The land use system in Russia changed considerably after 1990: 30.2 million ha of croplands were abandoned. Based on the own field investigations that were carried out in abandoned lands of different age (Luvic Phaeozems, deciduous forest zone; Moscow region, 54°50′N, 37°37′E), it has been shown that after 4–5 yr of abandonment, the former croplands acted as a stable sink of CO2. The net ecosystem production (NEP) in the post-agrogenic ecosystems averaged 245 ± 73 g C m−2 yr−1 for the first 15 yr after land use change that corresponds to an estimated 74 ± 22 Tg C yr−1 for the total area of abandoned lands in Russian Federation. Currently, the Russian territory acts as an absolute sink of atmospheric CO2 at a rate about 0.90 Pg C yr−1. Using three different approaches, it was demonstrated that after 1990, the carbon sequestration in Russian soils (0–20 cm layer) has averaged 34 ± 2.2 Tg C yr−1. This soil C forms net biome production (NBP) where carbon lifetime is much longer than in ‘Kyoto forests’. Thus, the post-agrogenic ecosystems in Russia provide with the additional CO2 sink in NEP and NBP that could annually compensate about 25% of the current fossil fuel emissions in the Russian Federation.