Charcoal, soot, and combustion-aerosol peaks at the Younger Dryas onset record an exceptional, continental-to-hemispheric biomass-burning episode.

The proponent compilation's "extraordinary episode" could not be reproduced by independent reanalysis, and the field's reference charcoal synthesis sees no onset pulse; fires occurred, as they always do — the exceptional part is unsupported.

The exceptional biomass-burning episode is weakly supported. While proponent compilations suggest an unprecedented hemispheric conflagration, independent continental charcoal syntheses detect only gradual, climate-tracking shifts in fire regimes. The strongest opposing consideration is that the claimed impact-winter fire pulse depends heavily on exceptionalist statistical treatments of selected proxies that independent custodians of the charcoal databases reject.

Wolbach et al. compile multiple combustion proxies and argue for an exceptional hemispheric biomass‑burning episode at the Younger Dryas onset (YDIH‑E017), giving the fire claim some positive support. Nonetheless, the primary independent charcoal synthesis (Marlon et al.) finds no continent‑wide fire pulse at that time (YDIH‑E016), and Holliday et al. (2020) challenge Wolbach’s proxy selection, statistical tests, and claimed exceptionalism (YDIH‑E018). The strongest opposing consideration is that charcoal records have limited temporal resolution and could miss a very brief, intense burning pulse, but as it stands the evidence for “exceptional, synchronous” burning is contested and substantially weaker than the more mundane interpretation of climate‑modulated fires.

Wolbach and colleagues compiled ice-core combustion aerosols and sedimentary charcoal and soot and inferred an extraordinary continental-to-hemispheric burning episode on the order of a tenth of Earth's biomass. Marlon and colleagues' independent North American charcoal synthesis found gradual climate-tracking fire and no continent-wide pulse at the onset, and Holliday and colleagues challenged the compilation's selection, chronological treatment, and claimed exceptionalism. The strongest opposing consideration is that a very short pulse could be smoothed out of charcoal databases and that Wolbach published a point-by-point reply. The field's own reference synthesis, built for unrelated purposes, does not see the extraordinary episode, and the data's custodians dispute that reading.

The affirmative case rests on one proponent compilation whose data selection, chronological-uncertainty treatment, and statistical exceptionalism were formally challenged by authors who built the underlying charcoal database, and whose ~9–10% biosphere-burn estimate did not reproduce under independent reanalysis. The unprejudiced continental baseline, assembled for unrelated fire-history purposes, shows fire tracking climate with no onset-specific pulse. Strongest opposing consideration: charcoal archives smooth and could underrepresent a very short or patchy pulse, and the proponents' same-journal reply leaves the exchange formally open — so "contradicted" overreaches; but with the independent baseline against it and only the contested selection for it, weak support is what remains.

The independent continental charcoal synthesis, assembled by the fire-history community for unrelated purposes, sees burning tracking climate across the deglaciation with no continent-wide pulse at the onset — a baseline the extraordinary-burning claim has to explain away. The proponent compilation's data selection, treatment of chronological uncertainty, and statistical exceptionalism were formally challenged by workers including two builders of the underlying database, and the reanalysis could not reproduce the global-burning interpretation. The strongest opposing consideration is that charcoal archives smooth chronology and a very brief pulse could in principle be underrepresented, and the proponents replied point-by-point in the same volume, leaving the exchange formally open. Fires certainly occurred; "exceptional and synchronous" is the unsupported word.

Fires occurred, as they always do; the 'extraordinary episode' claim (YDIH-E017) could not be reproduced by the charcoal database's own custodians (YDIH-E018), and the reference synthesis sees climate-tracking fire, not an onset conflagration (YDIH-E016).

Fire occurred through the deglaciation, but the reference charcoal synthesis sees climate-tracking burning with no onset-specific continental signal (YDIH-E016), and the 'extraordinary episode' compilation (YDIH-E017) was challenged on data selection and exceptionalism testing by the database's own custodians (YDIH-E018). The exchange is open, with the independent synthesis against the claim.

Fire occurred through the deglaciation, but the reference charcoal synthesis sees climate-tracking burning with no onset-specific continental signal (YDIH-E016), and the 'extraordinary episode' compilation (YDIH-E017) was challenged on data selection and exceptionalism testing by the database's own custodians (YDIH-E018). The exchange remains open, with the independent synthesis against the claim.

Fire occurred through the deglaciation, but the reference charcoal synthesis sees climate-tracking burning with no onset-specific continental signal (YDIH-E016), and the 'extraordinary episode' compilation (YDIH-E017) was challenged on selection and exceptionalism testing by the database's own custodians (YDIH-E018). The exchange remains open, with the independent synthesis against the claim.

Fire occurred through the deglaciation, but the reference charcoal synthesis sees climate-tracking burning with no onset-specific continental signal (YDIH-E016), and the 'extraordinary episode' compilation (YDIH-E017) was challenged on data selection and exceptionalism testing by the database's own custodians (YDIH-E018). The exchange is open, with the independent synthesis against the claim.

Fire occurred through the deglaciation, but the reference charcoal synthesis sees climate-tracking burning with no onset-specific continental signal (YDIH-E016), and the 'extraordinary episode' compilation (YDIH-E017) was challenged on data selection and exceptionalism testing by the database's own custodians (YDIH-E018). The exchange remains open, with the independent synthesis against the claim.

The proponent compilation exists, but the prior independent synthesis of North American charcoal records found no continent-wide fire response at the onset, and a dedicated 2020 critique challenged the compilation's data selection, statistical exceptionalism, and reproducibility (with a proponent reply). Fires certainly occurred — fires always occur; "exceptional and synchronous" is the unsupported part.

Continental-scale sedimentary charcoal syntheses indicate that biomass burning increased gradually throughout the deglaciation in response to climate change, showing no exceptional, synchronous firestorm at the Younger Dryas onset. Independent reanalyses of proponent burning compilations revealed severe data-selection biases, unsupported chronological adjustments, and unreplicable statistical claims of continental conflagration. The strongest opposing consideration is Wolbach et al.'s global compilation of soot and combustion aerosols, which estimated that roughly 9 to 10 percent of Earth's biomass burned at the boundary.

The unprejudiced baseline — Marlon et al. 2009's continental charcoal synthesis built for fire-history purposes — shows climate-tracking fire with no continent-wide signal at the onset, and the Wolbach compilation's extraordinary-burning verdict was formally challenged on data selection, chronology, and statistics by the database's own custodians (Holliday et al. 2020). The strongest opposing consideration is that charcoal records have smoothing limits that could in principle underrepresent a very short pulse, and the Wolbach reply keeps the exchange formally open — but the independent synthesis, twice over, cannot see the claimed hemispheric conflagration.

YDIH-E016's independent continental charcoal synthesis found gradual, climate-responsive changes and no continent-wide fire pulse specific to the Younger Dryas onset. YDIH-E018 also found that the exceptional burning result was not reproducible under different data-selection, chronological, and statistical treatments. The strongest opposing consideration is YDIH-E017's compilation of synchronous combustion peaks and its estimate of extraordinary biomass loss, but that result depends on the disputed selections and exceptionalism tests and was answered rather than independently replicated.

An independent continental charcoal synthesis finds no continent-wide fire pulse at Younger Dryas onset, only climate-tracking regimes; the proponent compilation claiming exceptional hemispheric burning is challenged on data selection, chronology, and exceptionalism statistics by the charcoal-database custodians themselves. Strongest opposing consideration is the ice-core combustion-aerosol peaks assembled by proponents, yet those peaks do not survive independent exceptionalism tests.

The independent North American charcoal synthesis was built by the fire-history community for its own purposes. It shows burning rising gradually through the deglaciation and tracking abrupt climate changes, with no continent-wide signal specific to the onset (E016). The supporting compilation reports synchronous peaks and a burn on the order of 9–10% of Earth's biomass (E017). Authors who include builders of the charcoal database it drew on challenged its data selection, chronological handling and exceptionalism statistics (E018); the compilation's authors replied, and the exchange is formally open. The claim's distinctive content, an exceptional continental-to-hemispheric episode, is precisely what the purpose-neutral synthesis was positioned to see and did not. Strongest opposing consideration: charcoal composites smooth chronology and could underrepresent a very short pulse, and the ledger answers the compilation's ice-core combustion-aerosol component only through the general challenge in E018.

The proponent compilation exists, but the prior independent synthesis of North American charcoal records found no continent-wide fire response at the onset, and a dedicated 2020 critique challenged the compilation's data selection, statistical exceptionalism, and reproducibility (with a proponent reply). Fires certainly occurred — fires always occur; "exceptional and synchronous" is the unsupported part.