DURHAM, N.C. -- Long before humans walked the Earth, when dinosaurs roamed supercontinent Pangea and greenhouse gas levels soared far beyond today's measurements, a powerful climate pattern was already influencing global weather systems. New research reveals that El Niño, the periodic warming of the tropical Pacific Ocean that can trigger worldwide weather disruptions, has been actively shaping Earth's climate for at least 250 million years - and it was often more intense than what we experience today.

In a study published in the Proceedings of the National Academy of Sciences, an international team of researchers used sophisticated climate modeling to peer deep into Earth's past. They discovered that the El Niño-Southern Oscillation (ENSO) has remained Earth's dominant mode of year-to-year climate variability throughout this vast period. This finding challenges previous uncertainties about the longevity and stability of this crucial climate pattern and provides new insights into how it might behave in our warming world.

The study reveals that El Niño-Southern Oscillation strength varied significantly over time, with some periods showing oscillations twice as strong as those we observe today. Surprisingly, these variations weren't directly linked to global average temperatures or even to the temperature difference between the eastern and western Pacific - factors that scientists had previously thought might control ENSO's intensity.