Decadal timescale shift in the ^14C record of a central equatorial Pacific coral
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Date
2003
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University of Arizona
Abstract
Coral skeletal radiocarbon records reflect seawater Δ^14C and are useful for reconstructing the history of water
mass movement and ventilation in the tropical oceans. Here, we reconstructed the inter-annual variability in central equatorial
Pacific surface water Δ^14C from 1922–1956 using near-monthly 14C measurements in a Porites sp. coral skeleton (FI5A) from
the windward side of Fanning Island (3°54'32"N, 159°18'88"W). The most pronounced feature in this record is a large, positive
shift in the Δ^14C between 1947 and 1956 that coincides with the switch of the Pacific Decadal Oscillation (PDO) from
a positive to a negative phase in the mid-1940s. Although the absolute Δ^14C values from 1950–1955 in FI5A differ from the
Δ^14C values of another coral core collected from the opposite side of the island, both records show a large, positive shift in
their Δ^14C records at that time. The relative increase in the Δ^14C of each record is consistent with the premise that a common
mechanism is controlling the Δ^14C records within each coral record. Overall, the Fanning Δ^14C data support the notion that a
significant amount of subtropical seawater is arriving at the Equator, but does not allow us to determine the mechanism for
its transport.
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Citation
A. G. Grottoli et al, "Decadal timescale shift in the ^14C record of a central equatorial Pacific coral," Radiocarbon 45 (2003): 91-99.