Modelling Climate and Water Isotope Signatures of El Niño in the Pliocene

Abstract:

The isotope enabled version of the Hadley Centre model (HadCM3) has been used to investigate El Niño in the Pliocene. This model does not simulate a permanent Pliocene El Niño, but instead shows ENSO variability which is reasonably similar to the modern. However, the model suggests the structure of El Niño was different in the Pliocene with El Niño temperature anomalies shifted towards the central Pacific and more strongly related to the Pacific Decadal Oscillation. Here we will consider how this different structure would appear in oxygen isotopes measured in proxy data at locations throughout the Pacific. We will show that there could be different ways of interpreting proxy data from this time and will highlight regions where the model suggests the interpretation of the proxy data is more robust.