Figure 4: Covariance between ENSO variability and Tropical Pacific mean state.

ENSO variability is presented as: s.d. of Mg/Ca values of N. dutertrei (black diamonds), s.d. of δ18O values N. dutertrei (white squares) and estimated % change in ENSO variability (open circles). The zonal gradient is calculated as the difference in SST between the Western Equatorial Pacific and the Eastern Equatorial Pacific (see Methods). All regressed parameters show significant correlation with the zonal gradient and underline the mechanism that links ENSO variability with the Tropical Pacific mean state during the last glacial–interglacial climate change.