A Historic El Niño Is Coming That Could Cost the World Trillions
Dartmouth climate scientist Justin Mankin says the El Niño now forming (advisory since June, peaking December–February, winding down by spring 2027) is on track to be the strongest on record, exceeding even 2015-16 and 1997-98, with the Australian Bureau of Meteorology projecting a Relative Oceanic Niño Index above 3.3 — a threshold never previously reached. Mankin's own research (with Chris Callahan, published in Science, 2023) found El Niño doesn't just produce a one-time GDP hit but permanently knocks economies off their growth trajectory; the 1997-98 event, estimated at $36bn in losses at the time, is now reassessed at roughly $5.7 trillion in cumulative global output lost by 2003. For the current event, Mankin estimates $10 trillion in global economic losses conservatively over five years, up to $14 trillion in tail scenarios.
The core argument. Justin Mankin, professor of geography at Dartmouth and director of its Climate Modeling and Impacts Group, argues that a record-breaking El Niño is underway, and that El Niño events of this kind do not merely cause a temporary economic shock — they permanently depress a country's growth trajectory. This reframes El Niño from a short-term price-level disruption into a structural macroeconomic event.
The forecast itself. The world has been in an El Niño advisory since June. Every major forecasting approach — statistical models descending from Mark Cane and Steve Zebiak's original 1980s physical model, and newer process-based simulations — currently converges on this event being warmer than the 2015-16 El Niño, previously the strongest on record. The Australian Bureau of Meteorology's Relative Oceanic Niño Index (RONI) is projected to exceed 3.3, a threshold, Mankin notes, that has never been reached before. Peak strength is expected in the Northern Hemisphere winter (December–February), with the event winding down by February–March 2027.
On the record
| Claim | Speaker | Expression | Horizon | Hedge | At | Status |
|---|---|---|---|---|---|---|
| Justin Mankin says every major El Niño forecasting method (statistical and process-based physical models) is converging on the current, unfolding El Niño being a record event since at least 1950, warmer than the previous record-holder, the 2015-16 El Niño. | Justin Mankin | El Niño intensity vs. 2015-16 record > | 2027-03-31 | base-case | 00:14:52 | OPEN |
| Mankin estimates the forthcoming El Niño will cause conservatively around $10 trillion in cumulative global economic losses over the next five years, with tail scenarios reaching up to $14 trillion, though only about 70% of that base estimate is supported by historical (in-sample) data, since a record El Niño layered on existing global warming is statistically out of sample. | Justin Mankin | cumulative global economic losses (USD) between 10000000000000 | 2031-08-14 | base-case | 00:45:13 | OPEN |