‘Collapse could be precipitous’: Super El Niño could push coral reefs to extinction

A potentially record-breaking super El Niño could push the world’s fragile coral reefs closer to extinction as ocean temperatures soar to unprecedented levels, David Obura, chair of the UN’s expert scientific panel on biodiversity, has warned.In an interview with news agency AFP, Obura, a Kenyan marine scientist and coral reef expert who chairs the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), said the developing climate phenomenon posed a major additional threat to already vulnerable coral species.

“This year's El Niño layers a terrifying level of additional risk,” Obura said.Corals are highly sensitive to heat and particularly vulnerable to climate change, which is warming the world’s oceans and increasing the frequency and intensity of damaging bleaching events.The developing El Niño in the tropical Pacific could intensify these pressures, putting some coral species at greater risk of extinction.El Niño is the warming phase of a natural climate cycle that temporarily raises global temperatures and alters cloud and wind patterns, increasing the risk of damaging weather events.Global forecasters expect the current episode to be the strongest on record, while sea surface temperatures in parts of the Pacific have already reached all-time highs months before its anticipated peak.

Obura recalled the devastating effects of the 1997-98 super El Niño, warning that the approaching event could be even more damaging after several major global coral bleaching episodes.“That this coming event is worse than that, after three intervening global bleaching events ... is a terrifying reality,” he said.

Nearly half of coral species face elevated extinction risk

Obura led a major reassessment of coral health published in the journal Nature on Thursday.The study found a sharp deterioration in the condition of reef-building coral species since the previous global assessment in 2008.“Our results show that by 2020, nearly half of coral species were at elevated relative risk of extinction” with climate change the main driver of this decline, Obura and dozens of other scientists wrote.The review examined hundreds of species on the International Union for Conservation of Nature's (IUCN) Red List, including staghorn and table corals. These species build mineral skeletons that give coral reefs their distinctive three-dimensional structure.The findings point to a significant deterioration in conditions for corals, Obura said, attributing the decline to accelerating warming and the continued absence of effective action to curb the broader drivers of coral loss.“This indicates conditions for corals are worsening significantly... not at all surprising given the accelerated warming and lack of abatement of global drivers of coral decline,” he said.However, the assessment was completed in 2020, meaning it does not capture the full impact of the warming and bleaching events that followed.

Record ocean heat raises fears of further reef losses

Since the assessment was completed, global ocean temperatures have climbed to unprecedented levels. The most severe coral bleaching episode on record, between 2023 and 2025, caused widespread mortality across reefs.Obura warned that a fresh assessment conducted after the developing El Niño could show an even larger share of coral species facing an elevated risk of extinction.“It is entirely possible that reassessing the status of corals just after this coming El Nino may show them to have crossed the 50 per cent mark of the proportion of species at elevated risk of extinction,” he said.Scientists warned last year that warm-water coral reefs had almost certainly passed a point of no return as ocean temperatures rose beyond levels that most reefs could withstand.The Nature study also highlighted the implications of projected ocean warming and other pressures, saying they would largely determine when and where conditions became unviable for corals, rather than whether that would happen at all.

Scientists warn reef collapse could happen rapidly

Obura cautioned that the timing of potential reef collapse remained uncertain, with outcomes varying according to when individual reef systems crossed their environmental thresholds.“When they hit their threshold the collapse of reefs in that region could be precipitous and we don't know if that is five, 15 or 30 years into the future, or maybe this year with the super El Nino ramping up?” he said.The developing El Niño has therefore raised concerns about whether already stressed coral ecosystems could withstand another period of extreme ocean heat.The latest assessment, meanwhile, indicates that the risks to reef-building species had already increased substantially by 2020, even before the subsequent record-breaking ocean temperatures and widespread bleaching.