Credit: concernusa.org
‘Global temperatures typically increase during an El Niño episode, and fall during La Niña’ – says BBC Science. This article also refers to ‘El Niño and La Niña, the warm and cool phases of a recurring climate pattern’. The featured research concludes that recent La Niñas are different, being more to do with warming, supported by ‘complex computer simulations’. The question is: does ‘the recent increase in multiyear La Niñas’ (per the study title) since 1998 suggest more cooling, or not? In the climate science world we read that ‘answers remain elusive’.
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Multiyear La Niña events have become more common over the last 100 years, according to a new study led by University of Hawai’i (UH) at Mānoa atmospheric scientist Bin Wang.
Five out of six La Niña events since 1998 have lasted more than one year, including an unprecedented triple-year event [Talkshop comment – no, occurred three times since 1950]. The study was published in Nature Climate Change.
“The clustering of multiyear La Niña events is phenomenal given that only ten such events have occurred since 1920,” said Wang, emeritus professor of atmospheric sciences in the UH Mānoa School of Ocean and Earth Science and Technology.
El Niño and La Niña, the warm and cool phases of a recurring climate pattern across the tropical Pacific, affect weather and ocean conditions, which can, in turn, influence the marine environment and fishing industry in Hawai’i and throughout the Pacific Ocean.
Long-lasting La Niñas could cause persistent climate extremes and devastating weather events, affecting community resilience, tourist industry and agriculture.
Determining why so many multiyear La Niña events have emerged recently and whether they will become more common has sparked worldwide discussion among climate scientists, yet answers remain elusive.
Wang and co-authors examined 20 La Niña events from 1920-2022 to investigate the fundamental reasons behind the historic change of the multiyear La Niña. Some long-lasting La Niñas occurred after a super El Niño, which the researchers expected due to the massive discharge of heat from the upper-ocean following an El Niño.
However, three recent multiyear La Niña episodes (2007–08, 2010–11, and 2020–22) did not follow this pattern.
They discovered these events are fueled by warming in the western Pacific Ocean and steep gradients in sea surface temperature from the western to central Pacific.
“Warming in the western Pacific triggers the rapid onset and persistence of these events,” said Wang. “Additionally, our study revealed that multiyear La Niña are distinguished from single-year La Niña by a conspicuous onset rate, which foretells its accumulative intensity and climate impacts.”
Results from complex computer simulations of climate support the observed link between multiyear La Niña events and western Pacific warming.
Full article here.
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Research article: Understanding the recent increase in multiyear La Niñas.
Tallbloke's Talkshop 
Last year’s long-range forecast…
MARCH 7, 2022
Increasing frequency of El Niño events expected by 2040
by University of Exeter
The study examined four possible scenarios for future carbon emissions, and found increased risk of El Niño events in all four.
This means El Niño events and associated climate extremes are now more likely “regardless of any significant mitigation actions” to reduce emissions, the researchers warn.
https://phys.org/news/2022-03-frequency-el-nio-events.html
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Assuming ENSO varies with carbon dioxide levels at 0.04% of the atmosphere 🤔
Let us not be mistake a cup of tea warming up with a cup of tea cooling down, and sending all its heat to sea surface. El nino goes from west to east, not upwards. Current sea surface “warming” is because the pacific is losing all the accumulated heat from last REAL 83, and 96-97 NINOS. CO2 has nothing to do with climate. http://www.giurfa.com/co2.pdf
It really is extremely bad science to make claims about clustering based on 100 years of data. We have no idea whether that’s a relevant or representative period of time. And since we have no idea what causes these things, us all just fluff and nonsense.
Study: The critical factors determining the frequency, duration and intensity change of multiyear La Niñas continue to be elusive.
. . .
Two types of multiyear La Niña involve different processes
. . .
First, we note that the onset of a multiyear La Niña features a substantially stronger cooling tendency than a single-year La Niña. [bold added]
https://www.nature.com/articles/s41558-023-01801-6#Sec3
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So more multiyear events means more cooling, or at least more than early 20thC.
Also:
One may wonder what distinguishes a double or triple La Niña. The results in Extended Data Fig. 8 indicate that double and triple La Niña events display a similar evolution during the first two years. However, the triple La Niña has a greater onset rate and exhibits stronger cooling in the central-eastern Pacific and stronger easterly anomalies over the WP [Western Pacific] towards the end of the second year, signifying the persistence into the third year. [bold added]
So the third year extends the cooling period. They theorise that ‘extreme El Niño and La Niña events may share a common origin in WP warming.’
Nevertheless, to what extent the relative WP warming is attributed to anthropogenic forcing requires in-depth investigation.
Indeed, go for it. ‘To what extent’ – if any?