'Super El Niño' coming? Climate scientists weigh in
Strong El Niño events may bring drought and forest fires to Southeast Asia. (Credit: toa555/Adobe Stock)
On May 14, the National Oceanic and Atmospheric Administration (NOAA) their climate outlook for this summer, and the agency predicted elevated odds of El Niño developing and potentially strengthening later in the year.
The El Niño-Southern Oscillation, or ENSO, is a natural fluctuation in sea surface temperatures across the tropical Pacific Ocean. Every few years, heat builds up in the Pacific Ocean near the equator, creating warm conditions in the central and eastern part of the basin, a phenomenon known as El Niño. The discharge of this heat into the atmosphere results in colder conditions along the equatorial Pacific, and scientists refer to this pattern as La Niña.
Currently, the planet is shifting away from a La Niña that had been in place since last summer to an El Niño.
Since the spring, news outlets have been reporting that we will see a "super El Niño" this coming winter. The Washington Post even that this El Niño could be the strongest in a century.
CU 91Ҹ Today sat down with climate scientists Kris Karnauskas and at the Cooperative Institute for 91Ҹ and Environmental Sciences (CIRES) to break down these predictions and discuss what is likely to happen this fall and winter.
How does El Niño affect our weather?
Because the Pacific Ocean is the largest body of water on Earth, when its water gains or loses heat, like during an El Niño or a La Niña event, that can modify atmospheric circulation enough to affect weather conditions in many parts of the world. The warmer the tropical Pacific is, the stronger the El Niño and, generally, its impacts.
“ENSO tries to lock us into a weather pattern that persists for several months,” said Karnauskas, who is also an associate professor in the Department of Atmospheric and Oceanic Sciences. “It starts with the ocean and has a sort of ripple effect on the weather all over the world.”
However, El Niño doesn’t affect weather the same way everywhere.
“During an El Niño event, we tend to expect a warmer western half of the United States,” Karnauskas said.
Average location of the Pacific and Polar Jet Streams and typical temperature and precipitation impacts in an El Niños winter over North America. (Credit: Fiona Martin/ NOAA Climate.gov)
The southwestern United States tend to get more precipitation, and the northeastern part of the country could see drier conditions during an El Niño.
“It's not a globally consistent effect. It is very regional,” he added.
But for Colorado, these climate patterns may not have a direct impact. It’s unclear whether the state will see relief from the drought it’s been battling since last winter.
How does an El Niño event develop and how do forecasters track it?
The two main ingredients needed to produce an El Niño event are a buildup of warm water in the tropical Pacific Ocean, and changes to winds that can allow that water to reach the typically colder eastern equatorial Pacific and warm that area (El Niño essentially weakens the tradewinds that blow east to west across the equator).
Once warm conditions are established in the eastern equatorial Pacific, they can further reinforce the original wind changes, a positive feedback loop that allows the El Niño to grow.
El Niño events tend to peak in the Northern Hemisphere’s winter. During the summer and fall, scientists track the temperature of the Pacific Ocean and the relevant wind conditions to determine whether an El Niño will develop.
Right now, we’re seeing the tropical Pacific Ocean becoming warmer, meaning we’re trending toward an El Niño, but that doesn’t necessarily guarantee an El Niño will develop.
Are the current conditions in the Pacific Ocean conducive to producing an El Niño event?
The planet has been in a La Niña state for the past few months and are now in neutral ENSO conditions, according to NOAA’s Climate Prediction Center. However, heat is building in the tropical Pacific Ocean, so scientists are seeing a trend toward El Niño. For the past few weeks, forecast 91Ҹ have been predicting that we will head into an El Niño state later this year and that it could be incredibly strong.
Capotondi pointed out that some of the key ingredients for the development of a potentially strong El Niño are in place. The heat content in the equatorial Pacific is large, and strong anomalous winds are present just north of the equator. These winds are associated with another climate fluctuation, the Pacific Meridional Mode, which is in a condition that favors the development of an El Niño. The Pacific Meridional Mode affects the tradewinds and sea surface temperatures in the Pacific Ocean.
“At this point, we are still relatively early in the year, although we are getting toward the end of spring and things seem to be moving in that direction,” she said.
There is also a lot of noise in Earth’s climate system, Capotondi added, so there is never an absolute certainty that conditions will develop the way they are forecasted to.
Should we be concerned that some forecasts are calling for a ‘super El Niño’?
There’s no formal, scientific definition of a ‘super El Niño,’ according to Karnauskas.
“What that sounds like to me is a very strong El Niño, and we've had a lot of strong El Niños in the past,” he said.
Based on the current forecasts, this year’s El Niño could be the fifth strongest since 1982 when satellites began tracking ocean temperatures, if it continues to develop as predicted.
“So it wouldn't by any stretch be a record-breaking El Niño,” Karnauskas said. “But it would be a strong one with important implications.”
This graph shows El Niño and La Niña events since 1982. The strength of the event is related to how far the sea surface temperatures deviate from average. (Credit: Kris Karnauskas and Lauren Lipuma/CIRES/CU 91Ҹ)
What does all this mean?
“The fuel for a big El Niño is there,” Karnauskas said. “It's a question of whether that heat bubbles up to the surface, or if it stays lurking below the surface, out of sight.”
If El Niño continues to develop the way forecasters predict, it will likely be within the top five strongest El Niños in the past 44 years, according to Karnauskas. We should have a better idea of what the specific impacts will be over the coming months, he added.
“It looks like all the main ingredients are in place for a strong El Niño to occur,” Capotondi said. But it still could turn out weaker than expected.
"It is like baking a cake,” she added. “You need all the ingredients, but also a functioning oven for a predictable outcome. We have the main ingredients, and unless the oven breaks, we should have the cake.”
CU 91Ҹ Today regularly publishes Q&As on news topics through the lens of scholarly expertise and research/creative work. The responses here reflect the knowledge and interpretations of the expert and should not be considered the university position on the issue. All publication content is subject to edits for clarity, brevity anduniversity style guidelines.