THE past year was the hottest on record, but 2023 is unlikely to hold that dubious honour for long. 2024 is expected to be even hotter, as the El Ni帽o climate pattern in the Pacific Ocean reaches its full strength on top of warming driven by greenhouse gases. 鈥淲e鈥檝e never had a big El Ni帽o like this on the background of global warming,鈥� says at the Met Office, the UK鈥檚 national weather service. 鈥淲e are really entering an unprecedented situation.鈥�
According to preliminary numbers from the World Meteorological Organization鈥檚 (WMO), global average temperatures in 2023 were about 1.4掳C above the pre-industrial average measured between 1850 and 1900. That smashed the previous record from 2016 by more than 0.1掳C. 鈥淭hat鈥檚 a big jump, equivalent to five years of global warming,鈥� says Scaife.
Factors that made 2023 so hot are likely to push the dial even further next year, possibly raising the annual average above the totemic 1.5掳C target for the first time. (Omar Baddour at the WMO says one dataset suggests temperatures in 2023 may have exceeded 1.5掳C, but the actual number is likely to be lower.)
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The most significant of these factors is global warming driven by the rising concentration of greenhouse gases we are releasing into the atmosphere, which was responsible for about 1.28掳C of the rise seen in 2023.
The other major factor is the shift to warmer El Ni帽o conditions in the Pacific after the colder La Ni帽a pattern persisted for three years in a rare 鈥渢riple dip鈥�. Historically, the warming influence of El Ni帽o is greater the year after it first develops, as the anomaly strengthens into December and January. 鈥淯sually, El Ni帽o is a synonym of extreme events around the world,鈥� says Baddour.
Other, smaller factors behind 2023鈥檚 heat, such as unusually hot temperatures in the North Atlantic Ocean and a volcanic eruption in 2022 that injected water vapour into the upper atmosphere, may also add to next year鈥檚 temperatures. 鈥�2024 is going to be extreme,鈥� says Scaife.
at the Woodwell Climate Research Center in Massachusetts anticipates 鈥渃ontinuing weirdness, surprises and records broken by large margins鈥� in 2024. While we could see the classic impacts of a strong El Ni帽o 鈥� for instance, drought and heat in South America, Australia and South-East Asia 鈥� unusual combinations of ocean temperatures could affect the jet stream that drives weather in unexpected ways.
鈥淭his combination of factors has never occurred in recorded history, so predictions about [the next few months鈥橾 weather are particularly murky,鈥� she says.
Still, Francis says she would be very surprised if the global average temperature for all of 2024 rose more than 1.5掳C above the pre-industrial average. Scaife says it is hard to say without clear forecasts, but thinks it is possible we see average temperatures next year rise above 1.5掳C.
Crossing this threshold for a single year wouldn鈥檛 be a breach of the Paris agreement target to keep temperatures below 1.5掳C 鈥� that would require the 20-year average to rise 1.5掳C above the pre-industrial average.
But Scaife points out this has little bearing on the impacts of that heat on people and ecosystems right now. 鈥淲hether it slightly tips over or not makes no difference,鈥� he says. 鈥淭he point is we鈥檙e very close.鈥�
