Fewer El Niño and La Niña events in a warmer world, says computer model

Posted: August 27, 2021 by oldbrew in atmosphere, climate, Cycles, data, ENSO, modelling, Ocean dynamics
Tags: ,
ENSO1

Credit: concernusa.org

A key premise of most computer models seems to be that the atmosphere, with its 0.04% CO2 content, drives ocean temperatures. As most of the energy is in the oceans, why wouldn’t it be the other way round?
– – –
The cycling between warm El Niño and cold La Niña conditions in the eastern Pacific (commonly referred to as the El Niño-Southern Oscillation, ENSO) has persisted without major interruptions for at least the last 11,000 years, says Phys.org.

This may change in the future according to a new study published in the journal Nature Climate Change by a team of scientists from the IBS Center for Climate Physics (ICCP) at Pusan National University in South Korea, the Max Planck Institute of Meteorology, Hamburg, Germany, and the University of Hawaiʻi at Mānoa, U.S.

The team conducted a series of global climate model simulations with an unprecedented spatial resolution of 10 km in the ocean and 25 km in the atmosphere.

Boosted by the power of one of South Korea’s fastest supercomputers (Aleph), the new ultra-high-resolution climate model simulations can now realistically simulate tropical cyclones in the atmosphere and tropical instability waves in the equatorial Pacific Ocean, which both play fundamental roles in the generation and termination of El Niño and La Niña events.

“Our supercomputer ran non-stop for over one year to complete a series of century-long simulations covering present-day climate and two different global warming levels. The model generated 2 quadrillion bytes of data; enough to fill up about 2,000 hard disks,” says Dr. Sun-Seon Lee who conducted the experiments.

Analyzing this enormous dataset, the team focused on a long-standing problem: how will ENSO change in response to increasing greenhouse gas concentrations.

“Two generations of climate scientists have looked at this issue using climate models of varying complexity. Some models simulated weaker; others predicted larger eastern Pacific temperature swings in a future warmer climate. The jury was still out,” says Prof. Axel Timmermann, co-corresponding author and Director of the ICCP.

He adds “What is common to these models is that their simulated temperatures in the equatorial Pacific, west of Galapagos, were always too cold compared to the observations. This prevented them from properly representing the delicate balance between positive and negative feedback processes that are important in the ENSO cycle.”

By capturing small-scale climatic processes at the highest computationally possible resolution, the ICCP team was able to alleviate these ocean temperature biases, leading to substantial improvements in the representations of ENSO and its response to Global Warming.

“The result from our computer simulations is clear: Increasing CO2 concentrations will weaken the intensity of the ENSO temperature cycle,” says Dr. Christian Wengel, first author of the study and former postdoctoral researcher at the ICCP, now at the Max Planck Institute of Meteorology in Hamburg in Germany.

By tracing the movement of heat in the coupled atmosphere/ocean system the scientists identified the main culprit of the collapse of the ENSO system: Future El Niño events will lose heat to the atmosphere more quickly due to the evaporation of water vapor, which has the tendency to cool the ocean.

In addition, the reduced future temperature difference between the eastern and western tropical Pacific will also inhibit the development of temperature extremes during the ENSO cycle. However, these two factors are partly offset by a projected future weakening of tropical instability waves.

Normally these oceanic waves, which can encompass up to 30% of the earth’s entire circumference, develop during La Niña conditions. They replace colder equatorial waters with warmer off-equatorial water, thereby accelerating the demise of a La Niña event.

The new , which resolve the detailed structure of these waves, demonstrate that the associated negative feedback for ENSO will weaken in the future.

Full article here.

Comments
  1. Gamecock says:

    Junk science writ large.

    ‘The model generated 2 quadrillion bytes of data’

    Reification fallacy. Model output is NOT data.

  2. pameladragon says:

    More models, just what is needed to finally put all debate about CAGW to rest….

  3. oldbrew says:

    ‘In addition, the reduced future temperature difference between the eastern and western tropical Pacific will also inhibit the development of temperature extremes during the ENSO cycle.’

    If the polar regions get warmer for whatever reasons, a reduced temperature difference with the equator is also likely to occur.
    – – –
    From the study abstract:
    ‘we show that a quadrupling of atmospheric CO2 causes a robust weakening of future simulated ENSO sea surface temperature variability.’

    That’s a lot of CO2 🙄

    A robust simulated future. Amusing.

  4. Paul Vaughan says:

    Recipe$ Sci11UN$ UNcertainly Mowin’ “DO!’ ln(163*67*43*19*11*7*3*2*1)

    With nothing bot parameter tweak$ another team easily find$ opposite result$.

    Why’$air davo$nos. well: nothing important or fundamental need be discovered as billions are spent (repeatedly) on modeling at (increasingly) “unprecedented” resolution.

    “Where the river is $swine din big nuggets$ there find in” — Johnny Horton

    Hi$story cooked for caste system, with false assumptions (“the free spice” of supercommputin’)

  5. Gamecock says:

    With 2 quadrillion bytes of data, and a buck-eighty-five, you can get a cup of coffee at Starbucks.

  6. Phoenix44 says:

    If I ran a computer model of the economy that had a resolution of every single person in the world, would that mean it was right?

    Or would I still have to get the assumptions about every person’s behaviour right?

    These clowns assume they understand fully every process and so just need bigger models. They never consider that their problem might be their assumptions.

  7. tom0mason says:

    On another virtualized planet the computer models perfectly shows how the climate operates. Fortunately on THIS real planet weather and climate operates differently …

  8. Coeur de Lion says:

    Was ENSO different during the MWP?

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