El Niño climate shifts date back 250 million years

Scientists looking at weather patterns from El Niños and La Ninas millions of years ago may help predict future weather shifts in a world suffering from global warming.

Research indicates the mass of unusually warm water on either side of the equator in the eastern Pacific Ocean known as El Niño has been around for at least 250 million years.

This revelation comes from a team of researchers at Duke University including Shineng Hu, assistant professor of climate dynamics at Duke’s Nicholas School of the Environment, who led a new modeling study.

How has El Niño evolved?

“The El Niño–Southern Oscillation (ENSO), originating in the central and eastern equatorial Pacific, is a defining mode of interannual climate variability with profound impact on global climate and ecosystems,” wrote the researchers.

“However, an understanding of how the ENSO might have evolved over geological timescales is still lacking, despite a well-accepted recognition that such an understanding has direct implications for constraining human-induced future ENSO changes.”

The study shows the massive temperature swings of El Niño and its sister effect, La Niña, took place when continent locations were different than today.

The temperature tango of El Niño

“In each experiment, we see active El Niño Southern Oscillation, and it’s almost all stronger than what we have now, some way stronger, some slightly stronger,” said Hu.

The findings are a boon for climate scientists studying El Niño. This system significantly alters the jet stream, leading to drier conditions in the northwest U.S. while simultaneously soaking the southwest with unusual rains.

Similarly, La Niña shifts the jet stream north, causing drought in the southwestern U.S., East Africa, and intensifying the monsoon season in South Asia.

Hu explained that atmospheric noise – the winds – can act just like a random kick to this pendulum, contributing to the strength of El Niño during earlier periods.

Insights from the past

To explore the ancient history of the El Niño weather phenomenon, the researchers used a climate modeling tool employed by the Intergovernmental Panel on Climate Change (IPCC) to project future climates. Instead of looking ahead, the scientists ran simulations to study the deep past.

“The model experiments were influenced by different boundary conditions, like different land-sea distribution, different solar radiation, different CO2,” said Hu.

The researchers identified two primary factors historically impacted the magnitude of these climate oscillations: the thermal structure of the ocean and atmospheric winds.

Hu noted that previous studies largely focused on ocean temperatures, overlooking the influence of surface winds.

“So part of the point of our study is that, besides ocean thermal structure, we need to pay attention to atmospheric noise as well and to understand how those winds are going to change,” Hu said.

The research highlights that understanding the Earth’s ancient climate patterns is crucial for accurate future projections. “If we want to have a more reliable future projection, we need to understand past climates first,” Hu said.

Ancient oceans and atmospheric dynamics

During the Mesozoic era, Earth’s continents were in different locations. The Panthalassic Ocean existed west of the supercontinent Pangea and experienced dramatic temperature oscillations.

Higher concentrations of atmospheric CO2 and lower solar radiation, factors that created a warmer global climate than today’s, largely influenced these oscillations.

Understanding these ancient oceans provides key insights into how current and future climate systems may behave.

With the planet facing rising CO2 levels, studying past oscillations offers clues to potential changes in the strength and frequency of El Niño events.

Implications for modern climate predictions

The findings from this study carry significant implications for how scientists approach modern climate predictions.

By understanding the intensity and persistence of ancient El Niño and La Niña events, researchers can refine their models to anticipate future climate variability. This is especially important as the current global climate faces increasing pressures from human-induced changes.

With the past revealing stronger and more frequent oscillations, similar conditions could happen under future climate scenarios.

Predicting how El Niño and La Niña evolve in a warming world requires scientists to consider not only ocean temperatures but also atmospheric dynamics and surface winds.

These elements are critical to determine the impact of future oscillations on global weather patterns from droughts and floods to other extreme weather events.

The study is published in the journal Proceedings of the National Academy of Sciences.

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