Stabilizing CO2 concentrations with incomplete international cooperation

Many stabilization scenarios have examined the implications of stabilization on the assumption that all regions and all sectors of all of the world's economies undertake emissions mitigations wherever and whenever it is cheapest to do so. This idealized assumption is just one of many ways in which emissions mitigation actions could play out globally, but not necessarily the most likely. This paper explores the implications of generic policy regimes that lead to stabilization of CO₂ concentrations under conditions in which non-Annex I regions delay emissions reductions and in which carbon prices vary across participating regions. The resulting stabilization scenarios are contrasted with the idealized results. Delays in the date by which non-Annex I regions begin to reduce emissions raise the price of carbon in Annex I regions relative to the price of carbon in Annex I in an idealized regime for any given CO₂ concentration limit. This effect increases the longer the delay in non-Annex I accession, the lower the non-Annex I carbon prices relative to the Annex I prices, and the more stringent the stabilization level. The effect of delay is very pronounced when CO₂ concentrations are stabilized at 450 ppmv, however the effect is much less pronounced at 550 ppmv and above. For long delays in non-Annex I accession, 450 ppmv stabilization levels become infeasible.     

Variations in atmospheric CO2 at the Meteorological Research Institute, Tsukuba, Japan

Since April 1986, measurements of the CO₂ concentration in the surface air have been conducted at the Meteorological Research Institure (MRI, 36°04 N, 140°07 E, 25 m above sea level) in Tsukuba, located 50 km northeast of Tokyo, Japan. The CO₂ data measured over times between 11:00 Japan Standard Time (JST) and 16:00 JST (C _N ) were considered to be representative of the air (within a few ppmv) in the planetary boundary layer. To evaluate the representative CO₂ level on a spatial scale larger than that of the C _N record, the CO₂ data with hour-to-hour variation less than 1 ppmv were selected (C _P ). Comparison of these data with those of Ryori (39°02 N, 141°50 E), a continental station operated by the Japan Meteorological Agency, indicates that the C _P record provides a representative CO₂ level in the air on spatial scales of at least a few hundred kilometers.The C _N record allows an investigation of the internanual changes in photosynthesis/respiration against changes in climatological parameters. Within a small temperature anomaly (ca.±1 °C) respiration is sensitive to the temperature change, while photosynthesis is less sensitive. When the temperature anomaly is large, however, photosynthesis and respiration tend to be competitive.     

Cumulative CO2 emissions: shifting international responsibilities for climate debt

In contrast to many discussions based on annual emissions, this article presents calculations and projections of cumulative contributions to the stock of atmospheric CO₂ by the major players, China, Europe, India, Japan and the USA, for the period 1900–2080. Although relative contributions to the climate problem are changing dramatically, notably due to the rapid industrialization of China, long-term responsibilities for enhanced global warming have not been transparently quantified in the literature. The analysis shows that if current trends continue, by the middle of this century China will overtake the USA as the major cumulative contributor to atmospheric concentrations of CO₂. This has enormous implications for the debate on the ethical responsibilities of the major greenhouse gas emitters. Effective climate policy will require both the recognition of shared responsibility and an unprecedented degree of cooperation.     

Comparing CO2 Storage and Advection Conditions at Night at Different Carboeuroflux Sites

Anemometer and CO₂ concentration data from temporary campaigns performed at six CARBOEUROFLUX forest sites were used to estimate the importance of non-turbulent fluxes in nighttime conditions. While storage was observed to be significant only during periods of both low turbulence and low advection, the advective fluxes strongly influence the nocturnal CO₂ balance, with the exception of almost flat and highly homogeneous sites. On the basis of the main factors determining the onset of advective fluxes, the ‘advection velocity’, which takes net radiation and local topography into account, was introduced as a criterion to characterise the conditions of storage enrichment/depletion. Comparative analyses of the six sites showed several common features of the advective fluxes but also some substantial differences. In particular, all sites where advection occurs show the onset of a boundary layer characterised by a downslope flow, negative vertical velocities and negative vertical CO₂ concentration gradients during nighttime. As a consequence, vertical advection was observed to be positive at all sites, which corresponds to a removal of CO₂ from the ecosystem. The main differences between sites are the distance from the ridge, which influences the boundary-layer depth, and the sign of the mean horizontal CO₂ concentration gradients, which is probably determined by the source/sink distribution. As a consequence, both positive and negative horizontal advective fluxes (corresponding respectively to CO₂ removal from the ecosystem and to CO₂ supply to the ecosystem) were observed. Conclusive results on the importance of non-turbulent components in the mass balance require, however, further experimental investigations at sites with different topographies, slopes, different land covers, which would allow a more comprehensive analysis of the processes underlying the occurrence of advective fluxes. The quantification of these processes would help to better quantify nocturnal CO₂ exchange rates.     

Consequences of Incomplete Surface Energy Balance Closure for CO2 Fluxes from Open-Path CO2/H2O Infrared Gas Analysers

We present an approach for assessing the impact of systematic biases in measured energy fluxes on CO₂ flux estimates obtained from open-path eddy-covariance systems. In our analysis, we present equations to analyse the propagation of errors through the Webb, Pearman, and Leuning (WPL) algorithm [Quart. J. Roy. Meteorol. Soc. 106, 85–100, 1980] that is widely used to account for density fluctuations on CO₂ flux measurements. Our results suggest that incomplete energy balance closure does not necessarily lead to an underestimation of CO₂ fluxes despite the existence of surface energy imbalance; either an overestimation or underestimation of CO₂ fluxes is possible depending on local atmospheric conditions and measurement errors in the sensible heat, latent heat, and CO₂ fluxes. We use open-path eddy-covariance fluxes measured over a black spruce forest in interior Alaska to explore several energy imbalance scenarios and their consequences for CO₂ fluxes.     

Determinants of CO2 emission for post-Soviet Union independent countries

This article analyses the determinants of CO₂ emission for 15 post-Soviet Union independent (PSI) countries given their recent transition to market-based economies and their relatively high levels of corruption. The direct and indirect effects of economic growth on CO₂ emission for the PSI countries are derived using a multiple-equation generalized method of moment (GMM) approach to account for simultaneity among corruption, growth and CO₂ emission. A linear relationship between gross domestic product (GDP) and CO₂ emission was observed from the analysis. Furthermore, GDP influences CO₂ emission directly, but also indirectly through its impact on corruption. Similarly, corruption affects CO₂ emission directly, as well as indirectly through its impact on GDP. Political democracy and economic freedom increase CO₂ emission indirectly through their impact on economic growth. Improved energy efficiency and the EU climate policy reduce CO₂ emission, while inflows of foreign direct investment tend to increase CO₂ emission.

Policy relevance

First, PSI countries need to invest more in efficient energy technologies to mitigate CO₂ emission levels significantly. Second, PSI policies aimed at reducing deforestation (thereby increasing population density) may help mitigate carbon emission. Third, PSI countries would be well served to recognize the detrimental effects of foreign direct investment before embarking on a misguided policy path that attracts such inflows at any cost.     

An Alternative Approach for CO2 Flux Correction Caused by Heat and Water Vapour Transfer

Energy and CO₂ fluxes are commonly measured above plant canopies using an eddy covariance system that consists of a three-dimensional sonic anemometer and an H₂O/CO₂ infrared gas analyzer. By assuming that the dry air is conserved and inducing mean vertical velocity, Webb et al. (Quart. J. Roy. Meteorol. Soc. 106, 85-100, 1980) obtained two equations to account for density effects due to heat and water vapour transfer on H₂O/CO₂ fluxes. In this paper, directly starting with physical consideration of air-parcel expansion/compression, we derive two alternative equations to correct for these effects that do not require the assumption that dry air is conserved and the use of the mean vertical velocity. We then applied these equations to eddy flux observations from a black spruce forest in interior Alaska during the summer of 2002. In this ecosystem, the equations developed here led to increased estimates of CO₂ uptake by the vegetation during the day (up to about 20%), and decreased estimates of CO₂ respiration by the ecosystem during the night (approximately 4%) as compared with estimates obtained using the Webb et al. approach.     

The Influence of Advection on the Short Term CO 2 -Budget in and Above a Forest Canopy

An experimental micrometeorological set-up was established at the CARBOEURO-FLUX site in Tharandt, Germany, to measure all relevant variables for the calculation of the vertical and horizontal advective fluxes of carbon dioxide. The set-up includes two auxiliary towers to measure horizontal and vertical CO₂ and H₂O gradients through the canopy, and to make ultrasonic wind measurements in the trunk space. In combination with the long-term flux tower an approximately even-sided prism with a typical side-length of 50 m was established. It is shown that under stable (nighttime) conditions the mean advective fluxes have magnitudes on the same order as the daily eddy covariance (EC) flux, which implies that they play a significant, but not yet fully understood, role in the carbon budget equation. The two advective fluxes are opposite and seem to cancel each other at night (at least for these measurements). During the day, vertical advection tends to zero, while horizontal advection is still present implying a flow of CO₂ out of the control volume. From our measurements, a mean daily gain of 2.2 gC m^–2 d^–1 for the horizontal advection and a mean daily loss of 2.5 gC m^–2d^–1 for the vertical advection is calculated for a period of 20 days. However the large scatter of the advective fluxes has to be further investigated. It is not clear yet whether the large variability is natural or due to measurement errors and conceptual deficiencies of the experiment. Similar results are found in the few comparable studies.     

Production of N2O,CH4, and CO2 from soils in the tropical savanna during the dry season

Emissions of N₂O, CH₄, and CO₂ from soils at two sites in the tropical savanna of central Venezuela were determined during the dry season in February 1987. Measured arithmetic mean fluxes of N₂O, CH₄, and CO₂ from undisturbed soil plots to the atmosphere were 2.5×10⁹, 4.3×10¹⁰, and 3.0×10¹³ molecules cm^-2 s^-1, respectively. These fluxes were not significantly affected by burning the grass layer. Emissions of N₂O increased fourfold after simulated rainfall, suggesting that production of N₂O in savanna soils during the rainy season may be an important source for atmospheric N₂O. The CH₄ flux measurements indicate that these savanna soils were not a sink, but a small source, for atmospheric methane. Fluxes of CO₂ from savanna soils increased ninefold two hours after simulated rainfall, and remained three times higher than normal after 16 hours. More research is needed to clarify the significance of savannas in the global cycles of N₂O, CH₄, CO₂, and other trace gases, especially during the rainy season.     

Slovenia's climate policy efforts: CO2 tax and implementation of EU ETS

Slovenia is required to reduce its greenhouse gas emissions to an average of 8% below the base year 1986 in the period 2008–2012, due to the ratification of the Kyoto Protocol in 2002. It was the first of the transition countries to implement a CO₂ tax in 1997. At the beginning of 2005, Slovenia joined other EU Member States by implementing the Emissions Trading Scheme. In contrast with other new EU Member States, Slovenia will be a net buyer of allowances. Therefore future movements on the emissions market will play an important role in the compliance costs of achieving the Kyoto target. The main purpose of this article is to present the establishment and characteristics of the first national allocation plan (NAP1) and to describe the main elements of the second national allocation plan (NAP2) for Slovenia within the EU Emissions Trading Scheme, the expected movements on the emissions allowances market in Slovenia, the expected compliance cost of achieving the Kyoto target and to present the main characteristics and efficiency of the CO₂ tax in Slovenia.     

Vehicle tax policies and new passenger car CO2 performance in EU member states

This article explores the causes for differences in the average CO₂ emissions intensity of the new passenger car (NPC) fleet in member states (MS) across Europe. Although EU policies mitigating CO₂ emissions from NPCs have been in place since 1999, MS strongly diverge in the absolute amount and relative change in emissions over the last decade. The authors employ a qualitative approach to analyse the factors, in particular national vehicle taxes, contributing to this divergence and the relative contribution of national and European policies in reducing national CO₂ emissions from NPCs. The analysis shows that there has been a significant reduction in CO₂ emissions intensity of NPCs since 2007 across most MS, compared with the six years previous to that date. This would indicate that EU-wide policies, such as the CO₂ vehicles regulation, along with the economic recession in 2008, have influenced national NPC CO₂ emissions. Generally, countries with CO₂-differentiated vehicle taxes are observed as more likely to have achieved greater reductions in CO₂ emissions. However, over the same period there have been many confounding factors, such as economic instability in the EU, that also influence NPC emissions. Using more detailed case study analyses of six countries, the authors find that there is scope for well-designed national vehicle tax policies to drive NPC emissions down further than the EU average. In countries with the highest success rate, such as the Netherlands, the design of the vehicle tax, as part of a well-aligned policy package, has been very important in delivering the biggest reductions in CO₂ emissions from NPCs.

POLICY RELEVANCE

The transport sector continues to be an intractable source of CO₂ emissions. Governments around the world are seeking effective policies to deal with the increase in passenger car CO₂ emissions appropriate to their own circumstances. This article examines the experience of EU MS with CO₂-differentiated vehicle taxes in reducing CO₂ emissions in the context of other national and international contributing factors. It should therefore both be useful to policy makers and contribute to climate policy research in general.     

基于生产与消费视角的CO2环境库茨涅兹曲线的实证研究

 基于生产和消费视角,对人均GDP和单位GDP的CO₂排放之间的内在关系进行了实证分析。对1990-2004年44个国家的人均GDP与生产型和消费型的单位GDP的CO₂排放进行面板数据的单位根检验和协整分析,在此基础上,对CO₂环境库茨涅兹曲线（EKC）进行模拟。结果显示：无论是从生产视角还是从消费视角,单位GDP的CO₂排放量都具有显著的倒"U"形状,符合环境库茨涅兹曲线特征。但对于多数发展中国家,消费型单位GDP的CO₂排放量总是低于生产型单位GDP的CO₂排放量,表明多数发展中国家在国际贸易中存在着内涵CO₂排放的净出口,这对从生产角度核算国家温室气体排放体系提出了挑战。最后,分析了CO₂环境库茨涅兹曲线对中国应对气候变化的启示。     

Effects of an Urban Park and Residential Area on the Atmospheric CO2 Concentration and Flux in Seoul, Korea

The CO₂ concentrations and fluxes over an urban forest site (Namsan) and an urban residential region (Boramae) in Seoul, Korea, during the non-growing season (2–4 March 2011), the growing season (10–12 June 2011), and the late-growing season (22–24 September 2011) were analyzed. The CO₂ concentrations of two sites showed nearly the same diurnal variation, with a maximum value occurring during the night and a minimum value occurring during daytime, as well as the same seasonal variation, with a maximum value during the non-growing season (early spring) and a minimum value during the growing season (summer). The CO₂ flux over the urban forest did not show any typical diurnal variation during the non-growing season, but did show diurnal variation with a small positive value during the night and a large negative value during daytime in the growing and late-growing seasons due to photosynthesis in the urban forest. The CO₂ flux over the urban residential region showed a positive daily mean value for all periods, with large values during the non-growing season and small values during the growing season, and it also showed diurnal variation with two maxima at 0600–1000 LST and 1800–2400 LST, and two minima at 0300-0600 LST and 1100-1500 LST, and was strongly correlated with the use of liquefied natural gas for cooking and heating by surrounding houses.     

山西省城市大气CO2本底筛分对比及特征分析

基于典型城市站太原站2018年3月—2019年2月的大气CO₂在线观测资料,利用筛分法(Meteorological filtering method, MET)和黑碳示踪法(Black Carbon tracer, BC)进行本底/非本底的筛分,得到了本底浓度的变化特征。结果表明,太原大气CO₂浓度季均值冬季最高,夏季最低;不同季节呈“单峰型”日变化特征,日振幅均在26.0×10^-6以上;4个季节CO₂浓度与地面风速存在显著负相关关系;CO₂浓度抬升区域主要受当地工业布局的影响,最大抬升幅度在秋季达17.4×10^-6;使用气象筛分法(MET)得到年均本底浓度为(431.4±19.9)×10^-6,人为排放等对其影响为23.5×10^-6,年振幅比同纬度其它本底站大,为34.5×10^-6;黑碳示踪法(BC)得到冬季季均本底浓度为(445.0±22.9)×10^-6,比MET筛...     

Challenges to addressing non-CO2 greenhouse gases in China’s long-term climate strategy

Under the Paris Agreement, countries are encouraged to submit long-term low greenhouse gas emissions development strategies. Such strategies will merge emissions goals with socio-economic objectives and enable countries to increase their ambition over time, thus offering an opportunity to close the gap between the current emissions trajectory and the Agreement’s ‘well below 2°C’ target. China is in the process of preparing its own long-term strategy. We argue in this article that non-CO₂ greenhouse gases (NCGGs) should be an essential component of China’s long-term low-emissions strategy. To incorporate NCGGs into China’s long-term low-emissions development strategy, key scientific and institutional challenges should be addressed, such as uncertainty about the accuracy of NCGG emissions inventories; uncertainty about future projections of NCGG emissions; and institutional coordination deficits and imbalanced policy approaches. Overcoming these barriers will have significant implications for climate change mitigation and can open a path for the development of concrete follow-up actions.

Key policy insights

• Non-CO₂ greenhouse gases (NCGGs) make up around 17% of China’s GHG emissions, but China has no quantified target to limit or reduce these gases.

• NCGG emissions mitigation should be an essential component of China's long-term low-emissions strategy, which is currently under development.

• Considerable uncertainty exists over both historical NCGG emissions data and forecasts. This poses challenges to developing a comprehensive multi-gas strategy.

• Institutional challenges must also be addressed, such as fragmentation of responsibility for NCGGs.

     

钢铁工业CO2的排放现状及主要的捕集方法

简要讨论了目前CO₂等温室气体的危害、钢铁工业CO₂的排放现状及来源,并针对我国钢铁行业的发展状况,分析了温室气体CO₂的捕集方法.     

Marginal abatement cost estimates for non-CO2 greenhouse gases: lessons from RECLAIM

Recognizing the potential for over- as well as under-estimating the mitigation costs of non-CO₂ greenhouse gases in an offset programme, this article examines the accuracy of cost estimates prepared by government agencies for the control of other types of emissions from small/medium sources via an offset programme. Specifically, analogy is made to the control of SO_x and NO_x controlled by California's Regional Clean Air Incentives Market (RECLAIM) Program. Even allowing for the energy crisis in 2000–2001 that drove up NO_x emissions and control costs, it appears that the engineering cost methods used turned out to be generally accurate, defined as ±25%. Although such a finding does not ensure that the same results will apply to the case of non-CO₂ GHGs, it certainly reinforces the growing literature on ex ante—ex post cost comparisons of environmental controls.     

What if negative emission technologies fail at scale? Implications of the Paris Agreement for big emitting nations

A cumulative emissions approach is increasingly used to inform mitigation policy. However, there are different interpretations of what ‘2°C’ implies. Here it is argued that cost-optimization models, commonly used to inform policy, typically underplay the urgency of 2°C mitigation. The alignment within many scenarios of optimistic assumptions on negative emissions technologies (NETs), with implausibly early peak emission dates and incremental short-term mitigation, delivers outcomes commensurate with 2°C commitments. In contrast, considering equity and socio-technical barriers to change, suggests a more challenging short-term agenda. To understand these different interpretations, short-term CO₂ trends of the largest CO₂ emitters, are assessed in relation to a constrained CO₂ budget, coupled with a ‘what if’ assumption that negative emissions technologies fail at scale. The outcomes raise profound questions around high-level framings of mitigation policy. The article concludes that applying even weak equity criteria, challenges the feasibility of maintaining a 50% chance of avoiding 2°C without urgent mitigation efforts in the short-term. This highlights a need for greater engagement with: (1) the equity dimension of the Paris Agreement, (2) the sensitivity of constrained carbon budgets to short-term trends and (3) the climate risks for society posed by an almost ubiquitous inclusion of NETs within 2°C scenarios.

POLICY RELEVANCE

Since the Paris meeting, there is increased awareness that most policy ‘solutions’ commensurate with 2°C include widespread deployment of negative emissions technologies (NETs). Yet much less is understood about that option’s feasibility, compared with near-term efforts to curb energy demand. Moreover, the many different ways in which key information is synthesized for policy makers, clouds the ability of policy makers to make informed decisions. This article presents an alternative approach to consider what the Paris Agreement implies, if NETs are unable to deliver more carbon sinks than sources. It illustrates the scale of the climate challenge for policy makers, particularly if the Agreement’s aim to address ‘equity’ is accounted for. Here it is argued that much more attention needs to be paid to what CO₂ reductions can be achieved in the short-term, rather than taking a risk that could render the Paris Agreement’s policy goals unachievable.