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Assuming responsibility for emission reduction is an important part of participating in the global governance of climate change. Countries with a carbon neutrality target now cover about 75% of global greenhouse gas emissions. Carrying out fairness evaluations of their carbon neutrality targets provide a strong basis for the global carbon inventory. In this paper, the target years of carbon neutrality for major countries and regions under the global target of 2 °C and 1.5 °C are studied using the burden sharing model. On this basis, this paper simulates the possible pathways of carbon neutrality and evaluates the ambition of emission reduction targets in terms of annual emission reduction, per capita emission, and cumulative per capita emission. The results show that, from the perspective of equity, most of the developing countries cannot meet the global goal of 1.5 °C. The United States and the European Union nations could achieve carbon neutrality by 2050 by continuing their annual emission reductions under their existing NDC targets. However, to achieve carbon neutrality by 2060, China's annual emission reduction rate from 2030 to 2050 will be 6.7%, and the annual amount of emission reduction accounts for 51% of the global amount under the 1.5 °C target. Meanwhile, China would become the main force behind global cumulative emissions in the following decades. Thus, the emission reduction pathways China chooses will have an important impact on global climate mitigation progress. Based on the above research conclusions, this paper proposes that developed countries and developing countries should explore bilateral or multilateral cooperation in technology and finance in the field of climate change. Under the great pressure to achieve carbon neutrality, China needs to carry out research on the overall emission reduction pathways as soon as possible and clarify the paths at the scale of sectors, industries, provinces, and time stages. [ABSTRACT FROM AUTHOR]

Understanding the drivers of CO2 emissions changes is useful in supporting future mitigation. This study applies a log-mean divisia index decomposition to assess four drivers of CO2 emissions changes – population, income, energy intensity and carbon intensity – in 138 countries worldwide over the period 2000–2017. At the global level, income and population are the main drivers of increased emissions over time, with contributions of 116% and 60% to global CO2 emissions changes, respectively. Energy intensity is the key mitigation driver, with a contribution of −80%. Although carbon intensity increased CO2 emissions overall over the period 2000–2017 with a contribution of 4%, it has started to reduce emissions in recent years. China, the United States of America, the European Union, India and Russia are the five regions responsible for most changes in global emissions. The five regions together contribute −73% of the energy intensity effect, and China's income contribution is 83% in relation to the total of 116%. At the national level, in 2017, CO2 emissions returned to below 2000 levels in 62% of Annex I (developed) countries but increased in 88% of non-Annex I (mostly developing) countries. Among the 35 countries realizing CO2 emissions reductions, 24 were driven primarily by energy intensity, six by carbon intensity, three by economic recession, and one by population decrease. Among the 103 countries with increasing CO2 emissions, 63 were driven primarily by income, 26 by population, nine by carbon intensity increase, and five by energy intensity increase. Our analysis emphasizes the necessity of considering differences in national development stages when formulating climate change mitigation policies. Key policy insights Over the period 2000–2017, at the global and national levels, CO2 emissions increases were driven mainly by economic development and population growth, and mitigation was driven mainly by energy intensity improvement. Improving energy intensity and carbon intensity is the key to mitigating CO2 emissions. Carbon intensity is expected to play an increasing role in the future. In over one-third of Annex I countries, CO2 emissions increased from 2000 to 2017. To meet the Paris Agreement goals, Annex I countries will need to enhance mitigation ambition by further tapping the mitigation potentials of energy and carbon intensity. In accordance with national circumstances, development needs and international support, non-Annex I countries should achieve low-carbon economic and energy transitions and peak CO2 emissions as early as possible. [ABSTRACT FROM AUTHOR]

The Kyoto Protocol inspires the idea of establishing emissions trading scheme, regarding economic-effectiveness as a significant factor to achieve reduction targets and meet obligation. With this trend, marginal abatement cost curves (MACCs) have been used in climate policy analysis under general equilibrium framework, and have been proved a valid device to highlight the superiority of ETS. This paper focuses on the comparison of MACCs at industry level in China, derived by us from CGE, GCAM and TIMES respectively. It's clear that there is no dynamic adjustment process in these models, so we use linear interpolation method to introduce carbon tax to simulate actual situation. Meanwhile, we also take data from potential and cost study into account. To make our work more targeted, we pay close attention to energy-intensive industries with high carbon emissions level such as electricity, cement and steel, which are most likely to be covered in carbon market. The results indicate how MACCs change and illustrate why they change, depending on applied methodology and underlying assumptions. As we ignore the indirect effects, for instance, tax distortions and non-financial costs during above simulation, the emissions abatement cost we achieve by using integral calculus won’t be equivalent to real cost. Therefore, it's a wise decision for government department and research institute to be cautious when using MACCs as basis of policy making and academic studies. [ABSTRACT FROM AUTHOR]

Towards a low carbon world, the global emission space in the future will be very restricted, which will have a significant impact on the deployment of energy infrastructure system. A low carbon energy system will be the key to achieve 2 degrees trajectory. This paper addresses this issue by combining the Equitable Access to Sustainable Development model (EASD) and the Global Change Assessment model (GCAM) to analyze the development of regional energy consumption and power generation in the process of combating climate change. GCAM, a dynamic-recursive integrated model, has divided the world into 14 regions. Under the long term targets resulting in harmonized radiative forcing levels, the carbon constraints of all regions are quantified in EASD through the allocation based on the per capita, the convergence and the status-quo basis, respectively. These constraints are then set as the policy scenarios in GCAM simulations. The findings underline the substantial reductions in coal consumption and huge growth in renewable energy and nuclear in all regions. The fossil fuel consumption of developed regions has to plummet at once on the per capita basis and peak before 2020 on both the convergence and the status-quo basis. In developing regions, the nuclear and the coal/gas with carbon capture and storage (CCS) gradually dominate the power supply. CCS and nuclear are the two main technology choices for electricity generation in developed regions. [ABSTRACT FROM AUTHOR]