“During past ice ages the tropical Pacific Ocean behaved rather as it does to day in an El Niño event, bringing downpours to some places and drought to others.” Thus began a 2002 article Nature magazine (12 Jul 2002)
Studies by Stott and Kouvatas suggest that “shifts between warm and cool global average temperatures look, from the perspective of the tropical Pacific, like super El Niños. So too do the swings from shorter-term warming and cooling spells, called interstadials and stadials, that punctuated the last ice age.”
“It’s not clear whether these changes imply that the climate was persistently in an El Niño-like phase during ice ages, or whether such phases came and went every few years, as they do at present, but more frequently and more intensely,” says Lowel Stott of the University of Southern California.
It’s not global warming, it’s ocean warming, and it’s leading into the next ice age.
See “Ice ages looked like El Niño,” Nature, 12 Jul 2002