Apparent Atlantic warming cycle likely an artefact of climate forcing, modellers claim

Posted: March 5, 2021 by oldbrew in climate, Cycles, modelling, Natural Variation, Ocean dynamics, opinion, research, volcanos

Atlantic Multidecadal Oscillation 1880 to Nov 2018 based on the ERSSTv3b dataset [image credit: Giorgiogp2, bender235 @ Wikipedia]

No prizes for guessing who is behind this one. Climate models ‘prove’ humans are the problem, not nature – heard it before?
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Volcanic eruptions, not natural variability, were the cause of an apparent “Atlantic Multidecadal Oscillation,” a purported cycle of warming thought to have occurred on a timescale of 40 to 60 years during the pre-industrial era, according to a team of climate scientists who looked at a large array of climate modeling experiments. reporting.

The result complements the team’s previous finding that what had looked like an “AMO” occurring during the period since industrialization is instead the result of a competition between steady human-caused warming from greenhouse gases and cooling from more time-variable industrial sulphur pollution.

“It is somewhat ironic, I suppose,” said Michael E. Mann, distinguished professor of atmospheric science and director, Earth System Science Center, Penn State. “Two decades ago, we brought the AMO into the conversation, arguing that there was a long-term natural, internal climate oscillation centered in the North Atlantic based on the limited observations and simulations that were available then, and coining the term ‘AMO.’ Many other scientists ran with the concept, but now we’ve come full circle. My co-authors and I have shown that the AMO is very likely an artefact of climate change driven by human forcing in the modern era and natural forcing in pre-industrial times.”

The researchers previously showed that the apparent AMO cycle in the modern era was an artifact of industrialization-driven climate change, specifically the competition between warming over the past century from carbon pollution and an offsetting cooling factor, industrial sulphur pollution, that was strongest from the 1950s through the passage of the Clean Air Acts in the 1970s and 1980s.

But they then asked, why do we still see it in pre-industrial records?

Their conclusion, reported today (Mar. 5) in Science, is that the early signal was caused by large volcanic eruptions in past centuries that caused initial cooling and a slow recovery, with an average spacing of just over half a century. The result resembles an irregular, roughly 60-year AMO-like oscillation.

“Some hurricane scientists have claimed that the increase in Atlantic hurricanes in recent decades is due to the uptick of an internal AMO cycle,” said Mann. “Our latest study appears to be the final nail in the coffin of that theory. What has in the past been attributed to an internal AMO oscillation is instead the result of external drivers, including human forcing during the industrial era and natural volcanic forcing during the pre-industrial era.”

Full article here.
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Research paper example:
Tracking the Atlantic Multidecadal Oscillation through the last 8,000 years (2011)
Quote: ‘Here, we show that distinct, ∼55- to 70-year oscillations characterized the North Atlantic ocean-atmosphere variability over the past 8,000 years.’

  1. ivan says:

    More Mann made global warming – just the thing one can expect when they start with the result and then try to find the problem.

  2. NeilC says:

    We certainly live in a dystopian world

  3. tallbloke says:

    Dr fraudpants at his finest.

  4. oldbrew says:

    Never mind the data, we’ve got climate models 🙄

    What would you like our models to prove today?

    Mann suggested that while some influential scientists continue to dismiss certain climate change trends as the result of a supposed internal AMO climate cycle, the best available scientific evidence does not support the existence of such a cycle.

    A model is ‘scientific’ evidence since when? Apart from actual data, it’s the ‘best available’ 🤣

  5. JB says:

    “Our latest study appears to be the final nail in the coffin of that theory.”
    There are coffins prepared for this one, and others to come too.

    “distinguished professor of atmospheric science and director, Earth System Science Center, Penn State.”

    Such a distinction; “we’ve come full circle” So now you’re back where you started, and what the Mann gang thought was science all along never was. By admission their original ideas were not working, and to resurrect them tossing in volcanic action seemed to make the model work.

    How could anyone go wrong with such distinguished analysis?

  6. Coeur de Lion says:

    Golly, what wonderful stuff is CO2! To shift the enormous volumes of water and heat energy in the AMO by using four molecules per ten thousand in the air above!! Don’t forget Mark Steyn’s ‘A Disgrace to the Profession’ which contains the opinions of a hundred world class scientists on Mikey Mann and which should have shut him up for ever if he had any pride.

  7. stpaulchuck says:

    I’ve given up on computer models and gone back to entrails of sheep. I get much better results.

  8. Phoenix44 says:

    Such utter garbage. How does he know what anthropogenic forcing was unless he knows what it was? He can’t because he cant prove what it is now – there’s no agreement about ECS or TCS or any other parameter, which is why the climate models all produce different results.

    So if we have a large range now for ECS how can it possibly produce a fit to the AMO cycle?

  9. Tom Williams says:

    This crazy reverse engineering is like the “epicycles” that were used to preserve the myth that Earth was the center of the Solar System. There is so much ego, vested interest, power, etc. invested in the Climate Change cult. I fear that intelligent discourse won’t reverse the pattern – rather a lot of humanitarian crises and suffering will force it.

  10. oldbrew says:

    We can’t model it, therefore it doesn’t exist 😆

    ‘Climate has no internal variability,’ Mann & Co. claim
    Date: 11/03/21 Dr David Whitehouse, GWPF Science Editor

    Judith Curry: “Relying on global climate models, which don’t adequately simulate the multi-decadal internal variability, to ‘prove’ that such multi-decadal internal variability doesn’t exist, is circular reasoning (at best). How does this stuff get published in a journal like Science? Peer review is sooooo broken.”
    . . .
    There is another way of looking at Mann’s findings. Roger Pielke Jnr remarked, “Maybe it’s just me, but it would seem that it should be much bigger news that 15,000+ peer-reviewed climate research papers published since 2000 are based on a non-existent phenomenon and are thus now discredited.“
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    El Nino/La Nina must be in line for the chop too?