PROGRAM TITLE: Ocean-Atmosphere Carbon Fluxes (JGOFS) ACTIVITY STREAM: Process Research SCIENCE ELEMENT:
Biogeochemical Dynamics DEPARTMENT OF COMMERCE NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATIONDESCRIPTION: Since the Industrial Revolution, the concentrations of atmospheric CO2, a major greenhouse gas, have been increasing. The increase of CO2 in the atmosphere, largely due to fossil fuel combustion, is predicted to have profound consequences for our future climate. However, while various model-based scenarios of the Earth's response to this increase have been constructed, the validity of these models is highly sensitive to the uncertainties in quantitative global estimates of the sources and sinks of CO2 and the processes which regulate them. As articulated in the 1990 IPCC Scientific Assessment of Climate Change, oceanic uptake of atmospheric CO2 is estimated to be 2 gigatons (1015 grams) per year, 37% of the anthropogenic CO2 derived from fossil fuel combustion (5.4 gigatons per year). Unfortunately, the oceanic uptake term is highly uncertain, since it is based on the difference between measurements of CO2 accumulated in the atmosphere (3.4 gigatons per year) and historical records of fossil fuel combustion; that is, our uncertainty with regard to the fate of anthropogenic CO2 results from a lack of direct measurements of changes in the carbon content of the biosphere and the ocean. Producing reliable predictions of future climate scenarios requires a quantitative understanding of the ocean's response to the CO2 increases. The goal of the Ocean-Atmosphere Carbon Fluxes project is to provide a predictive understanding, through observations and modeling, of the role of the ocean in sequestering the increasing burden of atmospheric CO2. This program encompasses NOAA's primary contribution to the Joint Global Ocean Flux Study (JGOFS) of the of the International Geosphere Biosphere Program (IGBP). The principle thrusts of the Ocean-Atmosphere Carbon Fluxes project are: -- carbon system measurements on deep ocean survey cruises to better understand the variability of carbon storage between the surface and deep ocean on decadal timescales, -- time-series measurements of atmospheric CO2 and carbon-13 through NOAA's global cooperative flask sampling network, and -- oceanic and atmospheric general circulation modeling to examine uptake of CO2 by the ocean and terrestrial biosphere. STAKEHOLDERS: This project has strong linkages to JGOFS. It also supports the International Global Atmospheric Chemistry (IGAC) program of IGBP. The IGAC program includes global measurements and modeling of atmospheric CO2 and it's isotopic composition. Measurements made along meridional ocean sections and process study cruises supported by this project will be a useful "ground-truthing" component of the NASA SeaWIFS Ocean Color Satellite mission. The Ocean-Atmosphere Carbon Fluxes project also has strong ties to DOE's Carbon Dioxide Research Program, which supports CO2 measurements on WOCE cruises. Additionally, DOE is providing certified seawater reference materials to NOAA and other government/academic investigators to ensure analytical measurement quality control and performance monitoring of coulometers used to measure total CO2 in seawater samples collected on U.S. and international research vessels. SHORT-TERM POLICY PAYOFFS: The degree to which models can accurately predict future climate scenarios (e.g., greenhouse warming) is intimately coupled to the quality and quantity of environmental data. There are presently vast regions of the ocean for which carbon system data are lacking. This project will help provide carbon system measurements in these regions so that reliable predictions of future climate be made. PROGRAM CONTACT: James F. Todd, Office of Global Programs, 1100 Wayne Avenue, Suite 1225, Silver Spring, MD 20910 (301) 427-2089 X32.