Abstract
This study evaluated global impacts of current climate and energy policies (CPs) in major economies and the Nationally Determined Contributions (NDCs) on global energy-related CO2 emission and energy systems by using a global energy systems model: DNE21+. CPs could contribute to reduction of global cumulated energyrelated CO2 emissions in 2011-2030 by 41 Gt-CO2 relative to baseline, and achieve about half of the target of that of NDCs. Expansion of renewables and improvement of energy efficiency in power and transportation sectors are mainly promoted in an NDC scenario in consideration of CPs. Compared with an optimized scenario which focuses only on CO2 emissions reduction, measures taken in power and transportation sectors for the NDC scenario seem excessive and increase measure costs of climate mitigation. Comprehensive measures, e.g., increase of gas-fired power plants including carbon capture and storage and nuclear power plants, improvement of energy efficiency in industry sector, and increase of gas use and electrification in residential and commercial sector are assessed to be cost-efficient. Although energy policies do not always aim at climate mitigation, coherent and inclusive policy design by considering cost-efficient global decarbonization and other national policy objectives in order to achieve sustainable development will become significantly important under the Paris Agreement.
