A possible paleoclimatic enso indicator in the spatial variation of annual tree-ring C-14

Preliminary investigations show regional differences in atmospheric C-14 activity archived in tree-ring cellulose may reflect oceanic and atmospheric shifts associated with ENSO (El Nino-Southern Oscillation) events. Much of the shared variation between sites in Washington and Arizona can be attributed to global forcings such as anthropogenic C-14-depleted CO2 emissions and modulation of C-14 production. The contrasted residual variation between the Washington and Arizona data sets correlates with the annual Southern Oscillation Index (SOI) of the previous year. The spatial differences between DELTAC-14 data sets may provide a proxy indicator of ENSO phenomenon.