Tracking Down a CO2 Source

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Science  14 Jan 2000:
Vol. 287, Issue 5451, pp. 193
DOI: 10.1126/science.287.5451.193c

The carbonate ion content of seawater influences many important properties of the atmosphere and ocean, such as the atmospheric concentration of CO2 and the preservation of calcium carbonate shells on the sea floor. Broecker et al. have compared the size distribution of calcium carbonate grains in marine sediments from a site on the Ontong Java Plateau in the western equatorial Pacific to similar measurements made in the Equatorial Atlantic to determine whether the world ocean experienced a decrease in carbonate ion concentration during the past 8000 years. Their results from both sites are consistent with a decline large enough to account for the ∼22 parts per million increase in the atmospheric concentration of CO2 that occurred over the same interval. In contrast, Indermühle et al. recently have suggested that this CO2 increase was due to a large decrease in terrestrial biomass.—HJS

Paleoceanography14, 744 (1999); Nature398, 121 (1999).

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