 The decrease in the mean wind power in the tropical Pacific over the last 00 years has resulted in a reduction of the ocean available potential energy, which indicates a reduction in the thermocline tilt over the same time interval (Fig. 0). This flattening of the thermocline occurred around the time of the climate regime-shift in the late 0000s (Guilderson and Schrag, 0000) and is associated with a weakening of the zonal winds along the equator (Vecchi et al., 0000). A flatter thermocline can lead to stronger El Nin˜o events (Fedorov and Philander, 0000, 0000).  Federov 0000  On interannual time scales, the perturbation available potential energy E is anticorrelated with sea surface temperatures in the eastern tropical Pacific so that negative values of E correspond to El Niño conditions, and positive values correspond to La Niña conditions (Fig. 0). This correlation is related to changes in the slope of the thermocline associated with El Niño and La Niña. When the thermocline slope increases (as during La Niña; Fig. 0a), the warmer and lighter water is replaced by colder and hence heavier water thus raising the center of mass of the system and increasing its gravitational potential energy..  As the GPE increases