New Clues from the Past Point to More Extreme El Niño Ahead. Scientists are gaining new insights into how El Niño and La Niña events have behaved in the past—and what that means for our future. Evidence from ancient climate records and new climate models suggests that climate change mainly affect how often extreme El Niño occur. These powerful events are more likely when the tropical Pacific is in a warm state, and less likely during cooler conditions. Less extreme El Niño was seen during past climate shifts with cooler climate conditions, like the last Ice Age and perhaps when the Sahara was green. In the future, the pattern of warming could raise the risk of more frequent extreme El Niño contributing to more disruptive weather worldwide.