El Niño causes extreme droughts, floods and forest fires in many parts of the world. However, scientists have shown that this is not a new phenomenon – it was already happening 250 million years ago.

Today, it is popular to link almost all types of noticeable weather and climate anomalies to human influence – and politicians and the media alike often claim that humans are to blame for natural disasters of various kinds.

The exact causes of weather-related phenomena are often difficult to pinpoint. However, even when the continents came together to form the supercontinent Pangea, there were various forms of “extreme weather”, and scientists have discovered that El Niño is much older than previously known.

The ocean phenomenon recurs along with the Southern Oscillation atmospheric phenomenon in the eastern Pacific between approximately every two to seven years. The two phenomena are linked by the common name ENSO (El Niño – Southern Oscillation) and usually last for 9 to 12 months.

The phenomenon affects the temperature, speed and strength of ocean currents and leads to extreme weather in the form of droughts, floods and forest fires, affecting millions of people in places like South America and Australia.

“Long before human history”

Until now, it has been unclear how far back in time the climate phenomenon extends. But in a new study published in the scientific journal Proceedings of the National Academy of Sciences (PNAS), an international team of researchers concluded that El Niño and the Southern Oscillation have a history of at least 250 million years.

– Through climate simulations, we found that ENSO has been a leading climate phenomenon long before human history. This was a major discovery for us, says Zhengyao Lu, a physical geography researcher at Lund University who participated in the study.

The research team used a global climate model and calculations of atmospheric and oceanic processes to map the history of ENSO over a period of ten million years. They also found that the weather phenomenon was significantly stronger in several earlier historical periods than today.

– A better understanding of ENSO’s history can give us new insights into how the phenomenon may change in the future. The results suggest that ENSO will continue to be the most significant source of annual climate variability globally, Lu explains.

Could lead to better forecasts

The new study is said to help scientists develop more realistic climate models in the future in terms of topography, greenhouse gas levels, solar radiation and bathymetry. Zhengyao Lu says the research will provide important information for future climate projections.

– Recent and future extreme El Niño events may be driven primarily by anthropogenic climate change. But on a timescale of 250 million years, natural variability and other factors have led to major changes. In any case, understanding how this climate phenomenon behaves in an increasingly warming world is of utmost importance, he concludes.