Abstract

The isotope enabled version of the Hadley Centre model (HadCM3) has been used to investigate El Niño in the mid-Pliocene Warm Period (~3.2Ma). This model does not simulate a permanent Pliocene El Niño, but instead shows ENSO variability which is reasonably similar to the modern. The model shows large centennial scale variability in ENSO , making it difficult to state whether the amplitude of El Niño was stronger or weaker in the Pliocene; however the simulation consistently shows a decrease in the frequency of El Niño in the Pliocene and a change in the structure with El Niño temperature anomalies shifted towards the central Pacific. 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.