The Chinese Carbon-Neutral Goal:Challenges and Prospects

On 22 September 2020,within the backdrop of the COVID-19 global pandemic,China announced its climate goal for peak carbon emissions before 2030 and to reach carbon neutrality before 2060.This carbon-neutral goal is generally considered to cover all anthropogenic greenhouse gases.The planning effort is now in full swing in China,but the pathway to decarbonization is unclear.The needed transition towards non-fossil fuel energy and its impact on China and the world may be more profound than its reform and development over the past 40 years,but the challenges are enormous.Analysis of four representative scenarios shows significant differences in achieving the carbon-neutral goal,particularly the contribution of non-fossil fuel energy sources.The high target values for nuclear,wind,and bioenergy have approached their corresponding resource limitations,with solar energy being the exception,suggesting solar’s critical role.We also found that the near-term policies that allow for a gradual transition,followed by more drastic changes after 2030,can eventually reach the carbon-neutral goal and lead to less of a reduction in cumulative emissions,thus inconsistent with the IPCC 1.5°C scenario.The challenges and prospects are discussed in the historical context of China’s socio-economic reform,globalization,international collaboration,and development.

Earth System Model FGOALS-s2: Coupling a Dynamic Global Vegetation and Terrestrial Carbon Model with the Physical Climate System Model

Earth System Models （ESMs） are fundamental tools for understanding climate-carbon feedback. An ESM version of the Flexible Global Ocean-Atmosphere-Land System model （FGOALS） was recently developed within the IPCC AR5 Coupled Model Intercomparison Project Phase 5 （CMIP5） modeling framework, and we describe the development of this model through the coupling of a dynamic global vegetation and terrestrial carbon model with FGOALS-s2. The performance of the coupled model is evaluated as follows. The simulated global total terrestrial gross primary production （GPP） is 124.4 PgC yr-I and net pri- mary production （NPP） is 50.9 PgC yr-1. The entire terrestrial carbon pools contain about 2009.9 PgC, comprising 628.2 PgC and 1381.6 PgC in vegetation and soil pools, respectively. Spatially, in the tropics, the seasonal cycle of NPP and net ecosystem production （NEP） exhibits a dipole mode across the equator due to migration of the monsoon rainbelt, while the seasonal cycle is not so significant in Leaf Area Index （LAI）. In the subtropics, especially in the East Asian monsoon region, the seasonal cycle is obvious due to changes in temperature and precipitation from boreal winter to summer. Vegetation productivity in the northern mid-high latitudes is too low, possibly due to low soil moisture there. On the interannual timescale, the terrestrial ecosystem shows a strong response to ENSO. The model- simulated Nifio3.4 index and total terrestrial NEP are both characterized by a broad spectral peak in the range of 2-7 years. Further analysis indicates their correlation coefficient reaches -0.7 when NEP lags the Nifio3.4 index for about 1-2 months.

Preface to the Special Issue on Carbon Neutrality: Important Roles of Renewable Energies, Carbon Sinks, NETs, and non-CO_(2) GHGs

The year 2020 witnessed milestone commitments to carbon neutrality with the EU,China,USA,Japan,South Korea,Canada,and South Africa,each pledging to reach net-zero carbon emissions.Countries that have adopted or have considered net-zero targets now represent 63%of the total contributions to global greenhouse gas(GHG)emissions.With the efforts of all parties,the 26th Conference of the Parties(COP26)achieved a package of outcomes in the Glasgow Climate Pact.Here,a breakthrough consensus was reached on reducing coal,controlling methane,and halting deforestation(Wang et al.,2022,Page 1209).To achieve net-zero carbon,we need to take action to implement the Paris Agreement and the Glasgow Climate Pact Since the global temperature slowdown of the nationally determined contributions(NDC)scenario is only 0.6°C,all countries need to pursue stricter carbon reduction policies for a more sustainable world.(Fu et al,2022,Page 1209).

Novel Cylinder Movement Modeling Method Based on Aerodynamics

The cylinder movement is affected by multiple factors and it is difficult to establish the accurate movement model of the cylinder. In order to improve the reliability of the production line design and to speed up the production line debugging, a novel cylinder movement modeling method based on aerodynamics is proposed. The kinetic theory, thermodynamic theory and kinematics knowledge are applied and integrated various factors which affect the movement characteristics of the cylinder are considered. According to the proposed mathematical model of cylinder movement, thecombined simulation software of cylinder movement based on Visual Studio and Visual Component （3D Create） is developed to calculate thevelocity, accel- eration and movement time of the cylinders during the running of the assembly line. Comparison results of cylinder＇s movement time under different intake air and displacement show that the mathematical model of cylinder movement based on aerodynamic is more accurate and the degree of fittingis 0.9846, which proves the effectiveness of the combined simulation software of cylinder movement. By the cylinder movement modeling method based on aerodynamic, accurate value of takt and the debug parameters can be calculated as a reference for the designers and debuggers of the cylinder-driven assembly lines.

Assimilating the LAI Data to the VEGAS Model Using the Local Ensemble Transform Kalman Filter: An Observing System Simulation Experiment

Information on the spatial and temporal patterns of surface carbon flux is crucial to understanding of source/sink mechanisms and projection of future atmospheric CO2 concentrations and climate. This study presents the construction and implementation of a terrestrial carbon cycle data assimilation system based on a dynamic vegetation and terrestrial carbon model Vegetation-Global-Atmosphere-Soil(VEGAS) with an advanced assimilation algorithm, the local ensemble transform Kalman filter(LETKF, hereafter LETKF-VEGAS). An observing system simulation experiment(OSSE) framework was designed to evaluate the reliability of this system, and numerical experiments conducted by the OSSE using leaf area index(LAI) observations suggest that the LETKF-VEGAS can improve the estimations of leaf carbon pool and LAI significantly, with reduced root mean square errors and increased correlation coefficients with true values, as compared to a control run without assimilation. Furthermore, the LETKF-VEGAS has the potential to provide more accurate estimations of the net primary productivity(NPP) and carbon flux to atmosphere(CFta).

Preface to Special Topic on Atmospheric Greenhouse Gas Measurement and Application in China

China initiated a national carbon trading market in December 2017.Commitments and actions to reduce greenhouse gas(GHG)emissions require consistent,reliable and timely information on GHG emissions.GHG monitoring and modeling studies provide GHG emission estimates to evaluate and guide progress towards emission reductions.GHG monitoring has mainly focused on global-scale background networks over the last few decades,while recent efforts have been made on regional and urban scales,such as projects in the Beijing-Tianjin-Hebei city cluster,in Paris,Washington-Baltimore.

2022年夏季长江流域破纪录的高温干旱事件导致了植被光合作用显著下降

2022年夏季,一场破纪录的高温干旱席卷了长江流域,造成了自2000年以来7~9月最严重的高温、水汽压差增强和土壤湿度减少,但此次事件对陆地生态系统及其碳通量的影响尚不清楚.利用最新的多源数据,本研究及时评估了其对植被绿度和光合作用的影响.结果表明,这一复合极端事件导致长江流域植被绿度和光合作用普遍减少,特别是重庆和湖南的植被NDVI、总初级生产力(GPP)和近红外反射率(NIRv)分别下降了5%~8%、12%和11%.整个长江流域平均NDVI下降了0.04(5.16%),总GPP下降了84.50 Tg C(7.46%)和NIRv下降了0.01(7.43%),是自2000年以来夏季最大的降幅.将长江流域区分为森林、灌木和农田3种主要植被类型,平均NDVI在农田地区下降最强,而光合作用在森林地区降幅最大.另外,研究发现除了农田NDVI的减少主要是高温胁迫引起,其他植被类型NDVI的减少和所有植被类型光合能力的下降主要是由增加的VPD导致.而随着全球变暖复合极端气候事件的强度和频率增加,其将潜在增加长江流域生态系统的脆弱性,并严重威胁其固碳能力.