PMEL's Underway pCO₂ Measurement Program Background and Mission Statement

Human activity is rapidly changing the composition of the earth's atmosphere, contributing to its warming from excess carbon dioxide (CO₂) along with other trace gases such as water vapor, chlorofluorocarbons, methane and nitrous oxide. Carbon dioxide is one of the major anthropogenic greenhouse gases, contributing about 60% of the total change in radiative forcing due to human perturbations. The release of CO₂ from fossil fuel consumption or the burning of forests for farming or pasture contributes almost 7 pentagrams of carbon (1 Pg C = 1 x 10¹⁵ g C) to the atmosphere each year. Approximately 3 Pg C of this "anthropogenic CO₂" accumulates in the atmosphere annually, and the remaining 4 Pg C is stored in the terrestrial biosphere and the ocean. The ocean plays a critical role in the global carbon cycle as a vast reservoir that exchanges carbon rapidly with the atmosphere, and takes up a substantial portion of anthropogenically-released carbon from the atmosphere. A significant impetus for carbon cycle research over the past several decades has been to achieve a better understanding of the oceans's role as a sink for anthropogenic CO₂.

The observational efforts to detect the rate of changes in the uptake of CO₂ in the surface waters and to develop regional CO₂ flux maps are well documented and justified in the Ocean Carbon and Climate Change Implementation Strategy for U.S. Carbon Research (Doney et al., 2004). Under the support of NOAA's Office of Climate Observation, PMEL is collaborating with other NOAA investigators and academic partners to document ocean carbon sources and sinks by outfitting research ships and commercial vessels with automated carbon dioxide sampling equipment to analyze the carbon exchange between the ocean and atmosphere. This task is coordinated at the national level within 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.