El Niño tops 2015 on a trend-adjusted index whose data starts in 2008
Australia's Bureau of Meteorology says weekly average sea-surface temperatures in the central Pacific are at a record weeks before El Niño's December peak. Planners in exposed sectors still have 1997-98 and 2015-16 as their closest guide, because the record describes ocean heat and no source yet counts this year's damage.
The Scientist · Science desk
What happened
- A separate record came in September, when scientists declared the highest daily sea-surface temperature in the central-eastern Pacific, beating the mark set in the 2015 El Niño.
- Temperatures above 30C were recorded for the first time in parts of the tropical Pacific, with record temperature anomalies and exceptional subsurface warmth.
- The World Meteorological Organization says drought and flood disruption is already being reported in several regions, with food security concerns in parts of East Africa and the Asia-Pacific.
Why it matters
- What it limits constraint Planners cannot scale 2015 loss figures by ocean temperature alone, because the BBC reports that an El Niño's strength does not automatically set impacts at any one location.
- Who's exposed exposure The regions hit in 1997-98 and 2015-16 (south-east Asia, southern Africa, East Africa) are the obvious places to test supply chains and food-security exposure first.
- Who has to decide decision Treating 2015-16 as the stress case is supportable on this evidence; budgeting for outcomes beyond it is a bet the sources do not back.
- What doesn't add up contradiction Hausfather calls the event unprecedented, yet the World Meteorological Organization sees no evidence that climate change makes El Niño events stronger, and part of the raw warmth is background ocean warming.
The comparison with 2015 rests on a short record. Raw sea-surface readings now include background ocean warming from climate change, which the BBC reports is starting to mask the strength of the natural El Niño signal [4]. Australian and US forecasters therefore use a Relative Ocean El Niño Index to strip that extra warming out and compare events across history [4]. On that index, the Bureau's average weekly data now exceed levels in December 2015, but the series only goes back to 2008 [5]. Of the four earlier events the BBC lists, only 2015-16 falls inside it [20].
A reading above 30C is a raw temperature. Raw temperatures carry the background warming the index removes, so a raw record is easier to set today than it was in 2015, by an amount the BBC does not quantify [3][4].
Dr Zeke Hausfather, a climate scientist at Berkeley Earth, told the BBC: "We are currently witnessing an El Niño event that is unprecedented in the historical record" [6]. He also said "The strength of El Niño this year is spilling out of the traditional El Niño region" [8]. The BBC's comparison with the events of 1972-73, 1982-83, 1997-98 and 2015-16 shows much more widespread warmth across the Pacific and into the Gulf of Mexico [7]. Part of that reflects long-term ocean warming, but not all of it [19].
Impacts are a separate question. In 1997-98, severe drought in south-east Asia contributed to extensive peat and forest fires, while parts of East Africa had devastating floods [11]. In 2015-16, drought and wildfire returned to south-east Asia, and southern Africa had one of its worst droughts in decades, which triggered a major humanitarian crisis [12]. Strong events also tend to suppress Atlantic hurricanes and boost Pacific activity, a pattern the BBC says has been seen in 2026 [13]. The most widespread impacts are expected later this year and into 2027, so what has been counted so far is early [18].
In our view, 2015-16 is the right stress case for planning, and a record index is a fair reason to test against it. The sources do not support going further and expecting worse outcomes than 2015. An ocean temperature index cannot say where the drought, fire and flooding will land.
According to the World Meteorological Organization, there is no evidence at present that climate change is driving stronger or more frequent El Niño events, and the BBC notes that remains an active area of research [9]. El Niño releases extra ocean heat into the atmosphere, and with human-driven warming that is expected to make 2026 one of the warmest years on record, with high global temperatures likely to continue into 2027 [17]. Hausfather called the latest projections "astonishing" and said they are likely to set new records "by a remarkable amount" [16].
What to watch
- Whether December readings from the European and US forecasting centres match the predicted peak, and whether the trend-adjusted index stays above its December 2015 level.
- First measured regional losses in south-east Asia, southern Africa and East Africa, which would be the first like-for-like impact data against 2015-16.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence68
- Adoption
- Insufficient
- Hype gap+20
- Incentives
- Insufficient
- Confidence62
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Australia's Bureau of Meteorology said average weekly sea-surface temperatures in the central Pacific have reached their highest level on record.
- [2]
Scientists declared a new record for daily sea surface temperatures in the central-eastern Pacific in September, exceeding the previous record set during the very strong El Niño of 2015.
- [3]
Temperatures above 30C have been recorded for the first time in parts of the tropical Pacific, alongside record sea-surface temperature anomalies and exceptional subsurface warmth.
- [4]
The Pacific is also warming due to human-induced climate change, which is starting to mask the strength of the natural warming during El Niño; Australian and US official forecasters now use a Relative Ocean El Niño Index (RONI) to remove this additional warming signal and compare with historical events.
- [5]
Using the RONI measure, the Bureau of Meteorology's average weekly data, which only goes back to 2008, now exceeds levels during the record-breaking December of 2015.
- [6]
"We are currently witnessing an El Niño event that is unprecedented in the historical record," Dr Zeke Hausfather, a climate scientist at Berkeley Earth, told the BBC.
- [7]
Comparisons with previous major events in 1972-73, 1982-83, 1997-98 and 2015-16 show much more widespread ocean warmth across the Pacific and into the Gulf of Mexico.
- [8]
"The strength of El Niño this year is spilling out of the traditional El Niño region," Dr Hausfather said.
- [9]
The World Meteorological Organization says there is currently no evidence that climate change is making El Niño events stronger or more frequent, though it remains an active area of scientific research.
- [10]
The strength of an El Niño does not automatically determine the scale of impacts in any one location, and regional effects can vary considerably from one event to another.
- [11]
During the 1997-98 event, severe drought across south-east Asia contributed to extensive peat and forest fires, while parts of East Africa experienced devastating floods.
- [12]
During the 2015-16 El Niño, severe drought and wildfire activity returned to parts of south-east Asia, while southern Africa experienced one of its worst droughts in decades, triggering a major humanitarian crisis.
- [13]
Strong El Niño events typically suppress Atlantic hurricanes while boosting activity across parts of the Pacific, a pattern that has also been observed during 2026.
- [14]
The World Meteorological Organization says drought and flood-related disruption is already being reported in several regions, with growing concerns over food security in parts of East Africa and the Asia-Pacific.
- [15]
Forecasts from the European Centre for Medium Range Weather Forecasts and the US National Oceanic and Atmospheric Administration indicate El Niño is likely to peak in December.
- [16]
Dr Hausfather said the latest projections were "astonishing" and are likely to set new records "by a remarkable amount".
- [17]
El Niño releases additional heat from the oceans into the atmosphere; combined with human-driven climate change, that is expected to help make 2026 one of the warmest years on record, with unusually high global temperatures likely to continue into 2027.
- [18]
The most widespread El Niño impacts are expected later this year and into 2027, although its influence is already being felt across parts of the world.
- [19]
Part of the widespread Pacific warmth reflects the long-term warming of the oceans, but scientists say it is not the whole story.
- [20]
Of the four earlier events the BBC lists (1972-73, 1982-83, 1997-98, 2015-16), only 2015-16 falls within a weekly series that begins in 2008.
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Sources
1 independent publisher whose own reporting we read for this story.
- bbc.co.ukSuper El Niño sets another record as it strengthens to 'unprecedented levels'
1 article · October 13, 2026
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