Believe it or not, average global surface temperatures have actually been relatively cool over the last three years — but that's about to change.

Why it matters: Temperatures are expected to jump this year — and 2024 could set a new global record.

The big picture: A rare "triple dip" La Niña in the tropical Pacific Ocean kept temperatures in check in 2022, with the year ranking fifth-warmest since instrument records began.

• La Niña events are characterized by cooler-than-average waters in the equatorial tropical Pacific, and tend to put a lid on global temperatures.
• But 2022 still wound up as the fifth warmest year on record according to NASA and the Copernicus Climate Change Service. And if the phenomena dissipates, as forecasts increasingly indicate, global temperatures would likely jump this year and even more so next year.
• If an El Niño event — characterized by milder than average ocean temperatures — sets in across the tropical Pacific, 2023 could even meet or come close to hitting a record high.

What they're saying: "I forecast about a 15% possibility of a new record in 2023. And if we are in an El Niño by the end of 2023, an almost certainty of a new record in 2024," Gavin Schmidt, who heads NASA's Goddard Institute for Space Studies in New York, told Axios via email.

Zoom in: According to NASA, the record-warmest year occurred in 2020 and 2016, the latter of which occurred when there was a major El Niño underway. This has led some climate change doubters to claim that global warming halted in 2016.

• However, surface temperatures are just one sign of global warming. Other climate indicators all showed signs of continued global warming during 2022. Ocean heat content hit a record high, a recent study found.
• Glaciers continued to shrink, sea levels kept rising, and extreme weather and climate events continued to batter countries around the world.
• Studies tied many of these deadly extreme events to human-caused climate change.

What's next: This year looks milder than the last few years have been. It has a decent chance of at least making it into the top five, if not the top three warmest years, depending on how a transition to an El Niño plays out.

• Then 2024 has a higher likelihood of setting a new record, scientists told Axios. This is in part because there is a lag in the atmosphere's response to El Niño.

Threat level: The U.K. Met Office is forecasting that global average temperatures in 2023 will be at least 1.2°C (2.16°F) above the pre-industrial average. Keep in mind that the Paris Agreement tries to limit warming to 1.5°C.

• If warming exceeds this goal, studies show, the odds of potentially devastating climate change consequences will increase, such as greater melting of the polar ice sheets and the loss of tropical coral reefs.
• Zeke Hausfather, climate research lead at payments company Stripe, said 2023 looks warmer than the past few years, but pinpointing exactly how much is difficult at this point.
• "Given lags in the surface temperature response a transition to El Niño conditions in the latter half of 2023 would have more of an impact on 2024," he said via email.