Threshold effects of population aging on carbon emissions: From the perspective of industrial structure and residential consumption.

Population aging and climate change caused by anthropogenic greenhouse gas emissions are two of the major challenges facing contemporary humanity. Based on panel data for 63 countries from 2000 to 2020, this paper empirically identifies and explores the threshold effects of population aging on carbon emissions, and tests in a causal inference framework the mediating effect mechanism of aging on carbon emissions through two pathways: industrial structure and consumption. Results show that generally when the percentage of the elderly population is higher than 14.5 %, carbon emissions related to industrial structure and residential consumption are significantly reduced although the threshold effects differ across countries. Particularly for lower-middle-income countries, the direction of the threshold effect is uncertain, which indicates the less importance of population aging for carbon emissions in these countries.

The Effects on Energy Markets of Achieving a 1.5 °C Scenario.

Net zero emission scenarios are aligned with the criteria for the Paris Agreement to keep global warming below 1.5 °C. By soft-linking an energy model with a macroeconomic model, we create a similar pathway to the net zero emission scenario from the International Energy Agency (IEA) to 2050 both of demand for fossil fuels and total CO2 emissions. Soft-linking entails that we insert endogenous variables from one model into the other model. We implement measures such as CO2 taxes, improved energy efficiency, more renewables in electricity production and other sectors, easier substitution between electricity and fossil fuels for final users, and drastically limiting future production of oil, gas and coal. Our conclusion is that net zero is possible by introducing very strict measures, e.g., a high rate of energy efficiency improvement, far above what has been achieved in the past. While our partial equilibrium energy model, similar to the IEA model, overlooks the potential rebound effects, i.e., more energy used by consumers due to lower prices caused by energy efficiency improvement, our macroeconomic model does capture the rebound effects and has to implement stricter supply-side measures to reduce fossil fuel use to achieve the 1.5 °C scenario.

Financial Measures to Reduce Carbon Emissions in Britain, Japan and the United States: A SWOT Analysis.

To mitigate global warming, China, the world's largest greenhouse gas emitter, has set the goals of achieving carbon peak by 2030 and carbon neutrality by 2060, and financial measures could play an important role. To avoid unnecessary costs, China could learn from the experience of other countries to better understand the potential role of financial measures in achieving carbon emission reduction goals. Hence, this article adopts a SWOT analysis to compare the financial measures taken by Britain, Japan and the United States in the process of carbon emission reduction in the last twenty years. This article finds that government funds and financial innovation have contributed markedly to carbon emission reduction in those three countries. With the help of the SWOT analysis, we recommend that China take financial measures to help achieve carbon peaking and carbon neutrality goals from four aspects: formulating proper policy, regulating carbon trading market, strengthening international cooperation, and promoting innovation.

Experimental and modeling evidence of hydroxyl radical production in iron electrocoagulation as a new mechanism for contaminant transformation in bicarbonate electrolyte.

Iron electrocoagulation is designed for sustainable high-efficiency and high-flexibility water purification applications. Recent advances reported that hydroxyl radicals (•OH)-based oxidative transformation of organic contaminants can occur in iron electrocoagulation. However, there is still a lack of mechanistic understanding the production of •OH in bicarbonate electrolyte, which presents a critical knowledge gap in the optimization of iron electrocoagulation technology towards practical application. Combined with contaminant degradation, radical quenching experiments, and spectroscopic techniques, we found that •OH was produced at rate of 16.1 µM∙h - 1 during 30-mA iron electrocoagulation in bicarbonate electrolyte through activation of O2 by Fe(II) under pH-neutral conditions. High yield of •OH occurred at pH 8.5, likely due to high adsorbed Fe(II) that can activate O2 to enhance •OH production. Mössbauer and X-ray photoelectron spectroscopy measurements substantiated that Fe(II)-adsorbed lepidocrocite was the dominant solid Fe(II) species at pH 8.5. A process-based kinetic modeling was developed to describe the dynamic of •OH production, Fe(II) oxidation, and contaminant degradation processes in iron electrocoagulation. Findings of this study extend the functionality of electrocoagulation from phase separation to •OH-based advanced oxidation process, which provides a new perspective for the development of electrocoagulation-based next generation sustainable water purification technology.

Smoothing a reference pathway based on discrete exogenous projections.

In integrated assessment studies and scenario analysis, typically we need to calibrate a model to follow an exogenous pathway, e.g., the shared socioeconomic pathways. In these exogenous pathways, the data of key variables such as GDP and energy consumption are typically provided every five or ten years. In some cases, we need a yearly smooth pathway that is consistent with such an exogenous pathway with data of only every five years. Hence, this piece of study provides a method to obtain a smooth yearly pathway based on exogenous data of limited years.•An approach to smoothing time series of discrete variables is provided•An example is used to illustrate the approach based on the data in World Energy Outlook 2019.

Temporal-Spatial Evolution and Influencing Factors of Coordinated Development of the Population, Resources, Economy and Environment (PREE) System: Evidence from 31 Provinces in China.

Facing the increasingly severe friction among the domains of population, resources, economy and environment (PREE) in a system, theoretical guidance for the sustainable development of a PREE system can be obtained by exploring the coordinated development of a PREE system during its temporal-spatial evolution process. Based on the PREE data of 31 provinces in China from 2010 to 2019, this study uses a spatial measurement method to analyze the temporal and spatial evolution characteristics of the PREE systems of China's provinces. The results show that the overall coordination level of China's provincial PREE systems fluctuated but improved from moderate imbalance to moderate coordination. However, the differences in the regional coordination level first decreased and then increased. The distribution characteristics of the system coordination level changed from "high in the east and low in the west" to "high in the west and low in the east", resulting in the "inversion" phenomenon of the system coordination level. The spatial correlation of the coordination level of the PREE system among provinces and cities gradually increased. The coordination level of the PREE system in the eastern, central and western regions was noticeably different, accompanied by different degrees of polarization and showing different dynamic evolution trends. In the analysis of influencing factors, it was found that seven factors, such as per capita GDP, the proportion of environmental pollution control investment to GDP and per capita energy production, promoted the coordinated development of China's PREE system to varying degrees. The coordinated and stable development of China's PREE system should be adjusted and optimized from the perspectives of different regions, scales and systems.

Optimization of operation conditions for domestic sewage treatment using a sequencing batch biofilm filter.

A sequencing batch biofilm filter (SBBF) was applied to treat domestic sewage. The bioreactor consisted of fibrous filler in the upper part and ceramsite filter media in the lower part. The impacts of the most important factors including dissolved oxygen (DO), water temperature and hydraulic retention time (HRT) were evaluated on contaminants removal during the operation of the SBBF. Changes in DO (1.5-4.0 mg/L) and water temperature (2-30 °C) had little effect on the removal of chemical oxygen demand (COD), but had a greater impact on the removal of total nitrogen (TN) and NH4+-N. Changes in HRT (8-14 h) had little effect on the removal of COD, but had a greater impact on the removal of TN, NH4+-N and total phosphorus. The optimal operating parameters for the SBBF were as follows: DO of 2-3 mg/L, water temperature above 10 °C, and HRT of 10-13 h. Furthermore, a simple kinetic model was developed, reflecting the relationship between COD and HRT.

A warmer policy for a colder climate: Can China both reduce poverty and cap carbon emissions?

Reducing global carbon dioxide (CO2) emissions is often thought to be at odds with economic growth and poverty reduction. Using an integrated assessment modeling approach, we find that China can cap CO2 emissions at 2015 level while sustaining economic growth and reducing the urban-rural income gap by a third by 2030. As a result, the Chinese economy becomes less dependent on exports and investments, as household consumption emerges as a driver behind economic growth, in line with current policy priorities. The resulting accumulated greenhouse gas emissions reduction 2016-2030 is about 60billionton (60Mg) CO2e. A CO2 tax combined with income re-distribution initially leads to a modest warming due to reduction in sulfur dioxide (SO2) emissions. However, the net effect is eventually cooling when the effect of reduced CO2 emissions dominates due to the long-lasting climate response of CO2. The net reduction in global temperature for the remaining part of this century is about 0.03±0.02°C, corresponding in magnitude to the cooling from avoiding one year of global CO2 emissions.

An economic evaluation of solar radiation management.

Economic evaluations of solar radiation management (SRM) usually assume that the temperature will be stabilized, with no economic impacts of climate change, but with possible side-effects. We know from experiments with climate models, however, that unlike emission control the spatial and temporal distributions of temperature, precipitation and wind conditions will change. Hence, SRM may have economic consequences under a stabilization of global mean temperature even if side-effects other than those related to the climatic responses are disregarded. This paper addresses the economic impacts of implementing two SRM technologies; stratospheric sulfur injection and marine cloud brightening. By the use of a computable general equilibrium model, we estimate the economic impacts of climatic responses based on the results from two earth system models, MPI-ESM and NorESM. We find that under a moderately increasing greenhouse-gas concentration path, RCP4.5, the economic benefits of implementing climate engineering are small, and may become negative. Global GDP increases in three of the four experiments and all experiments include regions where the benefits from climate engineering are negative.

Climate change impacts on crop yield: evidence from China.

When estimating climate change impact on crop yield, a typical assumption is constant elasticity of yield with respect to a climate variable even though the elasticity may be inconstant. After estimating both constant and inconstant elasticities with respect to temperature and precipitation based on provincial panel data in China 1980-2008, our results show that during that period, the temperature change contributes positively to total yield growth by 1.3% and 0.4% for wheat and rice, respectively, but negatively by 12% for maize. The impacts of precipitation change are marginal. We also compare our estimates with other studies and highlight the implications of the inconstant elasticities for crop yield, harvest and food security. We conclude that climate change impact on crop yield would not be an issue in China if positive impacts of other socio-economic factors continue in the future.