Background Information

Human activity is rapidly changing the composition of the earth's atmosphere, causing the greenhouse warming effect from excess carbon dioxide (CO₂) and other trace gas species such as chlorofluorocarbons, methane, and nitrous oxide. Combined, these gases play a critical role in controlling the earth's climate due to the increased trapping of outgoing infrared radiation. This mechanism has a large potential for significantly altering the world's climate.

Of all the anthropogenic CO₂ that has been released into the atmosphere, only about half still remains there; it is the "missing" CO₂ for which the global ocean is considered to be a dominant sink. Understanding the assimilation process is critical in determining the moderating role the oceans will play in delaying and damping the greenhouse warming predicted in the coming decades. Our goal is to help provide quantitative answers to the ways in which the oceans regulate and assimilate the excess CO₂, so that we can better predict the ocean's role in the natural climate cycle.

In response to these concerns, the Pacific Marine Environmental Laboratory (PMEL) conducted Cruise CGC-90 to the southwest Pacific onboard the research vessel (R/V) Malcolm Baldrige under the sponsorship of the Climate and Global Change Program(C&GC) of the National Oceanic and Atmospheric Administration (NOAA). Chemical and hydrographic data from 68 CTD stations were collected along the cruise track (Fig. 1). Several tracers were measured during the cruise, including chlorofluorocarbons, helium, tritium, total carbon dioxide (TCO₂), ¹³C, pH, nutrients, salinity and oxygen. The following data report summarizes the TCO₂, salinity, temperature, and nitrate data from 63 stations of this cruise.