Ancient El Niño? Mysterious climate cycle blamed for millennia of chaotic weather.
A new study says the dance between El Niño and its cold counterpart, La Niña, was present on our planet at least 250 million years ago, and was often much stronger than the oscillations we see today.
Climate troublemakers El Niño and La Niña have been around for a long time. A really, really long time.
A new study says the dance between El Niño and its counterpart, La Niña, was present on our planet at least 250 million years ago and was often much stronger than the oscillations we see today.
Overall, the entire cycle is known as the El Niño-Southern Oscillation (ENSO), and it remains one of the most important climate patterns on Earth. It affects weather worldwide.
El Niño is a natural climate pattern in which surface sea water temperatures in the central and eastern tropical Pacific Ocean are warmer than average.
Whether the water temperatures in that region are warm (El Niño) or cold (La Niña), they can have confounding and cascading effects on the weather around the globe − fueling droughts, blizzards and hurricanes.
Scientists now expect the strong El Niño that started in 2023 to soon transition into a La Niña − but that hasn't happened yet.
A typical La Niña winter in the U.S. brings cold and snow to the Northwest and unusually dry conditions to most of the Southern states, according to the Climate Prediction Center. The Southeast and mid-Atlantic also tend to see higher-than-average temperatures in a La Niña winter.
El Niño explained
El Niño means the Little Boy, or Christ Child in Spanish. El Niño originally was recognized by fishermen off the coast of South America in the 1600s with the appearance of unusually warm water in the Pacific Ocean around Christmas.
The entire natural climate cycle swings between warmer and cooler seawater in a region along the equator in the tropical Pacific. La Niña is marked by cooler-than-average ocean water in the region.
Climate scientists study El Niño because it can alter the jet stream, drying out the U.S. Northwest while soaking the Southwest with unusual rains, according to a release from Duke University. Its counterpart, the cool blob La Niña, can push the jet stream north, drying out the southwestern U.S. while also causing drought in East Africa and intensifying the monsoon season in South Asia.
Why is this study important?
"Past climates inform our future," study lead author Xiang Li of Duke University explained in an e-mail to Paste BN. "Only by studying climate changes in the past can we understand the driving mechanisms for climate changes in the future and make reliable climate projections. ENSO is the most prominent mode of climate variability, and affects climate and extreme weather worldwide.
"Therefore, it’s of vital relevance and significance to study and understand the past changes of ENSO."
Studying the deep past
For the study, researchers used the same climate modeling tool used by the Intergovernmental Panel on Climate Change to try to project climate change into the future, except they ran it backward to see the deep past.
"In each experiment, we see (an) active El Niño Southern Oscillation, and it's almost all stronger than what we have now, some way stronger, some slightly stronger," said study co-author Shineng Hu, an assistant professor of climate dynamics at Duke University.
“At times in the past, the solar radiation reaching Earth was about 2% lower than it is today, but the planet-warming CO2 was much more abundant, making the atmosphere and oceans way warmer than present," Hu said.
In the Mezozoic period, 250 million years ago, South America was the middle part of the supercontinent Pangea, and the oscillation occurred in the Panthalassic Ocean to its west.
Was the result a surprise?
"To our knowledge, there were no other studies systematically investigating the geological history of ENSO, due to the lack of geological evidence in the deep past," Li told Paste BN. Using a state-of-the-art model, "our study uncovers the geological history of ENSO as far back as the past 250 million years. It is surprising and exciting to see the amplitude of ENSO varies greatly in the geological past."
Hu summed it up this way: "If we want to have a more reliable future projection, we need to understand past climates first."
The study was published Monday in the Proceedings of the National Academy of Sciences.
(This story has been updated to add new information.)