Histone demethylase required for G2/M phase cell cycle progression (By similarity). Specifically demethylates dimethylated 'Lys-36' (H3K36me2) of histone H3, an epigenetic repressive mark, thereby acting as a transcription activator (By similarity). May play a role in the regulation of the circadian clock (By similarity). 2 2-oxoglutarate + N(6),N(6)-dimethyl-L-lysyl(36)-[histone H3] + 2 O2 = 2 CO2 + 2 formaldehyde + L-lysyl(36)-[histone H3] + 2 succinate Binds 1 Fe(2+) ion per subunit.