Regional spatial inventories (cadastres) of GHG emissions in the Energy sector: Accounting for uncertainty

An improvement of methods for the inventory of greenhouse gas (GHG) emissions is necessary to ensure effective control of commitments to emission reduction. The national inventory reports play an important role, but do not reflect specifics of regional processes of GHG emission and absorption for large-area countries. In this article, a GIS approach for the spatial inventory of GHG emissions in the energy sector, based on IPCC guidelines, official statistics on fuel consumption, and digital maps of the region under investigation, is presented. We include mathematical background for the spatial emission inventory of point, line and area sources, caused by fossil-fuel use for power and heat production, the residential sector, industrial and agricultural sectors, and transport. Methods for the spatial estimation of emissions from stationary and mobile sources, taking into account the specifics of fuel used and technological processes, are described. Using the developed GIS technology, the territorial distribution of GHG emissions, at the level of elementary grid cells 2 km?×?2 km for the territory of Western Ukraine, is obtained. Results of the spatial analysis are presented in the form of a geo-referenced database of emissions, and visualized as layers of digital maps. Uncertainty of inventory results is calculated using the Monte Carlo approach, and the sensitivity analysis results are described. The results achieved demonstrated that the relative uncertainties of emission estimates, for CO₂ and for total emissions (in CO₂ equivalent), depend largely on uncertainty in the statistical data and on uncertainty in fuels’ calorific values. The uncertainty of total emissions stays almost constant with the change of uncertainty of N₂O emission coefficients, and correlates strongly with an improvement in knowledge about CH₄ emission processes. The presented approach provides an opportunity to create a spatial cadastre of emissions, and to use this additional knowledge for the analysis and reduction of uncertainty. It enables us to identify territories with the highest emissions, and estimate an influence of uncertainty of the large emission sources on the uncertainty of total emissions. Ascribing emissions to the places where they actually occur helps to improve the inventory process and to reduce the overall uncertainty.     

Termites and global methane—another assessment

New CH₄ emission data from a number of Northern and Southern Hemispheric, tropical and temperate termites, are reported, which indicate that the annual global CH₄ source due to termites is probably less than 15 Tg. The major uncertainties in this estimate are identified and found to be substantial. Nevertheless, our results suggest that termites probably account for less than 5% of global CH₄ emissions.     

Emissions of Nitrous Oxide and Methane from Conventional and Alternative Fuel Motor Vehicles

This paper provides estimates of emissions of two important but often not well-characterized greenhouse gas (GHG) emissions related to transportation energy use: methane (CH₄) and nitrous oxide (N₂O). The paper focuses on emissions of CH₄ and N₂O from motor vehicles because unlike emissions of CO₂, which are relatively easy to estimate, emissions of CH₄ and N₂O are a function of many complex aspects of combustion dynamics and of the type of emission control systems used. They therefore cannot be derived easily and instead must be determined through the use of published emission factors for each combination of fuel, end-use technology, combustion conditions, and emission control system. Furthermore, emissions of CH₄ and N₂O may be particularly important with regard to the relative CO₂-equivalent GHG emissions of the use of alternative transportation fuels, in comparison with the use of conventional fuels. By analyzing a database of emission estimates, we develop emission factors for N₂O and CH₄ from conventional vehicles, in order to supplement recent EPA and IPCC estimates, and we estimate relative emissions of N₂O and CH₄ from different alternative fuel passenger cars, light-duty trucks, and heavy-duty vehicles.     

Estimates of indirect global warming potentials for CH4, CO and NOX

Emissions may affect climate indirectly through chemical interactions in the atmosphere, but quantifications of such effects are difficult and uncertain due to incomplete knowledge and inadequate methods. A preliminary assessment of the climatic impact of changes in tropospheric O₃ and CH₄ in response to various emissions is given. For a 10% increase in the CH₄ emissions the relative increase in concentration has been estimated to be 37% larger. The radiative forcing from enhanced levels of tropospheric O₃ is estimated to 37% of the forcing from changes in CH₄. Inclusion of indirect effects approximately doubles the climatic impact of CH₄ emissions. Emissions of NO_x increase tropospheric O₃, while the levels of CH₄ are reduced. For emissions of NO_x from aircraft, the positive effects via O₃ changes are significantly larger than the negative through changes in CH₄. For NO_x emitted from surface sources, the effects through changes in O₃ and CH₄ are estimated to be of similar magnitude and large uncertainty is connected to the sign of the net effect. Emissions of CO have positive indirect effects on climate through enhanced levels of tropospheric o₃ and increased lifetime of CH₄. These results form the basis for estimates of global warming potentials for sustained step increases in emissions.     

Global Modelling of the Atmospheric Methyl Bromide Budget

A global three-dimensional chemical transport model has been used to identify and evaluate possible candidates for the `missing' surface source required to balance the atmospheric budget of methyl bromide. Both natural and anthropogenic emissions of methyl bromide are `coloured' in the model, thus allowing the global CH₃Br distribution to be broken-down into its source components. These coloured CH₃Br tracers are then combined in various ways to create one base-line emission scenario and five further plausible scenarios. The additional emission scenarios are specifically designed to test whether the geographical distribution and seasonal cycles of additional vegetation and/or increased biomass burning emissions are consistent with atmospheric observations of methyl bromide mixing ratios. Due to an imbalance in our current understanding of the methyl bromide budget, simulated CH₃Br mixing ratios from the base-line emission scenario are significantly lower than atmospheric measurements. Both the inclusion of a vegetation source in the tropics and a double strength biomass burning source substantially improve the agreement between model simulations and atmospheric measurements compared with the base-line emission scenario. While measurement data provides useful information on global fluxes and regional CH₃Br seasonal cycles, small differences between the simulated seasonal cycles of different emission scenarios makes it difficult to distinguish between the relative likelihoods of model scenarios containing a tropical vegetation source or an increased biomass burning source. Further measurements performed in continental mid-to-high northern latitudes, central-southern Africa and South America would be of particular benefit in future attempts to constrain the location and magnitude of the natural terrestrial sources of methyl bromide.     

南京和长三角地区CO_2与CH_4人为排放清单估算的不确定性分析

目前温室气体清单的编制主要基于IPCC方法,该方法用于特定城市或区域清单编制时可能会引起较大的不确定性,而目前对城市/区域尺度清单的不确定性的分析还存在很大的欠缺。本文通过南京市和长三角温室气体排放因子甄选,应用IPCC方法计算了2009年南京市和长三角的人为温室气体排放量,并以其为个例利用蒙特卡洛方法开展城市和区域尺度的温室气体人为排放清单不确定性的初步探究。研究结果表明:南京市CH4和CO2排放量的95%的概率分布范围分别为(1.08~1.86)×105t和(6.50~7.41)×107t,不确定性分别为-21.74%~34.78%和-7.01%~5.87%;长三角CH4和CO2排放量的95%的概率分布范围分别为(4.07~5.89)×106t和(1.62~1.82)×109t,不确定性分别为-15.60%~22.24%和-6.04%~5.34%。     

Seasonal Variations of CH_4 Emissions in the Yangtze River Delta Region of China Are Driven by Agricultural Activities

Developed regions of the world represent a major atmospheric methane(CH_4) source, but these regional emissions remain poorly constrained. The Yangtze River Delta(YRD) region of China is densely populated(about 16% of China's total population) and consists of large anthropogenic and natural CH_4 sources. Here, atmospheric CH_4 concentrations measured at a 70-m tall tower in the YRD are combined with a scale factor Bayesian inverse(SFBI) modeling approach to constrain seasonal variations in CH_4 emissions. Results indicate that in 2018 agricultural soils(AGS, rice production) were the main driver of seasonal variability in atmospheric CH_4 concentration. There was an underestimation of emissions from AGS in the a priori inventories(EDGAR—Emissions Database for Global Atmospheric Research v432 or v50), especially during the growing seasons. Posteriori CH_4 emissions from AGS accounted for 39%(4.58 Tg, EDGAR v432) to 47%(5.21 Tg, EDGAR v50) of the total CH_4 emissions. The posteriori natural emissions(including wetlands and water bodies) were1.21 Tg and 1.06 Tg, accounting for 10.1%(EDGAR v432) and 9.5%(EDGAR v50) of total emissions in the YRD in2018. Results show that the dominant factor for seasonal variations in atmospheric concentration in the YRD was AGS,followed by natural sources. In summer, AGS contributed 42%(EDGAR v432) to 64%(EDGAR v50) of the CH_4 concentration enhancement while natural sources only contributed about 10%(EDGAR v50) to 15%(EDGAR v432). In addition, the newer version of the EDGAR product(EDGAR v50) provided more reasonable seasonal distribution of CH_4 emissions from rice cultivation than the old version(EDGAR v432).     

Methane emission from West Siberian forest-steppe and subtaiga reed fens

Methane emission from West Siberian forest-steppe and subtaiga reed fens (that is, fens dominated by Phragmites australis) observed in summer 2013, is considered using the static chamber method. The obtained medians of CH₄ fluxes varied from -0.08 to 2.7 mg CH₄/m² per hour. Eenvironmental factors affecting methane emission are analyzed. It was found that CH₄ emissions from the reed fens correlate only with the concentration of salt ions in the wetland water and with the plant community structure. The latter probably also depends on water salinity. It was revealed that in fens the ratio between fluxes of CH₄ and CO₂ does not depend on the water table level that contradicts the general pattern simulated by mathematical models of CH₄ emission. It was found that Phragmites australis fens and similar ecosystems should be considered as a separate wetland class from the point of view of methane emission study.     

The geography of global urban greenhouse gas emissions: an exploratory analysis

The purpose of this paper is to describe global urban greenhouse gas emissions by region and sector, examine the distribution of emissions through the urban-to-rural gradient, and identify covariates of emission levels for our baseline year, 2000. We use multiple existing spatial databases to identify urban extent, greenhouse gas emissions (CO₂, N₂O, CH₄ and SF₆) and covariates of emissions in a “top-down” analysis. The results indicate that urban activities are significant sources of total greenhouse gas emissions (36.8 and 48.6 % of total). The urban energy sector accounts for between 41.5 and 66.3 % of total energy emissions. Significant differences exist in the urban share of greenhouse gas emissions between developed and developing countries as well as among source sectors for geographic regions. The 50 largest urban emitting areas account for 38.8 % of all urban greenhouse gas emissions. We find that greenhouse gas emissions are significantly associated with population size, density, growth rates, and per capita income. Finally, comparison of our results to “bottom-up” estimates suggest that this research’s data and techniques are best used at the regional and global scales.     

Contributions of individual countries?? emissions to climate change and their uncertainty

We have compiled historical greenhouse gas emissions and their uncertainties on country and sector level and assessed their contribution to cumulative emissions and to global average temperature increase in the past and for a the future emission scenario. We find that uncertainty in historical contribution estimates differs between countries due to different shares of greenhouse gases and time development of emissions. Although historical emissions in the distant past are very uncertain, their influence on countries?? or sectors?? contributions to temperature increase is relatively small in most cases, because these results are dominated by recent (high) emissions. For relative contributions to cumulative emissions and temperature rise, the uncertainty introduced by unknown historical emissions is larger than the uncertainty introduced by the use of different climate models. The choice of different parameters in the calculation of relative contributions is most relevant for countries that are different from the world average in greenhouse gas mix and timing of emissions. The choice of the indicator (cumulative GWP weighted emissions or temperature increase) is very important for a few countries (altering contributions up to a factor of 2) and could be considered small for most countries (in the order of 10%). The choice of the year, from which to start accounting for emissions (e.g. 1750 or 1990), is important for many countries, up to a factor of 2.2 and on average of around 1.3. Including or excluding land-use change and forestry or non-CO₂ gases changes relative contributions dramatically for a third of the countries (by a factor of 5 to a factor of 90). Industrialised countries started to increase CO₂ emissions from energy use much earlier. Developing countries?? emissions from land-use change and forestry as well as of CH₄ and N₂O were substantial before their emissions from energy use.     

Radiative forcing from surface NO x emissions: spatial and seasonal variations

The global three-dimensional Lagrangian chemistry-transport model STOCHEM has been used to follow changes in the tropospheric distributions of methane CH₄ and ozone O₃ following the emission of pulses of the oxides of nitrogen NO _x . Month-long emission pulses of NO _x produce deficits in CH₄ mixing ratios that bring about negative radiative forcing (climate cooling) and decay away with e-folding times of 10–15 years. They also produce short-term excesses in O₃ mixing ratios that bring about positive radiative forcing (climate warming) that decay over several months to produce deficits, with their attendant negative radiative forcing (climate cooling) that decays away in step with the CH₄ deficits. Total time-integrated net radiative forcing is markedly influenced by cancellation between the negative CH₄ and long-term O₃ contributions and the positive short-term O₃ contribution to leave a small negative residual. Consequently, total net radiative forcing from NO _x emission pulses and the global warming potentials derived from them, show a strong dependence on the magnitudes, locations and seasons of the emissions. These dependences are illustrated using the Asian continent as an example and demonstrate that there is no simple robust relationship between continental-scale NO _x emissions and globally-integrated radiative forcing. We find that the magnitude of the time-integrated radiative forcing from NO _x -driven CH₄ depletion tends to approach and outweigh that from ozone enhancement, leaving net time-integrated radiative forcings and global warming potentials negative (climate cooling) in contrast to the situation for aircraft NO _x (climate warming). Control of man-made surface NO _x emissions alone may lead to positive radiative forcing (climate warming).     

我国甲烷排放情景分析:IPAC模型结果

近期发布的IPCC第六次评估报告再次强调了短寿命期温室气体减排对温升减缓的作用。甲烷是最重要的短寿命期非CO₂温室气体。在各国提出各自新的减排目标之后,针对甲烷减排的行动方案也越来越多。甲烷减排正在成为下一阶段各国和全球合作的重点领域之一。本文在我国碳减排目标下的能源转型基础上,结合其他非能源活动的减排排放源的减排技术选择基础上,利用IPAC模型对未来甲烷的排放情景进行了分析。在模型设定的两个情景分析基础之上,研究发现,到2050年的能源转型可明显减少能源活动的甲烷排放,和2015年相比能源活动的排放可减少67％。和其他行业相比,能源部门的甲烷减排具有更好的协同性。如果考虑进一步减排甲烷,则需要在考虑其他大气污染物减排的基础上,可通过实现天然气的进一步减排来实现。同时其他部门的甲烷减排也具有很大潜力,低甲烷排放情景可以实现到2050年将甲烷排放减少到1 494万吨,和2015年相比全范围排放可减排58％。     

Application of stable isotope analysis for improved understanding of the methane budget: comparison of TROICA measurements with TM3 model simulations

Presented is a detailed comparison of CH₄ and δ¹³C–CH₄ measurements with simulations of the global transport model TM3. Experimental data were obtained during campaigns along the Trans-Siberian railroad in the framework of the TROICA project. Two summer (1999 and 2001) and one spring (2003) expeditions are evaluated. Model simulations include sensitivity tests to further investigate the isotopic composition of natural gas and emissions from Siberian wetlands. Comparison of the average mixing ratio of methane and its isotopic composition (δ¹³C) has been performed for different geographic zones, including the European part of Russia, Western Siberia and Central Siberia. Simulations are in reasonable agreement with the measurements for the European part of Russia and confirm a high contribution of natural gas to the observed methane levels. An increase of emission from bogs shifts the simulated methane isotopic composition closer to the observations. The relative importance of the Western Siberia emissions in current inventories is underestimated in comparison with other wetland regions in the former USSR. Simulated average mixing ratios are in a good agreement with the observations in Central Siberia, while ¹³C(CH₄) values tend to be higher than measured in all considered scenarios. These results point to a bias in the modeled source mixture over Russia, which could be repaired by shifting emissions from isotopically heavy methane sources (e.g. coal, oil or biomass burning) to light sources (e.g. wetlands, ruminants, waste treatment). Alternatively, the average isotopic signature of Siberian wetlands may be lighter than expected.     

Assessment of greenhouse gases emission from civil aviation in Russia

The greenhouse gases emission (CO₂, CH₄, and N₂O) from domestic and international aviation in the Russian Federation is assessed. In 2007, the total emission of CO₂, CH₄, and N₂O amounted to 18.4 million tons of CO₂-equivalent, which is 21% below the 1990 level. Carbon dioxide dominates in the component composition of the emissions, its part in 2007 accounted for 99.1% of the emission. Taking into account the tendency towards increasing fuel consumption due to intense aircraft traffic it can be expected that compared to the present level the greenhouse gases emissions in 2012 and 2020 will increase by 15 and 45%, respectively. Accounting for the increased aircraft emissions as well as plans of foreign countries to include the international aviation into the scheme of greenhouse gases emission allowance (trade credits) it is expedient to make more precise the greenhouse gases emissions from the Russian aviation based on the detailed flight data for all types of the aircraft.     

旋转正压大气中的非线性Schrödinger方程和大气阻塞

本文利用WKB方法导出了旋转正压大气中的非线性Rossby波所满足的立方Schrödinger方程,指出在1≤m≤2的情况下,非线性Schrödinger方程具有包络孤立波解,同时我们还对大气中的包络Rossby孤立波的流场进行了计算,结果得到了阻塞高压和切断低压等结构,并且这些阻塞系统能够维持五天以上。     

Methane and nitrous oxide emissions in the agricultural sector of Russia

Anthropogenic emissions of methane (CH₄) and nitrous oxide (N₂O) from livestock agriculture (enteric fermentation, animal waste management systems, and pasture manure) and plant growing of the Russia (CH₄ emissions from rice fields, direct and indirect N₂O emissions from agricultural lands) are considered. In 2004, the total emissions of these greenhouse gases in the agricultural sector amounted to 1.4 × 10⁵ thousand t CO₂-equivalent, which corresponds to 45% of the 1990 level (3.1 × 10⁵ thousand t CO₂-equivalent). In 2004, the contribution of N₂O to the total agricultural emissions was approximately twice (67.0%) that of CH₄ (33.0%). Direct N₂O emissions from agricultural soils (0.5 × 10⁵ thousand t CO₂-equivalent) and CH₄ emissions from the internal fermentation of domestic animals (0.4 × 10⁵ thousand t CO₂-equivalent) are the most significant sources in the agricultural sector of the Russian Federation. In 2004, all these agricultural sources emitting methane and nitrous oxide contributed about 7% CO₂-equivalent to the total emission of the anthropogenic greenhouse gases in Russia.     

Greenhouse Gas Emissions from Hydroelectric Reservoirs in Tropical Regions

This paper discusses emissions by power-dams in the tropics. Greenhouse gas emissions from tropical power-dams are produced underwater through biomass decomposition by bacteria. The gases produced in these dams are mainly nitrogen, carbon dioxide and methane. A methodology was established for measuring greenhouse gases emitted by various power-dams in Brazil. Experimental measurements of gas emissions by dams were made to determine accurately their emissions of methane (CH₄) and carbon dioxide (CO₂) gases through bubbles formed on the lake bottom by decomposing organic matter, as well as rising up the lake gradient by molecular diffusion.The main source of gas in power-dams reservoirs is the bacterial decomposition (aerobic and anaerobic) of autochthonous and allochthonous organic matter that basically produces CO₂ and CH₄. The types and modes of gas production and release in the tropics are reviewed.     

Analysis of change in relative uncertainty in GHG emissions from stationary sources for the EU 15

Total uncertainty in greenhouse gas (GHG) emissions changes over time due to “learning” and structural changes in GHG emissions. Understanding the uncertainty in GHG emissions over time is very important to better communicate uncertainty and to improve the setting of emission targets in the future. This is a diagnostic study divided into two parts. The first part analyses the historical change in the total uncertainty of CO₂ emissions from stationary sources that the member states estimate annually in their national inventory reports. The second part presents examples of changes in total uncertainty due to structural changes in GHG emissions considering the GAINS (Greenhouse Gas and Air Pollution Interactions and Synergies) emissions scenarios that are consistent with the EU’s “20-20-20” targets. The estimates of total uncertainty for the year 2020 are made under assumptions that relative uncertainties of GHG emissions by sector do not change in time, and with possible future uncertainty reductions for non-CO₂ emissions, which are characterized by high relative uncertainty. This diagnostic exercise shows that a driving factor of change in total uncertainty is increased knowledge of inventory processes in the past and prospective future. However, for individual countries and longer periods, structural changes in emissions could significantly influence the total uncertainty in relative terms.     

Measurement of methane flux over an evergreen coniferous forest canopy using a relaxed eddy accumulation system with tuneable diode laser spectroscopy detection

Very few studies have conducted long-term observations of methane (CH₄) flux over forest canopies. In this study, we continuously measured CH₄ fluxes over an evergreen coniferous (Japanese cypress) forest canopy throughout 1?year, using a micrometeorological relaxed eddy accumulation (REA) system with tuneable diode laser spectroscopy (TDLS) detection. The Japanese cypress forest, which is a common forest type in warm-temperate Asian monsoon regions with a wet summer, switched seasonally between a sink and source of CH₄ probably because of competition by methanogens and methanotrophs, which are both influenced by soil conditions (e.g., soil temperature and soil moisture). At hourly to daily timescales, the CH₄ fluxes were sensitive to rainfall, probably because CH₄ emission increased and/or absorption decreased during and after rainfall. The observed canopy-scale fluxes showed complex behaviours beyond those expected from previous plot-scale measurements and the CH₄ fluxes changed from sink to source and vice versa.     

Assessment of changes in methane emissions from marsh ecosystems of northern Eurasia in the 21st century using regional climate model results

Changes in methane emissions into the atmosphere from terrestrial ecosystems are assessed with models for the European and Asian parts of Russia using the model unit of a methane cycle and calculations with a regional climate model. The calculations were performed for the present-day base period (1991–2000), for the middle (2041–2050), and late (2091–2100) 21st century using the SRES A2 anthropogenic emission scenario. The average emissions for the base period were equal to 8 Mt CH₄/year for the European part of Russia and 10 Mt CH₄/year for the Asian part. By the middle of the 21st century, they increased up to 11 and 13 Mt CH₄/year, and by the late 21st century, up to 14 and 17 Mt CH₄/year. These tendencies are associated with the increased warm period of the soil and dependence of the integral methane production on temperature. It is predicted that the maximum depth of freezing will lessen in the southern regions of the European and Asian parts of Russia by the late 21st century.