Process mechanisms of carbon storage and carbon cycle in earth system are the scientific foundation for analyzing the cause of climate change, forecasting the climate change trend, and making mitigation and adaptation countermeasures, which have attracted great attention from the scientific community and international community. Since the late 1980s, Chinese scientists have carried out a great deal of research on the terrestrial ecosystem carbon cycle, and have made great progress in many fields. In this paper, we review the history of the research on the terrestrial carbon cycle in China, summarize the results of the carbon storage in terrestrial ecosystems and its spatial patterns, evaluate the uncertainties of the research, and put forward important scientific issues which are needed to be addressed urgently. Overall, the research on the carbon cycle of terrestrial ecosystems in China consists of four stages of development, i.e., the early carbon cycle research, the comprehensive study on the carbon cycle at regional scale, the experimental research on the adaptation of ecosystem carbon cycle to climate change, and the coupling cycles of C-N-H₂O and the regional regulation and control. Most studies indicate that carbon storage of terrestrial ecosystems in China and its spatial pattern are controlled by temperature and precipitation. About 97.95–118.93 Pg carbon is stored in soil, forest and grassland in China. Since the mid 1970s, many management measures such as afforestation and forest management, grassland protection, farming system reformation and conservation tillage, have played important roles in carbon sequestration. However, large uncertainty exists among the evaluation results with various methods. In the future we should focus on the integrated monitoring system of the dynamics of carbon storage and carbon sink, foresight studies on the coupling cycles of ecosystem C-N-H₂O and its regional regulation and control, quantitative assessment on the carbon budget and the potential of carbon sink of ecosystems in China, the evaluation of the economic benefit of various technologies for increasing carbon sink of typical ecosystems, and the measurable, reportable and verifiable scientific data and technical supports for establishing the policy framework of greenhouse gas management and carbon trading at national scale.

This paper focuses on the eco—environmental aspects of U.S. biofuel production, a grand energy challenge with an important role in addressing new alternative energy sources. Policy driven approaches have made U.S. biofuels attractive for economic, environmental and strategic reasons with a potential to improve national security issues. Despite the many potential benefits of biofuels we will examine causes for concerns relating to biofeedstock supplies, agro—chemical usage on intensively managed landscapes and potential impacts to terrestrial wildlife in North America. The environmental and economic effects of future biofuels are generally perceived as positive; nonetheless, it will be critical to peruse and develop a biofuels economy with caution to safeguard systems sustainability.

Biomass is an abundant, domestically available source of clean energy that has the potential to greatly reduce greenhouse gas emissions. Production of biofuels from cellulosic biomass is attractive because of its low fossil energy-to-carbon ratio compared to corn and other grain-based technologies. However, biofuel production systems are not simple. They are subject to multiple factors: energy supply, economic development in rural communities, land and ecosystem protection, potential for reduction of greenhouse gas emission, and social training. This paper provides a brief overview of the environmental and economic impacts of bioenergy development. Different regions should have their own optimized portfolio of biomass species or energy crops according to regional climate and ecological conditions. Near-future biotechnology challenges include understanding and manipulation of biomass formation and breakdown of cell wall, biomass pretreatment and selection of plant variants with improved sugar yields, and high throughput characterization and selection of enzymes and microbes for cellulose deconstruction. Life-cycle assessment and development of sustainable criteria and indicators are addressed in addition to the emphasis of the importance of environmental security and public health associated with bioenergy development.

Input—output analysis (IOA) has been applied to study the integrated ecological—economic systems for decades. In this article, a physical input monetary output (PIMO) model is developed to aggregate economic systems with the associated ecological systems. The PIMO model utilizes economic information integrated in monetary input—output tables (MIOTs) and societal metabolism information provided by the method of material flow analysis (MFA). The fundamental process of applying PIMO model to practice is to make a PIMO table based on an existing MIOT. The computational framework of the PIMO model is then expressed by a set of mathematical correlations to represent mass balances of each economic sector and the entire economic system. Although there are four major categories of uncertainty in this approach, the PIMO model is relatively easy and sufficient to study an integrated national economic system and associated ecological system. A general algorithm of PIMO analysis is presented in this article and exampled with a case study on China's economy. In the case study, a PIMO table for China's economy is compiled with 43 economic sectors, 10 categories of resources, and 6 categories of wastes. Impacts on societal metabolism are studied by increasing final demands in different sectors. Each sector's influence on specific categories of resources or wastes is also studied by the PIMO model. Finally, the PIMO model is applied to evaluate a particular policy established by the Chinese central government. Results suggest that specific scenarios are suitable to achieve the predefined environmental goals.

Through an examination of the institutions of energy governance in China, this paper identifies a number of key features which are likely to determine the future evolution of its energy sector. At one level are the embedded institutions which have their roots in more than four thousand years of history and derive from the country's origin as an hydraulic agrarian regime. At another level, analysis of the current institutional environment shows how the formal structures government and the legal system operate in the context of these deeply rooted values to provide the framework for policy making and implementation in the energy sector. In the contemporary world, events within and outside China conspire to drive energy up or down the policy agenda of the central government, and the government in turn may look outwards to seek new ideas to apply to old and new challenges in the field of energy.

This paper presents an energy—economic—environment model based on the dynamic CGE (Computable General Equilibrium) model approach. A policy simulation was conducted to determine the potential and policy choices for China in order to reduce CO₂ emissions towards 2020. The results show that carbon tax and investment adjustments are effective measures to alleviate CO₂ emission increases, but can lead to negative impacts on GDP. Technological improvements can have positive impacts on GDP in regard to CO₂ abatement. Under high technological improvement with a mid-level carbon tax scenario, and low technological improvement with mid-level carbon tax and mid-level investment adjustment scenario, China' s CO₂ emissions in 2020 will reach 9.27–9.55 billion tons and CO₂ emissions intensity will decline by 0.138–0.143 ton (10³ Yuan RMB)^-1. According to the mitigation target proclaimed by Chinese government, China should reduce CO₂ emissions intensity from 0.241 to 0.145 t (10³ Yuan RMB)^-1 from 2005 to 2020 (in constant 2007 RMB). However, it is not easy to realize a 40% mitigation target because increasing energy efficiency at a faster rate than the normal rate of technological improvement means greater costs for investment in equipment renewal and depreciation before 2020. Moreover, in future, energy supply constraints may have positive effects on the mitigation of CO₂ emissions. China needs to devote major efforts to developing low carbon technologies, in addition, international community should provide and increase support to China in this area.

China and the United States are both countries with huge carbon emission, and the volume of trade between them is large. Due to the differences in natural resources, technology, equipment and energy use efficiency, there is a large carbon emission transfer from the United States to China by Sino—U. S. merchandise trade. This paper adopts the input-output analysis method, and combines the systems of economy, energy consumption and trade to establish a carbon emission transfer model based on international trade. And then it calculates the carbon emission transfer by Sino—U.S. merchandise trade in 1997 and 2002. The conclusions are as follows: (i) In 1997 and 2002, the total carbon emissions of China' s industry sectors by exporting merchandise to the U.S. reached 40.1013 Mt C (million tonnes of carbon equivalent) and 50.5621 Mt C, accounting for 6.61% and 8.33% of total carbon emissions of China' s industry sectors; while the total carbon emissions of the United States' industry sectors by exporting merchandise to China were 2.9065 Mt C and 3.3561 Mt C, accounting for only 0.53% and 0.66% of the total carbon emissions of the United States' industry sectors; (ii) In 1997 and 2002, the carbon emission transfer from the United States to China by Sino—U.S. merchandise trade reached 37.1975 Mt C and 47.1960 Mt C. Specially, the contributions of chemical industry, metal smelting and pressing sector are prominent; (iii) In 1997 and 2002, there were equivalent to 6.77% and 9.32% of the United States' industry sectors' total carbon emissions transferred to China. China has made part of contribution to carbon emission reduction for the United States. Developed countries such as the United States should provide climate—friendly and environment—friendly techniques to developing countries such as China.

This paper analyzed the essential concepts of the effective geological factors of economic value for onshore natural gas regions in China and the interrelated factors were researched systematically. The main issues that have been discussed are as follows: the cost of development and investment more related to the depth of reservoir and the sand parameters of overlying formation of natural gas region; production cost is mostly affected by natural geographical elements and corresponding material parameters of the deposit; the reservoir abundance, efficiency thickness, porosity of reservoir, permeability and the type of the gas reserve are the main affecting factors of production. Based on these researches, the factor — weighted computing formula for investment costs, price factors and the discrimination for economic value of onshore natural gas fields were studied. Seven examples of typical onshore natural gas fields in western, middle and eastern China were analyzed with criteria for the geological reserves that have been developed and several suggestions for the sustainable development of Chinese natural gas industry were presented.

This paper applies the panel unit root, heterogeneous panel cointegration test and panel—based dynamic OLS recently developed to re—investigate the Environmental Kuznets Curves for 30 provinces in mainland China from 1985 to 2007. The empirical results show that there is a positive long—term cointegrated relationship between economic growth and three types of environmental pollution. The relationships take on inverted U—shaped EKCs, but the turning points in these curves differ from those found in previous studies. We then analyze the spatial pattern of environmental—economy in China based on the estimations of this study. Most provinces in central and western China are not above the turning points of the EKCs, where industrial pollution emissions show an increasing trend. At present, China is subject to tremendous environmental pressures, and will need to meet enormous cost for pollution emissions reduction. However, environmental economic policies should differ over time and region.

Compost provides benefits such as pathogen inactivation, weed suppression, slow release of nutrients, soil improvement, water conservation, and is an advantageous tool in moving towards more sustainable agricultural systems. Lots of greenhouse gases (GHGs) especially CH4 are emitted from the heap during composting process, which play an important role in global warming. The purposes of this study were to quantify and characterize the GHGs emissions, so as to compare and optimize the operation conditions, then to minimize GHGs emissions. We examined GHGs emissions from composting in forced aeration systems and turning systems with or without the addition of calcium superphosphate (CS), using the static chamber method. The compost degraded 51%–55% of initial total carbon (TC) in turning piles, while about 44% in forced aeration piles after 76 days composting. CH₄ emissions from turning piles with and without CS were respectively 15.35 and 15.27 g Mg^-1 dry material (DM), higher than forced aeration piles (7.76 g Mg^-1 DM, with CS, and 3.22 g Mg^-1 DM, without CS). N₂O emissions were less than 0.1% of initial total nitrogen (TN) in the forced aeration piles, and -0.1% of initial TN in the turning piles. Energy consumption used for treating manure equaled to 3.27, 3.4, 12.29 and 11.89 kg CO₂-C equivalent Mg^-1 DM, for turning with CS, turning without CS, forced aeration with CS, forced aeration without CS, respectively. The addition of CS had little effect on GHGs emissions, due to high porosity and adequate aeration caused by large dose of straw as bulking agent. Although forced aeration composting is an intensive technology widely used in large-scale processing of manure wastes for land saving and easy operation, turning aeration may be more appropriate in rural areas of China, considering the less construction cost and greenhouse gas emissions, and its high efficiency in degrading organic carbon.

It is very difficult to simulate hydrological processes in alpine basin because of the impact of ice-snow and limited availability of ground observation stations. Satellite imagery is an attractive alternative to supplement ground based data in ungauged basin. The Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite sensors are particularly attractive due to their high temporal and spatial resolution. The objective of this study is to integrate temperature data with meteorological stations and SCA (Snow Covered Area) estimated from MODIS into Xinanjiang Model and test if MODIS data could be helpful for runoff modeling in an ungauged alpine basin. The analysis was performed for Niqu Basin in the upper reach of Yangtze River. The study was carried out as follows. Firstly, a critical temperature was acquired according to SCA from MODIS data for judging the periods with snow accumulation, snow melting and no snow. Then the precipitation form was identified and snowmelt water equivalent was computed accordingly. Finally the classified precipitation was as input to the Xinanjiang Model for simulating runoff series. The simulated runoff data by Xinanjiang Model with such a modified input were compared with pure precipitation input. The result indicated that model performance with the modification scheme of precipitation was better than that with original input of precipitation. The result suggests the potential for developing modification scheme and the possibility of improving the accuracy of the prediction of hydrological processes for water resources management and ecological water demand in ungauged alpine basin by Xinanjiang Model.