EC measured with different analytical protocols averaged 7.9 ± 1.5, 5.4 ± 1.1, and 2.8 ± 0.6 m2/g at 532, 670, and 1047 nm, respectively. The Angström exponent (α) determined from adjusted AE and PA bap ranged from 1.19 to 1.46. The largest values of α occurred during the afternoon hours when the organic fraction of total carbon was highest. Significant biases associated with filter-based measurements of bap, BC, and EC are method-specific. Correcting for these biases must take into account differences in aerosol concentration, composition, and sources. 相似文献