The world's oceans are the largest sinks of carbon dioxide (CO₂) emitted by man’s activity taking up approximately 2 billion metric tons of CO₂ a year, or about 30% of the 6.6 billion tons emitted annually. The uptake of CO₂ by the ocean is not evenly distributed but varies by region, year and season. Indeed, there are large regions of the ocean, such as the equatorial Pacific, where C0₂ is released. Determination of regional sources and sinks of carbon dioxide in the ocean are of critical importance to international policy decision making, as well as for forecasting long term climate trends. The oceans are the largest sustained sink of anthropogenic carbon and changes in this sink will be determined by monitoring regional and seasonal patterns of carbon uptake and release. In order to quantify the amount of CO₂ taken up by the ocean on a yearly basis, we need to identify the varying sources and sinks. An important component of this effort is to obtain more systematic observations of pCO₂ (Figure 1) in the ocean by installing autonomous systems, underway pCO₂ analyzers, on volunteer observing ships Figure 2).

In this project NOAA investigators and academic partners are outfitting research and commercial vessels with automated carbon dioxide sampling equipment to analyze the carbon exchange between the ocean and atmosphere. This task is coordinated at national level with the U.S. Carbon Cycle Science Program and its subcommittee on Ocean Carbon and Climate change (OCCC). We work with the International Ocean Carbon Coordination Project (IOCCP) for international coordination exercises. The IOCCP is a joint endeavor of the SCOR/IOC CO₂ panel and the IGBP-IHDP-WCRP Global Carbon Project. Collaborative efforts are underway to combine datasets in the Atlantic through a Memorandum of Understanding with the European Union project Carbo-Oceans. Pacific collaboration is established through the PICES working group 13. In addition there are one-on-one interactions with investigators in Iceland, France, the United Kingdom, Australia, New Zealand, and Japan on reciprocal data exchange and logistics support.
 

Documenting carbon sources and sinks relies critically on other efforts undertaken under sponsorship of the Office of Climate Observations (OCO) including implementation of the ship lines, and moored and drifting buoys. The surface water pCO₂ programs support climate services by providing knowledge and quantification of climate forcing of the radiatively important gas, carbon dioxide. The near-term focus is on completion of the Northern Hemisphere ocean carbon observing system to provide data for quantifying carbon dioxide sources and sinks over the coterminous United States through inverse modeling in collaboration scientists involved in the atmospheric CO₂ observing system.

The project is a partnership of AOML, AOML/GOOS, PMEL, LDEO of Columbia University, RSMAS of the University of Miami, and the Bermuda Institute of Ocean Sciences (BIOS). The partners are responsible for operation of the pCO₂ systems on the ships, auxiliary measurements, data reduction and data management from all ships. The following ships have pCO₂ systems on them: NOAA ship Ronald H. Brown, NOAA ship Ka'imimoana, RVIB Palmer, cruise ship Explorer of the Seas, container ship Columbus Waikato, container ship Skogafoss, and container ship Oleander.

The pCO₂ systems are already installed on cruise ship Explorer of the Sea, Royal caribbean cruise lines and the M/V Skogafoss (Ports of call: Norfolk, Reykjavik, St Johns, Halifax, Boston, with round trip duration of approximately 3 weeks) and will soon be installed onboard the M/V Oleander (bi-weekly crossing, between Newark, NJ to Bermuda; Figure 3), and the M/V Sealand Express.