Super El Niño 2026–27 → Macro Shock — Pre-registration

The thesis

We pre-register, as of 2026-10-03, a falsifiable claim; thresholds before outcomes. The 2026–27 El Niño — daily Niño 3.4 at +3.11 °C on 2026-09-21, above the 2015 daily record (Carbon Brief, 2026-09-21, updated 2026-09-30), ONI v6 at +1.8 °C for JJA 2026 and rising (NOAA CPC, September 2026) — is a physically persistent, record-class event transmitting as a sustained supply-side inflation impulse in the “sticky inflation / mild stagflation” band: +0.5 to +1.5 pp on global/US headline inflation versus the counterfactual, year over year, over four to six quarters from autumn 2026; absorbed by the policy system without breaking.

Three legs, each separately falsifiable:

• Leg A (physical). Reaches “very strong” status — ONI v6 ≥ +2.0 in a release covering Oct 2026–Jan 2027 — holds strong or better through Feb 2027, then turns toward La Niña during 2027, consistent with past very-strong events (NOAA CPC ONI history); WMO puts persistence through Feb 2027 at “nearly 100 %” (Update, 2026-09-03 — the source’s figure, not our probability).
• Leg B (transmission). Food-and-freight shocks add the band’s impulse — first visible in the FAO Food Price Index (≥ +15 % YoY before Jul 2027), commodity curves, freight rates, and a major-exporter staple restriction.
• Leg C (policy and distribution). Central banks delay easing rather than hike aggressively; damage concentrates in climate-vulnerable, debt-burdened emerging markets; no systemic collapse — no G20 cascade, no sustained 2× freight regime, no de-anchoring of expectations.

Scope discipline: the banded base case, tested two-sidedly — falsified by negligible pass-through, by physical collapse of the premise, or by a breach into the tail. Physics is graded evidence, not the claim; no re-litigation of ENSO science.

What would prove it wrong

F1 kills the causal premise: post-mortem on the alarm. F2 and F3 must fail together to kill the economics — event physically real, economically negligible. F4 kills the band from above: tail vindicated, Leg A confirmed. Confirmation is positive, not survival: transmission signals in the releases that adjudicate F2, an attributable easing delay in the F3 record, the La Niña whiplash beginning on schedule. No condition fires merely because a date passes without drama.

Two disciplines are pre-registered: F1 is decided on ONI v6 only, revised values included, since values can shift for two months after posting (Huang et al., 2025; NOAA CPC) — every physical claim here names its thermometer — and F2/F3 stay inadmissible until their baselines (the OIS paths, the Sep-2026 CPI food+energy share, the Drewry/BDI freight baseline) are verbatim on the record. A discipline, not an escape hatch.

Where things stand

Supporting: August’s monthly anomaly (≈ +2.45 °C, ONI convention) exceeds the peak of every prior event except 2015–16 — the fastest development on record (Carbon Brief, 2026-09-21/30). WMO’s first-ever unequivocal Update (2026-09-03) expects a very-strong peak late in 2026 on subsurface heat above +8 °C. Fourteen systems, 674 runs, project a Nov–Jan peak near +4.1 °C; the source cautions: extrapolation — no system verified at an event of this size, models ran the summer about 0.3 °C warm.

The first transmission flicker, moderate grade: FAO’s index averaged 136.0 in September, +5.8 % YoY near a four-year high, sugar +6.1 % m/m, FAO citing weather and transport concerns (FAO press release, 2026-10-02). Peru’s ENFEN commission holds an El Niño Costero alert in force (Comunicado 16-2026, 2026-09-14) — a coastal, not basin, frame. Impact channels are live: Indonesian fires on track for the century record (Carbon Brief, 2026-09-11), plus a positive Indian Ocean Dipole (SON +0.9 °C) and warm tropical Atlantic that compound agriculture impacts and muddy attribution (WMO Seasonal Update).

Against, at full strength: the record is metric-dependent. On RONI the event sits ≈ 0.7 °C below the 1982–83 daily record (Carbon Brief, 2026-09-21/30) — and RONI is NOAA’s official monitoring metric since February 2026 (NWS Statement 26-05); Australia’s Bureau of Meteorology moved to relative indices in 2025, finding conventional anomalies overstate ENSO in a warming climate (BoM, 2025-09-09). History tempers transmission: the IMF’s canonical study finds modest, heterogeneous, short-run price-and-inflation pass-through (WP/15/89, Cashin et al., 2015) — and food prices fell through the 2015–16 peak to a seven-year low (FAO series). Today’s FAO rise mixes weather with transport and war/tariff premia — not decomposable; attributing it to ENSO now would be post-hoc. Absorption capacity (growth, diversified chains, reserves, no mechanical ENSO channel into wage inflation) is an untested scenario, not a fact: the band may err pessimistic too. A band this wide over six quarters risks mid-course unfalsifiability; the mitigation is procedural: verbatim baselines, F2/F4 keyed to published numbers. The counter bites on the “super” adjective and Leg B’s magnitude, not on persistence: a late-2026 exit looks close to implausible.

At registration no falsifier is close: the JAS ONI v6 release (~2026-10-09) is F1’s first adjudication — ≥ +2.5 confirms “super”, < +2.0 the first F1(a) strike; the September CPI (~2026-10-14) locks the F2(a) baseline; the October FAO print (~2026-11-06) shows whether +5.8 % runs toward or away from +15 %; five-year breakevens, 2.37 % (FRED T5YIE, 2026-10-02), sit far under F4(e). Still open: front-month curve shapes for wheat, soy, sugar; which staple export restrictions are active; the next ENFEN bulletin’s substance. Confidence: medium — high on persistence, medium-low on the transmission band.

How to read this series

Each episode carries the full ledger forward — nothing deleted, met conditions stay met, changes only as dated revision entries — until the sunset verdict and honest retrospect. Cadence is irregular, keyed to the release calendar above. Survival is not confirmation: the scorecard moves on published numbers, both directions, or not at all.