Observations of carbon in the subsurface ocean are critical for understanding the mechanisms responsible for oceanic CO2 uptake—the most important sink for fossil fuel CO2— and its sensitivity to climate change. Monitoring the ocean acidification and its possible impacts on ecosystems has recently arisen as an additional strong motivation for these efforts. National and regional research projects fund several important observational efforts, but for addressing what is really is a global problem, international coordination remains fundamental. Recognising this, the ocean carbon community has maintained a strong international collaboration, through IOCCP and GO-SHIP, and in the past WOCE-JGOFS and CLIVAR. Data synthesis has been an important end-product. Here we report on the ongoing international effort to synthesise ocean carbon data into one global product, GLODAPv2. This effort builds upon the previous and ongoing global and regional syntheses GLODAP, CARINA and PACIFICA that are largely complementary. We will unite these products into one global package. Additionally we will gather, quality control and append all data not currently part of any existing product. The end result will be a collection of data from approximately 700 cruises, from the early 1970s until the near present. These data will allow production of decadal distribution maps for the critical biogeochemical parameters. Ultimately, GLODAPv2 will evolve into an international routine data synthesis project, releasing global quality controlled datasets on a semi regular schedule.