El Nino could make 2027 hottest year, scientists say

El Nino could help make 2027 the hottest year recorded, climate scientists said, as the natural Pacific warming cycle adds a temporary heat boost to long-term human-caused climate change.

NOAA puts the odds at 69 percent that the current El Nino will be the strongest in its dataset going back to 1950, using its Relative Oceanic Nino Index. The Climate Brink dashboard, which draws on NOAA satellite-and-buoy sea surface records, says daily sea surface temperatures in the Nino 3.4 region are about 2.6C above a rolling 30-year average.

Climate Brink also aggregates forecasts that put El Nino on course to peak at a 3.9C anomaly in November, above the 3C anomaly detected in the 2015 El Nino.

Climate scientists Zeke Hausfather and Andrew Dessler calculate that El Nino will add a temporary 0.3C to the long-term warming trend, resulting in a 2027 temperature of 1.76C above preindustrial levels. NOAA senior scientist Mike McPhaden gave a similar estimate, saying 2027 could reach 1.7C above preindustrial levels if model forecasts bear out.

El Nino is the warming phase of the El Nino-Southern Oscillation in the tropical Pacific. It develops when trade winds ease and allow warm water to move back east and rise to the surface, changing storm and cloud patterns with effects across the global atmosphere, University of Miami climate scientist Emily Becker said.

Those effects can mean hotter and drier conditions in some places and cooler and wetter weather in others. Indonesia’s long dry season has fed wildfires that have burned hundreds of thousands of hectares. NOAA’s Michelle L’Heureux said stronger events can bring more typical El Nino impacts, though none are guaranteed.

Scientists cited in the article said climate change increases El Nino’s impacts because a greenhouse-gas-warmed atmosphere holds more moisture, while climate change can dry soils and deepen drought where El Nino brings dry conditions. McPhaden said climate change may also be amplifying the El Nino cycle itself, but scientists have less consensus on that question.