El Niño officially develops amid record weather extremes: NOAA

El Niño, the ocean and atmosphere cycle in the tropical Pacific that can supercharge global extreme weather events, is officially back after about a four-year hiatus, NOAA announced Thursday morning.

Why it matters: El Niño holds large sway over global weather patterns. It is likely to increase global average surface temperatures, leading to an all-time record warm year in 2023 or 2024, surpassing the El Niño year of 2016.

• El Niño will also contribute to heat waves, droughts, floods and other weather extremes, which already are worsening from human-caused climate change.
• It is influencing the North Atlantic hurricane season, making for an especially uncertain outlook.

Zoom in: El Niño events are characterized by unusually warm sea surface temperatures in the equatorial tropical Pacific, particularly across the central and eastern Pacific.

• NOAA's advisory on Thursday morning indicates that both ocean temperatures and atmospheric conditions are sufficient for an El Niño to be declared.
• During an El Niño, the ocean conditions in turn drive atmospheric responses. These include a reversal of the typical trade winds across the ocean basin and shifts, where heavy tropical downpours tend to develop near the equator.

The intrigue: Some climate scientists and meteorologists told Axios they are looking toward the coming months to a year or more with trepidation and curiosity, given that the oceans already are record-warm going into the event, and are now likely to get even warmer.

• “The global oceans are very warm right now and I’m afraid that this is putting us into territory that we don’t have much experience with,” Michelle L'Heureux, chief of Climate Prediction Center's El Niño-Southern Oscillation team, said in an interview.
• And on land, scorching heat waves have struck large swaths of Asia this spring, while Canada is amid what is likely to be its worst wildfire season on record.
• Fires burning in Quebec turned the skies in New York City a bright, otherworldly orange on Wednesday.
• Given that El Niño years tend to yield global temperature milestones and are associated with notable extreme weather and climate events, L'Heureux said this event could provide a preview of what our typical climate will look like in a decade or two as warming continues.
• “It is a little bit nerve-wracking,” she said.

Of note: The natural climate phenomenon now occurs against a backdrop of a rapidly warming planet being worsened by human emissions of fossil fuels. It makes the evolution and impacts more uncertain — and potentially more significant, experts told Axios.

• NOAA's Climate Prediction Center forecasts this El Niño has an 84% likelihood of exceeding moderate intensity and a 56% chance of reaching "strong" criteria.

Between the lines: Zeke Hausfather, climate research lead at payments company Stripe, said that El Niño's development means there is about a 30% to 50% chance that 2023 will set a record for the warmest year in instrument records, which date back to 1850.

• However, 2024 is even more likely to do so, provided the El Niño continues to develop and strengthen.

• Kim Cobb, director of the Institute at Brown for Environment and Society who is the first climate scientist to sit on the president's intelligence advisory board, said the next annual temperature record may be considerably higher than 2016's.
• "A new global temperature record is by no means an unusual occurrence of late, but I suspect the magnitude of any new El Niño-related new record may be shocking to many, as it was in 2016," Cobb said in an email.

Yes, but: While it's clear that ocean temperatures and atmospheric conditions now support the El Niño designation, it is not guaranteed to continue developing into a long-lasting event, L'Heureux cautioned.

• In fact, the extraordinarily warm sea surface temperatures present across the tropical Pacific Ocean could complicate its intensification, since typically the waters in the western Pacific are cooler than they are now. That affects weather patterns in the central and eastern Pacific integral to El Niño's progression.
• “It also makes me wonder how the event is going to unfold going forward,” she said, noting the record-warm oceans have the potential to cause a "black swan" outcome.

What they're saying: Cobb said she is particularly concerned about El Niño's ocean-related effects.

• "Going into this El Niño with record-breaking ocean temperatures in many basins is worrying, from the standpoint of marine ecosystems, given that this El Niño will drive additional ocean warming," Cobb said.
• "Many ecosystems, including many coral reefs, are still reeling from the impacts of the 2016 El Nino-related marine heat waves."