Assessing decarbonization pathways and their implications for energy security policies in Japan     

Ken Oshiro  Mikiko Kainuma  Toshihiko Masui 《Climate Policy》2016,16(4):S63-S77

For countries without sufficient fossil fuel resources such as Japan, climate policies in the mid- to long term need to satisfy requirements not only for decarbonisation but also for energy security in the context of limitations on renewable energies and nuclear power. This study assesses the feasibility of decarbonization pathways to 2050 and their effects on energy security, considering the latest energy and climate policies in Japan using the AIM/Enduse model. The analysis illustrates that deep decarbonization by 2050 is technically feasible even without nuclear power based on three elements: energy efficiency improvements, low-carbon electricity and electrification in end-use sectors. These decarbonization pathways, in the long term, could also contribute to enhanced energy security, reducing import dependency to less than a half of the total primary energy and reducing import bills for fossil fuels by around 70% compared with the current level. Notably, renewable energies could play a strategically significant role in satisfying both climate and energy security requirements. In the mid-term (to 2030), however, although GHG emissions are reduced by 14–20% from 1990 levels, import dependency is relatively stable at today's levels, particularly without the restart of nuclear power. Given the limited potential for renewable energies in the mid-term, it is suggested that the availability of nuclear power will have negative impacts on carbon intensity and energy security, and policies to enhance the security of fossil fuels, including diversification of fuel sources and supply routes, will be required for the foreseeable future.

Policy relevance

Considering the scarcity of indigenous fossil fuel resources and the uncertain availability of nuclear power in Japan, renewable energy could play a strategically significant role in replacing unabated fossil fuels, which would contribute to satisfying both climate and energy security requirements in the long term. However, the renewable energy potential is insufficient to eliminate the requirement for fossil fuels by 2030; therefore the unavailability of nuclear power would affect energy security considerably. Thus, policies in the mid-term would still require enhancement of the energy security of fossil fuels, including the diversification of fuel sources and supply routes, as well as alleviation of the impacts of price volatility.  相似文献   

Review of the experience with monitoring uncertainty requirements in the Clean Development Mechanism     

Igor Shishlov  Valentin Bellassen 《Climate Policy》2016,16(6):703-731

In order to ensure the environmental integrity of carbon offset projects, emission reductions certified under the Clean Development Mechanism (CDM) have to be ‘real, measurable and additional’, which is ensured, inter alia, through the monitoring, reporting and verification (MRV) process. MRV, however, comes at a cost that ranges from several cents to €1.20 and above per tCO₂e depending on the project type. This article analyses monitoring uncertainty requirements for carbon offset projects with a particular focus on the trade-off between monitoring stringency and cost. To this end, existing literature is reviewed, overarching monitoring guidelines, as well as the ten most-used methodologies are scrutinized, and finally three case studies are analysed. It is shown that there is indeed a trade-off between the stringency and the cost of monitoring, which if not addressed properly may become a major barrier for the implementation of offset projects in some sectors. It is then demonstrated that this trade-off has not been systematically addressed in the overarching CDM guidelines and that there are only limited incentives to reduce monitoring uncertainty. Some methodologies and calculation tools as well as some other offset standards, however, do incorporate provisions for a trade-off between monitoring costs and stringency. These provisions may take the form of discounting emissions reductions based on the level of monitoring uncertainty – or more implicitly through allowing a project developer to choose between monitoring a given parameter and using a conservative default value.

Policy relevance

The CDM Executive Board acknowledged that monitoring uncertainty has not been treated in a consistent manner and the draft standard on uncertainty was subsequently presented in May 2013. This article supports the implementation of this standard for more comprehensive, yet cost-efficient accounting for monitoring uncertainty in carbon offset projects. Moreover, in the light of the ongoing discussions on the New Market Mechanisms as well as the operationalization of the Green Climate Fund and different national mitigation policies, the CDM experience provides valuable insights with regards to the treatment of monitoring uncertainty and constitutes a solid basis for designing uncertainty requirements for new mechanisms to mitigate climate change.  相似文献   

Controlling GHG emissions from the transportation sector through an ETS: institutional arrangements in Shenzhen,China   总被引：1，自引：0，他引：1  

Jingjing Jiang  Xiaoming Ma  Lixin Miao 《Climate Policy》2016,16(3):353-371

Many different approaches are needed to achieve reductions in GHG emissions from the transportation sector. Carbon emissions trading schemes (ETSs) are widely used in industry and are effective in reducing the overall social cost of emissions abatement. This article reports the development of a downstream ETS for the transportation sector and its application in Shenzhen, China. The ETS was devised as a mandatory cap-and-trade scheme and, as a first step, was applied to public transportation. An integrated cap was set on the total emissions from buses and taxis: an absolute cap for existing vehicles and a relative increment for new entrants. Allowances were allocated by grandfathering or benchmarking and a ‘reverse mechanism’ was established to encourage the transformation of urban transportation to a low-carbon system. Online fuel consumption monitoring was used to quantify the emissions from vehicles, and the operators were required to surrender enough allowances or credits to account for their verified annual emissions. The mechanisms for allowance trading and carbon offsets provided sufficient flexibility to make emissions abatement and the use of new-energy vehicles and environmentally friendly travel within Shenzhen's urban transportation system economically attractive.

Policy relevance

The transportation sector is becoming a major contributor to the growth in China's GHG emissions. Achieving large reductions in GHG emissions from the transportation sector is a great challenge and requires both technology and policy innovation. The tradable carbon permit is a popular concept in mitigating climate change, but the introduction of a cap-and-trade ETS into the transportation sector is a relatively innovative concept. Shenzhen has launched the first cap-and-trade ETS in a developing country and is currently exploring ways to mitigate carbon emissions by a downstream cap-and-trade ETS for the transportation sector. This article considers the main institutional arrangements and regulatory framework of Shenzhen's transportation carbon ETS. It not only refreshes the theoretical analysis and practical application of downstream cap-and-trade carbon emissions trading in urban transportation, but also provides developing countries with a cost-effective instrument to mitigate their rapid growth in traffic carbon emissions during urbanization.  相似文献   

Do lunar and meteoritic archives record temporal variations in the composition of solar wind noble gases and nitrogen? A reassessment in the light of Genesis data     

《Chemie der Erde / Geochemistry》2016,76(4):463-480

Since about half a century samples from the lunar and asteroidal regoliths been used to derive information about elemental and isotopic composition and other properties of the present and past solar wind, predominantly for the noble gases and nitrogen. Secular changes of several important compositional parameters in the solar wind were proposed, as was a likely secular decrease of the solar wind flux. In 2004 NASA’s Genesis mission returned samples which had been exposed to the solar wind for almost 2.5 years. Their analyses resulted in an unprecendented accuracy for the isotopic and elemental composition of several elements in the solar wind, including noble gases, O and N. The Genesis data therefore also allow to re-evaluate the lunar and meteorite data, which is done here. In particular, claims for long-term changes of solar wind composition are reviewed.Outermost grain layers from relatively recently irradiated lunar regolith samples conserve the true isotopic ratios of implanted solar wind species. This conclusion had been made before Genesis based on the agreement of He and Ne isotopic data measured in the aluminum foils exposed to the solar wind on the Moon during the Apollo missions with data obtained in the first gas release fractions of stepwise in-vacuo etch experiments. Genesis data allowed to strengthen this conclusion and to extend it to all five noble gases. Minor variations in the isotopic compositions of implanted solar noble gases between relatively recently irradiated samples (<100 Ma) and samples irradiated billions of years ago are very likely the result of isotopic fractionation processes that happened after trapping of the gases rather than indicative of true secular changes in the solar wind composition. This is particularly important for the ³He/⁴He ratio, whose constancy over billions of years indicates that hardly any ³He produced as transient product of the pp-chains has been mixed from the solar interior into its outer convective zone. The He isotopic composition measured in the present-day solar wind therefore is identical to the (D + ³He)/⁴He ratio at the start of the suns’s main sequence phase and hence can be used to determine the protosolar D/H ratio.Genesis settled the long-standing controversy on the isotopic composition of nitrogen in lunar regolith samples. The ¹⁵N/¹⁴N ratio in the solar wind as measured by Genesis is lower than in any lunar sample. This proves that nitrogen in regolith samples is dominated by non-solar sources. A postulated secular increase of ¹⁵N/¹⁴N by some 30% over the past few Ga is not tenable any longer. Genesis also provided accurate data on the isotopic composition of oxygen in the solar wind, invaluable for cosmochemisty. These data superseded but essentially confirmed one value – and disproved a second one – derived from lunar regolith samples shortly prior to Genesis.Genesis also confirmed prior conclusions that lunar regolith samples essentially conserve the true elemental ratios of the heavy noble gases in the solar wind (Ar/Kr, Kr/Xe). Several secular changes of elemental abundances of noble gases in the solar wind had been proposed based on lunar and meteoritic data. I argue here that lunar data – in concert with Genesis – provide convincing evidence only for a long-term decrease of the Kr/Xe ratio by almost a factor of two over the past several Ga. It appears that the enhancement of abundances of elements with a low first ionisation potential in the solar wind (FIP effect) changed with time.Finally, Genesis allows a somewhat improved comparison of the present-day flux of solar wind Kr and Xe with the total amount of heavy solar wind noble gases in the lunar regolith. It remains unclear whether the past solar wind flux has been several times higher on average than it is today.  相似文献   

Decadal Methane Emission Trend Inferred from Proxy GOSAT XCH₄ Retrievals: Impacts of Transport Model Spatial Resolution     

Sihong ZHU  Liang FENG  Yi LIU  Jing WANG  Dongxu YANG 《大气科学进展》2022,39(8):1343-1359

In recent studies, proxy XCH₄ retrievals from the Japanese Greenhouse gases Observing SATellite (GOSAT) have been used to constrain top-down estimation of CH₄ emissions. Still, the resulting interannual variations often show significant discrepancies over some of the most important CH₄ source regions, such as China and Tropical South America, by causes yet to be determined. This study compares monthly CH₄ flux estimates from two parallel assimilations of GOSAT XCH₄ retrievals from 2010 to 2019 based on the same Ensemble Kalman Filter (EnKF) framework but with the global chemistry transport model (GEOS-Chem v12.5) being run at two different spatial resolutions of 4° × 5° (R4, lon × lat) and 2° × 2.5° (R2, lon × lat) to investigate the effects of resolution-related model errors on the derived long-term global and regional CH₄ emission trends. We found that the mean annual global methane emission for the 2010s is 573.04 Tg yr ^–1 for the inversion using the R4 model, which becomes about 4.4 Tg yr ^–1 less (568.63 Tg yr ^–1) when a finer R2 model is used, though both are well within the ensemble range of the 22 top-down results (2008–17) included in the current Global Carbon Project (from 550 Tg yr ^–1 to 594 Tg yr ^–1). Compared to the R2 model, the inversion based on the R4 tends to overestimate tropical emissions (by 13.3 Tg yr ^–1), which is accompanied by a general underestimation (by 8.9 Tg yr ^–1) in the extratropics. Such a dipole reflects differences in tropical–mid-latitude air exchange in relation to the model’s convective and advective schemes at different resolutions. The two inversions show a rather consistent long-term CH₄ emission trend at the global scale and over most of the continents, suggesting that the observed rapid increase in atmospheric methane can largely be attributed to the emission growth from North Africa (1.79 Tg yr ^–2 for R4 and 1.29 Tg yr ^–2 for R2) and South America Temperate (1.08 Tg yr ^–2 for R4 and 1.21 Tg yr ^–2 for R2) during the first half of the 2010s, and from Eurasia Boreal (1.46 Tg yr ^–2 for R4 and 1.63 Tg yr ^–2 for R2) and Tropical South America (1.72 Tg yr^–2 for R4 and 1.43 Tg yr ^–2 for R2) over 2015–19. In the meantime, emissions in Europe have shown a consistent decrease over the past decade. However, the growth rates by the two parallel inversions show significant discrepancies over Eurasia Temperate, South America Temperate, and South Africa, which are also the places where recent GOSAT inversions usually disagree with one other.  相似文献   

Greenhouse gas emissions from global cities under SSP/RCP scenarios, 1990 to 2100     

《Global Environmental Change》2022

Projections of greenhouse gas (GHG) emissions are critical to enable a better understanding and anticipation of future climate change under different socio-economic conditions and mitigation strategies. The climate projections and scenarios assessed by the Intergovernmental Panel on Climate Change, following the Shared Socioeconomic Pathway (SSP)-Representative Concentration Pathway (RCP) framework, have provided a rich understanding of the constraints and opportunities for policy action. However, the current emissions scenarios lack an explicit treatment of urban emissions within the global context. Given the pace and scale of urbanization, with global urban populations expected to increase from about 4.4 billion today to about 7 billion by 2050, there is an urgent need to fill this knowledge gap. Here, we estimate the share of global GHG emissions driven by urban areas from 1990 to 2100 based on the SSP-RCP framework. The urban consumption-based GHG emissions are presented in five regional aggregates and based on a combination of the urban population share, 2015 urban per capita CO₂eq carbon footprint, SSP-based national CO₂eq emissions, and recent analysis of urban per capita CO₂eq trends. We find that urban areas account for the majority of global GHG emissions in 2015 (61.8%). Moreover, the urban share of global GHG emissions progressively increases into the future, exceeding 80% in some scenarios by the end of the century. The combined urban areas in Asia and Developing Pacific, and Developed Countries account for 65.0% to 73.3% of cumulative urban consumption-based emissions between 2020 and 2100 across the scenarios. Given these dominant roles, we describe the implications for potential urban mitigation in each of the scenario narratives in order to meet the goal of climate neutrality within this century.  相似文献   

The impact of agricultural trade approaches on global economic modeling     

《Global Environmental Change》2022

Researchers explore future economic and climate scenarios using global economic and integrated assessment models to understand long-term interactions between human development and global environmental changes. However, differences in trade modeling approaches are an important source of uncertainty in these types of assessments, particularly for regional projections. In this study, we modified the Global Change Analysis Model (GCAM) to include a novel logit-based Armington trade structure, to examine two approaches to modeling trade: (1) an approach that represents segmented regional markets (SRM), and (2) an approach that represents integrated world markets (IWM). Our results demonstrate that assuming IWM, i.e., homogeneous product modeling and neglecting economic geography, could lead to lower cropland use (i.e., by 115 million hectares globally) and terrestrial carbon fluxes (i.e., by 25%) by the end of the century under the default GCAM scenario, compared with the logit-based Armington SRM structure. The results are highly heterogeneous across regions, with more pronounced regional trade responses driven by global market integration. Our study highlights the critical role that assumptions about future trade paradigms play in global economic and integrated assessment modeling. The results imply that closer harmonization of trade modeling approaches and trade parameter values could increase the convergence of regional results among models in model intercomparison studies.  相似文献   

The policy discourse on negative emissions,land-based technologies,and the Global South     

《Global Environmental Change》2022

Negative emissions are increasingly seen as a policy option to limit climate change. However, the most readily available technologies that could deliver negative emissions require, if deployed at scale, large amounts of land, with huge risks for livelihoods and the environment. This land is often assumed to be in the Global South. This article analyzes the nascent policy discourse on negative emissions by assessing 116 policy documents by 97 organizations with a focus on land-based technologies (afforestation and reforestation, bioenergy with carbon capture and storage, biochar, soil carbon sequestration). We conclude that this policy discourse is largely centered in the Global North (mostly in the United States, the United Kingdom, and Germany), with only five organizations directly linked to the Global South. 61% of the organizations in our sample, however, somehow refer to the Global South in their contributions, with nongovernmental organizations being most strongly focused on the role of the Global South and in particular the risks for vulnerable countries. While the earlier policy discourse on negative emissions was linked to a more general “geoengineering” discourse, this link has loosened in the last years. Overall, in the documents that we studied, negative emissions technologies seem to become more accepted, and parts of the discourse shift towards deployment. Bioenergy with carbon capture and storage seems more often associated with risks if compared to other land-based negative emissions technologies, especially with a view to the Global South.  相似文献   

Greenhouse gas emissions from Mediterranean agriculture: Evidence of unbalanced research efforts and knowledge gaps     

《Global Environmental Change》2021

Designing effective mitigation policies for greenhouse gas (GHG) emissions from agriculture requires understanding the mechanisms by which management practices affect emissions in different agroclimatic conditions. Agricultural GHG emissions and carbon sequestration potentials have been extensively studied in the Mediterranean biome, which is a biodiversity hot spot that is highly vulnerable to environmental changes. However, the absolute magnitude of GHG emissions and the extent to which research efforts match these emissions in each production system, are unknown. Here, we estimated GHG emissions and potential carbon sinks associated with crop and livestock production systems in the Mediterranean biome, covering 31 countries and assessing approximately 10,000 emission items. The results were then combined with a bibliometric assessment of 797 research publications to compare emissions estimates obtained with research efforts for each of the studied items. Although the magnitude of GHG emissions from crop production and the associated carbon sequestration potential (261 Tg CO₂eq yr⁻¹) were nearly half of those from livestock production (367 Tg CO₂eq yr⁻¹), mitigation research efforts were largely focused on the former. As a result, the relative research intensity, which relates the number of publications to the magnitude of emissions, is nearly one order of magnitude higher for crop production than for livestock production (2.6 and 0.4 papers Tg CO₂eq⁻¹, respectively). Moreover, this mismatch is even higher when crop and livestock types are studied separately, which indicates major research gaps associated with grassland and many strategic crop types, such as fruit tree orchards, fiber crops, roots and tubers. Most life cycle assessment studies do not consider carbon sequestration, although this single process has the highest magnitude in terms of annual CO₂eq. In addition, these studies employ Tier 1 IPCC factors, which are not suited for use in Mediterranean environments. Our analytical results show that a strategic plan is required to extend on-site field GHG measurements to the Mediterranean biome. Such a plan needs to be cocreated among stakeholders and should be based on refocusing research efforts to GHG balance components that have been afforded less attention. In addition, the outcomes of Mediterranean field studies should be integrated into life cycle assessment-based carbon footprint analyses in order to avoid misleading conclusions.  相似文献   

Explanation of dominant oblique radio emission at Jupiter and comparison to the terrestrial case     

F. Mottez  S. Hess 《Planetary and Space Science》2010,58(10):1414-1422

The Io-Jupiter S-bursts are series of quasi-periodic impulsive decameter radio emissions from the magnetic flux tube connecting Jupiter to its closest galilean satellite Io. This paper discusses the possibility, suggested by previous works by Hess et al., that the S-bursts are triggered by upgoing electrons accelerated (downward) by trapped Alfvén waves, that have mirrored above the Jupiter ionosphere. According to this theory, the S-bursts would correspond to wave modes that propagate at oblique angles with respect to the magnetic field. Oblique propagation is also inferred for the more slowly varying components of Io-Jupiter radio emissions. Previous works, mainly based on observations of the terrestrial AKR, whose generation process is closely related to those of S-bursts, showed that these waves are emitted on perpendicular wave modes. This discrepancy between the Jovian and Terrestrial cases has led to a controversy about the credibility of the S-bursts model by Hess et al. In the present paper, we show that indeed, the most unstable wave modes for Earth AKR, and Io-Jupiter S-bursts, as they are seen from ground based radio-telescopes, are not the same. Several causes are evaluated: observational bias, the different degree of plasma magnetization above Earth and Jupiter, the role of a cold plasma component and of plasma auroral cavities. Furthermore, we make predictions about what kind of radiation modes a probe crossing the low altitude Io-Jupiter flux tube will see.  相似文献