Intergovernmental Panel On Climate Change Method Research Articles

Estimation of soil carbon change from rotation cropping of rapeseed with wheat in the hydrotreated renewable jet life cycle

Rapeseed is being considered as a potential feedstock for hydrotreated renewable jet (HRJ) fuel in the USA through its cultivation in rotation with wheat. The goal of this research was to determine the impact of soil C changes, induced through replacing the fallow period with rapeseed in rotation with wheat, and the effects it would have on emission of greenhouse gases (GHG) of rapeseed HRJ. The Intergovernmental Panel on Climate Change (IPCC) (Tier 1) method was used with modifications to determine the changes in soil C of wheat–wheat–rapeseed (WWR) relative to the reference wheat–wheat–fallow (WWF) rotation for 20 years of cultivation. The 27 case scenarios were conducted to study the impacts of changes in management practices (tillage practice and residue input) on changes in soil C for WWR rotation in multiple locations in 10 US states. The CO2 emissions resulting from soil C changes were incorporated into the rapeseed HRJ pathway in order to evaluate the GHG emissions. Introducing rapeseed to replace the fallow period with wheat could either increase or decrease changes in soil C, depending on management practices. Soil C is predicted to increase with increased residue input and reduced tillage. The greatest gain of soil C was found when using high residue input for wheat and rapeseed under no tillage, resulting in the best management practice. Conversely, adding low residue input to both crops with full tillage created the highest loss of soil C, referring to as the worst management practice. Soil C changes varied across locations from −0.22 to 0.32 Mg C ha−1 year−1. Consequently, the GHG emissions of rapeseed HRJ ranged from 4 to 70 g CO2 eq./MJ, comparing to 46 g CO2 eq./MJ for excluding soil C change. The rapeseed HRJ exhibited the GHG savings of 65–96 % for the best practice and 20–42 % for the worst practice when compared to petroleum jet fuel. Based on results using the modified IPCC method, adoption of high residue input with no tillage for the rotation cropping of rapeseed with wheat had the potential to increase soil C. However, the method has limitations for predicting soil C changes regarding crop management practices. Biogeochemical-based models that have a potential to capture processes of C and N dynamics in soil and yield may be better suited to quantify regional variations in soil C changes for the rotation cropping of rapeseed with wheat.

Constraining anthropogenic CH4 emissions in Nanjing and the Yangtze River Delta, China, using atmospheric CO2 and CH4 mixing ratios

Methane (CH4) emissions estimated with the Intergovernmental Panel on Climate Change (IPCC) inventory method at the city and regional scale are subject to large uncertainties. In this study, we determined the CH4:CO2 emissions ratio for both Nanjing and the Yangtze River Delta (YRD), using the atmospheric CH4 and CO2 concentrations measured at a suburban site in Nanjing in the winter. The atmospheric estimate of the CH4:CO2 emissions ratio was in reasonable agreement with that calculated using the IPCC method for the YRD (within 20%), but was 200% greater for the municipality of Nanjing. The most likely reason for the discrepancy is that emissions from unmanaged landfills are omitted from the official statistics on garbage production.

Comparison of greenhouse gas emission accounting methods for steel production in China

Abstract Steel production is an environmentally sensitive process accounting for 10% of greenhouse gas (GHG) emissions in China, which represents 4–5% of the world's total anthropogenic GHG emissions. This study presents and compares three GHG emissions accounting methods for steel production in China, which are the Intergovernmental Panel on Climate Change (IPCC) method, the Life Cycle Inventory Localization (LCIL) method, and the Comprehensive Energy Consumption (CEC) method. Different criteria such as sources of data, energy input-based and process-based analyses, and benefits and limitations of the three methods are compared and discussed. On the basis of the data collected and system boundary defined in this study, the total GHG emissions of the IPCC, LCIL, and CEC methods are estimated as 1.717, 1.715, and 1.959 kg CO 2 -e/kg steel, respectively. The results of the IPCC and CEC methods show that the coal and coke combustion contributes 90.2% and 84.5% of total energy related GHG emissions during steel production in China, respectively. For the LCIL method, it quantifies the GHG emissions from each individual sub-processes associated with the sintering process to the electric arc furnace process. The results of the LCIL method indicate that the hotspot area for GHG emissions during steel production is the blast furnace process, which accounts for 78.4% of the total energy related GHG emissions. These three methods can be applied to other countries to investigate their GHG emissions. Moreover, the comparison of these three methods provides insights for adopting appropriate methods to calculate GHG emissions for steel production.

Application of the roundtable on sustainable biofuels method to regional differences in nitrous oxide emissions for the rapeseed hydrotreated renewable jet life cycle

Abstract Hydrotreated Renewable Jet (HRJ) fuel has increasingly become important for the aviation sector to address energy security and climate change mitigation. Rapeseed ( Brassica Napus ) is a favored candidate feedstock for HRJ because of its high quality oil content and agroeconomic benefit to replace the fallow period in wheat/fallow rotations. We conducted research to evaluate regional differences in nitrous oxide (N 2 O) emissions for rapeseed cultivation in several counties in 10 states in the United States (U.S.). The Roundtable on Sustainable Biofuels (RSB) methodology was applied, and results were compared to the Intergovernmental Panel on Climate Change (IPCC) guidelines. In this study, yield, nitrogen fertilizer rate, and types were held constant for all locations in order to understand the similarities and differences in the RSB and IPCC methods for estimating N 2 O emissions. From the results, the RSB-calculated N 2 O emissions varied for different U.S. states, though regional differences were very small, 0.72–0.73 kg N 2 O Mg −1 seed, while N 2 O emissions from IPCC method were the same for all sites, 0.87 kg N 2 O Mg −1 seed. The difference between the RSB and IPCC methods is caused by the indirect N 2 O emissions from ammonia emissions and nitrate leaching. However, the influence of indirect effect is relatively small compared to overall N 2 O emissions. The utilization of the RSB method may not be justified for estimating regional variations in N 2 O emissions. As a consequence, the preliminary greenhouse gas (GHG) of rapeseed HRJ fuel using the RSB method in several locations had small differences in result, 42.7–43.0 g CO 2 eq/MJ compared to 45.9 g CO 2 eq/MJ using the IPCC method.

Experimental measurement of the biomass of Olea europaea L.

Olive ( Olea europaea L.) is an evergreen tree extensively cultivated for its fruit in many warm parts of Southern Europe, North Africa, South Asia and Oceania. The objective of this paper was to obtain information on the total biomass productivity of the olive grove as well as on individual tree biomass productivity and the proportions of the tree components. The study was carried out in Central Italy and estimation of tree woody biomass and total biomass was made by direct measurement and through Intergovernmental Panel on Climate Change (IPCC) methodology. To determine the biomass of all the tree parts (including fruits and prunings) of the olive grove, the forestry estimation methodology named “model tree” was adopted and one representative tree was felled and uprooted; the biomass of main trunk, branches, leaves, twigs and roots was determined separately, using their volume, weight and density; also fruits and prunings of this tree were recorded. Wood density, biomass expansion factor, root/shoot ratio, carbon fraction of dry matter and carbon content of the single tree and tree component were calculated. The study showed that “model tree” methodology is suitable for olive grove; IPCC method can be successfully used with good reliability when direct measurement of biomass expansion factor and carbon fraction are obtained from a representative tree of the olive grove. The C stock evaluation methodology made in this research and the calculation of biomass expansion factor can be considered as the first scientific contribution in estimating productivity, CO 2 sequestration, carbon stocks and yield of olive groves. Key words: Biomass, biomass expansion factor, Intergovernmental Panel on Climate Change (IPCC), tree volume, root/shoot ratio, Olea europaea, CO 2 sequestration.

Making sense of methods to audit emissions – various audit methods to estimate dairy production carbon footprint

A dairy farm greenhouse gas (GHG) model was applied in this study to compare the Intergovernmental Panel on Climate Change (IPCC) method and the life cycle assessment (LCA) procedure, which are the principal methods for quantifying the carbon footprint of dairy production. The objectives of this paper were to compare the auditing methods in estimating the carbon footprint of grass and confinement dairy systems and to assess the methods in estimating the footprint of grass-based dairy farms varying in cow genetic potential, stocking rate and level of concentrate feeding. The input data used to operate the model was based on published research studies. The results of the study showed that the IPCC and LCA methods ranked the carbon footprint of dairy systems differently. For example, the IPCC method found that the carbon footprint of the confinement dairy system was 8% lower than the grass system, but the LCA results show that the confinement system increased the carbon footprint by 16%. The comparison of grass-based dairy systems, differing in cow genotype, stocking rate and concentrate fed per cow also showed that the methods did not agree on the ranking of dairy systems carbon footprint. The re-ranking of dairy systems carbon footprint occurred because the IPCC method excludes emissions associated with imported goods, for example, concentrate. Thus, it is incorrect to consider only components of the dairy system relevant for policy reporting such as that used by IPCC when estimating the carbon footprint of dairy produce. Instead, holistic approaches, such as LCA, which consider on and off-farm GHG emissions should be used. Therefore, reform of the present policy framework is required to enable quantification of the impact of mitigation strategies on global emissions. The evaluation of the carbon footprint from grass-based systems differing in cow genotype also demonstrated that selecting cows solely for milk production will increase the carbon footprint of grass-based dairy systems relative to cows selected on a combination of traits, because of reduced cow fertility and thus higher emissions from replacement heifers.

Improving regional soil carbon inventories: Combining the IPCC carbon inventory method with regression kriging

Regional assessments of change in soil organic carbon (SOC) stocks due to land-use change are essential for supporting policy and management decisions related to greenhouse gas emissions and mitigation through carbon sequestration in soils. We have developed an improved approach by integrating geostatistical techniques with the Intergovernmental Panel on Climate Change (IPCC) carbon inventory approach to assess the impact of no-till management and crop-residue retention on SOC changes at a regional scale. Specifically, the improved approach utilizes regression kriging (RK) to estimate reference carbon stocks for the IPCC method. In our case study, we compared the results from the RK method with a simple averaging (SA) method to derive the reference stocks as implemented in the Tier 2 IPCC approach, for a seven state area of the Midwestern United States. Using this improved method, we predict that eliminating tillage and retaining crop residues on all croplands of the study area would result in 11,735GgCyr−1 sequestration for 20years in the top 30cm of the soil profile. Most cropland area would sequester 0.2–0.75MgCha−1yr−1. However, at a few places, the predicted rate of sequestration was more than 0.75MgCha−1yr−1, with an upper limit of 1.1MgCha−1yr−1. The highest rates of carbon accumulation were associated with favorable environmental conditions, such as lower slope positions and cold, temperate, moist climates. Validating predicted SOC change at 18 sites with varying soil types and environmental conditions showed that the RK approach to estimate reference carbon stocks decreased global prediction errors by 45% relative to the default reference values. The increase in prediction accuracy was due to using spatially varying SOC stocks rather than simple data averaging to derive reference SOC values. The uncertainty analysis demonstrated that there was more precision in the results from the RK approach in comparison to the results from the SA approach. These results suggest that improved geostatistical approach is a promising technique for improving soil carbon inventories that utilize the IPCC method, and will provide more precise results for informing public policy and management decisions while retaining ease of application.

Estimates of carbon stored in harvested wood products from the United States forest service northern region, 1906-2010

BackgroundGlobal forests capture and store significant amounts of CO2 through photosynthesis. When carbon is removed from forests through harvest, a portion of the harvested carbon is stored in wood products, often for many decades. The United States Forest Service (USFS) and other agencies are interested in accurately accounting for carbon flux associated with harvested wood products (HWP) to meet greenhouse gas monitoring commitments and climate change adaptation and mitigation objectives. This paper uses the Intergovernmental Panel on Climate Change (IPCC) production accounting approach and the California Forest Project Protocol (CFPP) to estimate HWP carbon storage from 1906 to 2010 for the USFS Northern Region, which includes forests in northern Idaho, Montana, South Dakota, and eastern Washington.ResultsBased on the IPCC approach, carbon stocks in the HWP pool were increasing at one million megagrams of carbon (MgC) per year in the mid 1960s, with peak cumulative storage of 28 million MgC occurring in 1995. Net positive flux into the HWP pool over this period is primarily attributable to high harvest levels in the mid twentieth century. Harvest levels declined after 1970, resulting in less carbon entering the HWP pool. Since 1995, emissions from HWP at solid waste disposal sites have exceeded additions from harvesting, resulting in a decline in the total amount of carbon stored in the HWP pool. The CFPP approach shows a similar trend, with 100-year average carbon storage for each annual Northern Region harvest peaking in 1969 at 937,900 MgC, and fluctuating between 84,000 and 150,000 MgC over the last decade.ConclusionsThe Northern Region HWP pool is now in a period of negative net annual stock change because the decay of products harvested between 1906 and 2010 exceeds additions of carbon to the HWP pool through harvest. However, total forest carbon includes both HWP and ecosystem carbon, which may have increased over the study period. Though our emphasis is on the Northern Region, we provide a framework by which the IPCC and CFPP methods can be applied broadly at sub-national scales to other regions, land management units, or firms.

Evaluation of the effect of accounting method, IPCC v. LCA, on grass-based and confinement dairy systems’ greenhouse gas emissions

Life cycle assessment (LCA) and the Intergovernmental Panel on Climate Change (IPCC) guideline methodology, which are the principal greenhouse gas (GHG) quantification methods, were evaluated in this study using a dairy farm GHG model. The model was applied to estimate GHG emissions from two contrasting dairy systems: a seasonal calving pasture-based dairy farm and a total confinement dairy system. Data used to quantify emissions from these systems originated from a research study carried out over a 1-year period in Ireland. The genetic merit of cows modelled was similar for both systems. Total mixed ration was fed in the Confinement system, whereas grazed grass was mainly fed in the grass-based system. GHG emissions from these systems were quantified per unit of product and area. The results of both methods showed that the dairy system that emitted the lowest GHG emissions per unit area did not necessarily emit the lowest GHG emissions possible for a given level of product. Consequently, a recommendation from this study is that GHG emissions be evaluated per unit of product given the growing affluent human population and increasing demand for dairy products. The IPCC and LCA methods ranked dairy systems’ GHG emissions differently. For instance, the IPCC method quantified that the Confinement system reduced GHG emissions per unit of product by 8% compared with the grass-based system, but the LCA approach calculated that the Confinement system increased emissions by 16% when off-farm emissions associated with primary dairy production were included. Thus, GHG emissions should be quantified using approaches that quantify the total GHG emissions associated with the production system, so as to determine whether the dairy system was causing emissions displacement. The IPCC and LCA methods were also used in this study to simulate, through a dairy farm GHG model, what effect management changes within both production systems have on GHG emissions. The findings suggest that single changes have a small mitigating effect on GHG emissions (<5%), except for strategies used to control emissions from manure storage in the Confinement system (14% to 24%). However, when several management strategies were combined, GHG emissions per unit of product could be reduced significantly (15% to 30%). The LCA method was identified as the preferred approach to assess the effect of management changes on GHG emissions, but the analysis indicated that further standardisation of the approach is needed given the sensitivity of the approach to allocation decisions regarding milk and meat.

Testing models of aquatic N2O flux for inland waters

The current Intergovernmental Panel on Climate Change (IPCC) method for tabulating agricultural nitrous oxide (N2O) emissions suggests that aquatic ecosystems may be important N2O sources. However, estimates are highly uncertain, and the method to estimate emissions is rarely tested. The default IPCC emission factor for groundwater and surface drainage (EF5-g; defined as N2O-N:nitrate-N) has been lowered recently. Our data support further reduction. Notably, we present the first EF5-gdata under ice, which reflects groundwater inputs not confounded by gas exchange. These under-ice data suggest an EF5-gof 0.13%, approximately half the current IPCC default value. Our data from the open-water season also suggest a reduction to 0.11% (based on annual means). The data highlight major problems with the IPCC method. EF5-gwas extremely variable, with the highest values observed in a stream that was a net sink of N2O. Testing the overall method for freshwater emissions is more problematic because of the multidecade transit time from headwaters in our study region to the Atlantic Ocean and limited information on emissions from lakes.

Night and day: short‐term variation in nitrogen chemistry and nitrous oxide emissions from streams

Summary1. Diel variation in metabolism contributes to variation in oxygen (O2) concentrations in streams. This variation in O2 and other parameters (e.g. pH) can in turn affect the rates of microbial nitrogen (N) processing, concentrations of nitrogenous solutes and production of the greenhouse gas nitrous oxide (N2O). We investigated diel variability in emissions of N2O and the magnitude of short‐term variability in N solutes across 10 streams.2. Nitrous oxide fluxes varied on average 2.3‐fold over diel cycles. Concentrations would be underestimated by sampling around noon, but N2O fluxes would not show a consistent bias. Time‐weighted mean daily N2O flux was strongly related to nitrate concentration (r2 = 0.58). Diel patterns in N2O and dissolved N species were often complex (rather than simple sinusoidal curves), probably reflecting complex underlying processes.3. Reliance on samples obtained around noon would overestimate daily mean nitrate concentrations by 5% and underestimate ammonium by 32% (average bias across all streams and dates).4. Dissolved organic N did not show consistent day–night variation. However, the magnitude of diel variability was similar to that observed for dissolved inorganic N. Organic and inorganic N concentrations were often similar. Both appear to be dynamic components of stream N budgets.5. The Intergovernmental Panel on Climate Change (IPCC) relies upon an emission factor to estimate indirect agricultural N2O emissions from streams and ground water. The measured emission factor (defined as the ratio of concentrations of N2O‐N to ‐N) was typically below the recently revised IPCC default figure. Measured values varied on average 1.8‐fold over approximately 24‐h periods and were slightly higher at night than by day. The emission factor was actually highest in streams that were net sinks for N2O, highlighting a conceptual problem in the current IPCC method.6. Typical sampling programmes rely on daytime‐only sampling, which might cause bias in results. In our study streams, the bias was generally small. Diel variation in nitrate concentrations was related to mean temperature; variation in ammonium and N2O concentrations was greatest at low concentrations of nitrite and ammonium.

The effect of methodology on estimates of greenhouse gas emissions from grass-based dairy systems

The objective of this study was to compare two standard methodologies, Intergovernmental Panel on Climate Change (IPCC) method and life cycle analysis (LCA), for quantifying greenhouse gas (GHG) emissions from dairy farms. Both methods were applied to model the GHG emissions from 9 dairy farm systems differing in strain of Holstein-Friesian cow and type of grass-based feed systems using the physical performance findings of previously published work. The strains of Holstein-Friesian cow used were; high milk production North American (HP), high fertility and survival (durability) North American (HD), and New Zealand (NZ). The alternate grass-based feed systems were; high grass allowance (HG, control); high stocking rate (HS) and high concentrate supplementation (HC). The milk production systems were modelled using a previously developed integrated economic-GHG farm model. The model calculated GHG emissions using the LCA approach and was extended to quantify GHG emissions using the IPCC method. The study found that the method of reporting GHG emissions (per unit of product or per unit area) affected the ranking of emissions of dairy systems investigated. Greenhouse gas emission were greater when calculated using the LCA method rather than the IPCC method. Both methods found reducing inputs or the intensity of dairy production reduced GHG emissions per hectare. When emissions were expressed per unit of product the methodologies did not rank farming systems in the same order. The effect of feed system on emissions per unit of product was inconsistent between methodologies because the IPCC method excludes indirect GHG emissions from farm pre-chains, i.e. concentrate production. Both methodologies agreed that animals selected solely for milk production (HP) had higher GHG emissions per unit of product relative to strains selected on a combination of traits. The results indicate that if dairy systems targeting a net reduction in global GHG for projected increases in meat and milk production are to be developed, a holistic approach such as LCA, should be used to assess emissions on a per unit product basis.

Bottom–up assessment of potentials and costs of CO2 emission mitigation in the buildings sector: insights into the missing elements

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) has calculated and shown that, currently, the buildings sector has the largest potential for low-cost carbon dioxide (CO2) mitigation in the short to medium term from application of technological options among the sectors examined, based on bottom–up studies. The potential estimates, however, were derived with no regard to indirect costs of CO2 mitigation, associated benefits, and non-technological options; these factors might change the magnitude of the potential and the costs associated with its implementation. The question emerges how accurate the indicators of the economic potential are according to the current IPCC method and how much they might change if all factors mentioned were taken into account. While research results are presently not sufficient to fully answer this question and quantitative analyses of non-technological options, transaction costs associated with barriers, and non-energy benefits are scarce and fragmented, this paper makes a first attempt to assess the presently available literature in the field. The paper concludes that the ballpark is right for the figures reporting the cost-effective potentials in the buildings sector; however, these assessments indeed need to be corrected by incurred transaction costs and co-benefits relevant for the particular assessment, as well as the potential of non-technological options. The paper also outlines a research agenda in the area so that a possible next Assessment Report of the IPCC can derive a more accurate estimate of the bottom–up potential of CO2 mitigation.

Greenhouse Gas Emission Potential of the Municipal Solid Waste Disposal Sites in Thailand

Open dumping and landfilling are the prevalent solid waste disposal practices in Thailand. Surveys on the disposal sites revealed the presence of 95 landfills and 330 open dumps. Methane emission potential at these sites was estimated by three methods. Results of the Intergovernmental Panel on Climate Change (IPCC) method, Landfill Gas Emission model (LandGEM), and closed flux chamber technique were compared. The methane emission potential of 366 Gg/yr using the IPCC method was higher than the estimations of the LandGEM and closed flux chamber method of 115 Gg/yr and 103 Gg/yr, respectively. An understanding of the methane emission potential initiated the analysis of upgrading the open dumps into landfills, adding landfills to meet the future needs and utilization of landfill gases. Upgrading the open dumps to landfills increased the methane emission rates and their utilization potential. Approximately 20 additional landfills may be required to meet future demands. Landfill gas (LFG) utilization appears to be feasible in the large-scale landfills.

Predicted soil organic carbon stocks and changes in Kenya between 1990 and 2030

Under the United Nations Framework Convention on Climate Change (UNFCCC), Non-Annex 1 countries such as Kenya are obliged to report green house gas (GHG) emissions from all sources where possible, including those from soils as a result of changes in land use or land management. At present, the convention encourages countries to estimate emissions using the most advanced methods possible, given the country circumstances and resources. Estimates of soil organic carbon (SOC) stocks and changes were made for Kenya using the Global Environment Facility Soil Organic Carbon (GEFSOC) Modelling System. The tool conducts analysis using three methods: (1) the Century general ecosystem model; (2) the RothC soil C decomposition model; and (3) the Intergovernmental Panel on Climate Change (IPCC) method for assessing soil C at regional scales. The required datasets included: land use history, monthly mean precipitation, monthly mean minimum and maximum temperatures for all the agro-climatic zones of Kenya and historical vegetation cover. Soil C stocks of 1.4–2.0 Pg (0–20 cm), compared well with a Soil and Terrain (SOTER) based approach that estimated ∼1.8–2.0 Pg (0–30 cm). In 1990 48% of the country had SOC stocks of <18 t C ha −1 and 20% of the country had SOC stocks of 18–30 t C ha −1, whereas in 2000 56% of the country had SOC stocks of <18 t C ha −1 and 31% of the country had SOC stocks of 18–30 t C ha −1. Conversion of natural vegetation to annual crops led to the greatest soil C losses. Simulations suggest that soil C losses remain substantial throughout the modelling period of 1990–2030. All three methods involved in the GEFSOC System estimated that there would be a net loss of soil C between 2000 and 2030 in Kenya. The decline was more marked with RothC than with Century or the IPCC method. In non-hydric soils the SOC change rates were more pronounced in high sandy soils compared to high clay soils in most land use systems.

Estimates of direct nitrous oxide emissions from Canadian agroecosystems and their uncertainties

Using a revised Intergovernmental Panel on Climate Change (IPCC) methodology and the process-based model DeNitrification and DeComposition (DNDC), we estimated N2O emissions from agroecosystems in Canada for each census year from 1981 to 2001. Based on the IPCC methodology, direct emissions of N2O ranged from 12.9 to 17.3 with an average of 15.1 Tg CO2 equivalents, while the DNDC model predicted values from 16.0 to 24.3 with an average of 20.8 Tg CO2 equivalents over the same period, and showed a large interannual variation reflecting weather variability. On a provincial basis, emissions estimated by IPCC and DNDC methods were highest in Alberta, Saskatchewan and Ontario, intermediate for Manitoba and Quebec and lowest in British Columbia and the Atlantic provinces. The greatest source of emissions estimated by the IPCC method was from N fertilizer (avg. 6.32 Tg CO2 equiv. in Canada), followed by crop residues (4.24), pasture range and paddocks (PRP) (2.77), and manure (1.65). All sources of emissions, but especially those from fertilizers, increased moderately over time. Monte Carlo Simulation was used to determine the uncertainty associated with the 2001 emission estimates for both IPCC and DNDC methodologies. The simulation generated most likely values of 19.2 and 16.0 Tg CO2 equivalents for IPCC and DNDC, respectively, with uncertainties of 37 and 41%, respectively. Values for the IPCC estimates varied between 28% for PRP and manure and 50% for N fertilizer and crop residues. At the provincial level, uncertainty ranged between 15 and 47% with higher values on the prairies. Sensitivity analyses for IPCC estimates showed crop residues as the most important source of uncertainty followed by synthetic N-fertilizers. Our analysis demonstrated that N2O emissions can be effectively estimated by both the DNDC and IPCC methods and that their uncertainties can be effectively estimated by Monte Carlo Simulation. Key words: Nitrous oxide, IPCC, DNDC model, Uncertainty analysis, Monte Carlo Simulation

Energy consumption and CO 2 emissions in Turkey: Empirical analysis and future projection based on an economic growth

In this study, Turkey's energy sector was overviewed during the period of 1970–2002. The total energy consumption (TEC) was modeled by using the economic growth (proxied by gross national product—GNP) and population increase, which are the two important factors to determine the energy consumption for developing countries. In addition, the relationship between the TEC and total CO 2 (TCO 2) emission was studied. For this purpose, regression analysis was performed and the strong relationship between TEC and TCO 2 ( R 2 = 0.998 ) was modeled. Also, results showed that a regression model can be used to predict the TEC from the country population and the GNP with high confidence ( R 2 = 0.996 ). Using the models developed in the study, TEC as a function of the targeted economic growth (annual rate of GNP increase) published in the National Development Plan and TCO 2 based on the TEC were forecasted up to year 2015. Additionally, the TCO 2 was also calculated by the intergovernmental panel on climate change (IPCC) method and the results from the two methods were compared. It was seen that the values predicted by IPCC method were considerably higher. Based on the findings of the study, some recommendations were presented to be considered for the future energy policies to conform to the Framework Convention on Climate Change signed by Turkey on 18 December 2003.

Deriving grassland management factors for a carbon accounting method developed by the Intergovernmental Panel on Climate Change.

Grassland management affects soil organic carbon (SOC) storage and can be used to mitigate greenhouse gas emissions. However, for a country to assess emission reductions due to grassland management, there must be an inventory method for estimating the change in SOC storage. The Intergovernmental Panel on Climate Change (IPCC) has developed a simple carbon accounting approach for this purpose, and here we derive new grassland management factors that represent the effect of changing management on carbon storage for this method. Our literature search identified 49 studies dealing with effects of management practices that either degraded or improved conditions relative to nominally managed grasslands. On average, degradation reduced SOC storage to 95% +/- 0.06 and 97% +/- 0.05 of carbon stored under nominal conditions in temperate and tropical regions, respectively. In contrast, improving grasslands with a single management activity enhanced SOC storage by 14% +/- 0.06 and 17% +/- 0.05 in temperate and tropical regions, respectively, and with an additional improvement(s), storage increased by another 11% +/- 0.04. We applied the newly derived factor coefficients to analyze C sequestration potential for managed grasslands in the U.S., and found that over a 20-year period changing management could sequester from 5 to 142 Tg C yr(-1) or 0.1 to 0.9 Mg C ha(-1) yr(-1), depending on the level of change. This analysis provides revised factor coefficients for the IPCC method that can be used to estimate impacts of management; it also provides a methodological framework for countries to derive factor coefficients specific to conditions in their region.

Potential Soil C Sequestration on U.S. Agricultural Soils

Soil carbon sequestration has been suggested as a means to help mitigate atmospheric CO2 increases, however there is limited knowledge aboutthe magnitude of the mitigation potential. Field studies across the U.S. provide information on soil C stock changes that result from changes in agricultural management. However, data from such studies are not readily extrapolated to changes at a national scale because soils, climate, and management regimes vary locally and regionally. We used a modified version of the Intergovernmental Panel on Climate Change (IPCC) soil organic C inventory method, together with the National Resources Inventory (NRI) and other data, to estimate agricultural soil C sequestration potential in the conterminous U.S. The IPCC method estimates soil C stock changes associated with changes in land use and/or land management practices. In the U.S., the NRI provides a detailed record of land use and management activities on agricultural land that can be used to implement the IPCC method. We analyzed potential soil C storage from increased adoption of no-till, decreased fallow operations, conversion of highly erodible land to grassland, and increased use of cover crops in annual cropping systems. The results represent potentials that do not explicitly consider the economic feasibility of proposed agricultural production changes, but provide an indication of the biophysical potential of soil C sequestration as a guide to policy makers. Our analysis suggests that U.S. cropland soils have the potential to increase sequestered soil C by an additional 60–70 Tg (1012g) C yr− 1, over present rates of 17 Tg C yr−1(estimated using the IPCC method), with widespread adoption of soil C sequestering management practices. Adoption of no-till on all currently annually cropped area (129Mha) would increase soil C sequestration by 47 Tg C yr−1. Alternatively, use of no-till on 50% of annual cropland, with reduced tillage practices on the other 50%, would sequester less – about37 Tg C yr−1. Elimination of summer fallow practices and conversionof highly erodible cropland to perennial grass cover could sequester around 20 and 28Tg C yr−1, respectively. The soil C sequestration potentialfrom including a winter cover crop on annual cropping systems was estimated at 40Tg C yr−1. All rates were estimated for a fifteen-yearprojection period, and annual rates of soil C accumulations would be expected to decrease substantially over longer time periods. The total sequestration potential we have estimated for the projection period (83 Tg C yr−1) represents about 5% of 1999total U.S. CO2 emissions or nearly double estimated CO2 emissionsfrom agricultural production (43 Tg C yr−1). For purposes ofstabilizing or reducing CO2 emissions, e.g., by 7% of 1990 levels asoriginally called for in the Kyoto Protocol, total potential soil C sequestration would represent 15% of that reduction level from projected 2008 emissions(2008 total greenhouse gas emissions less 93% of 1990 greenhouse gasemissions). Thus, our analysis suggests that agricultural soil C sequestration could play a meaningful, but not predominant, role in helping mitigate greenhouse gas increases.

National-scale estimation of changes in soil carbon stocks on agricultural lands

Average annual net change in soil carbon stocks under past and current management is needed as part of national reporting of greenhouse gas emissions and to evaluate the potential for soils as sinks to mitigate increasing atmospheric CO 2. We estimated net soil C stock changes for US agricultural soils during the period from 1982 to 1997 using the IPCC (Intergovernmental Panel on Climate Change) method for greenhouse gas inventories. Land use data from the NRI (National Resources Inventory; USDA-NRCS) were used as input along with ancillary data sets on climate, soils, and agricultural management. Our results show that, overall, changes in land use and agricultural management have resulted in a net gain of 21.2 MMT C year −1 in US agricultural soils during this period. Cropped lands account for 15.1 MMT C year −1, while grazing land soil C increased 6.1 MMT C year −1. The land use and management changes that have contributed the most to increasing soil C during this period are (1) adoption of conservation tillage practices on cropland, (2) enrollment of cropland in the Conservation Reserve Program, and (3) cropping intensification that has resulted in reduced use of bare fallow.