This study analyzes the role of energy intensity improvement in the short term (to the year 2020) and midterm (to the year 2050) in the context of long-term greenhouse gases (GHG) stabilization scenarios. The data come from the latest Emissions Scenarios Database and were reviewed in the Fourth Assessment Report (AR4) by the Intergovernmental Panel on Climate Change. In this study, quantitative decomposition analyses using the extended Kaya identity are applied to the stabilization scenarios in Categories I to IV of Table SPM.5 in the AR4.