China's pre-2020 CO2 emission reduction potential and its influence

China achieved the reduction of CO2 intensity of GDP by 45% compared with 2005 at the end of 2017, realizing the commitment at 2009 Copenhagen Conference on emissions reduction 3 years ahead of time. In future implementation of the "13th Five-Year Plan (FYP)," with the decline of economic growth rate, decrease of energy consumption elasticity and optimization of energy structure, the CO2 intensity of GDP will still have the potential for decreasing before 2020. By applying KAYA Formula decomposition, this paper makes the historical statistics of the GDP energy intensity decrease and CO2 intensity of energy consumption since 2005, and simulates the decrease of CO2 intensity of GDP in 2020 and its influences on achieving National Determined Contribution (NDC) target in 2030 with scenario analysis. The results show that China's CO2 intensity of GDP in 2020 is expected to fall by 52.9%-54.4% than the 2005 level, and will be 22.9%-25.4% lower than 2015. Therefore, it is likely to overfulfill the decrease of CO2 intensity of GDP by 18% proposed in the 13th FYP period. Furthermore, the emission reduction potentiality before 2020 will be conducive to the earlier realization of NDC objectives in 2030. China's CO2 intensity of GDP in 2030 will fall by over 70% than that in 2005, and CO2 emissions peak will appear before 2030 as early as possible. To accelerate the transition to a low-carbon economy, China needs to make better use of the carbon market, and guide the whole society with carbon price to reduce emissions effectively. At the same time, China should also study the synergy of policy package so as to achieve the target of emission reduction.