Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 6 1st Alexander von Humboldt International Conference 2006 10.5194/adgeo-6-103-2006 http://www.adv-geosci.net/6/103/2006/ http://www.adv-geosci.net/6/103/2006/adgeo-6-103-2006.html http://www.adv-geosci.net/6/103/2006/adgeo-6-103-2006.pdf 103 110 2006-01-09 Impact of global warming on ENSO phase change W. Cabos Narvaez F. Alvarez-Garcia M. J. OrtizBeviá Departamento de Física, Universidad de Alcala 28871 – Alcala de Henares, Madrid, Spain We compare the physical mechanisms involved in the generation and decay of ENSO events in a control (present day conditions) and Scenario (Is92a, IPCC 1996) simulations performed with the coupled ocean-atmosphere GCM ECHAM4-OPYC3. A clustering technique which objectively discriminates common features in the evolution of the Tropical Pacific Heat Content anomalies leading to the peak of ENSO events allows us to group into a few classes the ENSO events occurring in 240 years of data in the control and scenario runs. In both simulations, the composites of the groups show differences in the generation and development of ENSO. We present the changes in the statistics of the groups and explore the possible mechanisms involved.