Methods record locked 11 August 2026. Independent sensitivity analysis and preregistration, not a reproduction of Kennett et al. (2015).
The 23-site chronology can be compatible with a common event without resolving one decade-scale global fallout horizon. Updating selected radiocarbon dates to IntCal20 does not repair missing direct dates or weak stratigraphic association.
Selected IntCal20 results: Bull Creek 11,070±60 14C BP → MAP ~13,015 cal BP, ~95% 13,070–12,838; Lingen regional Usselo 10,950±50 → MAP ~12,875, ~95% 13,041–12,761; Aalsterhut GrA-49515 11,020±75 → MAP ~12,915, ~95% 13,066–12,773; Aalsterhut wildfire 10,870±15 → MAP ~12,760, ~95% 12,824–12,747; Barber Creek charcoal below the claimed proxy zone 10,500±50 → MAP ~12,595, ~95% 12,661–12,460.
These are simple calibration sensitivities, not OxCal Bayesian site models.
A 2024 PNAS correction says early incorrect versions of some Bayesian scripts appeared in Supporting Information, while the published figures/tables used the correct code. SCRIBE will not run a stale mirror and call it a reproduction. A full IntCal20 rerun requires the official corrected CQL, all determinations and stratigraphic assumptions.
H0: no unique global fallout. H1: ET event near the ~12.87 ka early North Atlantic transition. H2: ET event nearer ~12.825 ka Pt/YDB interval. H3: multiple closely spaced freshwater/ocean, volcanic and extraterrestrial disturbances.
Chronology: reproduce original model first, then IntCal20 and pre-specified quality/selection sensitivities. Geochemistry: blind split samples; full HSE suite, Os and suitable Cr/Ni/O isotopes, shock petrography, robust nanodiamond identification and volcanic controls. Ice: paired 26Al/10Be across a continuous interval with baselines, blanks, replicates and preferably a second core. Causality: establish fallout/volcanic/hydrological/climate order inside the same archive.
Null results and failed replications are published. One Pt spike, black layer, microsphere or elevated 26Al/10Be ratio is not sufficient by itself.
Freshwater/ocean-circulation change is strongly relevant; clustered volcanism is a serious trigger/precondition candidate; a cosmic event near the transition remains possible but unconfirmed. Proving one would not prove a lost civilisation.