In respect to CO2 emissions, the post-Soviet states are a scientifically interesting object of research, as each of the countries has developed via different paths since reclaiming independence from the Soviet Union. Given that each country has a different approach to the use of fossil resources, it is essential to assess their input to global carbon footprint individually. Such assessment then allows to find certain actions in the development of legislation and to apply focused techniques to reduce carbon emissions. The aim of this study was to evaluate the fossil CO2 emissions produced in the Baltic States from 1991 onward, describing challenges relating to sustainability and socio-economic, scientific, and integrated approaches to sustainable development, including clean and efficient use of energy, and thus addressing climate challenges. This paper reports on data on CO2 emissions in the Baltic States. The results show that the transition of the Baltic States from the specificities of the Soviet Union’s economy to an economy integrated into global markets has led to a significant reduction in CO2 emissions. However, the development and implementation of national policies for sustainable development are still crucial for mitigation of the climate crisis. Further actions must include the implementation and monitoring of policies for sustainable development, changing of the consumption and production patterns, education and awareness of sustainability, and adaptation to global climate change, while also addressing sustainability challenges.