The findings indicate that ENSO persisted through dramatically different continental arrangements, including during the era of the supercontinent Pangea. "In each simulation, we observe an active El Niño-Southern Oscillation, frequently stronger than the current cycle," said Shineng Hu, assistant professor of climate dynamics at Duke University's Nicholas School of the Environment.

The team used a climate modeling tool employed by the Intergovernmental Panel on Climate Change (IPCC) for future projections but adapted it to simulate 26 distinct "slices" of 10-million-year periods from the past. These simulations considered factors such as ancient continental positions, solar radiation levels, and atmospheric CO₂ concentrations, highlighting ENSO's resilience and variability under different global conditions.

Two main factors were found to influence the strength of ancient El Niño events: ocean thermal structure and "atmospheric noise" from ocean surface winds. This underscores the importance of both oceanic and atmospheric factors in understanding climate oscillations.

The research has significant implications for current and future climate understanding. By showing ENSO's long-term persistence and variability, it offers context for interpreting modern climate change and refining future projections. "If we want more reliable future predictions, understanding past climates is essential," Hu emphasized, pointing to the study's potential for improving climate preparedness.