Numerous national and international science plans developed in the past few years have identified the uptake and storage of CO2 in all ocean basins and the biogeochemical responses to changes in environmental conditions (warming, acidification, circulation changes) as key issues that need to be addressed (e.g. Doney et al., 2004). The issues require quantification of major fluxes and stocks of carbon in the ocean, and a good understanding of the major physical, biological and chemical mechanisms driving biogeochemical cycling. The integration of biogeochemical observations into aspects of the CLIVAR Indian Ocean observational plan will be a major step towards addressing these research issues.