Methane emission from rice paddy soils, aerotolerance of methanogens and global thermal warming

In vitro methane emissions from different rice paddy soils and algal mats were studied under anoxic and atmospheric conditions. Methane production from rice paddy soils cultivating different strains of rice was found to be appreciable under anoxic conditions, but considerably reduced under atmospheric conditions, and dependent on rice cultivars (strains). A contradictory result was obtained with a Gobindabhog cultivated rice field (a strain of rice with aroma), where methane yield under anoxic was greater than that under atmospheric conditions. The results indicated aerotolerance of methanogens or the possible existence of microaerophilic methanogens. The results from algal mats corroborated these findings.Methane has been considered to be an important greenhouse gas contributing significantly to global thermal warming (GTW). Flooded rice paddy fields have been considered to be a most prominent source of abiogenic methane emission, though considerable uncertainty exists regarding the true estimates of methane emission. Factors affecting methane emission and its abatement have been examined. In spite of increasing methane emission, rice cultivation leads to enormous utilization of the green house gas carbon dioxide and release of oxygen to the atmosphere. Thus, the contribution of methane to GTW (from rice paddy cultivation) is more than compensated by carbon dioxide absorption.Appropriate steps have been suggested for the reduction of methane emissions, the most important of which is the restoration of methane sinks.     

Estimation of Nitrous Oxide Emissions from US Grasslands

2 O) emissions from temperate grasslands are poorly quantified and may be an important part of the atmospheric N₂O budget. In this study N₂O emissions were simulated for 1052 grassland sites in the United States using the NGAS model of Parton and others (1996) coupled with an organic matter decomposition model. N₂O flux was calculated for each site using soil and land use data obtained from the National Resource Inventory (NRI) database and weather data obtained from NASA. The estimates were regionalized based upon temperature and moisture isotherms. Annual N₂O emissions for each region were based on the grassland area of each region and the mean estimated annual N₂O flux from NRI grassland sites in the region. The regional fluxes ranged from 0.18 to 1.02 kg N₂O N/ha/yr with the mean flux for all regions being 0.28 kg N₂O N/ha/yr. Even though fluxes from the western regions were relatively low, these regions made the largest contribution to total emissions due to their large grassland area. Total US grassland N₂O emissions were estimated to be about 67 Gg N₂O N/yr. Emissions from the Great Plains states, which contain the largest expanse of natural grassland in the United States, were estimated to average 0.24 kg N₂O N/ha/yr. Using the annual flux estimate for the temperate Great Plains, we estimate that temperate grasslands worldwide may potentially produce 0.27 Tg N₂O N/yr. Even though our estimate for global temperate grassland N₂O emissions is less than published estimates for other major temperate and tropical biomes, our results indicate that temperate grasslands are a significant part of both United States and global atmospheric N₂O budgets. This study demonstrates the utility of models for regional N₂O flux estimation although additional data from carefully designed field studies is needed to further validate model results.     

Toward a CO2 zero emissions energy system in the Middle East region

Climate change and energy security are global challenges requiring concerted attention and action by all of the world’s countries. Under these conditions, energy supplier and exporter countries in the Middle East region are experiencing further challenges, such as increasing domestic energy demand while energy exports have to concurrently be kept at high levels. Middle East countries process the largest proven oil and gas reserves in the world and contribute a large fraction of the world’s CO₂ emissions from the use of these as fuels both domestically and internationally. This paper addresses different policies that could dramatically change the future course of the Middle East region toward a zero CO₂ emission energy system. To this aim, an integrated energy supply–demand model has been developed to analyze required commitments including renewable energy and energy efficiency targets and the potential of nuclear power, all of which should need to be considered in order to reduce CO₂ emissions by 2100. The results indicate that nearly 43% of the global energy of the Middle East region can be supplied from non-fossil fuel resources in 2100.     

Panel heterogeneous distribution analysis of trade and modernized agriculture on CO2 emissions: The role of renewable and fossil fuel energy consumption

In line with the global target of reducing climate change and its impact, this study explored the causal relationship between CO₂ emissions, modernized agriculture, trade openness, aggregate and disaggregate energy consumption in 14 African countries from 1990–2013 using a panel quantile estimation procedure. The empirical results showed that value addition to agricultural commodities declines CO₂ emissions in countries with high pollution levels. The study revealed a positive nexus between CO₂ emissions and energy consumption homogeneously distributed across quantiles. Trade openness was found to lower CO₂ emissions in countries with lower and higher levels of environmental pollution. While fossil fuel energy consumption was found to exacerbate CO₂ emissions, renewable energy consumption confirmed its mitigating effect on environmental pollution. The institution of climate‐smart agricultural options will sustainably increase productivity and income while adapting to climate change by reducing greenhouse gas emissions. Diversification of energy technologies with clean and modern energy sources like renewables avoid the over‐dependence on fossil fuels for agricultural purposes. Trade policies can stimulate flows of technology and investment opportunities for specialization in production and economies of scale. Hence, the consideration of policies that boost agricultural sector productivity and create an efficient market for international trade in Africa will help in improving livelihoods.     

Solid Waste Treatment as a High-Priority and Low- Cost Alternative for Greenhouse Gas Mitigation

The increased concern about environmental problems caused by inadequate waste management, as well as the concern about global warming, promotes actions toward a sustainable management of the organic fraction of the waste. Landfills, the most common means to dispose of municipal solid waste (MSW), lead to the conversion of the organic waste to biogas, containing about 50% methane, a very active greenhouse gas (GHG). One unit of methane has a global warming potential of 21 computed for a 100-year horizon or 56 computed for 20 years. The waste sector in Israel contributes 13% of total greenhouse gases (GHG) emissions for a time horizon of 100 years (for a time horizon of 20 years, the waste sector contribution equals to more than 25% of total GHG emissions). The ultimate goal is to minimize the amount of methane (CH₄) by converting it to CO₂. This can be achieved by physicochemical means (e.g., landfill gas flare, incineration) or by biological processes (e.g., composting, anaerobic digestion). Since the waste in Israel has a high organic material content, it was found that the most cost-effective means to treat the degradable organic components is by aerobic composting (investment of less than US$ 10 to reduce emission of one ton CO₂ equivalent per year). Another benefit of this technology is the ability to implement it within a short period. The suggested approach, which should be implemented especially in developing countries, could reduce a significant amount of GHG at relatively low cost and short time. The development of a national policy for proper waste treatment can be a significant means to abate GHG emissions in the short term, enabling a gain in time to develop other means for the long run. In addition, the use of CO₂ quotas will credit the waste sector and will promote profitable proper waste management.     

Assessing alternatives for mitigating net greenhouse gas emissions and increasing yields from rice production in China over the next twenty years

Assessments of the efficacy of mitigation of greenhouse gas (GHG) emissions from paddy rice systems have typically been analyzed based on field studies. Extrapolation of the mitigation potential of alternative management practices from field studies to a national scale may be enhanced by spatially explicit process models, like the DeNitrification and DeComposition (DNDC) model. Our objective was to analyze the impacts of mitigation alternatives, management of water, fertilizer, and rice straw, on net GHG emissions (carbon dioxide, methane, and nitrous oxide fluxes), yields, and water use. After constructing a GIS database of soil, climate, rice cropping area and systems, and management practices, we ran DNDC with 21-yr alternative management schemes for each of the approximately 2500 counties in China. Results indicate that, despite large-scale adoption of midseason drainage, there is still large potential for additional methane reductions from Chinese rice paddies of 20 to 60% over 2000-2020. However, changes in management for reducing CH4 emissions simultaneously affect soil carbon dynamics as well as N2O emissions and can thereby reorder the ranking of technical mitigation effectiveness. The order of net GHG emissions reduction effectiveness found here is upland rice > shallow flooding > ammonium sulfate > midseason drainage > off-season straw > slow-release fertilizer > continuous flooding. Most of the management alternatives produced yields comparable to the baseline; however, continuous flooding and upland rice significantly reduced yields. Water management strategies appear to be the most technically promising GHG mitigation alternatives, with shallow flooding providing additional benefits of both water conservation and increased yields.     

Long-term global availability of steel scrap

Primary steelmaking involves CO₂-intensive processes, but the expansion of secondary steel production is limited by the global availability of steel scrap. The present work examines global scrap consumption in the past (1870–2012) and future scrap availability (2013–2050) based on the historical trend. The results reveal that (i) historically, the consumption of old scrap has been insufficient compared with the amounts of discarded steel, and (ii) based on historical scrap consumption, the future availability of scrap will not be sufficient to satisfy the two assumed cases of steel demand. Primary steelmaking is expected to remain the dominant process, at least up until 2050. Under the reference-demand case of 2.19 billion tons in crude steel production by 2050, the total production of pig iron and direct reduced iron could reach 1.35 billion tons. Consumption of old scrap could reach 0.76 billion tons. Because the availability of scrap will be limited in the context of the global total, it is important to research and develop innovative low-carbon technologies for primary steelmaking and to explore their economic viability if we are to aim for achieving large reductions in CO₂ emissions from the iron and steel industry.     

Electricity systems with near-zero emissions of CO2 based on wind energy and coal gasification with CCS and hydrogen storage

Emissions from electricity generation will have to be reduced to near-zero to meet targets for reducing overall greenhouse gas emissions. Variable renewable energy sources such as wind will help to achieve this goal but they will have to be used in conjunction with other flexible power plants with low-CO₂ emissions. A process which would be well suited to this role would be coal gasification hydrogen production with CCS, underground buffer storage of hydrogen and independent gas turbine power generation. The gasification hydrogen production and CO₂ capture and storage equipment could operate at full load and only the power plants would need to operate flexibly and at low load, which would result in substantial practical and economic advantages. This paper analyses the performances and costs of such plants in scenarios with various amounts of wind generation, based on data for power demand and wind energy variability in the UK. In a scenario with 35% wind generation, overall emissions of CO₂ could be reduced by 98–99%. The cost of abating CO₂ emissions from the non-wind residual generation using the technique proposed in this paper would be less than 40% of the cost of using coal-fired power plants with integrated CCS.     

Investigation of Nanoparticle Additives to Biodiesel for Improvement of the Performance and Exhaust Emissions in a Compression Ignition Engine

Worldwide energy demand has been growing steadily during the past five decades and most experts believe that this trend will continue to rise. The amount of emitted harmful emission gases increases in parallel with increasing energy consumption. This increase has forced many countries to take various precautions, and various restrictions on emitted emissions have been carried. In this study, effects of addition of oxygen containing nanoparticle additives to biodiesel on fuel properties and effects on diesel engine performance and exhaust emissions were investigated. Two different nanoparticle additives, namely MgO and SiO₂, were added to biodiesel at the addition dosage of 25 and 50 ppm. Fuel properties, engine performance, and exhaust emission characteristics of obtained modified fuels were examined. As a result of this study, engine emission values NO_x and CO were decreased and engine performance values slightly increased with the addition of nanoparticle additives.     

Estimating rainforest biomass stocks and carbon loss from deforestation and degradation in Papua New Guinea 1972–2002: Best estimates,uncertainties and research needs

Reduction of carbon emissions from tropical deforestation and forest degradation is being considered a cost-effective way of mitigating the impacts of global warming. If such reductions are to be implemented, accurate and repeatable measurements of forest cover change and biomass will be required. In Papua New Guinea (PNG), which has one of the world's largest remaining areas of tropical forest, we used the best available data to estimate rainforest carbon stocks, and emissions from deforestation and degradation. We collated all available PNG field measurements which could be used to estimate carbon stocks in logged and unlogged forest. We extrapolated these plot-level estimates across the forested landscape using high-resolution forest mapping. We found the best estimate of forest carbon stocks contained in logged and unlogged forest in 2002 to be 4770 Mt (±13%). Our best estimate of gross forest carbon released through deforestation and degradation between 1972 and 2002 was 1178 Mt (±18%). By applying a long-term forest change model, we estimated that the carbon loss resulting from deforestation and degradation in 2001 was 53 Mt (±18%), rising from 24 Mt (±15%) in 1972. Forty-one percent of 2001 emissions resulted from logging, rising from 21% in 1972. Reducing emissions from logging is therefore a priority for PNG. The large uncertainty in our estimates of carbon stocks and fluxes is primarily due to the dearth of field measurements in both logged and unlogged forest, and the lack of PNG logging damage studies. Research priorities for PNG to increase the accuracy of forest carbon stock assessments are the collection of field measurements in unlogged forest and more spatially explicit logging damage studies.     

A reappraisal of WRI's estimates of greenhouse gas emissions

Excessive emissions of certain trace gases such as carbon dioxide, methane, nitrous oxide, carbon monoxide and chlorofluorocarbons are likely to result in global warming due to increased concentration of these greenhouse gases (GHGs). Therefore, measures to control GHG emissions are essential and the current international debate is on how to arrive at optimal GHG limitation strategies. To set emission targets or to distribute the burden of costs of various control measures, it is necessary to identify the major emitters. The World Resources Institute has assessed countrywide contributions to global GHG emissions for 1987. This paper disagrees with the basic approach adopted by WRI because it fails to apportion sinks on a logical basis by keeping in mind equity considerations; it does not account for the residence time of different GHGs; and it uses unreliable and outdated data for estimating the emissions. Using recent and reliable data for India and Brazil as well as the IPCC global warming potential for various GHGs, the shares in global emissions have been recalculated. The paper concludes that if only current emissions are considered there is considerable bias against those countries which are latecomers to the process of industrialization.     

World tropical wood trade : Economic overview

Tropical wood is attracting global attention in the light of dwindling sources of industrial raw material supplies, increasing concern for conservation and growing requirements for huge investments. This study examines the changing character of the world hardwood trade, and the factors that will affect future supply, demand and price. It also considers the likely implications of recent large-scale attempts to grow tropical species for pulp, developments in microtechnology and biotechnology on wood, and the proposed international commodity agreement for tropical timber. The study emphasizes the need for huge investments on a global scale in afforestation and research to fully realize the potential of the tropical biomass.     

Integrated rice-fish culture: Coupled production saves resources

Rice is a key component in global food security, as it is the main ingredient in the daily diets of around 3 billion people, especially in Asia. Like all agricultural production, rice cultivation depends on scarce natural resources. This article briefly outlines the utilization of land and water in rice production, and suggests an approach for optimizing use efficiency, namely through the combination of rice and fish culture. The authors argue that the utilization of land and fresh water is optimized through integrated and complementary production of rice and fish — two basic foods items in daily local diets. The article reviews currently available scientific literature on integrated rice‐fish systems. Rice‐fish culture systems are briefly characterized, and respective yield potential and interactions between rice and fish are discussed. Results of socio‐economic surveys regarding the adoption of integrated rice‐fish culture are summarized. The article also reviews literature on the impact of fish culture on rice field ecology as outlined in studies on weed infestation, insect populations, and greenhouse gas emissions. The article concludes that rice‐fish culture can be an option to help rice producing countries keep pace with soaring domestic demand for food, especially fish. Integrated rice and fish culture optimizes the benefits of scarce land and water resources through complementary use, and exploits the synergies between fish and plant.     

Estimation and Spatiotemporal Analysis of Methane Emissions from Agriculture in China

Estimating and analyzing the temporal and spatial patterns of methane emissions from agriculture (MEA) will help China formulate mitigation and adaptation strategies for the nation’s agricultural sector. Based on the Tier 2 method presented in the 2006 guidelines of the Intergovernmental Panel on Climate Change (IPCC) and on existing reports, this article presents a systematic estimation of MEA in China from 1990 to 2006, with a particular emphasis on trends and spatial distribution. Results from our study indicate that China’s MEA rose from 16.37 Tg yr⁻¹ in 1990 to 19.31 Tg yr⁻¹ in 2006, with an average annual increase of 1.04%. Over the study period, while emissions from field burning of crop residues remained rather low, those from rice cultivation and from livestock typically decreased and increased, respectively, showing extremely opposite trends that chiefly resulted from changes in the cultivated areas for different rice seasons and changes in the populations of different animal species. Over the study period, China’s high-MEA regions shifted generally northward, chiefly as a result of reduced emissions from rice cultivation in most of China’s southern provinces and a substantial growth in emissions from livestock enteric fermentation in most of China’s northern, northeastern, and northwestern provinces. While this article provides significant information on estimates of MEA in China, it also includes some uncertainties in terms of estimating emissions from each source category. We conclude that China’s MEA will likely continue to increase in the future and recommend a demonstration study on MEA mitigation along the middle and lower reaches of the Yellow River. We further recommend enhanced data monitoring and statistical analysis, which will be essential for preparation of the national greenhouse gas (GHG) inventory.     

Impact of forest policies on timber production in India: a review

Until the 20th century, forest policies across the globe focused primarily on effective forest utilization for timber production. Subsequent loss of forest land prompted many countries to review and amend such policies, in an attempt to incorporate the principles of conservation and sustainable forest management. One of the countries to implement such changes was India, which introduced new policies, acts and programmes to regulate forest conversion and degradation, beginning in the 1980s. These policies, acts, and programmes included the Forest Conservation Act of 1980, the National Forest Policy of 1988 and the Hon. Supreme Court Order of 1996. All of these regulations affected the timber supply from government forest areas, and created a huge gap in timber supply and demand. Currently, this deficit is met through imports and trees outside forests (TOFs). Timber production from government forest areas is abysmally low (3.35% of total demand) compared to potential timber production from TOFs, which fulfil 45% of the total timber demand in India. This implies that TOFs have immense potential in meeting the growing timber demand; however, they have not been fully utilized due to discrepancies in state level TOFs’ policies. The present paper provides a review of different forest policies, acts and guidelines in relation to timber production in India, and provides specific recommendations in order to maximize timber production in the context of increasing demand for timber products.     

Modelling future copper ore grade decline based on a detailed assessment of copper resources and mining

The concept of “peak oil” has been explored and debated extensively within the literature. However there has been comparatively little research examining the concept of “peak minerals”, particularly in-depth analyses for individual metals. This paper presents scenarios for mined copper production based upon a detailed assessment of global copper resources and historic mine production. Scenarios for production from major copper deposit types and from individual countries or regions were developed using the Geologic Resources Supply-Demand Model (GeRS-DeMo). These scenarios were extended using cumulative grade-tonnage data, derived from our resource database, to produce estimates of potential rates of copper ore grade decline.The scenarios indicate that there are sufficient identified copper resources to grow mined copper production for at least the next twenty years. The future rate of ore grade decline may be less than has historically been the case, as mined grades are approaching the average resource grade and there is still significant copper endowment in high grade ore bodies. Despite increasing demand for copper as the developing world experiences economic growth, the economic and environmental impacts associated with increased production rates and declining ore grades (particularly those relating to energy consumption, water consumption and greenhouse gas emissions) will present barriers to the continued expansion of the industry. For these reasons peak mined copper production may well be realised during this century.     

Feeding fossil fuels to the soil: An analysis of energy embedded and technological learning in the fertilizer industry

In this paper, we assess energy demand due to fertilizer consumption in the period 1961–2001. Based on historical trends of gross energy requirements, we calculated that in 2001, global energy embedded in fertilizer consumption amounted to 3660 PJ, which represents about 1% of the global energy demand. Total energy demand has increased at an average rate of 3.8% p.a. Drivers behind the trend are rising fertilizer consumption and a shift towards more energy intensive fertilizers. Our results show that despite significant energy efficiency improvements in fertilizer manufacture (with exception of phosphate fertilizer in the last 20 years) improvements in energy efficiency have not been sufficient to offset growing energy demand due to rising fertilizer consumption. Furthermore, we found that specific energy consumption of ammonia and urea developed in close concordance with the learning curve model, showing progress ratios of 71% for ammonia production and 88% for urea. This suggests an alternative approach for including technological change in energy intensive industries in middle and long-term models dealing with energy consumption and CO₂ emissions, while few learning curves exist for energy efficiency of end use technologies.     

Energy and CO2 from high performance recycled aggregate production

The use of recycled concrete aggregates (RCA) in applications other than road sub-layers is limited by two factors: the high porosity of RCA in comparison with natural aggregates, and the restrictions set forth in standards and building codes. Research efforts aimed at alleviating these restrictions are focused on improving the quality of coarse RCAs by reducing the amount of adhered cement pastes, which is the weakest element in this system and influences the rheological behaviour.This paper presents an analysis of the environmental impacts of the recent mechanical and thermo-mechanical processing techniques which produce high performance RCA by reducing the volume of adhered cement paste. Based on published data, processing scenarios were established. These scenarios permit making rough estimates of energy consumption, CO₂ emissions, fines generation and product quality. Using these data and the available emission factors from several countries, an objective comparison was made between these innovating processes and conventional recycling.The production of fines increases from 40% up to as much as 70% as the volume of adhered cement paste on the RCA is reduced. Fuel fed thermo-mechanical process energy consumption, per tonne of recycled aggregate, varies between 36 and 62 times higher than conventional recycling processes. Mechanical processing, combined with microwave heating, increases energy consumption from 3 to a little more than 4 times conventional recycling. Consequently, CO₂ emissions released by conventional coarse aggregate production go from 1.5 to 4.5 kgCO₂/t, to around 200 kgCO₂/t, for that of fossil fuel fed thermo-mechanical treatments.Mechanical and mechanical/microwave treatments appear to have the greatest environmental potential. Notwithstanding, the further development of markets for fines is crucial for reducing environmental loads.     

Impact of Human Activities on Carbon Dioxide (CO<Subscript>2</Subscript>) Emissions: A Statistical Analysis

Summary The balance of evidence suggests a perceptible human influence on global ecosystems. Human activities are affecting the global ecosystem, some directly and some indirectly. If researchers could clarify the extent to which specific human activities affect global ecosystems, they would be in a much better position to suggest strategies for mitigating against the worst disturbances. Sophisticated statistical analysis can help in interpreting the influence of specific human activities on global ecosystems more carefully. This study aims at identifying significant or influential human activities (i.e. factors) on CO₂ emissions using statistical analyses. The study was conducted for two cases: (i) developed countries and (ii) developing countries. In developed countries, this study identified three influential human activities for CO₂ emissions: (i) combustion of fossil fuels, (ii) population pressure on natural and terrestrial ecosystems, and (iii) land use change. In developing countries, the significant human activities causing an upsurge of CO₂ emissions are: (i) combustion of fossil fuels, (ii) terrestrial ecosystem strength and (iii) land use change. Among these factors, combustion of fossil fuels is the most influential human activity for CO₂ emissions both in developed and developing countries. Regression analysis based on the factor scores indicated that combustion of fossil fuels has significant positive influence on CO₂ emissions in both developed and developing countries. Terrestrial ecosystem strength has a significant negative influence on CO₂ emissions. Land use change and CO₂ emissions are positively related, although regression analysis showed that the influence of land use change on CO₂ emissions was still insignificant. It is anticipated, from the findings of this study, that CO₂ emissions can be reduced by reducing fossil-fuel consumption and switching to alternative energy sources, preserving exiting forests, planting trees on abandoned and degraded forest lands, or by planting trees by social/agroforestry on agricultural lands.     

Scenario Modeling Potential Eco-Efficiency Gains from a Transition to Organic Agriculture: Life Cycle Perspectives on Canadian Canola,Corn, Soy,and Wheat Production

We used Life Cycle Assessment to scenario model the potential reductions in cumulative energy demand (both fossil and renewable) and global warming, acidifying, and ozone-depleting emissions associated with a hypothetical national transition from conventional to organic production of four major field crops [canola (Brassica rapa), corn (Zea mays), soy (Glycine max), and wheat (Triticum aestivum)] in Canada. Models of these systems were constructed using a combination of census data, published values, and the requirements for organic production described in the Canadian National Organic Standards in order to be broadly representative of the similarities and differences that characterize these disparate production technologies. Our results indicate that organic crop production would consume, on average, 39% as much energy and generate 77% of the global warming emissions, 17% of the ozone-depleting emissions, and 96% of the acidifying emissions associated with current national production of these crops. These differences were almost exclusively due to the differences in fertilizers used in conventional and organic farming and were most strongly influenced by the higher cumulative energy demand and emissions associated with producing conventional nitrogen fertilizers compared to the green manure production used for biological nitrogen fixation in organic agriculture. Overall, we estimate that a total transition to organic production of these crops in Canada would reduce national energy consumption by 0.8%, global warming emissions by 0.6%, and acidifying emissions by 1.0% but have a negligible influence on reducing ozone-depleting emissions.