New paper finds permanent El Niños did not occur when Earth was 3C warmer

During the Pliocene epoch, the Earth was about 3C warmer than today. Alarmists assume the Pliocene period predicts what climate conditions will be like in 100 years if global warming resumes, and assume that a "permanent El Nino" would occur without the normal oscillation back & forth to colder La Ninas. However, a paper published today in the journal Climate of the Past finds that the alarmist assumption that permanent El Ninos occurred in the Pliocene is "unrealistic."

Clim. Past, 7, 903-915, 2011
www.clim-past.net/7/903/2011/
Cold tongue/Warm pool and ENSO dynamics in the Pliocene

A. S. von der Heydt, A. Nnafie, and H. A. Dijkstra
Institute of Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands
Abstract. It has been suggested that a "permanent" El Niño climate state has existed in the warm Pliocene. One of the main pieces of evidence of such conditions is the small east-west sea surface temperature (SST) difference that is found in proxy temperature records of the equatorial Pacific. Using a coupled version of the Zebiak-Cane model of intermediate complexity for the tropical Pacific, we study the sensitivity of the time-mean Pacific background state and El Niño/Southern Oscillation (ENSO) variability to Pliocene climate changes. The parameters varied in this sensitivity study include changes in the trade wind strength due to a reduced equator-to-pole temperature gradient, higher global mean temperatures and an open Panama gateway. All these changes lead to a westward shift of the position of the cold tongue along the equator by up to 2000 km. This result is consistent with data from the PRISM3D Pliocene SST reconstruction. Our model further suggests that ENSO variability is present in the Pliocene climate with only slight changes as compared to today. A background climate that would resemble a "permanent" El Niño with weak to no east-west temperature difference along the equator is only found for very weak trade winds which seem unrealistic for the Pliocene climate.

Final Revised Paper (PDF, 4216 KB)   Discussion Paper (CPD)