CORAL-REEFS - SOURCES OR SINKS OF ATMOSPHERIC CO2

Because the precipitation of calcium carbonate results in the sequestering of carbon, it frequently has been thought that coral reefs function as sinks of global atmospheric CO2. However, the precipitation of calcium carbonate is accompanied by a shift of pH that results in the release of CO2. This release of CO2 is less in buffered sea water than fresh water systems; nevertheless, coral reefs are sources, not sinks, of atmospheric carbon. Using estimated rates of coral reef carbonate production, we compute that coral reefs release 0.02 to 0.08 Gt C as CO2 annually. This is approximately 0.4% to 1.4% of the current anthropogenic CO2 production due to fossil fuel combustion.