Carbon isotope sequences at Ocean Drilling Program Site 1143, South China Sea, reveal a long-term cyclicity of similar to500 kyr that is superimposed on the glacial cycles and is present in long delta(13)C sequences from all oceans. The Quaternary delta(13)C record is punctuated by four delta(13)C maximum events: delta(13)Cmax-I, which began in marine isotope stage (MIS) 3 around 50-60 kyr ago, delta(13)Cmax-II (MIS 13, 0.47-0.53 Ma), delta(13)Cmax-III (MIS 27-29, 0.97-1.04 Ma) and delta(13)Cmax-VI (MIS 53-57, 1.55-1.65 Ma). As the same cyclicity is also found in carbonate curves, the delta(13)Cmax events must denote major reorganization in the carbon reservoir of the global ocean. They also are associated with major changes in glacial cyclicity, such as the Mid-Brunhes Event following delta(13)Cmax-II and the Mid-Pleistocene Revolution following delta(13)Cmax-III, which in turn were associated with expansion of the ice sheets. From a carbon perspective, therefore, the Quaternary period has passed through three major stages, and each appears to represent a further step in ice cap development.