National Greenhouse Gas Emission Inventory Research Articles

Three years of CO2, CH4 and N2O fluxes from different sheepfolds in a semiarid steppe region, China

To better assess greenhouse gas (GHG) emissions from livestock folds in semi-arid steppe zones and reduce uncertainties in regional and national GHG emission inventories, we measured the fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from sheepfolds under contrasting management regimes (i.e., summer sheepfolds under continuous and rotational grazing strategies and the winter sheepfold) for 3 consecutive years. Our results showed that these GHG fluxes had high intra-annual and interannual variations, emphasizing the importance of multi-year measurement for achieving temporally representative annual budgets. Sheep presence and temperature appeared to be the key factors driving CH4, CO2 and N2O fluxes from sheepfolds, e.g., higher GHG emissions usually occurred in seasons with sheep presence. However, the sheepfold type exerted a distinct influence on the temperature sensitivity of GHG fluxes, i.e., the Q10 values for GHG fluxes were generally higher in summer sheepfolds than in winter sheepfold. The annual CH4, CO2 and N2O emissions for the 3 sheepfolds were estimated to be 1.5–16.5 kg C ha−1 yr−1 (or 1.9–2.6 g C yr−1sheep−1), 8.6–16.0 t C ha−1 yr−1 (or 5.1–6.6 kg C yr−1sheep−1) and 28.3–41.9 kg N ha−1 yr−1 (or 19.0–26.8 g N yr−1sheep−1), respectively. Averaging across the 3 years, the annual net GHG emissions (CH4 + CO2 + N2O) for all sheepfolds ranged from 47 to 71 t CO2-eq ha−1 yr−1 (or 27–36 kg CO2-eq yr−1 sheep−1), of which CO2 and N2O emissions contributed the most; moreover, the annual net GHG emissions had no significant differences between sheepfold types or grazing strategies. Given that local steppe soils have a lower magnitude of soil respiration (CO2) and N2O emissions and are also net sink for atmospheric CH4, the sheepfold sites in this region are undoubtedly one of the significant hotspots for GHG emissions and could be key areas to focus mitigation action.

County land use carbon emission and scenario prediction in Mianyang Science and Technology City New District, Sichuan Province, China

The role of carbon emissions resulting from land use change in the compilation of national greenhouse gas emission inventories is of paramount significance. This study is centered on the Mianyang Science and Technology City New Area located in Sichuan Province, China. We used the CLUE-S model and Sentinel-2A remote sensing data from 2017 to simulate and validate land use changes in 2022. Based on this validation, we established three simulation scenarios: a baseline scenario, an agricultural development scenario, and a construction development scenario. Using remote sensing data from 2022, we projected the land use for 2030. We also used CO2 concentration data collected in 2022 and 2023, processed the data using ArcGIS and Python, and conducted a quantitative analysis of carbon emissions under each scenario. Ultimately, the accuracy of both measured and predicted CO2 values for 2023 was juxtaposed and authenticated, thus concluding the investigative cycle of this study. Key findings include: (1) The accuracy of the CLUE-S model in the study area was assessed using overall accuracy, quantity disagreement and allocation disagreement indexes. In 2022, the overall accuracy is 98.19%, the quantity disagreement is 1.7%, and the allocation disagreement is 2.2%. (2) Distinct land resource utilization characteristics in scenarios, highlighting potential impacts on economic development and pollution. (3) Increased carbon emissions across scenarios, with construction development showing the highest rise (4.170%) and agricultural development the lowest (0.766%). (4) The predictive accuracy of the validation group's CO2 concentration values can reach 99.5%. This study proposes precise CO2 prediction at the county level, thus laying the groundwork for future research endeavors. Such findings are indispensable for informing carbon policy formulation and promoting low-carbon development strategies.

Increased nitrous oxide emissions from global lakes and reservoirs since the pre-industrial era

Lentic systems (lakes and reservoirs) are emission hotpots of nitrous oxide (N2O), a potent greenhouse gas; however, this has not been well quantified yet. Here we examine how multiple environmental forcings have affected N2O emissions from global lentic systems since the pre-industrial period. Our results show that global lentic systems emitted 64.6 ± 12.1 Gg N2O-N yr−1 in the 2010s, increased by 126% since the 1850s. The significance of small lentic systems on mitigating N2O emissions is highlighted due to their substantial emission rates and response to terrestrial environmental changes. Incorporated with riverine emissions, this study indicates that N2O emissions from global inland waters in the 2010s was 319.6 ± 58.2 Gg N yr−1. This suggests a global emission factor of 0.051% for inland water N2O emissions relative to agricultural nitrogen applications and provides the country-level emission factors (ranging from 0 to 0.341%) for improving the methodology for national greenhouse gas emission inventories.

Status and opportunities for improvement in greenhouse gas emission inventories for the cattle production in Latin America and the Caribbean region: A perspective

The Intergovernmental Panel on Climate Change (IPCC) provides the reference for national greenhouse gas emission (GHG) inventories towards standardized, accurate, measurable, and comparable National Inventory Reports (NIR). For compliance with the 1.5⁰C commitments under the Paris Agreement, most countries have made efforts to improve their inventory methods to tier 2 or 3. However, some relevant activities within Latin American and the Caribbean (LAC) countries, such as enteric methane emissions and methane and nitrous oxide emissions from cattle manure management are still estimated using tier 1 methods, which leads to a high uncertainty due to the importance of livestock emissions in the national totals for these countries. In this context, reducing the uncertainty in GHG inventories would not only improve the accuracy of national reports but it would also provide solid baselines for national mitigation initiatives e.g., Nationally Determined Contributions under the Paris Agreement, and accurate tools to venture into carbon bonds or payments for ecosystem services. The aim of this study was to review the status of national GHG inventories specifically for these three cattle emission categories in 11 LAC countries. We conducted a survey of GHG inventory experts in the 11 LAC countries, to identify the potential for improvement and the main barriers to achieving this. Despite some initiatives, there is still a large potential for reducing the uncertainty in LAC national GHG emission estimates, the barriers to or solutions can be categorized as technical, policy, and institutional issues. However, improving the GHG inventories of LAC countries, specifically for cattle emissions, is feasible in the medium term, as long as multilateral actions are considered, coherently linked under a comparable and verifiable methodology and including a commitment by countries to invest public funds in relevant research and innovations.

Limitations of farm management data in analyses of decadal changes in SOC stocks in the Danish soil‐monitoring network

AbstractChanges in soil organic carbon (SOC) storage in agricultural land are an important part of the Land Use, Land‐Use Change and Forestry component of national greenhouse gas emission inventories. Furthermore, as climate mitigation strategies and incentives for carbon farming are being developed, accurate estimates of SOC stocks are essential to verify any management‐induced changes in SOC. Based on agricultural mineral soils in the Danish soil‐monitoring network, we analysed management effects on SOC stocks using data from the two most recent surveys (2009 and 2019). Between 2009 and 2019, the average increase in SOC stock was 1.2 Mg C ha−1 for 0–50 cm despite a loss of 1.2 Mg C ha−1 from the topsoil (0–25 cm), stressing the importance of including deeper soil layers in soil‐monitoring networks. Comparing all four national surveys (1986, 1997, 2009, 2019), the mean SOC stock of mineral soils in Denmark appears stable. The change in SOC stock between 2009 and 2019 was analysed in detail in relation to management practices as reported by farmers. We found that the effects of single management factors were difficult to isolate from co‐varying factors including soil parameters and that the use of farm management data to explain changes in SOC stocks observed in soil‐monitoring networks appears limited. Uncertainty in SOC stock estimates also arises from low sampling frequency and statistical challenges related to regression to the mean. However, repeated stock measurements at decadal intervals still represent a benchmark for the overall development in regional and national SOC storage, as affected by actual farm management.

Greenhouse Gas Emissions Inventory of a University in the Philippines: the Case of UP Cebu

Estimating the carbon emission of a university is a key step towards carbon neutrality in the education sector and in contributing to the national greenhouse gas emission (GHG) inventory. Following the guidelines of the Philippine Climate Change Commission (CCC), this study examined the university GHG profile using the University of the Philippines Cebu (UPC) as a case study. The main goals were to create a GHG inventory that could serve as a model for other educational institutions in the Philippines and evaluate mitigation strategies that could potentially reduce emissions. Total emission of UPC in 2018 was estimated to be 1,520.6 tCO2e, equivalent to 1.1 tCO2e/capita/yr. The highest contributor to the UPC emission was student mobility, which accounted for 47.2% (717.5 tCO2e) of the total. As the university progressed through the K-12 transition years and assuming a business-as-usual scenario, it was projected that GHG emission had increased by 9.1% (151.4 tCO2e) in 2019 and by 13.6% (238.3 tCO2e) in 2020. If UPC had mitigated its emission in 2018 such as reducing its purchased electricity consumption to 7.5% by shifting to solar energy, total emission could have been reduced by 1.8% or 27.4 tCO2e. If there had been 10% less travels such as by opting to videoconferencing, UPC could have reduced its emission by 0.3% or 5.2 tCO2e. Finally, if UPC had reduced 10% of its solid waste disposal to landfills such as by recycling, carbon emission would have been lessened by 0.3% or 4.7 tCO2e. Through this research, UPC is the first national university in the Philippines to measure its carbon emissions using CCC guidelines. An understanding of the university carbon footprint could significantly raise awareness among stakeholders of their roles and responsibilities in creating a sustainable campus. Moving forward, it is recommended that the inventory would be continued for the succeeding years.

219 Developing country specific enteric methane emission factor of the South Korean dairy cattle production using the 2019 refined IPCC Tier 2 methodology

Abstract Dairy cattle farming was identified as an important source of enteric methane (CH4) emissions. In order to contribute to the improvement of the national greenhouse gas emission inventory, this work aims to develop emission factors (EF) for CH4 emissions from enteric fermentation in dairy cattle in South Korea. Information on dairy cattle herd characteristics, diet and management practices specific to the Korean dairy cattle population were gathered. EF was estimated according to the 2019 refinement to the 2006 Intergovernmental Panel on Climate Change (IPCC) using the Tier 2 approach. Three animal subcategories were considered: milking cows (650 kg body weight, BW), heifers 1~2 years (473 kg BW) and growing animals < 1 year (167 kg BW). The estimated enteric CH4 EFs for milking cows, heifers 1~2 years, growing animal < 1 year, were 139, 83 and 33 kg/head/year, respectively. South Korea adopted the Tier 1 default enteric CH4 EFs for GHG inventory reporting from the North America region. Compared with the generic Tier 1 default EF of 138 kg CH4/head/year proposed by the 2019 refinement to the 2006 IPCC guidelines for high milking cows, our suggested value is quite similar (139 kg CH4/ head/year). While enteric CH4 EFs values were 23% higher and 49% lower for heifers and growing animals < one year than Tier 1 default EFs values, respectively. In addition, enteric CH4 EF is highly correlated with the level of milk production, feed intake and digestibility and methane conversion factor (%Ym). The outcome of this study underscores the importance of obtaining country-specific EF to estimate national enteric CH4 emissions. Thus, this work is a step forward in the revision of dairy cattle enteric CH4 EF and can further support assessment of mitigation strategies in South Korean livestock farming systems.

Variability observed over time in methane emissions from abandoned oil and gas wells

Recent studies have reported methane (CH4) emissions from abandoned oil and gas wells across the United States and the United Kingdom. These emissions can reach hundreds of kg CH4 per year per well and are important to include in greenhouse gas emission inventories and mitigation strategies. Emission estimates are generally based on single, short-term measurements that assume constant emission rates over both short (hours) and longer (months/years) time periods. To investigate this assumption, we measure CH4 emissions from 18 abandoned oil and gas wells in the USA and the UK continuously over 24 h and then make repeat 24 -h measurements at a single site over 12 months. While the lack of historical records for these wells makes it impossible to determine the underlying leakage-pathways, we observed that CH4 emissions at all wells varied over 24 h (range 0.2-81,000 mg CH4 hr−1) with average emissions varying by a factor of 18 and ranging from factors of 1.1–142. We did not find a statistically significant relationship between the magnitude of emissions and variability or that variability is correlated with temperature, relative humidity or atmospheric pressure. The results presented here suggest high CH4 emission events tend to be short-lived, so short-term (< 1 h) sampling is likely to miss them. Our findings present the dynamic nature of CH4 emissions from abandoned oil and gas wells which should be considered when planning measurement methodologies and developing greenhouse gas inventories/mitigation strategies. Incorporation of these temporal dynamics could improve national greenhouse gas emissions inventories.

Sectoral performance analysis of national greenhouse gas emission inventories by means of neural networks

Annual greenhouse gas emissions have increased more than threefold between 1950 and 2014, posing a major threat to the integrity of the entire earth system and subsequently to humankind. Consequently, roadmaps towards low-carbon pathways are urgently needed. Our study contributes to a more detailed understanding of the dynamics of country based emission patterns and uses them to discuss prospective low-carbon pathways for countries. As availability of databases on sectoral emissions substantially increased, we employ machine learning techniques to classify emission features and pathways. By doing so, 18 representative emission patterns are derived. Overall emissions from seven sectors and for 167 countries covering the time span from 1950 to 2014 have been used in the analyses. The following significant trends can be observed: a) increasing per capita emissions due to growing fossil fuel use in many parts of the world, b) a decline in per capita emissions in some countries, and c) a shift in the emission shares, i.e., a reduction of agricultural and land use contributions in certain regions. Using the emission patterns, their dynamics, and best performing countries as role models, we show the possibility for gaining a decent human development without significantly increasing per capita emissions.

An approach for verifying biogenic greenhouse gas emissions inventories with atmospheric CO2 concentration data

Verifying national greenhouse gas (GHG) emissions inventories is a critical step to ensure that reported emissions data to the United Nations Framework Convention on Climate Change (UNFCCC) are accurate and representative of a country’s contribution to GHG concentrations in the atmosphere. Furthermore, verifying biogenic fluxes provides a check on estimated emissions associated with managing lands for carbon sequestration and other activities, which often have large uncertainties. We report here on the challenges and results associated with a case study using atmospheric measurements of CO2 concentrations and inverse modeling to verify nationally-reported biogenic CO2 emissions. The biogenic CO2 emissions inventory was compiled for the Mid-Continent region of United States based on methods and data used by the US government for reporting to the UNFCCC, along with additional sources and sinks to produce a full carbon balance. The biogenic emissions inventory produced an estimated flux of −408 ± 136 Tg CO2 for the entire study region, which was not statistically different from the biogenic flux of −478 ± 146 Tg CO2 that was estimated using the atmospheric CO2 concentration data. At sub-regional scales, the spatial density of atmospheric observations did not appear sufficient to verify emissions in general. However, a difference between the inventory and inversion results was found in one isolated area of West-central Wisconsin. This part of the region is dominated by forestlands, suggesting that further investigation may be warranted into the forest C stock or harvested wood product data from this portion of the study area. The results suggest that observations of atmospheric CO2 concentration data and inverse modeling could be used to verify biogenic emissions, and provide more confidence in biogenic GHG emissions reporting to the UNFCCC.

Nitrous oxide and methane emissions and nitrous oxide isotopic composition from waste incineration in Switzerland

Solid waste incineration accounts for a growing proportion of waste disposal in both developed and developing countries, therefore it is important to constrain emissions of greenhouse gases from these facilities. At five Swiss waste incineration facilities with grate firing, emission factors for N2O and CH4 were determined based on measurements of representative flue gas samples, which were collected in Tedlar bags over a one year period (September 2010–August 2011) and analysed with FTIR spectroscopy. All five plants burn a mixture of household and industrial waste, and two of the plants employ NOx removal through selective non-catalytic reduction (SNCR) while three plants use selective catalytic reduction (SCR) for NOx removal.N2O emissions from incineration plants with NOx removal through selective catalytic reduction were 4.3±4.0g N2O tonne−1 waste (wet) (hereafter abbreviated as t−1) (0.4±0.4g N2O GJ−1), ten times lower than from plants with selective non-catalytic reduction (51.5±10.6g N2O t−1; 4.5±0.9g N2O GJ−1). These emission factors, which are much lower than the value of 120g N2O t−1 (10.4g N2O GJ−1) used in the 2013 Swiss national greenhouse gas emission inventory, have been implemented in the most recent Swiss emission inventory. In addition, the isotopic composition of N2O emitted from the two plants with SNCR, which had considerable N2O emissions, was measured using quantum cascade laser spectroscopy. The isotopic site preference of N2O – the enrichment of 14N15NO relative to 15N14NO – was found to be 17.6±0.8‰, with no significant difference between the two plants. Comparison to previous studies suggests SP of 17–19‰ may be characteristic for N2O produced from SNCR. Methane emissions were found to be insignificant, with a maximum emission factor of 2.5±5.6g CH4 t−1 (0.2±0.5g CH4 GJ−1), which is expected due to high incinerator temperatures and efficient combustion.

Forest carbon accounting methods and the consequences of forest bioenergy for national greenhouse gas emissions inventories

While bioenergy plays a key role in strategies for increasing renewable energy deployment, studies assessing greenhouse gas (GHG) emissions from forest bioenergy systems have identified a potential trade-off of the system with forest carbon stocks. Of particular importance to national GHG inventories is how trade-offs between forest carbon stocks and bioenergy production are accounted for within the Agriculture, Forestry and Other Land Use (AFOLU) sector under current and future international climate change mitigation agreements. Through a case study of electricity produced using wood pellets from harvested forest stands in Ontario, Canada, this study assesses the implications of forest carbon accounting approaches on net emissions attributable to pellets produced for domestic use or export. Particular emphasis is placed on the Forest Management Reference Level (FMRL) method, as it will be employed by most Annex I nations in the next Kyoto Protocol Commitment Period. While bioenergy production is found to reduce forest carbon sequestration, under the FMRL approach this trade-off may not be accounted for and thus not incur an accountable AFOLU-related emission, provided that total forest harvest remains at or below that defined under the FMRL baseline. In contrast, accounting for forest carbon trade-offs associated with harvest for bioenergy results in an increase in net GHG emissions (AFOLU and life cycle emissions) lasting 37 or 90 years (if displacing coal or natural gas combined cycle generation, respectively). AFOLU emissions calculated using the Gross-Net approach are dominated by legacy effects of past management and natural disturbance, indicating near-term net forest carbon increase but longer-term reduction in forest carbon stocks. Export of wood pellets to EU markets does not greatly affect the total life cycle GHG emissions of wood pellets. However, pellet exporting countries risk creating a considerable GHG emissions burden, as they are responsible for AFOLU and bioenergy production emissions but do not receive credit for pellets displacing fossil fuel-related GHG emissions. Countries producing bioenergy from forest biomass, whether for domestic use or for export, should carefully consider potential implications of alternate forest carbon accounting methods to ensure that potential bioenergy pathways can contribute to GHG emissions reduction targets.

Estimation of CO2 emissions in the life cycle of roads through the disruption and restoration of environmental systems

Effects of disruption and restoration of terrestrial ecosystems have been largely overlooked when conducting assessments of greenhouse gas (GHG) emissions in road construction projects. This is an important oversight given the intensive land-conversion generated by linear infrastructure development, as well as the relevance given to carbon pool variations associated with land use and land-use changes by national inventories of GHG emissions and global reports. This paper describes the implementation of a methodology to classify those environmental systems in land-uses categories, to determine their carbon stocks (vegetation and soil), and to quantify CO2 emissions and removal related to their management at the different stages of road construction projects. The procedure is illustrated through its application in the impact assessment of road projects in the territory of Spain. This methodology integrates currently available information on carbon stocks and considers the accounting criteria adopted in national GHG emissions inventories. It is intended to constitute part of an integral assessment tool for GHG emissions in linear infrastructure projects. Four case studies are presented in which emissions from the disruption of environmental systems range from 0.55 to 3.66kTCO2km−1. This represents 5 to 13% of the total emissions in the construction stage, and 3.5 to 7% of the net CO2 balance, i.e., once the initial carbon sequestration by restoration planting has been discounted. Results also indicate that under ideal conditions the long-term effect of restoration may even fully offset this impact, though really such conditions are far from being the case in the usual development of plantations. This study confirms the advisability of systematically incorporating the analysis of land use and land-use changes into the assessment of GHG emissions of road projects for consideration in decision-making from the design stage to the maintenance stage in such projects.

Animal manure application and soil organic carbon stocks: a meta‐analysis

The impact of animal manure application on soil organic carbon (SOC) stock changes is of interest for both agronomic and environmental purposes. There is a specific need to quantify SOC change for use in national greenhouse gas (GHG) emission inventories. We quantified the response of SOC stocks to manure application from a large worldwide pool of individual studies and determined the impact of explanatory factors such as climate, soil properties, land use and manure characteristics. Our study is based on a meta-analysis of 42 research articles totaling 49 sites and 130 observations in the world. A dominant effect of cumulative manure-C input on SOC response was observed as this factor explained at least 53% of the variability in SOC stock differences compared to mineral fertilized or unfertilized reference treatments. However, the effects of other determining factors were not evident from our data set. From the linear regression relating cumulative C inputs and SOC stock difference, a global manure-C retention coefficient of 12% ± 4 (95% Confidence Interval, CI) could be estimated for an average study duration of 18 years. Following an approach comparable to the Intergovernmental Panel on Climate Change, we estimated a relative SOC change factor of 1.26 ± 0.14 (95% CI) which was also related to cumulative manure-C input. Our results offer some scope for the refinement of manure retention coefficients used in crop management guidelines and for the improvement of SOC change factors for national GHG inventories by taking into account manure-C input. Finally, this study emphasizes the need to further document the long-term impact of manure characteristics such as animal species, especially pig and poultry, and manure management systems, in particular liquid vs. solid storage.

Development of National Greenhouse Gas Emissions Inventories in the Context of International Climate Negotiations

Development of National Greenhouse Gas Emissions Inventories in the Context of International Climate Negotiations

Development of National Greenhouse Gas Emissions Inventories in the Context of International Climate Negotiations

Based on the principle ofcommon but differentiated responsibilities, the UNFCCC has different requirements on national GHG inventories submitted by Annex I and non-Annex I parties. Since 2007, the transparency of mitigation actions by developing countries, the submission frequency of national communications cored on national inventory and the relevant international consultation and analysis have become the key issues in climate negotiations. Relevant responsibilities of developing countries showed an increasing trend. Through the analysis of these different requirements, particularly on technical review system of national inventories on developed countries and of the current situation of China’s inventory development, the challenges faced by China are identified and the corresponding countermeasures are also put forward, including improving institutional arrangements and statistic system, building country-specific and comprehensive database and preparing for time-series inventory development. CitationZhu, S.-L., and W.-T. Wang, 2013: Development of national greenhouse gas emissions inventories in the context of international climate negotiations. Adv. Clim. Change Res.,4(1), doi: 10.3724/SP.J.1248.2013.060.

Estimation of the methane emission factor for the Italian Mediterranean buffalo

In order to contribute to the improvement of the national greenhouse gas emission inventory, this work aimed at estimating a country-specific enteric methane (CH4) emission factor for the Italian Mediterranean buffalo. For this purpose, national agriculture statistics, and information on animal production and farming conditions were analysed, and the emission factor was estimated using the Tier 2 model of the Intergovernmental Panel on Climate Change. Country-specific CH4 emission factors for buffalo cows (630 kg body weight, BW) and other buffalo (313 kg BW) categories were estimated for the period 1990–2004. In 2004, the estimated enteric CH4 emission factor for the buffalo cows was 73 kg/head per year, whereas that for other buffalo categories it was 56 kg/head per year. Research in order to determine specific CH4 conversion rates at the predominant production system is suggested.

Carbon estimation in harvested wood products using a country-specific method: Portugal as a case study

This study aims to contribute to the ongoing international debate on the choice of approaches and methods to be used for estimating the amount of carbon that has accumulated in harvested wood products (HWP), within the context of national greenhouse gas emission inventories. A method for estimating carbon accumulation in HWP was developed and applied to three accounting approaches currently under discussion, namely: the stock-change approach, the production approach and the atmospheric-flow approach. This method is consistent with tier 3 methods suggested by the Intergovernmental Panel on Climate Change. An estimation of the carbon accumulation in HWP in Portugal for the period 1990–2000 varied between 112 and 1016 Gg C year−1. The atmospheric-flow approach provided the most favourable results for the whole period, largely because Portugal acted as a net exporter of carbon. The production approach ranked second, because the HWP exported were mainly produced from domestically grown wood. The uncertainty level of the estimates was in general lower than the uncertainty level expected when using a method based on generic default data. In conclusion, a simple method such as the one developed in this study may be used to estimate carbon accumulation in HWP with acceptable uncertainty levels, provided that country-specific data are available.

National Greenhouse Gas Inventories: Understanding Uncertainties versus Potential for Improving Reliability

We investigated the Austrian national greenhouse gas emission inventory to review the reliability and usability of such inventories. The overall uncertainty of the inventory (95% confidence interval) is just over 10% of total emissions, with nitrous oxide (N2O) from soils clearly providing the largest impact. Trend uncertainty — the difference between 2 years — is only about five percentage points, as important sources like soil N2O are not expected to show different behavior between the years and thus exhibit a high covariance. The result is very typical for industrialized countries — subjective decisions by individuals during uncertainty assessment are responsible for most of the discrepancies among countries. Thus, uncertainty assessment cannot help to evaluate whether emission targets have been met. Instead, a more rigid emission accounting system that allows little individual flexibility is proposed to provide harmonized evaluation uninfluenced by the respective targets. Such an accounting system may increase uncertainty in terms of greenhouse gas fluxes to the atmosphere. More importantly, however, it will decrease uncertainty in intercountry comparisons and thus allow for fair burden sharing. Setting of post-Kyoto emission targets will require the independent evaluation of achievements. This can partly be achieved by the validation of emission inventories and thorough uncertainty assessment.

CO 2 emissions and carbon storage resulting from the non-energy use of fossil fuels in the Netherlands, NEAT results for 1993–1999

Estimating CO 2 emissions resulting from the non-energy use of fossil fuels is not straightforward, because part of the carbon is released quickly as CO 2 whereas another part is first embodied in organic chemicals. To contribute to a more accurate non-energy use CO 2 emission accounting, the Non-energy use Emission Accounting Tables (NEAT) model has been developed, which is in this paper applied to the Netherlands for the time period 1993–1999. For this period, we estimate the total non-energy use in CO 2 equivalents in the Netherlands to vary between 26.1 and 30.2 Mt CO 2. Of this total, 4.6–6.6 Mt CO 2 is emitted in industrial processes and during product use. The remainder is stored, resulting in an overall storage fraction of approximately 80%. Given the uncertainties involved, we cannot distinguish clear trends for the years of study. We show that the definition of non-energy use has a significant effect on the calculated storage fractions. The carbon storage according to the Dutch national greenhouse gas (GHG) emission inventory is 5–9 Mt CO 2 lower compared to the NEAT result. As a result, total fossil CO 2 emissions (including those from fossil fuel combustion) according to the national inventory are higher by the same amount, which is 3–5% of the total Dutch emissions. The difference is among other things caused by difficulties associated with the direct use of non-energy use figures from the Dutch energy statistics for CO 2 emission accounting. We recommend improving the Dutch GHG emission inventory making use of the results of this study.