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1.
Previous research has demonstrated that soil carbon sequestration through adoption of conservation tillage can be economically profitable depending on the value of a carbon offset in a greenhouse gas (GHG) emissions market. However adoption of conservation tillage also influences two other potentially important factors, changes in soil N2O emissions and CO2 emissions attributed to changes in fuel use. In this article we evaluate the supply of GHG offsets associated with conservation tillage adoption for corn-soy-hay and wheat-pasture systems of the central United States, taking into account not only the amount of carbon sequestration but also the changes in soil N2O emission and CO2 emissions from fuel use in tillage operations. The changes in N2O emissions are derived from a meta-analysis of published studies, and changes in fuel use are based on USDA data. These are used to estimate changes in global warming potential (GWP) associated with adoption of no-till practices, and the changes in GWP are then used in an economic analysis of the potential supply of GHG offsets from the region. Simulation results demonstrate that taking N2O emissions into account could result in substantial underestimation of the potential for GHG mitigation in the central U.S. wheat pasture systems, and large over-estimation in the corn-soy-hay systems. Fuel use also has quantitatively important effects, although generally smaller than N2O. These findings suggest that it is important to incorporate these two effects in estimates of GHG offset potential from agricultural lands, as well as in the design of GHG offset contracts for more complete accounting of the effect that no-till adoption will have on greenhouse gas emissions.  相似文献   

2.
Net greenhouse gas (GHG) emissions from Canadian crop and livestock production were estimated for 1990, 1996 and 2001 and projected to 2008. Net emissions were also estimated for three scenarios (low (L), medium (M) and high (H)) of adoption of sink enhancing practices above the projected 2008 level. Carbon sequestration estimates were based on four sink-enhancing activities: conversion from conventional to zero tillage (ZT), reduced frequency of summerfallow (SF), the conversion of cropland to permanent cover crops (PC), and improved grazing land management (GM). GHG emissions were estimated with the Canadian Economic and Emissions Model for Agriculture (CEEMA). CEEMA estimates levels of production activities within the Canadian agriculture sector and calculates the emissions and removals associated with those levels of activities. The estimates indicate a decline in net emissions from 54 Tg CO2–Eq yr–1 in1990 to 52 Tg CO2–Eq yr–1 in 2008. Adoption of thesink-enhancing practices above the level projected for 2008 resulted in further declines in emissions to 48 Tg CO2–Eq yr–1 (L), 42 TgCO2–Eq yr–1 (M) or 36 Tg CO2–Eq yr–1 (H). Among thesink-enhancing practices, the conversion from conventional tillage to ZT provided the largest C sequestration potential and net reduction in GHG emissions among the scenarios. Although rates of C sequestration were generally higher for conversion of cropland to PC and adoption of improved GM, those scenarios involved smaller areas of land and therefore less C sequestration. Also, increased areas of PC were associated with an increase in livestock numbers and CH4 and N2O emissions from enteric fermentation andmanure, which partially offset the carbon sink. The CEEMA estimates indicate that soil C sinks are a viable option for achieving the UNFCCC objective of protecting and enhancing GHG sinks and reservoirs as a means of reducing GHG emissions (UNFCCC, 1992).  相似文献   

3.
Carbon sequestration in agricultural soils is frequently promoted as a practical solution for slowing down the rate of increase of CO2 in the atmosphere. Consequently, there is a need to improve our understanding of how land management practices may affect the net removal of greenhouse gases (GHG) from the atmosphere. In this paper we examine the role of agriculture in influencing the GHG budget and briefly discuss the potential for carbon mitigation by agriculture. We also examine the opportunities that exist for increasing soil C sequestration using management practices such as reduced tillage, reduced frequency of summer fallowing, introduction of forage crops into crop rotations, conversion of cropland to grassland and nutrient addition via fertilization. In order to provide information on the impact of such management practices on the net GHG budget we ran simulations using CENTURY (a C model) and DNDC (a N model) for five locations across Canada, for a 30-yr time period. These simulations provide information on the potential trade-off between C sequestration and increased N2O emissions. Our model output suggests that conversion of cropland to grassland will result in the largest reduction in net GHG emissions, while nutrient additions via fertilizers will result in a small increase in GHG emissions. Simulations with the CENTURY model also indicated that favorable growing conditions during the last 15 yr could account for an increase of 6% in the soil C at a site in Lethbridge, Alberta. Presented at the International Workshop on Reducing Vulnerability of Agriculture and Forestry to Climate Variability and Climate Change, Ljubljana, Slovenia, 7–9 October 2002.  相似文献   

4.
This paper estimates the national level trend of India’s N2O emissions from 1985–2005 and detailed sub-regional (594 districts) level and sector emissions for the year 2005. N2O emissions are estimated using the latest methodologies (IPCC 2006), disaggregated activity data and indigenized emission factors. The estimates show that India’s N2O emissions have grown from 144?Gg in 1985 to 267?Gg in 2005 exhibiting a compounded annual growth rate of 3.1%, which has been gradually declining from 4.7% over 1985–1990 to 2.4% over 2000–2005. N-fertilizer application contributed most to N2O emissions, a 49% share in 2005 compared to 40% in 1985. Sub-regional (district-level) distribution of N2O emissions showed rising mean and spread over the years, with average emissions per districts increasing from 305?ton N2O per year in 1990 to 450?tons in 2005. The main reason being increased use of N-fertilizer. However crop selection plays an important role in N2O emissions and there are crops providing high economic returns but low N-fertilizer requirements. Agriculture sector could contribute considerably to GDP even with very low N2O emissions. Indian agriculture practices vary widely in input applications and crop yields across states. The gradual transition from traditional to modern agriculture over past two decades has enhanced the intensity of inputs like N-fertilizer. A simple correlation based on 1985–2005 trends shows that, ceteris paribus, a 10% increase in total crop production is accompanied with a 12.4% increase in N-fertilizer application and a 9.7% increase in total N2O emissions from India.  相似文献   

5.
Potential Soil C Sequestration on U.S. Agricultural Soils   总被引：1，自引：0，他引：1  
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.  相似文献   

6.
Agricultural soils are a major source of atmospheric nitrous oxide (N2O), a potent greenhouse gas (GHG). Because N2O emissions strongly depend on soil type, climate, and crop management, their inventory requires the combination of biophysical and economic modeling, to simulate farmers’ behavior. Here, we coupled a biophysical soil-crop model, CERES-EGC, with an economic farm type supply model, AROPAj, at the regional scale in northern France. Response curves of N2O emissions to fertilizer nitrogen (Nf) inputs were generated with CERES-EGC, and linearized to obtain emission factors. The latter ranged from 0.001 to 0.0225 kg N2O-N kg???1 Nf, depending on soil and crop type, compared to the fixed 0.0125 value of the IPCC guidelines. The modeled emission factors were fed into the economic model AROPAj which relates farm-level GHG emissions to production factors. This resulted in a N2O efflux 20% lower than with the default IPCC method. The costs of abating GHG emissions from agriculture were calculated using a first-best tax on GHG emissions, and a second-best tax on their presumed factors (livestock size and fertilizer inputs). The first-best taxation was relatively efficient, achieving an 8% reduction with a tax of 11 €/ t-CO2-equivalent, compared to 68 €/t-CO2 eq for the same target with the second-best scheme.  相似文献   

7.
The MAGICC (Model for the Assessment of Greenhouse gas Induced Climate Change) model simulation has been carried out for the 2000–2100 period to investigate the impacts of future Indian greenhouse gas emission scenarios on the atmospheric concentrations of carbon dioxide, methane and nitrous oxide besides other parameters like radiative forcing and temperature. For this purpose, the default global GHG (Greenhouse Gases) inventory was modified by incorporation of Indian GHG emission inventories which have been developed using three different approaches namely (a) Business-As-Usual (BAU) approach, (b) Best Case Scenario (BCS) approach and (c) Economy approach (involving the country’s GDP). The model outputs obtained using these modified GHG inventories are compared with various default model scenarios such as A1B, A2, B1, B2 scenarios of AIM (Asia-Pacific Integrated Model) and P50 scenario (median of 35 scenarios given in MAGICC). The differences in the range of output values for the default case scenarios (i.e., using the GHG inventories built into the model) vis-à-vis modified approach which incorporated India-specific emission inventories for AIM and P50 are quite appreciable for most of the modeled parameters. A reduction of 7% and 9% in global carbon dioxide (CO2) emissions has been observed respectively for the years 2050 and 2100. Global methane (CH4) and global nitrous oxide (N2O) emissions indicate a reduction of 13% and 15% respectively for 2100. Correspondingly, global concentrations of CO2, CH4 and N2O are estimated to reduce by about 4%, 4% and 1% respectively. Radiative forcing of CO2, CH4 and N2O indicate reductions of 6%, 14% and 4% respectively for the year 2100. Global annual mean temperature change (incorporating aerosol effects) gets reduced by 4% in 2100. Global annual mean temperature change reduces by 5% in 2100 when aerosol effects have been excluded. In addition to the above, the Indian contributions in global CO2, CH4 and N2O emissions have also been assessed by India Excluded (IE) scenario. Indian contribution in global CO2 emissions was observed in the range of 10%–26%, 6%–36% and 10%–38% respectively for BCS, Economy and BAU approaches, for the years 2020, 2050 and 2100 for P50, A1B-AIM, A2-AIM, B1-AIM & B2-AIM scenarios. CH4 and N2O emissions indicate about 4%–10% and 2%–3% contributions respectively in the global CH4 and N2O emissions for the years 2020, 2050 and 2100. These Indian GHG emissions have significant influence on global GHG concentrations and consequently on climate parameters like RF and ∆T. The study reflects not only the importance of Indian emissions in the global context but also underlines the need of incorporation of country specific GHG emissions in modeling to reduce uncertainties in simulation of climate change parameters.  相似文献   

8.
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.  相似文献   

9.
An emission pathway for stabilization at 6?Wm?2 radiative forcing   总被引：1，自引：0，他引：1  
Representative Concentration Pathway 6.0 (RCP6) is a pathway that describes trends in long-term, global emissions of greenhouse gases (GHGs), short-lived species, and land-use/land-cover change leading to a stabilisation of radiative forcing at 6.0 Watts per square meter (Wm?2) in the year 2100 without exceeding that value in prior years. Simulated with the Asia-Pacific Integrated Model (AIM), GHG emissions of RCP6 peak around 2060 and then decline through the rest of the century. The energy intensity improvement rates changes from 0.9% per year to 1.5% per year around 2060. Emissions are assumed to be reduced cost-effectively in any period through a global market for emissions permits. The exchange of CO2 between the atmosphere and terrestrial ecosystem through photosynthesis and respiration are estimated with the ecosystem model. The regional emissions, except CO2 and N2O, are downscaled to facilitate transfer to climate models.  相似文献   

10.
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.  相似文献   

11.
DNDC, a rainfall-driven and process-oriented model of soil carbon and nitrogen biogeochemistry, is applied to simulate the nitrous oxide emissions from agricultural ecosystem in Southeast China. We simulated the soil N2O emission during a whole rice-wheat rotation cycle (from Nov. 1, 1996 to Oct. 31, 1997) under three different conditions, which are A) no fertilizer, B) both chemical fertilizer and manure and, C) chemical fertilizer only. The processes of N2O emission were discussed in detail by comparing the model outputs with the results from field measurement. The comparison shows that the model is good at simulating most of the N2O emission pulses and trends. Although the simulated N2O emission fluxes are generally less than the measured ones, the model outputs during the dryland period, especially during the wheat reviving and maturing stages in spring, are much better than those during the paddy field period. Some sensitive experiments were made by simulating the N2O emissions in spring, when there is a smallest gap between the simulated fluxes and the measured ones. Meanwhile, the effects of some important regulating factors, such as the rainfall, N deposition by rainfall, temperature, tillage, nitrogen fertilizer and manure application on N2O emission during this period were analyzed. From the analysis, we draw a conclusion that soil moisture and fertilization are the most important regulating factors while the N2O emission is sensitive to some other factors, such as temperature, manure, tillage and the wet deposition of atmospheric nitrate.  相似文献   

12.
Strategies for mitigating the increasing concentration of carbon dioxide (CO2) in the atmosphere include sequestering carbon (C) in soils and vegetation of terrestrial ecosystems. Carbon and nitrogen (N) move through terrestrial ecosystems in coupled biogeochemical cycles, and increasing C stocks in soils and vegetation will have an impact on the N cycle. We conducted simulations with a biogeochemical model to evaluate the impact of different cropland management strategies on the coupled cycles of C and N, with special emphasis on C-sequestration and emission of the greenhouse gases methane (CH4) and nitrous oxide (N2O). Reduced tillage, enhanced crop residue incorporation, and farmyard manure application each increased soil C-sequestration, increased N2O emissions, and had little effect on CH4 uptake. Over 20 years, increases in N2O emissions, which were converted into CO2-equivalent emissions with 100-year global warming potential multipliers, offset 75–310% of the carbon sequestered, depending on the scenario. Quantification of these types of biogeochemical interactions must be incorporated into assessment frameworks and trading mechanisms to accurately evaluate the value of agricultural systems in strategies for climate protection.  相似文献   

13.
Designing effective mitigation policies for greenhouse gas (GHG) emissions from agriculture requires understanding the mechanisms by which management practices affect emissions in different agroclimatic conditions. Agricultural GHG emissions and carbon sequestration potentials have been extensively studied in the Mediterranean biome, which is a biodiversity hot spot that is highly vulnerable to environmental changes. However, the absolute magnitude of GHG emissions and the extent to which research efforts match these emissions in each production system, are unknown. Here, we estimated GHG emissions and potential carbon sinks associated with crop and livestock production systems in the Mediterranean biome, covering 31 countries and assessing approximately 10,000 emission items. The results were then combined with a bibliometric assessment of 797 research publications to compare emissions estimates obtained with research efforts for each of the studied items. Although the magnitude of GHG emissions from crop production and the associated carbon sequestration potential (261 Tg CO2eq yr−1) were nearly half of those from livestock production (367 Tg CO2eq yr−1), mitigation research efforts were largely focused on the former. As a result, the relative research intensity, which relates the number of publications to the magnitude of emissions, is nearly one order of magnitude higher for crop production than for livestock production (2.6 and 0.4 papers Tg CO2eq−1, respectively). Moreover, this mismatch is even higher when crop and livestock types are studied separately, which indicates major research gaps associated with grassland and many strategic crop types, such as fruit tree orchards, fiber crops, roots and tubers. Most life cycle assessment studies do not consider carbon sequestration, although this single process has the highest magnitude in terms of annual CO2eq. In addition, these studies employ Tier 1 IPCC factors, which are not suited for use in Mediterranean environments. Our analytical results show that a strategic plan is required to extend on-site field GHG measurements to the Mediterranean biome. Such a plan needs to be cocreated among stakeholders and should be based on refocusing research efforts to GHG balance components that have been afforded less attention. In addition, the outcomes of Mediterranean field studies should be integrated into life cycle assessment-based carbon footprint analyses in order to avoid misleading conclusions.  相似文献   

14.
Presented is the assessment of the contribution that such major types of the land use in Russia as arable lands, forage lands, settlements, and peatery make to anthropogenic fluxes of carbon dioxide CO2, methane CH4, and nitrogen oxide N2O, The assessment is based on the methods of computation monitoring carried out in the period from 2000 to 2011. The results of the study demonstrated that every year arable lands cause the emission of CO2 and N2O of about 117.0 and 74.9 million t CO2 equiv, and peatery, 0.54 and 105.4 thousand t CO2 equiv, respectively. The balance of soil carbon in hayfields and pastures is close to zero. The average emissions of CH4 and N2O from the manure of pasture animals amount to 0.2 and 5.0 million t CO2 equiv/year, and those from grass fires, 276.1 and 372.5 thousand t CO2 equiv/year, respectively. The carbon balance in permanent soils of settlements is also almost close to zero, and newly built-up lands are the source of CO2 (9.5 million t/year). The natural overgrowing of fallow lands leads to the accumulation of the soil carbon (about 92.4 million t CO2/year). It was revealed that the intensity of CO2 emission is defined by the soil carbon balance and that of other gases, by the amount of nitrogen fertilizers, plant residues, and manure coming to the soil. The total emission from the land use is 106.9 million t CO2 equiv/year that makes up 4.9% of the total anthropogenic emission of greenhouse gases in the Russian Federation.  相似文献   

15.
A coupled carbon cycle-climate model is used to compute global atmospheric CO2 and temperature variation that would result from several future CO2 emission scenarios. The model includes temperature and CO2 feedbacks on the terrestrial biosphere, and temperature feedback on the oceanic uptake of CO2. The scenarios used include cases in which fossil fuel CO2 emissions are held constant at the 1986 value or increase by 1% yr–1 until either 2000 or 2020, followed by a gradual transition to a rate of decrease of 1 or 2% yr–1. The climatic effect of increases in non-CO2 trace gases is included, and scenarios are considered in which these gases increase until 2075 or are stabilized once CO2 emission reductions begin. Low and high deforestation scenarios are also considered. In all cases, results are computed for equilibrium climatic sensitivities to CO2 doubling of 2.0 and 4.0 °C.Peak atmospheric CO2 concentrations of 400–500 ppmv and global mean warming after 1980 of 0.6–3.2 °C occur, with maximum rates of global mean warming of 0.2–0.3 °C decade–1. The peak CO2 concentrations in these scenarios are significantly below that commonly regarded as unavoidable; further sensitivity analyses suggest that limiting atmospheric CO2 to as little as 400 ppmv is a credible option.Two factors in the model are important in limiting atmospheric CO2: (1) the airborne fraction falls rapidly once emissions begin to decrease, so that total emissions (fossil fuel + land use-induced) need initially fall to only about half their present value in order to stabilize atmospheric CO2, and (2) changes in rates of deforestation have an immediate and proportional effect on gross emissions from the biosphere, whereas the CO2 sink due to regrowth of forests responds more slowly, so that decreases in the rate of deforestation have a disproportionately large effect on net emission.If fossil fuel emissions were to decrease at 1–2% yr–1 beginning early in the next century, emissions could decrease to the rate of CO2 uptake by the predominantly oceanic sink within 50–100 yrs. Simulation results suggest that if subsequent emission reductions were tied to the rate of CO2 uptake by natural CO2 sinks, these reductions could proceed more slowly than initially while preventing further CO2 increases, since the natural CO2 sink strength decreases on time scales of one to several centuries. The model used here does not account for the possible effect on atmospheric CO2 concentration of possible changes in oceanic circulation. Based on past rates of atmospheric CO2 variation determined from polar ice cores, it appears that the largest plausible perturbation in ocean-air CO2 flux due to changes of oceanic circulation is substantially smaller than the permitted fossil fuel CO2 emissions under the above strategy, so tieing fossil fuel emissions to the total sink strength could provide adequate flexibility for responding to unexpected changes in oceanic CO2 uptake caused by climatic warming-induced changes of oceanic circulation.  相似文献   

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

17.
The number of electric and electronic products (e-products) owned by Chinese households has multiplied in the past decade. In this study, we analyz the GHG emissions from e-products in Chinese households in order to understand and determine how to mitigate their effects on climate change. The results show that the usage stage of e-products has become an important source of GHG emissions in China, with total GHG emissions of these household e-products reaching about 663 million tons CO2 eq., accounting for about 8.85 % of all Chinese GHG emissions in 2012. The average GHG emission per household per year in China was 1538 kg CO2 eq. in 2012, a little higher than that of Norwegian households (1200 kg CO2 eq.). The electricity mix plays a very important role in GHG emissions, and the 78 % coal-fired power consumption accounted for 99.69 % of the total GHG emissions. Our research also supports the view that GHG emissions from household e-products increased with economic level. To reduce the GHG emissions of household e-products, the development of energy-saving e-products and changes to the electricity mix would be very effective measures.  相似文献   

18.
Uncertainty analysis facilitates identification of the most important categories affecting greenhouse gas (GHG) inventory uncertainty and helps in prioritisation of the efforts needed for development of the inventory. This paper presents an uncertainty analysis of GHG emissions of all Kyoto sectors and gases for Finland consolidated with estimates of emissions/removals from LULUCF categories. In Finland, net GHG emissions in 2003 were around 69 Tg (±15 Tg) CO2 equivalents. The uncertainties in forest carbon sink estimates in 2003 were larger than in most other emission categories, but of the same order of magnitude as in carbon stock change estimates in other land use, land-use change and forestry (LULUCF) categories, and in N2O emissions from agricultural soils. Uncertainties in sink estimates of 1990 were lower, due to better availability of data. Results of this study indicate that inclusion of the forest carbon sink to GHG inventories reported to the UNFCCC increases uncertainties in net emissions notably. However, the decrease in precision is accompanied by an increase in the accuracy of the overall net GHG emissions due to improved completeness of the inventory. The results of this study can be utilised when planning future GHG mitigation protocols and emission trading schemes and when analysing environmental benefits of climate conventions.  相似文献   

19.
A high resolution global model of the terrestrial biosphere is developed to estimate changes in nitrous oxide (N2O) emissions from 1860–1990. The model is driven by four anthropogenic perturbations, including land use change and nitrogen inputs from fertilizer, livestock manure, and atmospheric deposition of fossil fuel NO x . Global soil nitrogen mineralization, volatilization, and leaching fluxes are estimated by the model and converted to N2O emissions based on broad assumptions about their associated N2O yields. From 1860–1990, global N2O emissions associated with soil nitrogen mineralization are estimated to have decreased slightly from 5.9 to 5.7 Tg N/yr, due mainly to land clearing, while N2O emissions associated with volatilization and leaching of excess mineral nitrogen are estimated to have increased sharply from 0.45 to 3.3 Tg N/yr, due to all four anthropogenic perturbations. Taking into account the impact of each perturbation on soil nitrogen mineralization and on volatilization and leaching of excess mineral nitrogen, global 1990 N2O emissions of 1.4, 0.7, 0.4 and 0.08 Tg N/yr are attributed to fertilizer, livestock manure, land clearing and atmospheric deposition of fossil fuel NO x , respectively. Consideration of both the short and long-term fates of fertilizer nitrogen indicates that the N2O/fertilizer-N yield may be 2% or more.C. NBM Definitions AET mon (cm H2O) = monthly actual evapotranspiration - AET ann (cm H2O) = annual actual evapotranspiration - age h (years) = stand age of herbaceous biomass - age w (years) = stand age of woody biomass - atmblc (gC/m2/month) = net flux of CO2 from grid - biotoc (gC/g biomass) = 0.50 = convert g biomass to g C - beff h = 0.8 = fraction of cleared herbaceous litter that is burned - beff w = 0.4 = fraction of cleared woody litter that is burned - bfmin = 0.5 = fraction of burned N litter that is mineralized or converted to reactive gases which rapidly redeposit. Remainder assumed pyrodenitrified to N2. + N2O - bprob = probability that burned litter will be burned - burn h (gC/m2/month) = herbaceous litter burned after land clearing - burn w (gC/m2/month) = woody litter burned after land clearing - cbiomsh (gC/m2) = C herbaceous biomass pool - cbiomsw (gC/m2) = C woody biomass pool - clear (gC/m2/month) = woody litter C removed by land clearing - clearn (gN/m2/month) = woody litter N removed by land clearing - cldh (month–1) = herbaceous litter decomposition coefficient - cldw (month–1) = woody litter decomposition coefficient - clittrh (gC/m2) = C herbaceous litter pool - clittrw (gC/m2) = C woody litter pool - clph (month–1) = herbaceous litter production coefficient - clpw (month–1) = woody litter production coefficient - cnrath (gC/gN) = C/N ratio in herbaceous phytomass - cnrats (gC/gN) = C/N ratio in soil organic matter - cnratt (gC/gN) = average C/N ratio in total phytomass - cnratw (gC/gN) = C/N ratio in woody phytomass - crod (month–1) = forest clearing coefficient - csocd (month–1) = actual soil organic matter decompostion coefficient - decmult decomposition coefficient multiplier; natural =1.0; agricultural =1.0 (1.2 in sensitivity test) - fertmin (gN/m2/month) = inorganic fertilizer input - fleach fraction of excess inorganic N that is leached - fligh (g Lignin/ g C) = lignin fraction of herbaceous litter C - fligw (g Lignin/ g C) = 0.3 = lignin fraction of woody litter C - fln2o = .01–.02 = fraction of leached N emitted as N2O - fnav = 0.95 = fraction of mineral N available to plants - fosdep (gN/m2/month) = wet and dry atmospheric deposition of fossil fuel NO x - fresph = 0.5 = fraction of herbaceous litter decomposition that goes to CO2 respiration - fresps = 0.51 + .068 * sand = fraction of soil organic matter decomposition that goes to CO2 respiration - frespw = 0.3 * (* see comments in Section 2.3 under decomposition) = fraction of woody litter decomposition that goes to CO2 respiration - fsoil = ratio of NPP measured on given FAO soil type to NPFmiami - fstruct = 0.15 + 0.018 * ligton = fraction of herbaceous litter going to structural/woody pool - fvn2o = .05–.10 = fraction of excess volatilized mineral N emitted as N2O - fvol = .02 = fraction of gross mineralization flux and excess mineral N volatilized - fyield ratio of total agricultural NPP in a given country in 1980 to total NPPmiami of all displaced natural grids in that country - gimmob h (gN/m2/month) = gross immobilization of inorganic N into microbial biomass due to decomposition of herbaceous litter - gimmob s (gN/m2/month) = gross immobilization of inorganic N into microbial biomass due to decomposition of soil organic matter - gimmob w (gN/m2/month) = gross immobilization of inorganic N into microbial biomass due to decomposition of woody litter - graze (gC/m2/month) = C herbaceous biomass grazed by livestock - grazen (gN/m2/month) = N herbaceous biomass grazed by livestock - growth h (gC/m2/month) = herbaceous litter incorporated into microbial biomass - growth w (gC/m2/month) = woody litter incorporated into microbial biomass - gromin h (gN/m2/month) = gross N mineralization due to decomposition and burning of herbaceous litter - gromin s (gN/m2/month) = gross N mineralization due to decomposition of soil organic matter - gromin w (gN/m2/month) = gross N mineralization due to decomposition and burning of woody litter - herb herbaceous fraction by weight of total biomass - leach (gN/m2/month) = leaching (& volatilization) losses of excess inorganic N - ligton (g lignin-C/gN) = lignin/N ratio in fresh herbaceous litter - LP h (gC/m2/month)= C herbaceous litter production - LP (gC/m2/month) = C woody litter production - LPN h (gN/m2/month) = N herbaceous litter production - LPN W (gN/m2/month) = N woody litter production - manco2 (gC/m2/month) = grazed C respired by livestock - manlit (gC/m2/month) = C manure input (feces + urine) - n2oint (gN/m2/month) = intercept of N2O flux vs gromin regression - n2oleach (gN/m2/month) = N2O flux associated with leaching and volatilization of excess inorganic N - n2onat (gN/m2/month) = natural N2O flux from soils - n2oslope slope of N2O flux vs gromin regression - nbiomsh (gN/m2) = N herbaceous biomass pool - nbiomsw (gN/m2) = N woody biomass pool - nfix (gN/m2/month) = N2 fixation + natural atmospheric deposition - nlittrh (gN/m2) = N herbaceous litter pool - nlittrw (gN/m2) = N woody litter pool - nmanlit (gN/m2/month) = organic N manure input (feces) - nmanmin (gN/m2/month) = inorganic N manure input (urine) - nmin (gN/m2) = inorganic N pool - NPP acth (gC/m2/month)= actual herbaceous net primary productivity - NPP actw (gC/m2/month) = actual woody net primary productivity - nvol (gN/m2/month) = volatilization losses from inorganic N pool - plntnav (gN/m2/month)= mineral N available to plants - plntup h (gN/m2/month) = inorganic N incorporated into herbaceous biomass - plntup w (gN/m2/month) = inorganic N incorporated into woody biomass - precip ann (mm) = mean annual precipitation - precip mon (mm) = mean monthly precipitation - pyroden h (gN/m2/month) = burned herbaceous litter N that is pyrodenitrified to N2 - pyroden w (gN/m2/month) = burned woody litter N that is pyrodenitrified to N2 - recyc fraction of N that is retranslocated before senescence - resp h (gC/m2/month) = herbaceous litter CO2 respiration - resp s (gC/m2/month) = soil organic carbon CO2 respiration - resp w (gC/m2/month) = woody litter CO2 respiration - sand sand fraction of soil - satrat ratio of maximum NPP to N-limited NPP - soiloc (gC/m2) = soil organic C pool - soilon (gN/m2) = soil organic N pool - temp ann (°C) = mean annual temperature - temp mon (°C) = mean monthly temperature Now at the NOAA Aeronomy Laboratory, Boulder, Colorado.  相似文献   

20.
Increased precipitation during the vegetation periods was observed in and further predicted for Inner Mongolia. The changes in the associated soil moisture may affect the biosphere-atmosphere exchange of greenhouse gases. Therefore, we set up an irrigation experiment with one watered （W） and one unwatered plot （UW） at a winter-grazed Leymus chinensis-steppe site in the Xilin River catchment, Inner Mongolia. UW only received the natural precipitation of 2005 （129 mm）, whereas W was additionally watered after the precipitation data of 1998 （in total 427 mm）. In the 3-hour resolution, we determined nitrous oxide （N20）, methane （CH4） and carbon dioxide （CO2） fluxes at both plots between May and September 2005, using a fully automated, chamber-based measuring system. N20 fluxes in the steppe were very low, with mean emissions （±s.e.） of 0.9-4-0.5 and 0.7-4-0.5 μg N m^-2 h^-1 at W and UW, respectively. The steppe soil always served as a CH4 sink, with mean fluxes of -24.1-4-3.9 and -31.1-4- 5.3 μg C m^-2 h^-1 at W and UW. Nighttime mean CO2 emissions were 82.6±8.7 and 26.3±1.7 mg C m^-2 h^-1 at W and UW, respectively, coinciding with an almost doubled aboveground plant biomass at W. Our results indicate that the ecosystem CO2 respiration responded sensitively to increased water input during the vegetation period, whereas the effects on CH4 and N2O fluxes were weak, most likely due to the high evapotranspiration and the lack of substrate for N2O producing processes. Based on our results, we hypothesize that with the gradual increase of summertime precipitation in Inner Mongolia, ecosystem CO2 respiration will be enhanced and CH4 uptake by the steppe soils will be lightly inhibited.  相似文献   

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