Heat, Storm, Drought, Fire - Prolonged Climate Extremes as Cool La Niña Pacific Pattern Persists
As the tropical Pacific stays stuck in a cool phase, dangerous patterns persist worldwide
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Average Pacific sea-surface temperature departures (degrees Celsius) from the long-term average for the week centered on June 1, 2022 (NOAA)
UPDATE 6/24 - Australian media and a news article in Nature that I'd missed are reinforcing the likelihood of a rare three-winter La Niña. The Nature piece expands to include a discussion of a June 6 paper by Matt England and others on how a "collapse" (remember the various meanings of this word!) of Atlantic circulation driven by global warming could make such conditions more likely.
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The Pacific Ocean covers a third of the planet's surface, so it's no surprise that when its vast expanse along the Equator gets stuck in either a warm El Niño or cool La Niña phase, that has globe-spanning consequences. I wrote about these cycles frequently back at The New York Times.
Since September 2020, the Pacific has been in La Niña mode, with recent impacts ranging from intensified droughts parching the Horn of Africa, the American Southwest and southern South America to the extreme floods swamping Queensland, Australia, to reinforced forecasts of a very active Atlantic hurricane season and weaker Pacific season. The early-season deadly heat wave in India, fueled by human-driven global warming, was also likely spurred by the La Niña influence on global atmospheric circulation patterns.
The World Meteorological Organization just announced that the current La Niña cycle could persist into 2023, making it only the third "triple-dip" oceanic cool spell (three consecutive years Northern Hemisphere winters of La Niña conditions) since 1950. The organization issued maps of heat and rainfall forecasts through August that show just how dramatic that cool patch is:
Probabilistic forecasts of surface air temperature and precipitation for the season June-August 2022 (WMO)
The U.S. National Oceanic and Atmospheric Administration generally concurs, as does the research group at Columbia University that issues regular forecasts of this consequential climatic phenomenon, which is called the El Niño–Southern Oscillation, or ENSO for short.
Is any clarity emerging on how global heating will affect this phenomenon? Despite enormous increases in oceanic and atmospheric observation and analytical capacity, this remains a tough puzzle.
Seth Borenstein of the Associated Press wrote a fascinating article last month examining the warm-cool Pacific cycles since 1950, noting the odds seem to be tipping, in Northern Hemisphere winter, toward the La Niña phase:
An Associated Press statistical analysis of winter La Niñas show that they used to happen about 28% of the time from 1950 to 1999, but in the past 25 winters, they’ve been brewing nearly half the time. There’s a small chance that this effect could be random, but if the La Nina sticks around this winter, as forecast, that would push the trend over the statistically significant line.
He wrote, "What’s bothering many scientists is that their go-to climate simulation models that tend to get conditions right over the rest of the globe predict more El Ninos, not La Ninas."
I reached out to some longtime contacts to gauge what's going on. Richard Seager of Columbia's Lamont-Doherty Earth Observatory led a recent in-depth study of "persistent cold states" in the tropical Pacific and told me their analysis supports the idea that global warming could be tipping the balance toward La Niña. But he acknowledged other climate modeling work points in the opposite direction.
In an email exchange including Seager and others, Michelle L’Heureux, a meteorologist working on the ENSO cycle at NOAA's National Climate Prediction Center, offered helpful guidance:
"[I]t's very clear that the 40+ year trend is toward a La Niña-like state. To be clear (and this is important to emphasize), 'La Niña like' means that the *average state* of sea surface temperature, winds, convection across the tropical Pacific increasingly *resembles* La Niña, but a trend toward more La Niña-like averages doesn't mean a perpetual La Niña in month-to-month or season-to-season variability....
"It would be very difficult to connect this current event, albeit fairly unusual (especially as it did not occur after a major El Niño, as the other two did), to climate change. With that said, I was exchanging some emails with Seth Borenstein (AP) and he prompted me to start looking statistical significance of the recent frequency of La Niña and it stands out to me, especially when compared to the earlier part of the historical record (I had my colleague Mike Tippett examine the statistics as well so I think it's something).
"So while this is not peer reviewed anywhere, I do think there is an increased frequency of *La Niña events* when you compare the last few decades with the decades prior. That's worth continuing to monitor going forward... With that said, I don't think you can rule out natural, decadal variability as a cause of the more La Niña-like conditions at this point. But it's all starting to get a little suspicious!"
[Side-note: I love seeing the inquiries of as great journalist like Borenstein stimulating new research pathways!]
The bottom line, of course, is to work hard to turn the short-range forecasts for these events into responses on the ground where the need for resilience is greatest.
That's why I was heartened to see the World Meteorological Organization news release emphasize the organization's pledge to improve the utility of seasonal forecasts and to make sure weather warnings can reach everyone on Earth in the next five years.
Here's my related recent post:
U.N. Pushes to Cut Worldwide Vulnerability to Climate Extremes Through Better Early Warnings
For much more, I encourage you to explore an informative post on the current conditions and forecasts on the National Oceanic and Atmospheric Administration's ENSO blog by Emily Becker.
Also see Stu Waterman's valuable post at the Climate Adaptation Center website - La Nina and North America’s Weather.
I hope you subscribe to the Axios Generate newsletter, which is a great way to keep track of developments on a host of themes relevant to our Sustain What journey through the tireless reporting and writing of Ben Geman and Andrew Freedman.
The Friday newsletter includes links to stories Freedman filed this week on new science revealing a super drought in the Colorado River basin region 1,800 years ago that was far worse than what's under way at the moment and another on the latest heat storm brewing in the west.
Such work, called paleoclimatology, provides vital context in a media environment where words like "unprecedented" and "extreme" are tossed around. I even proposed #hugapaleoclimatologist as a clunky hashtag.
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