Ancient El Niños reveal limits to future climate projections

Posted: March 16, 2022 by oldbrew in data, ENSO, History, Natural Variation, predictions, research, Temperature, Uncertainty
Tags: ,


Unravelling the assumptions and the strange cause/effect logic suggested by the article is a challenge here. They say they’re looking for “clues on how sensitive El Niño is to changes in climate”, but “if there’s another big El Niño, it’s going to be very hard to attribute it to a warming climate or to El Niño’s own internal variations.”
Why invent such a conundrum at all?

– – –
The climate pattern El Niño varies over time to such a degree that scientists will have difficulty detecting signs that it is getting stronger with global warming, says Phys.org.

That’s the conclusion of a study led by scientists at The University of Texas at Austin that analyzed 9,000 years of Earth’s history.

The scientists drew on climate data contained within ancient corals and used one of the world’s most powerful supercomputers to conduct their research.

The study of the past, which was recently published in Science Advances, was motivated by the need to get a clearer picture of how climate change may affect El Niño in the future.

El Niño is the warm phase of the El Niño Southern Oscillation, a climate phenomenon that sets the stage every few years for weather patterns worldwide.

Strong El Niño events, such as the ones in 1997 and 2015 that brought wildfires to the rainforests of Borneo in Asia and caused widespread bleaching to the world’s coral reefs, happened about once a decade.

Computer models, however, are unclear about whether El Niño events will become weaker or stronger as the world warms due to climate change.

“Much of the world’s temperature and rainfall are influenced by what happens in the tropical Pacific Ocean where El Niño starts,” said the study’s lead author, Allison Lawman, who began the research as a Ph.D. project at the UT Jackson School of Geosciences and is now a postdoctoral researcher at the University of Colorado Boulder.

“The difference in rainfall between greater or fewer strong El Niño events is going to be a critical question for infrastructure and resource planners.”

Continued here.

Comments
  1. […] Ancient El Niños reveal limits to future climate projections […]

  2. Gamecock says:

    ‘The scientists drew on climate data contained within ancient corals’

    The phys.org article doesn’t tell us how they managed to accomplish that superhuman fete; teasing weather data from corals is an amazing superpower.

    ‘and used one of the world’s most powerful supercomputers to conduct their research’

    It’s the software that contains the intelligence; hardware has none. This assertion, along with stating Lawman’s credentials, is a transparent attempt to gen up credibility for the story.

  3. oldbrew says:

    scientists will have difficulty detecting signs that it is getting stronger with global warming

    How about signs that it isn’t getting stronger – or maybe weaker?

  4. JB says:

    “Computer models, however, are unclear…”

    Now if that isn’t the understatement of the century.

  5. oldbrew says:

    From the study (how it’s done):

    We synthesize published Holocene coral oxygen isotope (δ18O) records from the Northern Line Islands in the central equatorial Pacific that span the most recent 7000 years of the Holocene (26, 29, 33–36) (Kiritimati and Fanning Atolls; Fig. 1).
    . . .
    The oxygen isotopic composition of a coral’s carbonate skeleton is an established proxy that jointly reflects sea-surface temperature (SST) and the oxygen isotopic composition of seawater (37, 38), which is linearly related to sea-surface salinity (SSS) (39). On interannual (year-to-year) time scales, El Niño events bring warmer and wetter conditions to Kiritimati and Fanning, which collectively yield negative coral δ18O anomalies (33, 35, 40). Opposite effects occur during La Niña, in which cooler and drier conditions yield positive δ18O anomalies.

    https://www.science.org/doi/10.1126/sciadv.abm4313

    Also: However, similarly to the modern record, long negative tails are also found for two of the five nonoverlapping 30-year windows (Fig. 4E), which, along with the character of the PDFs, suggests that extreme El Niño events still occurred in the past. [bold added]

  6. gbaikie says:

    “The scientists drew on climate data contained within ancient corals and used one of the world’s most powerful supercomputers to conduct their research.”

    In this icehouse global climate, the tropics remain at near constant and uniform temperature.

  7. oldbrew says:

    The current La Niña is expected to decline soon according to BoM.

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