The Sleeping Dragon slumbered while El Nino was in the Greenhouse

Exploring the robustness of ENSO to substantial changes in boundary conditions is critical for developing a deep understanding of the basic physics of tropical atmosphere-ocean interaction We discuss the impact of higher than modern greenhouse gas concentrations and different continental configurations on ENSO as produced in NCAR's fully coupled general circulation model, CSM, and show that ENSO is remarkably robust. In fact, our results indicate an increasing role of ENSO in interannual variability as a function of warming polar temperatures. The interaction of ENSO and the mean state of the thermocline is described and the importance of upwelling of relatively cool water into the eastern equatorial Pacific is emphasized for understanding the role of ocean heat transport in past and future climate. Results from a simple two column ENSO model with resolved atmospheric dynamics and radiation are used to elucidate results from the coupled GCM framework.