Diagnosis of CO2 dynamics and fluxes in global coastal oceans

Global coastal oceans as a whole represent an important carbon sink but, due to high spatial–temporal variability, a mechanistic conceptualization of the coastal carbon cycle is still under development, hindering the modelling and inclusion of coastal carbon in Earth System Models. Although temperature is considered an important control of sea surface pCO₂, we show that the latitudinal distribution of global coastal surface pCO₂ does not match that of temperature, and its inter-seasonal changes are substantially regulated by non-thermal factors such as water mass mixing and net primary production. These processes operate in both ocean-dominated and river-dominated margins, with carbon and nutrients sourced from the open ocean and land, respectively. These can be conceptualized by a semi-analytical framework that assesses the consumption of dissolved inorganic carbon relative to nutrients, to determine how a coastal system is a CO₂ source or sink. The framework also finds utility in accounting for additional nutrients in organic forms and testing hypotheses such as using Redfield stoichiometry, and is therefore an essential step toward comprehensively understanding and modelling the role of the coastal ocean in the global carbon cycle.     

The role of China's terrestrial carbon sequestration 2010–2060 in offsetting energy-related CO2 emissions

Energy consumption dominates annual CO₂ emissions in China. It is essential to significantly reduce CO₂ emissions from energy consumption to reach national carbon neutrality by 2060, while the role of terrestrial carbon sequestration in offsetting energy-related CO₂ emissions cannot be underestimated. Natural climate solutions (NCS), including improvements in terrestrial carbon sequestration, represent readily deployable options to offset anthropogenic greenhouse gas emissions. However, the extent to which China''s terrestrial carbon sequestration in the future, especially when target-oriented managements (TOMs) are implemented, can help to mitigate energy-related CO₂ emissions is far from certain. By synthesizing available findings and using several parameter-sparse empirical models that have been calibrated and/or fitted against contemporary measurements, we assessed China''s terrestrial carbon sequestration over 2010–2060 and its contribution to offsetting national energy-related CO₂ emissions. We show that terrestrial C sequestration in China will increase from 0.375 ± 0.056 (mean ± standard deviation) Pg C yr⁻¹ in the 2010s to 0.458 ± 0.100 Pg C yr⁻¹ under RCP2.6 and 0.493 ± 0.108 Pg C yr⁻¹ under the RCP4.5 scenario in the 2050s, when TOMs are implemented. The majority of carbon sequestration comes from forest, accounting for 67.8–71.4% of the total amount. China''s terrestrial ecosystems can offset 12.2–15.0% and 13.4–17.8% of energy-related peak CO₂ emissions in 2030 and 2060, respectively. The implementation of TOMs contributes 11.9% of the overall terrestrial carbon sequestration in the 2020s and 23.7% in the 2050s. The most likely strategy to maximize future NCS effectiveness is a full implementation of all applicable cost-effective NCS pathways in China. Our findings highlight the role of terrestrial carbon sequestration in offsetting energy-related CO₂ emissions and put forward future needs in the context of carbon neutrality.     

1995 年-2009 年东北地区工业部门CO2排放演变及影响因素分析

工业部门的节能减排对于我国实现2020年减排目标意义重大,需要结合不同区域工业化发展阶段有针对性地提出相应的节能减排措施。以东北老工业基地为例,利用工业CO2排放估算模型及指数分解模型,定量分析了1995年-2009年区域工业CO2排放演变特征及其影响因素,并提出了相应的减排对策。研究结果表明,研究期内东北地区工业CO2排放构成变动较小,排放总量整体呈上升态势,振兴战略实施以来增长尤为迅猛,区域工业CO2排放强度则快速降低。工业产出规模的快速扩张及行业结构的变动是导致区域工业CO2排放总量迅速上升的主要因素,前者的贡献更为显著,行业CO2排放强度的降低则对区域工业CO2排放量快速增长起到了抑制作用,但研究期内该因素的减排效应仍难以抵消由工业规模快速扩张以及行业结构变动导致的CO2排放量增长。未来减缓东北地区工业部门CO2排放应在保持工业产出规模持续增长的前提下,更加注重降低行业CO2排放强度及优化工业结构。     

中国CO2排放强度下降的结构分解——基于1997年-2007年的投入产出分析

本文以中国1997年和2007年的投入产出表为基础,核算了CO₂排放强度的变化。结果表明,中国1997年CO_排放总量为381788.56万t,强度为5.04t/万元。2007年CO₂排放总量为775346.15万t,强度为4.23t/万元。10年间,CO₂排放强度降低近20%。在此基础上进一步构建结构分解分析模型,将促使CO₂排放强度降低的因素分解为4种效应,即能源效率因素、能源结构因素、产业结构效应和经济增长方式效应。计量结果表明,部门单位产出能源消费强度变化和部门能源消费结构变化是造成CO₂排放强度下降的因素,其中以前者的影响最为显著。而产业结构变化和经济增长方式变化是促使CO₂排放强度上升的因素,并且前者的影响更为显著。因此,未来要实现2020年CO₂排放强度比2005年下降40%～45%的目标,必须调整产业结构,改变经济增长方式,以充分挖掘经济增长结构和方式转变的节能减排潜力。     

高耗能行业CO2排放强度对生产技术变化的敏感性分析

"十一五"时期我国六大高耗能行业单位增加值能耗累计下降超过20%,研究高耗能行业CO2排放强度的敏感因素对实现2020年节能减排目标意义重大。本文首先对投入-产出模型在研究碳排放或能耗问题中的应用进行了整体的概述,将基于投入-产出模型的敏感性分析与相关方法进行比较,明确其优越性。然后,以我国2007年投入-产出表为数据基础,建立26部门的对称投入产出表,通过敏感性分析研究了不同行业生产技术变化对高耗能行业CO2排放强度的影响深度,得出结论:电力、热力生产和供应业技术系数变化对整体高耗能行业排放强度影响最为显著;大多数高耗能行业排放强度对本行业生产技术变化最为敏感;一般而言,直接生产技术系数变化带来的影响大于间接生产技术系数;考虑系数的结构相关性影响后,各高耗能行业排放强度普遍对关键技术系数的变化更为敏感。