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Evidence record

Is Earth’s magnetic field about to flip?

Every sentence on the exploration belongs to at least one claim below. Each says what kind of statement it is, what it rests on, what the evidence does not establish, and how far it was checked. Nothing here is a score, and none of it is a verdict on a belief or a theory.

Last checked 24 September 2026.

  • Source checked: 41
  • A judgement, not a fact: 8
  • Partly checked: 6
  • Presented as open: 2

If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.

What the question takes for granted

A forecasting question about a geophysical system. The record of past reversals is well established; whether and when the next begins is what the page says cannot be known, and one line of research reads the present anomaly as more suggestive than the rest do.

  • The field has reversed before

    Established

    Recorded in volcanic rock and ocean-floor patterns hundreds of times.

  • The present weakening could be the start of one

    Contested

    The decline is measured. Most work cited reads it as within normal variation; one 2016 study reads the anomaly beneath it as like the run-up to past transitions.

  • A reversal could in principle be forecast

    Open

    Dynamo simulations put the limit of predictability at about a century, far short of a reversal’s duration; simpler models might do better, untested.

How the question is labelled

Claim: The weakening

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The field

Kind
Framing. Signposting. It asserts nothing a source could check.

The question

Claim: The field has been weakening for as long as it has been measured

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "Is the Earth's magnetic field reversing now?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Reference work

    The source reads: Measurements have been made of the Earth's magnetic field more or less continuously since about 1840. ... If we look at the trend in the strength of the magnetic field over this time (for example the so-called 'dipole moment' shown in the graph below) we can see a downward trend.

  • Supports

    Recurrent ancient geomagnetic field anomalies shed light on future evolution of the South Atlantic Anomalyintroduction, first sentence

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: The strength of the axial dipole part of the geomagnetic field has been decreasing at an average rate of 16 nT/y over the past 180 y (1), for which there are direct measurements of field intensity.

What this does not establish

Direct measurement began around 1840. Brown and others 2018 report indirect observations suggesting decay since 1600 or earlier, which is less certain.

Later work looked for

Crossref, 2020 on, "axial dipole moment decay": Nilsson and others 2022 confirm the decline through the direct-measurement era; nothing that changes it.

Claim 3 · checked 24 September 2026 · AI-assisted audit

Claim: and it has flipped hundreds of times before

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

Crossref, 2019 on, "geomagnetic polarity time scale": revisions refine individual chron ages, not the count of hundreds.

Claim 4 · checked 24 September 2026 · AI-assisted audit

Claim: Neither fact predicts the next one.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from the sources’ statements that reversals are irregular and cannot be forecast (claims 17 and 60).

  • Context

    Reversals: Magnetic Flipsection "How often do reversals occur?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: Reversals are not predictable and are certainly not periodic in nature.

Claim 5 · checked 24 September 2026 · AI-assisted audit

Claim: Reversals are recorded in the rock and the current field is measurably declining,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "How often do reversals occur?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Reference work

    The source reads: As a matter of geological record, the Earth's magnetic field has undergone numerous reversals of polarity. We can see this in the magnetic patterns found in volcanic rocks, especially those recovered from the ocean floors.

  • Supports

    Flip Flop: Why Variations in Earth’s Magnetic Field Aren’t Causing Today’s Climate Changesection "2. Magnetic Pole Reversals"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record

    The source reads: In the past 200 years, Earth’s magnetic field has weakened about nine percent on a global average.

Later work looked for

Crossref, 2020 on, "axial dipole moment decay": the decline continues in the satellite era (Finlay and others 2020); nothing that changes it.

Claim 6 · checked 24 September 2026 · AI-assisted audit

Claim: which is why the question keeps being asked.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

Claim 7 · checked 24 September 2026 · AI-assisted audit

Claim: The decline has happened before without a reversal following,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: If we refer to the decline of the dipole through time, there are many examples of long dipole decreases in the paleomagnetic record that did not end with a reversal.

Later work looked for

Crossref, 2018 on, "geomagnetic reversal South Atlantic Anomaly" and "geomagnetic field reversing dipole decay": Nilsson and others 2022 (added) and Pavón-Carrasco and De Santis 2016 (added) are the relevant later and rival work; nothing reverses the review.

Claim 8 · checked 24 September 2026 · AI-assisted audit

Claim: and no method exists for forecasting one.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · A simulation · Review of the field

    The source reads: This predictability limit is at least 1 order of magnitude smaller than the time it takes for a reversal to occur. This leaves in principle little hope for predicting the next reversal.

  • Supports

    Reversals: Magnetic Flipsection "How often do reversals occur?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: Reversals are not predictable and are certainly not periodic in nature.

What this does not establish

Valet and Fournier note that low-dimensional models of reversal dynamics might in principle do better, and that this remains to be tested.

Later work looked for

Crossref, 2016 on, "predictability geodynamo forecast reversal": nothing found that claims a reversal forecast.

Claim 9 · checked 24 September 2026 · AI-assisted audit

Claim: Magnetic minerals in cooling lava record the direction of the field at the time they set.

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 4 (volcanic records of rapid field change)

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: the field direction changed by large amounts during the week or two required for cooling and acquisition of remanent magnetization

  • Supports

    Reversals: Magnetic Flipsection "How quickly do the poles 'flip'?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work

    The source reads: rocks that retain an imprint of the ancient magnetic field present when they were formed

What this does not establish

Lava is one recorder. Most reversal records are marine sediments, which smooth the signal (Valet and Fournier, abstract).

Later work looked for

How the method works; not a finding later work revises.

Claim 10 · checked 24 September 2026 · AI-assisted audit

Claim: Read in sequence, they show the poles swapping, irregularly, hundreds of times.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Flip Flop: Why Variations in Earth’s Magnetic Field Aren’t Causing Today’s Climate Changesection "2. Magnetic Pole Reversals"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record

    The source reads: Paleomagnetic records tell us Earth’s magnetic poles have reversed 183 times in the last 83 million years, and at least several hundred times in the past 160 million years. The time intervals between reversals have fluctuated widely

  • Supports

    Deciphering records of geomagnetic reversalssection 6.3

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: unlike Earth, where reversals are irregular and excursions more frequent

What this does not establish

The count comes largely from the ocean floor, whose volcanic rock records the sequence (BGS); the page’s "in cooling lava" is the mechanism, not the only archive.

Later work looked for

Crossref, 2019 on, "geomagnetic polarity time scale": no revision to the count of several hundred.

Claim 11 · checked 24 September 2026 · AI-assisted audit

Claim: The last full reversal was about 773,000 years ago.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 3.2 and section 6.1

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: Recent studies defend that the midpoint of the last reversal occurred at about 773 ka ago [Channell et al., 2010; Valet et al., 2014], which is consistent with recent U‐Pb zircon ages at 770.2 ± 7.3 ka

What this does not establish

The date is the midpoint; the transition’s onset is put no earlier than 778 ± 5 ka and its precursor at 790 ± 5 ka (Valet and Fournier, section 6.1).

Later work looked for

Crossref, 2016 on, "Matuyama-Brunhes age": the 773 ka midpoint is the current standard; NASA’s 2021 page still gives the older round 780,000.

Claim 12 · checked 24 September 2026 · AI-assisted audit

Claim: The field has been decaying at roughly five per cent a century since at least 1840,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Earth’s magnetic field is probably not reversingabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Measurement

    The source reads: The geomagnetic field has been decaying at a rate of ∼5% per century from at least 1840, with indirect observations suggesting a decay since 1600 or even earlier.

What this does not establish

Read from the abstract only; the paper’s own derivation of the rate was not read.

Later work looked for

Crossref, 2020 on, "axial dipole moment decay": Nilsson and others 2022 give 16 nT per year over the past 180 years for the axial dipole, consistent with the rate.

Corrected

24 September 2026. Previously: “The dipole has been decaying at roughly five per cent a century since at least 1840,” Integrity pass: the 2018 abstract gives the rate for the geomagnetic field, not for the dipole, and NASA’s nine per cent in 200 years is a global average of the field; the page now names the quantity its sources measure.

Claim 13 · checked 24 September 2026 · AI-assisted audit

Claim: which is close to a tenth of it gone.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

NASA’s figure is for the field on a global average over the past 200 years. Five per cent a century from 1840 compounds to about nine per cent by 2020, which is close to a tenth either way.

Later work looked for

Crossref, 2020 on, "axial dipole moment decay": nothing that changes the proportion.

Claim 14 · checked 24 September 2026 · AI-assisted audit

What the record shows

Claim: What the record shows

Kind
Framing. Signposting. It asserts nothing a source could check.

Reversals happen and are irregular

Claim: Reversals happen and are irregular

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.3

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: unlike Earth, where reversals are irregular and excursions more frequent

Later work looked for

Crossref, 2018 on, "geomagnetic reversal South Atlantic Anomaly" and "geomagnetic field reversing dipole decay": Nilsson and others 2022 (added) and Pavón-Carrasco and De Santis 2016 (added) are the relevant later and rival work; nothing reverses the review.

Claim 16 · checked 24 September 2026 · AI-assisted audit

Claim: The intervals between reversals are irregular, with no periodicity anyone has established.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "How often do reversals occur?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Reference work

    The source reads: Reversals are not predictable and are certainly not periodic in nature. Hence we can only speak about the average reversal interval.

  • Supports

    Flip Flop: Why Variations in Earth’s Magnetic Field Aren’t Causing Today’s Climate Changesection "2. Magnetic Pole Reversals"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: The time intervals between reversals have fluctuated widely

Later work looked for

Crossref, 2019 on, "geomagnetic reversal frequency periodicity": nothing establishing a periodicity.

Claim 17 · checked 24 September 2026 · AI-assisted audit

Claim: Over the past ten million years they have averaged about one reversal every 200,000 years, and the present interval has already run longer than that.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: The Brunhes chron has been unusually long with respect to the past 10 Ma, with an average of one reversal every 200 kyr.

  • Supports

    Reversals: Magnetic Flipsection "How often do reversals occur?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: In the last 10 million years, there have been, on average, 4 or 5 reversals per million years.

What this does not establish

The average depends on the window: NASA gives about 300,000 years over a longer span. That is a longer average, not a contradiction.

Later work looked for

Crossref, 2019 on, "geomagnetic polarity time scale": nothing that changes the average for this window.

Claim 18 · checked 24 September 2026 · AI-assisted audit

Claim: The switch itself is quick by geological standards: the directional change appears to take under a thousand years, with a precursor before it and a rebound after, neither longer than a few thousand.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.1

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: three successive phases of the reversal process are indicated with a precursor, a 180° switch, and a rebound ... The first and third phases are estimated to have lasted less than 2.5 kyr, while the directional polarity transition did not exceed 1 kyr.

  • Supports

    Deciphering records of geomagnetic reversalssection 7 (summary)

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: The duration of each phase does not exceed 3–4 kyr.

What this does not establish

The durations come from volcanic records, dated by assuming successive lava flows are evenly spaced in time, and the three phases are rarely seen in one record (Valet and Fournier, sections 6.1 and 7).

Later work looked for

Crossref, 2019 on, "geomagnetic polarity reversal duration transition": Yamamoto and others 2026 report two Eocene transitions of 18 and 70 thousand years; added to the page as claim 20.

Claim 19 · checked 24 September 2026 · AI-assisted audit

Claim: Those durations come from recent reversals, and not every reversal was quick: a deep-sea record of two transitions about 40 million years ago, published in 2026, puts them at 18,000 and 70,000 years.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Extraordinarily long duration of Eocene geomagnetic polarity reversalsabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: Previous palaeomagnetic records mainly from the last ~17 million years indicate that the reversal process typically occurs over ten thousand or fewer years. ... These transitions occur over 18 and 70 thousand years and are much longer than the typical 10 kyr duration for younger reversals.

  • Supports

    Extraordinarily long duration of Eocene geomagnetic polarity reversalsabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: Here we present an exceptionally resolved deep sea sedimentary palaeomagnetic record that captures two polarity transitions that occurred ~40 million years ago.

  • Supports

    Extraordinarily long duration of Eocene geomagnetic polarity reversalsResults and Discussion, "Variability of reversal durations from numerical geodynamo simulations"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: The estimated 18 ± 3 and 70 ± 6 kyr durations for transition 1 and 2, respectively, are both admissible in view of these numerical dynamo model results.

  • Qualifies

    Extraordinarily long duration of Eocene geomagnetic polarity reversalsIntroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: The estimated ~10 kyr duration of the entire reversal process in direction deduced from just seven reversal records

    The shorter durations rest on a handful of well-resolved recent reversals.

What this does not establish

One sedimentary record from one site (IODP Site U1408), with durations of 18 ± 3 and 70 ± 6 thousand years; the authors note numerical dynamo models also produce long transitions.

Later work looked for

Found by the currency search for claim 19; published January 2026, nothing later found.

Corrected

24 September 2026. Previously: “” The currency search found a 2026 record of Eocene transitions far longer than the recent ones the passage described; the page now says so.

Claim 20 · checked 24 September 2026 · AI-assisted audit

Claim: During a transition the field does not simply vanish.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Flip Flop: Why Variations in Earth’s Magnetic Field Aren’t Causing Today’s Climate Changesection "2. Magnetic Pole Reversals"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record

    The source reads: During a pole reversal, the magnetic field weakens, but it doesn’t completely disappear.

  • Supports

    Reversals: Magnetic Flipsection "I'm interested in a more technical description"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · A simulation

    The source reads: In such simulations, the strength of the main dipole appears to weaken, perhaps to about 10% of its normal value (but not vanish)

Later work looked for

Crossref, 2019 on, "geomagnetic polarity reversal transitional field": nothing that changes it.

Claim 21 · checked 24 September 2026 · AI-assisted audit

Claim: It becomes weaker and more complicated, no longer a simple two-pole field,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 7 (summary)

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: Large and systematic field intensity decreases occur during all‐polarity transitions. ... There are strong indications that the geomagnetic field was not dipolar during the last reversal.

What this does not establish

Valet and Fournier: the evidence is strongest for the last reversal, and less is available for the others.

Later work looked for

Crossref, 2019 on, "geomagnetic polarity reversal transitional field": nothing that changes it.

Corrected

24 September 2026. Previously: “It becomes weaker and more complicated, with multiple poles, before reorganising.” The records show a weak, non-dipolar transitional field. Several poles at once is what simulations show, and the BGS says those results are not known to hold for the real Earth; the sentence now says which is which.

Claim 22 · checked 24 September 2026 · AI-assisted audit

Claim: and in simulations several poles appear at once before it reorganises.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "I'm interested in a more technical description"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · A simulation · Reference work

    The source reads: the existing poles may wander across the globe and be joined by other temporary North and South magnetic poles (the 'non-dipole field')

What this does not establish

The BGS adds that these simulation results are not known to be strictly true of the real Earth.

Claim 23 · checked 24 September 2026 · AI-assisted audit

The present decline is real and not unprecedented

Claim: The present decline is real and not unprecedented

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: there are many examples of long dipole decreases in the paleomagnetic record that did not end with a reversal

Later work looked for

Crossref, 2018 on, "geomagnetic reversal South Atlantic Anomaly" and "geomagnetic field reversing dipole decay": Nilsson and others 2022 (added) and Pavón-Carrasco and De Santis 2016 (added) are the relevant later and rival work; nothing reverses the review.

Claim 24 · checked 24 September 2026 · AI-assisted audit

Claim: The dipole has been weakening since direct measurement began,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "Is the Earth's magnetic field reversing now?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Reference work

    The source reads: Measurements have been made of the Earth's magnetic field more or less continuously since about 1840.

  • Supports

    Recurrent ancient geomagnetic field anomalies shed light on future evolution of the South Atlantic Anomalyintroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: The strength of the axial dipole part of the geomagnetic field has been decreasing at an average rate of 16 nT/y over the past 180 y (1), for which there are direct measurements of field intensity.

Later work looked for

Crossref, 2020 on, "axial dipole moment decay": nothing that changes it.

Claim 25 · checked 24 September 2026 · AI-assisted audit

Claim: and a large region of low field strength over the South Atlantic has grown in both directions along its edges,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The CHAOS-7 geomagnetic field model and observed changes in the South Atlantic Anomalysection "Evolution of the South Atlantic Anomaly as seen by Swarm"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: the field intensity has decreased on the western edges of the anomaly, leading to its westwards expansion. ... leading to an eastward expansion of the anomaly in this direction.

What this does not establish

Measured from 2014 to 2019 at satellite altitude by Swarm.

Later work looked for

Crossref, 2020 on, "South Atlantic Anomaly": later conference abstracts describe continued growth and a split into western and eastern minima; nothing that reverses Finlay and others.

Claim 26 · checked 24 September 2026 · AI-assisted audit

Claim: which matters for satellites passing through it.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

Crossref, 2020 on, "South Atlantic Anomaly": later conference abstracts describe continued growth and a split into western and eastern minima; nothing that reverses Finlay and others.

Claim 27 · checked 24 September 2026 · AI-assisted audit

Claim: The present dipole is still strong, far above the values that preceded the last five reversals,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

The exponents in the excerpts are 10 to the 22nd power, flattened in the source texts as served.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: despite its present evolution the present dipole remains strong (~8 × 10²² A m²) and, thus, far from values that preceded the past five reversals (< ~ 4 × 10²² A m²). The present evolution falls within the normal range of field variability that prevailed for the past 2 Ma

    Notation restored: Superscripts restored from the Europe PMC full text (PMC6686389), which marks them with <sup>, read 2026-09-24. The text as extracted reads: despite its present evolution the present dipole remains strong (~8 × 1022 A m2) and, thus, far from values that preceded the past five reversals (< ~ 4 × 1022 A m2). The present evolution falls within the normal range of field variability that prevailed for the past 2 Ma

  • Supports

    The South Atlantic Anomaly: The Key for a Possible Geomagnetic Reversalabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: the current value of the dipolar moment (7.7 10²² A·m²) is not so low when compared with recent paleomagnetic data for the Holocene (last 12 ka) and for the entire Brunhes geomagnetic normal polarity (last ~0.8 Ma)

    Notation restored: Superscripts restored from the publisher’s HTML at frontiersin.org, which marks them with <sup>, read 2026-09-24. The text as extracted reads: the current value of the dipolar moment (7.7 10 22 A·m 2 ) is not so low when compared with recent paleomagnetic data for the Holocene (last 12 ka) and for the entire Brunhes geomagnetic normal polarity (last ~0.8 Ma)

Later work looked for

Crossref, 2018 on, "geomagnetic reversal South Atlantic Anomaly" and "geomagnetic field reversing dipole decay": Nilsson and others 2022 (added) and Pavón-Carrasco and De Santis 2016 (added) are the relevant later and rival work; nothing reverses the review.

Corrected

24 September 2026. Previously: “The present dipole is still strong by the standards of the past two million years, far above the values that preceded the last five reversals,” Integrity pass: the 2016 review says the dipole remains strong against the values before the last five reversals and that its present decline falls within the normal range of the past two million years; it does not rank today’s strength against that whole span.

Claim 28 · checked 24 September 2026 · AI-assisted audit

Claim: and long declines in the record have ended without one.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: there are many examples of long dipole decreases in the paleomagnetic record that did not end with a reversal

Later work looked for

Crossref, 2018 on, "geomagnetic reversal South Atlantic Anomaly" and "geomagnetic field reversing dipole decay": Nilsson and others 2022 (added) and Pavón-Carrasco and De Santis 2016 (added) are the relevant later and rival work; nothing reverses the review.

Claim 29 · checked 24 September 2026 · AI-assisted audit

Claim: A 2006 paper asked this question in its title.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Is Earth’s magnetic field reversing?bibliographic record (Crossref)

    Cited · Link answered, 19 October 2026 · Catalogue record only, 24 September 2026

    Title "Is Earth’s magnetic field reversing?", Earth and Planetary Science Letters 246, 1–16.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: see the more detailed statistical analysis by Constable and Korte [2006]

What this does not establish

Only the record was read. What the paper argues is reported here through the 2016 review that cites it (claim 31).

Corrected

24 September 2026. Previously: “A 2006 paper asked this question in its title and did not answer yes.” The paper could not be read, so its answer cannot be stated from it. What it found is now attributed to the review that reports it.

Claim 30 · checked 24 September 2026 · AI-assisted audit

Claim: A 2016 review of the reversal record cites its statistical treatment of the past two million years for the conclusion that the present decline falls within the normal range of variation,

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field

    The source reads: The present evolution falls within the normal range of field variability that prevailed for the past 2 Ma (see the more detailed statistical analysis by Constable and Korte [2006]).

What this does not establish

Constable and Korte 2006 was not read; its method and result are known here only through this review’s account.

Corrected

24 September 2026. Previously: “Its statistical treatment of the last two million years put the present decline inside the ordinary range of variation, which is still where the evidence sits.” The 2006 paper is closed, so its finding is now attributed to the open review that reports it. "Which is still where the evidence sits" left out a published rival reading (claim 33) and is replaced by the later work that supports the review.

Claim 31 · checked 24 September 2026 · AI-assisted audit

Claim: and a 2022 reconstruction of the past 9,000 years found anomalies like the South Atlantic one that came and went.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

A model built from indirect archaeological and geological records, with large uncertainties in the Southern Hemisphere; the disappearance of the present anomaly is the authors’ inference from an ancient analogue, not a forecast.

Later work looked for

Found by the currency search; published 2022, nothing later found that revises it.

Claim 32 · checked 24 September 2026 · AI-assisted audit

Claim: One 2016 study of the anomaly leans the other way. It reads the patches of reversed field beneath it, and the rate of decay, as like those before past reversals and excursions, while finding the dipole itself not especially low.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The South Atlantic Anomaly: The Key for a Possible Geomagnetic Reversalabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Model

    The source reads: The presence of the reversal patches at the CMB seems to be characteristic during the preparation phase of a geomagnetic transition. However, the current value of the dipolar moment ... is not so low ... although the rate of decay is similar to that given by previous documented geomagnetic reversals or excursions.

Other readings

Valet and Fournier 2016, Brown and others 2018 and Nilsson and others 2022 read the present field as within its normal range (claims 31, 32 and 49).

Later work looked for

Found by the currency search for claim 31; Brown and others 2018 and Nilsson and others 2022 read the anomaly the other way.

Corrected

24 September 2026. Previously: “” Added so the page reports the published rival reading rather than saying the evidence sits on one side only.

Claim 33 · checked 24 September 2026 · AI-assisted audit

Claim: What a reversal would and would not do

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The field would switch off and radiation would sterilise the surface.

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The field weakens and grows more complex rather than switching off.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

Crossref, 2019 on, "geomagnetic polarity reversal transitional field": nothing that changes it.

Corrected

24 September 2026. Previously: “The field weakens and turns multi-polar rather than switching off.” Multiple poles are what simulations show (claim 23); the observed record supports weaker and more complex.

Claim 36 · checked 24 September 2026 · AI-assisted audit

Claim: Even with no field at all, the atmosphere would still stop most of the radiation,

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "Is there any danger to life?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Reference work

    The source reads: At the Earth's surface, the atmosphere acts as an extra blanket to stop all but the most energetic of the solar and galactic radiation. In the absence of a magnetic field, the atmosphere would still stop most of the radiation.

Later work looked for

How the shielding works; not a finding later work revises.

Corrected

24 September 2026. Previously: “Above 65 degrees of geomagnetic latitude it already lets cosmic rays of every energy through, and people live there.” "And people live there" had no source. The BGS answers the misconception directly, on the atmosphere and on extinctions, so the entry now uses that.

Claim 37 · checked 24 September 2026 · AI-assisted audit

Claim: and reversals in the record do not line up with extinctions.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "Is there any danger to life?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Reference work

    The source reads: reversal patterns do not match patterns in species extinction during geological history

  • Supports

    Flip Flop: Why Variations in Earth’s Magnetic Field Aren’t Causing Today’s Climate Changesection "2. Magnetic Pole Reversals"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: geologic and fossil records from previous reversals show nothing remarkable, such as doomsday events or major extinctions

  • Qualifies

    Extraordinarily long duration of Eocene geomagnetic polarity reversalsabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: Occasional prolonged intervals of transitional, and weaker, geomagnetic fields would have exposed Earth’s Eocene environments to greater high-energy radiation from the sun for longer intervals of time, with potential impacts on biota.

What this does not establish

About extinctions. Whether long transitions affected life in lesser ways is raised as a possibility by Yamamoto and others 2026, not established.

Later work looked for

Crossref, 2019 on, "geomagnetic polarity reversal duration": Yamamoto and others 2026 suggest potential impacts on life during unusually long transitions, stated as possible rather than found.

Claim 38 · checked 24 September 2026 · AI-assisted audit

Claim: It is overdue.

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The intervals are irregular and no periodicity has been established.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "How often do reversals occur?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Reference work

    The source reads: Reversals are not predictable and are certainly not periodic in nature.

Later work looked for

Crossref, 2019 on, "geomagnetic reversal frequency periodicity": nothing establishing a periodicity.

Claim 40 · checked 24 September 2026 · AI-assisted audit

Claim: The present one is long against the average of the past ten million years,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: The Brunhes chron has been unusually long with respect to the past 10 Ma, with an average of one reversal every 200 kyr.

Later work looked for

Crossref, 2018 on, "geomagnetic reversal South Atlantic Anomaly" and "geomagnetic field reversing dipole decay": Nilsson and others 2022 (added) and Pavón-Carrasco and De Santis 2016 (added) are the relevant later and rival work; nothing reverses the review.

Claim 41 · checked 24 September 2026 · AI-assisted audit

Claim: which is a statistic and not a schedule.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from claim 40: with no periodicity, an average interval sets no due date.

  • Context

    Reversals: Magnetic Flipsection "How often do reversals occur?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: Hence we can only speak about the average reversal interval.

Claim 42 · checked 24 September 2026 · AI-assisted audit

Claim: The weakening proves one is starting.

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The field has declined before and recovered.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: there are many examples of long dipole decreases in the paleomagnetic record that did not end with a reversal

  • Context

    Earth’s magnetic field is probably not reversingabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026

    The source reads: neither of these SAA-like fields develop into an excursion or reversal. This suggests that the current weakened field will also recover without an extreme event such as an excursion or reversal.

Later work looked for

Crossref, 2018 on, "geomagnetic reversal South Atlantic Anomaly" and "geomagnetic field reversing dipole decay": Nilsson and others 2022 (added) and Pavón-Carrasco and De Santis 2016 (added) are the relevant later and rival work; nothing reverses the review.

Claim 44 · checked 24 September 2026 · AI-assisted audit

Claim: The dipole is still about twice the level it had fallen below before each of the last five reversals.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Review of the field

    The source reads: the present dipole remains strong (~8 × 10²² A m²) and, thus, far from values that preceded the past five reversals (< ~ 4 × 10²² A m²)

    Notation restored: Superscripts restored from the Europe PMC full text (PMC6686389), which marks them with <sup>, read 2026-09-24. The text as extracted reads: the present dipole remains strong (~8 × 1022 A m2) and, thus, far from values that preceded the past five reversals (< ~ 4 × 1022 A m2)

Later work looked for

Crossref, 2018 on, "geomagnetic reversal South Atlantic Anomaly" and "geomagnetic field reversing dipole decay": Nilsson and others 2022 (added) and Pavón-Carrasco and De Santis 2016 (added) are the relevant later and rival work; nothing reverses the review.

Corrected

24 September 2026. Previously: “The dipole is still roughly twice the strength it fell to before each of the last five reversals.” The source gives an upper bound for the values before past reversals (less than about 4), not a level they fell to.

Claim 45 · checked 24 September 2026 · AI-assisted audit

The direct answer, in a title

Claim: The direct answer, in a title

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: A 2018 paper in the Proceedings of the National Academy of Sciences is titled, in full, that the Earth's magnetic field is probably not reversing.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

The title and abstract were read; the full text is not available to this environment.

Claim 47 · checked 24 September 2026 · AI-assisted audit

Claim: Its argument is from the past rather than from a simulation of the core:

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Earth’s magnetic field is probably not reversingabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Model

    The source reads: We have derived a model of the geomagnetic field spanning 30–50 ka, constructed to study the behavior of the two most recent excursions

What this does not establish

Read from the abstract only; how the field model was built from its records was not read.

Corrected

24 September 2026. Previously: “Its argument is from the past rather than from a model of the core: it finds two earlier episodes,” The paper’s argument does rest on a model, of the field rather than of the core; the sentence now says what kind.

Claim 48 · checked 24 September 2026 · AI-assisted audit

Claim: a model of the field spanning 30,000 to 50,000 years ago finds two earlier episodes, about 49,000 and 46,000 years ago, when the field was comparable to today and carried an anomaly like the South Atlantic one, and neither developed into an excursion or a reversal.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Earth’s magnetic field is probably not reversingabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Model

    The source reads: At earlier times, centered at 49 and 46 ka, the field is comparable to today’s field, with an intensity structure similar to today’s South Atlantic Anomaly (SAA); however, neither of these SAA-like fields develop into an excursion or reversal.

  • Context

    Recurrent ancient geomagnetic field anomalies shed light on future evolution of the South Atlantic Anomalyabstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: We find evidence for recurrent hemispherical field asymmetries, related to quasiperiodic millennial-scale variations in the dipole moment.

What this does not establish

Read from the abstract only. Two past analogues are evidence that such a field need not reverse, not proof that this one will not.

Later work looked for

Crossref, 2018 on, "South Atlantic Anomaly" past analogues: Nilsson and others 2022 find recurrent anomalies over 9,000 years, consistent with it.

Claim 49 · checked 24 September 2026 · AI-assisted audit

Claim: Neither of the two most recent excursions, the Laschamp at 41,000 years and the Mono Lake at 34,000, resembles what the field is doing now either.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    Earth’s magnetic field is probably not reversingabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Earth and its record · Model

    The source reads: the two most recent excursions: the Laschamp and Mono Lake, centered at 41 and 34 ka, respectively. Here, we show that neither excursion demonstrates field evolution similar to current changes in the geomagnetic field.

  • Context

    Carbonate U/Th ages confirm the Mono Basin excursion as the Laschamps geomagnetic excursionabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026

    The source reads: This finding rejects the correlation of the Ash 15 excursion to the ca. 34.5 ka Mono Lake/Auckland excursion event and instead supports a growing body of evidence that favors an alternative interpretation: The geomagnetic event recorded at Ash 15 is a local expression of the ca. 41 ka Laschamps excursion.

What this does not establish

Read from the abstract only. The name is unsettled: a 2026 dating study finds the excursion at Mono Lake itself is the Laschamp, while the 34,000-year event recorded elsewhere keeps the name.

Later work looked for

Crossref, 2020 on, "Mono Lake excursion Laschamps": Ali and others 2026 date the excursion at the Mono Basin type section to the Laschamp; the 34,500-year event itself stands in other records, still called Mono Lake or Auckland.

Claim 50 · checked 24 September 2026 · AI-assisted audit

Claim: That is the state of the evidence, and it is not a guarantee.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from the paper’s own "probably" and from the rival reading in claim 33.

Claim 51 · checked 24 September 2026 · AI-assisted audit

What can be said about the next one

Claim: What can be said about the next one

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Hundreds of reversals in the rock,

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

Later work looked for

Crossref, 2019 on, "geomagnetic polarity time scale": no revision to the count.

Claim 53 · checked 24 September 2026 · AI-assisted audit

Claim: and no periodicity to be overdue against.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from claim 40.

  • Context

    Reversals: Magnetic Flipsection "How often do reversals occur?"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: Reversals are not predictable and are certainly not periodic in nature.

Claim 54 · checked 24 September 2026 · AI-assisted audit

Whether a reversal can be forecast at all

Claim: Whether a reversal can be forecast at all

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

  • Supports

    Earth’s dynamo limit of predictabilityabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026

    The source reads: how far in the future this can conceivably be done is still an open question

Claim 55 · checked 24 September 2026 · AI-assisted audit

Claim: The field is generated by convecting liquid iron in the outer core,

Kind
What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Reversals: Magnetic Flipsection "I'm interested in a more technical description"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Reference work

    The source reads: The source of the magnetic field is the iron-rich liquid outer core of the Earth. This liquid moves in complex ways as a result of the convection of the heat deep within the core and of the rotation of the planet.

  • Context

    Earth’s magnetic field is probably not reversingsignificance statement

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026

    The source reads: Earth’s magnetic field is generated in Earth’s convecting liquid iron outer core

Later work looked for

How the dynamo works; not a finding later work revises.

Claim 56 · checked 24 September 2026 · AI-assisted audit

Claim: and understanding how a system like that works is not the same as being able to predict it.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from the finding that dynamo simulations lose predictability within about a century (claim 59).

  • Context

    Earth’s dynamo limit of predictabilityabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026

    The source reads: suggest that the Earth's dynamo is likely unpredictable beyond a century

Corrected

24 September 2026. Previously: “The field is generated by convecting liquid iron in the outer core, a system whose behaviour is chaotic in simulations. A chaotic system can be understood without being predictable.” No source read calls the geodynamo chaotic; what they report is limited predictability from error growth in simulations, which the next paragraph states. The word is removed rather than asserted.

Claim 57 · checked 24 September 2026 · AI-assisted audit

Claim: Satellite measurements now map the field and its rate of change in detail, and let changes at the surface be traced to the top of the core.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The CHAOS-7 geomagnetic field model and observed changes in the South Atlantic Anomalyabstract; introduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: We present the CHAOS-7 model of the time-dependent near-Earth geomagnetic field between 1999 and 2020 based on magnetic field observations collected by the low-Earth orbit satellites ... we use Green’s functions relating the radial magnetic field at the core–mantle boundary to changes in the field intensity at satellite altitude

  • Supports

    The CHAOS-7 geomagnetic field model and observed changes in the South Atlantic AnomalyMaps of the field, secular variation and secular acceleration

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: Figure 13 presents maps of the radial component of the main field (MF), its first time derivative (secular variation, SV) and its second time derivative (secular acceleration, SA) from CHAOS-7 at the Earth’s surface, up to SH degree 20, in 2019.0.

Later work looked for

Crossref, 2020 on, "South Atlantic Anomaly": later conference abstracts describe continued growth and a split into western and eastern minima; nothing that reverses Finlay and others.

Corrected

24 September 2026. Previously: “which constrains the flow at the top of the core.” Finlay and others trace changes to the radial field at the core surface; they do not model the flow. Narrowed to what they do.

Claim 58 · checked 24 September 2026 · AI-assisted audit

Claim: Error growth in dynamo simulations still puts the forecast horizon at a few decades to a century, at least an order of magnitude short of the time a reversal takes,

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · A simulation · Review of the field

    The source reads: the limited predictability of the geodynamo, which is estimated to be on the order of a few decades to a century ... based on the study of so‐called error growth in a suite of numerical dynamo models. This predictability limit is at least 1 order of magnitude smaller

  • Context

    Earth’s dynamo limit of predictabilityabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · A simulation

    The source reads: the Earth's dynamo is likely unpredictable beyond a century, making decade timescale forecasts of the main magnetic field conceivable

What this does not establish

The limit is estimated from numerical dynamo models, not from the Earth. Valet and Fournier note that simpler models of reversal dynamics might have longer predictability, untested.

Later work looked for

Crossref, 2016 on, "predictability geodynamo forecast reversal": nothing found that extends the horizon.

Corrected

24 September 2026. Previously: “Error growth in dynamo models still puts the forecast horizon at a few decades to a century, an order of magnitude short” The source says at least an order of magnitude.

Claim 59 · checked 24 September 2026 · AI-assisted audit

Claim: so no one can say when the next one will begin.

Kind
Open question. Something the page says is not known.
Review
Presented as open. The page says this is unresolved, and the review found that it is.

  • Supports

    Earth’s dynamo limit of predictabilityabstract

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026

    The source reads: rendering longer‐term predictions, such as the timing of the next reversal, totally unpredictable

  • Supports

    Deciphering records of geomagnetic reversalssection 6.2

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: This leaves in principle little hope for predicting the next reversal.

Claim 60 · checked 24 September 2026 · AI-assisted audit

What it would cost

Claim: What it would cost

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: A weaker, more complex field would raise the radiation dose at satellite altitudes.

Kind
What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The CHAOS-7 geomagnetic field model and observed changes in the South Atlantic Anomalyintroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Physical systems · Measurement

    The source reads: The depth to which charged particles in the radiation belts penetrate ... depends on the intensity of the geomagnetic field. Anomalously weak magnetic field in the South Atlantic ... thus gives rise to enhanced charged particle flux

What this does not establish

An inference from how the radiation belts depend on field strength today; no source here models the radiation environment during a reversal.

Claim 62 · checked 24 September 2026 · AI-assisted audit

Claim: The South Atlantic Anomaly is the small version of it:

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The anomaly is a region of weak field with an enhanced radiation dose, which is the effect claim 62 extends to the whole field.

Claim 63 · checked 24 September 2026 · AI-assisted audit

Claim: satellites crossing that region record measurably more particle hits on their electronics.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    The CHAOS-7 geomagnetic field model and observed changes in the South Atlantic Anomalysection "Evolution of the South Atlantic Anomaly as seen by Swarm"

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record · Measurement

    The source reads: Nevertheless, the highest concentration of SEUs is clearly observed at mid and low latitudes in the South Atlantic Anomaly weak field region.

Later work looked for

Crossref, 2020 on, "South Atlantic Anomaly": later conference abstracts describe continued growth and a split into western and eastern minima; nothing that reverses Finlay and others.

Claim 64 · checked 24 September 2026 · AI-assisted audit

Claim: Navigation follows the field, and already has to keep correcting for the drift of the magnetic north pole.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Flip Flop: Why Variations in Earth’s Magnetic Field Aren’t Causing Today’s Climate Changesection "1."

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Earth and its record

    The source reads: The position of Earth’s magnetic north pole was first precisely located in 1831. Since then, it’s gradually drifted north-northwest by more than 600 miles (1,100 kilometers) ... This gradual shift impacts navigation and must be regularly accounted for.

  • Supports

    The CHAOS-7 geomagnetic field model and observed changes in the South Atlantic Anomalyintroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: To make use of the geomagnetic field for navigation one requires a good-quality magnetometer to measure it, and a reference field model that relates the magnetic vector, at the location and time of the measurement, to the geographic directions.

Later work looked for

How navigation uses the field; not a finding later work revises.

Corrected

24 September 2026. Previously: “Navigation follows the field, and so does the pattern of geomagnetically induced currents in power grids. Both would have to be redrawn.” No readable source supports a claim about how a reversal would change the pattern of induced currents in power grids, so that clause is removed. The navigation half is now tied to what NASA and Finlay and others say.

Claim 65 · checked 24 September 2026 · AI-assisted audit

Claim: A reversal would ask the same of it on a far larger scale.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from claim 65: navigation already corrects for a drifting pole, and a reversal moves the poles across the globe.

Claim 66 · checked 24 September 2026 · AI-assisted audit

Claim: Those are infrastructure problems on a timescale of centuries or longer, which is an unusual combination and makes them easy to either dismiss or exaggerate.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from the durations in claims 19 and 20.

Corrected

24 September 2026. Previously: “Those are infrastructure problems on a timescale of centuries,” A reversal runs over thousands of years and some far longer (claims 19 and 20); "centuries" alone understated it.

Claim 67 · checked 24 September 2026 · AI-assisted audit

What was read