The Republic of Korea was ranked 11th globally, in 2018, in terms of greenhouse gas emissions, of which the transportation sector contribution was estimated to be 14 % in 2017. Many policies have been drawn to enhance transport sustainability and reduce its emissions. According to the Climate Action Tracker (CAT), the policies and actions of South Korea to achieve the goal set in the Paris Agreement, are highly insufficient. Also, the environmental community in Korea has claimed the weakness of the 2017 emissions strategy. To increase policies’ efficiency an investigation of the drivers behind greenhouse gases needs to be considered. This paper is decomposing both overall greenhouse gases and transport sector greenhouse gases, to analyse the effect of economic growth, energy intensity, energy mix, technology, urbanization, R&D expenditure, and population. The LMDI results showed that GDP, R&D expenditure, and energy consumption have a strong effect on increasing carbon emissions. While population and urbanization factors have a weak effect for the analysis period 2003-2016, due to the stable urbanization and population rate within the period. The significant contribution of R&D expenditure in increasing GHG emissions showed an urgent need to revise the R&D investment to boost non-carbon transportation research. Additionally, the energy structure effect was not significant, as the reliance on fossil fuel is high despite the efforts to reduce it. This revealed that the adopted fuel policies need strengthening measures and continuous improvement. The study deduced the vital need to raise the use of renewable and non-carbon energy, to strengthen sustainable transportation policies and investments, with a focus on public transportation modes, and finally to establish a good environment for a vigorous system for the implementation and enhancement of active modes.