> If they were heating the oceans in a meaningful way compared to the sun, such a gradient would be apparent at tens and hundreds of kilometers. I think the El

> If they were heating the oceans in a meaningful way compared to the sun, such a gradient would be apparent at tens and hundreds of kilometers. I think the El Niño / La Niña oscillation is probably caused by cycles in underwater volcanic activity. Wikipedia says "Mechanisms that cause the oscillation remain under study."