Key Message to Policymakers
• In order to achieve '2-degree' global target, China's CO2 emissions have to be at peak before 2025.
• China can peak CO2 before 2025 and reduce emission 70 % by 2050 compared with that in 2020.
• Setting a cap for CO2 emissions in China is an effective way to limit CO2 emission increases.
In December, 2009, the Copenhagen Accord declared that deep cuts in global emissions are required 'so as to hold the increase in global temperature below 2 degrees Celsius'. At the climate conference in Cancun 1 year later, parties decided 'to hold the increase in global average temperature below 2 oC above preindustrial levels' and made a decision for 'strengthening the long-term global goal on the basis of best available scientific knowledge including in relation to a global average temperature rise of 1.5 oC'. The Copenhagen Accord called for an assessment that would consider strengthening the long-term goal. Further, the IPCC AR5 called on research communities to work on assessments by modelling on the emission pathway and feasibilities for the global target.
Recently, several global emission scenario studies present emission scenarios focusing on the 2-degree target, which requires global emissions to peak by 2020 at the latest (IPCC 2014). However, the commitment in the Copenhagen Accord does not agree with the global 2-degree target scenarios, which implies that further efforts are needed by each country. It is thus essential to perform more analysis at the country level to assess the potential for CO2 emission mitigation to follow the global 2-degree target pathway. This paper presents the key factors China needs to consider in order for it to follow the global target, based on modelling results from the IPAC modelling team in Energy Research Institute (ERI).
GHG emissions from energy use in China surpassed those of the United States in around 2006 and accounted for around 29 % of global emission in 2013 (Olivier et al. 2013). And due to rapid economic development, CO2 emissions are expected to increase significantly in the coming decades (IEA 2011; Kejun et al. 2009). This presents China with a huge challenge to peak in CO2 emission before 2025 and start deep cuts after 2030. Much more effort is thus required, not only in China, but by the reset of the world.
In this study we used the linked Integrated Policy Assessment Model of China (IPAC) for the quantitative analysis, which covers both global emission scenario analysis and China's national emission scenario analysis. IPAC is an integrated model developed by ERI and analyses effects of global, national and regional energy and environment policies. ERI itself has conducted long-term research in developing and utilising energy models since 1992 (Kejun et al. 2009).
In order to analyse global emission scenarios and China's emission scenario, three models are used, one being global and the other two national: the IPACEmission global model, the IPAC-CGE model and the IPAC-AIM/technology model. The three models are linked as shown in Fig. 2.1. The modules in IPAC are currently soft linked, which means the output from one module is used as the input for another.
The IPAC-Emission model is a global model within the IPAC family and presently covers nine regions, to be extended to 22. Because this model focuses on energy and land use activities, in order to simulate other gases emissions, the model was revised to cover the analysis for HFC, PHC, SF6, CH4 and N2O.
The IPAC-Emission global model is an extended version of the AIM-Linkage model used in IPCC Special Report on Emission Scenarios (SRES) (Kejun et al. 2000), which links social and economic development, energy activities and land use activities and offers a full range of emission analyses. The IPAC-Emission global model comprises four main parts: (1) society, economy and energy activities module, which mainly analyses demand and supply under conditions of social and economic development and determines energy prices; (2) energy technology module, which analyses the shortand mid-term energy utilisation technologies under different conditions and determines the energy demand under different technology
Fig. 2.1 Links among models in the research
compositions. The energy demand in this module modifies the shortand mid-term energy demand in module (1) so that the energy analysis in the macroeconomic model can better reflect shortand mid-term energy activities; (3) land use module, which analyses emissions from land use processes; and (4) industrial process emission module, which mainly analyses emissions from industrial production.
IPAC-AIM/technology is the main component of the IPAC model (Kejun et al. 1998), and it performs analyses based on the cost-minimization principle, i.e. technologies with the least costs will be selected to provide the energy service. The current version of IPAC-AIM/technology model includes 42 sectors and their products and more than 600 technologies, including existing and potential technologies.
IPAC-SGM is a computable general equilibrium model (CGE model) for China.
It is mainly responsible for analysing the economic impacts of different energy and environmental policies and can analyse midand long-term energy and environment scenarios. IPAC-SGM divides the overall economic system into household, government, agriculture, energy and other production sectors, 42 in total.
The key focus of this study is how China can support the global 2-degree target based on its emission pathway, as well as related issues. In order to analyse the feasibility of the 2-degree target for China's emission pathway and related options, we start from the global modelling analysis performed on the target to learn how China's current emissions are affected by the 2-degree emission scenario. Then the options for the 2-degree target for China are analysed via the national model, based on the previous emission scenario analysis for China.
In the IPAC scenario setting for China, input is also needed from other relevant studies, such as GDP, population and sector outputs (Shantong 2011; Xueyi and Xiangxu 2007). The IPAC modelling team also performed studies on these parameters by using IPAC-SGM and the population model. Economic activity is becoming one of the key research topics within IPAC modelling studies due to the large uncertainty surrounding economic development and its heavy impact on energy demand. Sector development trends are crucial for energy and emission scenarios in the modelling studies, as around 50 % of total final energy use in China is accounted for by energy-intensive sectors such as ferrous and non-ferrous metal manufacture, building material manufacture and the chemical industry (China Energy Statistical Yearbook 2013 2013). In the meantime, demand for energy-intensive products was simulated by input-output analysis with a focus on downstream sector development analysis. Table 2.1 gives a scenario for energy-intensive product output in China used in the emission scenarios.
The national analysis on economic development could much more reflect national experts' viewpoints, which normally has quite big difference with the global projection on China's GDP growth. This could be seen in comparison between global modelling excises and China's national model analysis, such as IEA's World Energy Outlook (WEO) and IPAC model (IEA 2011; Kejun et al. 2009). And the sector study for output analysis could present much more sight inside economy structure change, to think about the contribution for lower energy demand and emission from economic structure change.