Three-quarters of global greenhouse gas emissions come from burning fossil fuels for energy. To confront climate change, the world must move away from fossil fuels and decarbonise its energy systems. In the light of European Union documents, decarbonisation signifies the elimination of CO2 emissions on account of their harmfulness to the environment. The European Union is planning that by 2030, these emissions will be 40% lower in comparison to 1990. A fundamental query arises here: do the achievements of EU countries give cause for optimism in this regard? The aim of the study is an attempt to determine the tendency of changes concerning energy decarbonisation as well as to distinguish typological groups of bodies (EU countries) with similar dynamics in the researched phenomenon. Trend functions and the distance matrices of the growth rate of the researched phenomenon were used for the dynamic classification. The conducted research confirmed that EU countries indicate spatial differentiation in terms of CO2 emissions. It is related to the general socio-economic development of countries, their level of industrialisation, the quality of their natural environment, their degree of urbanisation, etc. The most favourable situation, in terms of the analysed phenomenon, i.e., the largest average decrease in CO2 per capita in the analysed period, was characteristic of Ireland, Greece, and Cyprus. On the other hand, an adverse situation relating to an increase in the indicator occurred in five EU countries, specifically in Luxembourg and Lithuania.