Global evaluation of the effects of agriculture and water management adaptations on the water-stressed population

Fresh water is one of the most important resources required for human existence, and ensuring its stable supply is a critical issue for sustainable development. The effects of a general set of agriculture and water management adaptations on the size of the world’s water-stressed population were assessed for a specific but consistent scenario on socio-economic development and climate change during the 21st century. To maintain consistency with agricultural land use change, we developed a grid-based water supply–demand model integrated with an agro-land use model and evaluated the water-stressed population using a water withdrawals-to-availability ratio for river basins. Our evaluation shows that, if no adaptation options are implemented, the world’s water-stressed population will increase from 1.8 billion in 2000 to about 3.3 billion in 2050, and then remain fairly constant. The population and economic growth rather than climate change will be dominant factors of this increase. Significant increase in the water-stressed population will occur in regions such as North Africa and the Middle East, India, Other South Asia, China and Southeast Asia. The key adaptation options differ by region, depending on dominant crops, increase in crop demand and so on. For instance, ‘improvement of irrigation efficiency’ and ‘enhancement of reclamation water’ seem to be one of important options to reduce the water stress in Southeast Asia, and North Africa and the Middle East, respectively. The worldwide implementation of adaptation options could decrease the water-stressed population by about 5 % and 7–17 %, relative to the scenario without adaptations, in 2050 and 2100, respectively.     

Consistent assessments of pathways toward sustainable development and climate stabilization

Many of the numerous difficult issues facing the world today involve relationships entailing trade‐offs and synergies. This study quantitatively assesses some alternative scenarios using integrated assessment models, and provides several indicators relating to sustainable development and climate change, such as indicators of income (per capita GDP), poverty, water stress, food access, sustainable energy use, energy security, and ocean acidification, with high consistencies among the indicators within a scenario. According to the analyses, economic growth helps improve many of the indicators for sustainable development. On the other hand, climate change will induce some severe impacts such as ocean acidification under a non‐climate intervention scenario (baseline scenario). Deep emission reductions, such as to 2°C above the pre‐industrial level, could cause some sustainable development indicators to worsen. There are complex trade‐offs between climate change mitigation levels and several sustainable development indicators. A delicately balanced approach to economic growth will be necessary for sustainable development and responses to climate change.     

Leachability and phytoavailability of nitrogen, phosphorus, and potassium from different bio-composts under chloride- and sulfate-dominated irrigation water

Concerns over increased phosphorus (P) application with nitrogen (N)-based compost application have shifted the trend to P-based composed application, but focusing on one or two nutritional elements does not serve the goals of sustainable agriculture. The need to understand the nutrient release and uptake from different composts has been further aggravated by the use of saline irrigation water in the recent scenario of fresh water shortage. Therefore, we evaluated the leachability and phytoavailability of P, N, and K from a sandy loam soil amended with animal, poultry, and sludge composts when applied on a total P-equivalent basis (200 kg ha(-1)) under Cl(-) (NaCl)- and SO4(2-) (Na2SO4)-dominated irrigation water. Our results showed that the concentration of dissolved reactive P (DRP) was higher in leachates under SO(4)(2-) than Cl(-) treatments. Compost amendments differed for DRP leaching in the following pattern: sludge > animal > poultry > control. Maize (Zea mays L.) growth and P uptake were severely suppressed under Cl(-) irrigation compared with SO4(2-) and non-saline treatments. All composts were applied on a total P-equivalent basis, but maximum plant (shoot + root) P uptake was observed under sludge compost amendment (73.4 mg DW(-1)), followed by poultry (39.3 mg DW(-1)), animal (15.0 mg DW(-1)), and control (1.2 mg DW(-1)) treatment. Results of this study reveal that irrigation water dominated by SO4(2-) has greater ability to replace/leach P, other anions (NO3(-)), and cations (K+). Variability in P release from different bio-composts applied on a total P-equivalent basis suggested that P availability is highly dependent on compost source.     

Adjoint inverse modeling of NOx emissions over eastern China using satellite observations of NO2 vertical column densities

A four-dimensional variational data assimilation system for optimization of NO_x emissions (RC4-NO_x) was developed. A parameterized NO_x chemistry scheme was introduced into the RC4-NO_x system, and key parameters such as chemical production and loss terms of NO_x were calculated in advance using the Community Multiscale Air Quality (CMAQ) modeling system. RC4-NO_x was applied to optimize NO_x emissions over eastern China (EC) in July 1996, 1999, and 2002 using Global Ozone Monitoring Experiment (GOME) satellite observations of NO₂ vertical column densities (VCDs) and a priori emissions from the Regional Emission Inventory in Asia (REAS). After assimilation, RC4-NO_x generally reproduced the spatial distribution, regional averaged values, and time evolution of GOME NO₂ VCDs. Over EC, a priori emissions were reduced by 20% in 1996 and by 8% in 1999, whereas a posteriori emissions were almost the same as a priori emissions in 2002. A priori emissions in the Beijing region were reduced by optimization over the whole simulation period. A posteriori emissions over the Yangtze Delta were larger than a priori emissions in 2002, although they were smaller in both 1996 and 1999. As in other areas, a priori emissions over the North China Plain were reduced in 1996; but those over the eastern part of the plain were increased in 1999, and the area of increased emissions moved slightly westward in 2002. In each region, the growth rates of a posteriori emissions during both 1996–1999 and 1999–2002 became generally larger than those of a priori emissions, and the trends of a posteriori emissions became similar to those of GOME NO₂ VCDs. Our inverse modeling analysis indicates that the rate of increase of NO_x emissions over EC from 1996 to 2002 was much larger for a posteriori emissions (49%) than for a priori emissions (19%).     

Regional-specific emission inventory for NH3, N2O, and CH4 via animal farming in South, Southeast, and East Asia

Ammonia, nitrous oxide, and methane emission from animal farming of South, Southeast, and East Asia, in 2000, was estimated at about 4.7 Tg NH₃–N, 0.51 Tg N₂O–N, and 29.9 Tg CH₄, respectively, using the FAO database and countries’ statistic databases as activity data, and emission factors taking account of regional characteristics. Most of these atmospheric components, up to 60–80%, were produced in China and India. Pakistan, Bangladesh, and Indonesia, which were large source countries next to China and India, contributed more than a few percent of total emission of each atmospheric component. The largest emission livestock were cattle whose contribution was considerably high in South, Southeast, and East Asia; more than one-fourth of ammonia and nitrous oxide emissions: more than half of methane emission. The other major livestock for nitrous oxide and ammonia emissions were pigs. For methane emission, buffaloes were second source livestock. To provide spatial distributions of these gases, the emissions of county and district level were allocated into each 0.5° grid by means of the weighting by high-resolution land cover datasets. The regions with considerable high emissions of all components were able to be found at the Ganges delta and the Yellow River basin. The spatial distributions for ammonia and nitrous oxide emissions were similar but had a substantial difference from methane distribution.     

An Urban Atmospheric Diffusion Model for Traffic-Related Emission Based on Mass-Conservation and Advection-Diffusion Equations

This paper proposes an atmospheric diffusion model for traffic-related emission in urban areas within a few hundred meters from relevant roads. The model adopts the mass-conservation (MC) principle for the velocity calculation and the advection-diffusion (AD) equation for the concentration calculation. This MC+AD combination was chosen to achieve fast calculation for complex geometries. To compensate for the inherent deficiencies of MC and AD, as many known properties possible of turbulent boundary-layer flow over obstacles are incorporated into the MC calculation, and the diffusivity in AD is derived from the velocity spectrum as a function of distance from the emission source. The model is evaluated against wind-tunnel experiments ranging from point-source emission in uniform urban canopy to along-road emission in real city geometries. The model performs well in relatively simple configurations, but the performance deteriorates considerably as the complexity increases. However, in real city geometries, the model exhibits distinctly better performance in terms of statistical indices than a conventional Gaussian-plume model that neglects the effect of individual buildings. The model is therefore a viable option for environmental assessment.     

International comparative study of 3R and waste management policy developments

Reduce, reuse, and recycle (3R) policies form the basis of waste management and global warming countermeasures globally, so we conducted a comparative study of 3R and waste management policies in the European Union (EU), USA, Korea, Japan, China, and Vietnam. An international workshop for 3R and waste management policymakers was held in Kyoto, Japan, and a bibliographic survey was also conducted to collect data. 3R policies are clearly given priority in the hierarchy of waste management in every country studied. Thermal recovery, which includes power generation from waste heat and methane gas collected from organic waste, is also a priority; this is consistent with the increased use of countermeasures to reduce greenhouse gas (GHG) emissions. In the EU, waste management is characterized by practical and effective 3R policies through the development of realistic regulations and by the policymakers??desire to simplify management systems. The policy ideal in China, however, is the development of a circular economy that targets reductions in the amount and hazardousness of waste. Limits on the number of final disposal sites, strategies for procuring resources, and GHG emission countermeasures are closely linked with 3R policies, and further development of 3R policies in parallel with such issues is expected.     

An international comparative study of end-of-life vehicle (ELV) recycling systems

End-of-life vehicles (ELV) have become a global concern as automobiles have become popular worldwide. An international workshop was held to gather data and to discuss 3R policies and ELV recycling systems, their background and present situation, outcomes of related policies and programs, the framework of recycling and waste management, and case studies on related topics in several countries and regions, as well as the essential points of the comparison. Legislative ELV recycling systems are established in the EU, Japan, Korea, and China, while in the US, ELV recycling is managed under existing laws on environmental protection. Since automobile shredding residue (ASR) has a high calorific value and ash content, and includes heavy metals as well as a mass of unclassified fine particles, recycling ASR is considered highly difficult. Countries with a legislative ELV system commonly set a target for recovery rates, with many aiming for more than 95 % recovery. In order to reach this target, higher efficiency in ASR recovery is needed, in addition to material recycling of collectable components and metals. Environmentally friendly design was considered necessary at the planning and manufacturing stages, and the development of recycling systems and techniques in line with these changes are required for sound ELV management.     

Influence of model grid resolution on NO2 vertical column densities over East Asia

NO₂ vertical column densities (VCDs) over East Asia in June and December 2007 were simulated by the Community Multi-scale Air Quality (CMAQ) version 4.7.1 using an updated and more elaborate version of the Regional Emission Inventory in Asia (REAS) version 2. The modeling system could reasonably capture observed spatiotemporal changes of NO₂ VCDs by satellite sensors, the Global Ozone Monitoring Experiment-2 (GOME-2), the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), and the Ozone Monitoring Instrument (OMI), even at the coarsest horizontal resolution of 80 km. The CMAQ simulations were performed in a sequence of three horizontal resolutions (80 km, 40 km, and 20 km) for June and December 2007 to investigate the influence of changes of horizontal resolution on the obtained NO₂ VCDs. CMAQ-simulated NO₂ VCDs generally increased with improvements in resolution from 80 km to 40 km and then to 20 km. Increases in the CMAQ-simulated NO₂ VCDs were greater for the change from 80 km to 40 km than for those from 40 km and 20 km, in which the increases of NO₂ VCDs due to the improvement of horizontal resolution were approached convergence at the horizontal resolution of approximately 20 km. Conversely, no clear convergences in NO₂ VCDs changes were found at near Tokyo and over the East China Sea. The biases of the NO₂ VCDs simulated at a resolution of 20 km against the satellite retrievals were ～36% near Beijing (CHN1) and ～78% near Shanghai (CHN2) in summer; these errors were found to be comparable to the horizontal resolution-dependent errors, which were 18–25% at CHN1 and 44–58% at CHN2 from 80 km to 40 km. Conversely, the influence of changes of horizontal resolution in winter was relatively less compared to that in summer.

Implications: NO₂ VCDs over East Asia in June and December 2007 were simulated using CMAQ version 4.7.1 and REAS version 2. The modeling system could reasonably capture observed spatiotemporal changes of NO₂ VCDs by satellite sensors. The CMAQ simulations were performed in a sequence of three horizontal resolutions, 80, 40, and 20 km, to investigate the influence of changes of horizontal resolution on the obtained NO₂ VCDs. The results suggested that the influence of changes of horizontal resolution was larger in summer compared to that in winter. The magnitude of the influence was comparable to the biases of the NO₂ VCDs simulated at a resolution of 20 km against the satellite retrievals.