ラシャンプ地磁気逆転

Approximately 42,000 years ago, Earth's magnetic field strength dropped to less than 6% of its current value during the Laschamp geomagnetic excursion. The event lasted roughly 800 years, with the minimum field persisting for approximately 250 years.

Cooper et al. (2021) dated this event precisely using radiocarbon calibration from New Zealand kauri trees (Agathis australis).

The authors named this period the 'Adams Transitional Geomagnetic Event' — a nod to Douglas Adams, since 42 is 'the answer to the ultimate question.'

The Laschamp field minimum coincides with the final extinction of Australian megafauna, the disappearance of Neanderthals from Europe, dramatic vegetation shifts, and expansion of cave art.

The ozone layer was significantly depleted during the field minimum due to increased cosmic radiation.

These consequences have conventionally been attributed to increased radiation. BERM proposes a complementary mechanism.

From BERM's perspective, the Laschamp excursion is a natural experiment in what happens when B_geo → 0.

When B_geo collapses, the natural EM shield weakens AND the CRY/RPM radical pair mechanism loses its reference field.

The second effect is BERM-specific: sustained disruption of circadian timing, melatonin synthesis, and reproductive regulation.

Modern ISS astronaut data shows the same physiological signature — confirming hypomagnetic CRY/RPM disruption.

Extended B_geo collapse means sustained CRY/RPM disruption and chronic melatonin suppression.

Multi-generational exposure to near-zero geomagnetic field represents cumulative reproductive stress across species.

CRY-independent organisms should show less Laschamp-coincident stress. Paleogenomic analysis should reveal CRY gene selection signatures.

The pattern should repeat at other geomagnetic excursions (Mono Lake, Blake, Brunhes-Matuyama).