For the past year, alarm bells have been going off in climate science: Last year’s average global temperature was so high, shooting up nearly 0.3°C above the previous year to set a new record, that human-driven global warming and natural short-term climate swings seemingly couldn’t explain it....Earth is entering an ominous new phase of accelerated warming, driven by a rapid decline in sunlight-dimming air pollution.

The combination of a 3-year-long La Niña, which suppressed global temperatures from 2020 to 2022, followed by a strong El Niño could account for the unexpected temperature jump, the work suggests. “Earth can do this,” says Shiv Priyam Raghuraman, a climate scientist at the University of Illinois Urbana-Champaign

During La Niña, strong trade winds push warm surface water west along the equator toward Indonesia and pull up a fountain of deep, cold water in the eastern Pacific that helps cool the planet. During El Niño, the winds collapse, allowing warm water to slosh east and shut off the ocean air conditioner.

Their study, published today in Atmospheric Chemistry and Physics, showed such spikes were rare, happening only 1.6% of the time, nearly always during an El Niño. But when a long La Niña set the stage, the probability of a spike jumped to 10.3%. And during those model years, the geographic pattern of warming often matched what occurred last year, such as a large increase in the tropical Atlantic Ocean.