Earth’s Magnetic Field Reversal 42,000 Years Ago Triggered a Global Environmental Crisis

Earth Core Magnetic Field

Nearly 42,000 years ago, when Earth’s magnetic fields reversed, this triggered major environmental changes, extinction events, and long-term changes in human behavior, a new study reports.

The findings, made possible by a new radiocarbon record derived from New Zealand’s ancient kauri trees, raise important questions about the evolutionary impacts of geomagnetic reversals and excursions throughout the deeper geological record, the authors say.

“Before this work,” says author Chris Turney in a related video, “we knew there were a lot of things happening around the world at 42,000 years ago, but we didn’t know precisely how… For the first time, we’ve been able to precisely date what happened when Earth’s magnetic fields last flipped.”

Written in the geological record are numerous instances where the planet’s magnetic poles flipped. Today, such an event would almost certainly wreak havoc with modern electronic and satellite technologies. However, the potential environmental impacts of such events are virtually unknown.

The most recent major magnetic inversion, the Laschamps excursion, a relatively short-lived geomagnetic event that occurred ~41,000 years ago, provides one of the best opportunities to study the potential impacts of extreme changes to Earth’s magnetic field. However, despite compelling evidence from several paleoenvironmental records that suggest it coincided with significant environmental and ecological changes, the ability to precisely characterize this event and determine its role — if any — in contemporaneous global changes has been limited by an uncertain radiocarbon calibration for the period.

In this study, Turney, Alan Cooper, and colleagues present a new, precisely dated atmospheric radiocarbon record derived from the tree rings of ancient kauri trees preserved for millennia in New Zealand wetlands. Like a missing keystone, this new record allowed the authors to better align other global radiocarbon and ice core records with the Laschamps.

Cooper et al. identified a significant increase in atmospheric radiocarbon during the period of weakening magnetic field strength that preceded polarity reversal. By modeling the consequences of this increase, they found that the geomagnetic field minimum, when Earth’s magnetic field was estimated to be only ~6% of current levels, triggered substantial changes in atmospheric ozone concentration and circulation.

These shifts may have caused synchronous global climate and environmental changes observed in other climate records that occurred ~42,000 years ago. The discovery that geomagnetic field fluctuations can affect atmospheric temperature and circulation on a global scale provides a model for understanding anomalous and sudden paleoenvironmental shifts, the authors say.

Reference: “A global environmental crisis 42,000 years ago” by Alan Cooper, Chris S. M. Turney, Jonathan Palmer, Alan Hogg, Matt McGlone, Janet Wilmshurst, Andrew M. Lorrey, Timothy J. Heaton, James M. Russell, Ken McCracken, Julien G. Anet, Eugene Rozanov, Marina Friedel, Ivo Suter, Thomas Peter, Raimund Muscheler, Florian Adolphi, Anthony Dosseto, J. Tyler Faith, Pavla Fenwick, Christopher J. Fogwill, Konrad Hughen, Mathew Lipson, Jiabo Liu, Norbert Nowaczyk, Eleanor Rainsley, Christopher Bronk Ramsey, Paolo Sebastianelli, Yassine Souilmi, Janelle Stevenson, Zoë Thomas, Raymond Tobler and Roland Zech, 19 February 2021, Science.
DOI: 10.1126/science.abb8677


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  • I've been checking SciTechDaily almost everyday since I first discovered it 20 years ago. Can't believe how often I have a Wow! reaction to something I read there, or forward to friends.
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  • Something I've been espousing for many years; generators turn into motors and vice versa; talk about an impact to our environment! No more cloud storage, at the least.

    I also don’t recall seeing this sort of "event" even being included in any of the “climate crisis models”, you know, the ones touting the evils human population, the existence of CO2 & the need for wind and solar.

    Remember, Mother Nature stores solar energy in the form of fossil fuels… just saying.

    Great article; real science vs. political science.

    • No one touts "evil" human population, but everyone touts the fact that CO2 exist in the atmosphere and that it has been the major greenhouse gas in the observed man made global warming.

      The reason you haven't seen this before is because it is a new claim, an extraordinary one to boot and seems not accepted by climate scientists, see my comment on the article.

    • We know more about these things, at the same time society is more invested in electric power and internet technology both.

      And yes, the north geomagnetic pol has seen a rapid movement in the last few decades, which is fodder for speculation:

      "Earth’s magnetic field is acting up and geologists don’t know why
      Erratic motion of north magnetic pole forces experts to update model that aids global navigation." [Nature 09 JANUARY 2019]

      "Update, 9 January: The release of the World Magnetic Model has been postponed to 30 January due to the ongoing US government shutdown.

      Something strange is going on at the top of the world. Earth’s north magnetic pole has been skittering away from Canada and towards Siberia, driven by liquid iron sloshing within the planet’s core. The magnetic pole is moving so quickly that it has forced the world’s geomagnetism experts into a rare move.

      On 15 January, they are set to update the World Magnetic Model, which describes the planet’s magnetic field and underlies all modern navigation, from the systems that steer ships at sea to Google Maps on smartphones.

      The most recent version of the model came out in 2015 and was supposed to last until 2020 — but the magnetic field is changing so rapidly that researchers have to fix the model now."

      "In the meantime, scientists are working to understand why the magnetic field is changing so dramatically. Geomagnetic pulses, like the one that happened in 2016, might be traced back to ‘hydromagnetic’ waves arising from deep in the core1. And the fast motion of the north magnetic pole could be linked to a high-speed jet of liquid iron beneath Canada2."

    • As opposed to - what? Follow the populists, who costly and dangerously do not care for facts of nature!?

  • "However, despite compelling evidence from several paleoenvironmental records that suggest it coincided with significant environmental and ecological changes, the ability to precisely characterize this event and determine its role — if any — in contemporaneous global changes has been limited by an uncertain radiocarbon calibration for the period."
    The new process definitively links ecological upheavals in the fossil record to the precise time of the magnetic reversal. Radiocarbon dating alone could not verify the correlation.
    The original sentence as quoted needs an intervention. She is NOT okay.

    • That's not why they are looking, it has astrobiological interest. (And we don't know that interstellar travel is possible.)

  • A song I heard recently:

    The whole world sitting on a ticking bomb
    The whole world sitting on a ticking bomb
    So keep your calm and carry on
    The whole world sitting on a ticking bomb
    The sun may never rise again
    The question ain't if but when
    The sea will mourn, the sky will fall
    The sun may never rise again
    The silent war has begun
    We're staring down loaded gun
    No refuge found no solid ground
    Assuming race can't be won
    Don't wait to say goodbye, you're running out of time
    Whatever you believe, it's easy to see
    The whole world sitting on a ticking bomb
    The whole world sitting on a ticking bomb
    So keep your calm and carry on
    The whole world sitting on a ticking bomb
    And it's about to explode
    The whole world, the whole world
    The whole world, the whole world

    • ? That's politics. (And if everyone tells you something, don't you think they may know something you don't?)

      Fauci is not involved in that politics, he is leading the pandemic effort.

  • The paper is paywalled, but it is of course an extraordinary series of claims which seems based on little to no evidence. The companion article in Science has scientists agree.

    "The study not only nails in fine detail the timing and magnitude of the magnetic swap, the most recent in Earth’s history, but is also among the first to make a credible, though speculative, case that these flips can affect the global climate, says Quentin Simon, a paleomagnetist at the European Center for Research and Teaching in Environmental Geoscience in Aix-en-Provence, France. But some paleoclimate scientists are skeptical of the team’s broader claims, saying other records show few traces of climate upheaval."

    "This is where other scientists say the study gets too speculative. Ice cores from Greenland and Antarctica that span the past 100,000 years capture stark temperature swings every few thousand years. But they show no shifts 42,000 years ago. A few Pacific Ocean records do show swings. But even if the shift occurred mostly in the tropics, as Cooper and colleagues suggest, it should be seen in the ice, says Anders Svensson, a glaciologist at the University of Copenhagen. “We just don’t see that.”

    The study team goes further to argue that a climate shift could account for a spate of curious events 42,000 years ago. Most notably, large mammals in Australia went extinct around that time. Neanderthals vanished from Europe, and elaborate cave paintings began to appear in Europe and Asia. Still, neither milestone in human evolution lines up well with the flip 42,000 years ago, and neither was sudden, says Thomas Higham, an archaeologist and radiocarbon expert at the University of Oxford. Linking them to the field reversal, he says, “seems to me to be pushing the evidence too far.”"

    [ ]

  • The author asserts, "... when Earth’s magnetic field was estimated to be only ~6% of current levels, triggered substantial changes in atmospheric ozone concentration and circulation."

    Where is the evidence that atmospheric ozone concentration changed? What is the proposed chemical reaction to destroy the ozone? What would prevent UV from being absorbed in the troposphere in the absence of stratospheric ozone. The same process today produces ozone in the tropics, which then rises and migrates to the poles. While tropospheric ozone would have a shorter half-life, I don't see any reason that it wouldn't still be produced and serve the function of absorbing UV-C. There is considerable hand-waving without specifics.

    Why would the claimed decline in ozone only affect megafauna? Why not especially sensitive animals like frogs? They basically claim that Neanderthals and Sapiens were playing 'musical chairs' with the available caves. Where are the estimates on cave abundance and hominid populations to demonstrate the scarcity of shelter?

    I'm left with the impression that these researchers are operating outside their areas of expertise, and engaging in poorly supported speculation.

American Association for the Advancement of Science

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