Record heat wave warning

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Heat waves are likely to await us when El Niño returns in late 2023. This phenomenon, along with the growing climate crisis, will push global temperatures ‘off the chart’.

The return of the El Niño weather phenomenon later this year will cause global temperatures to rise “out of the ordinary” and trigger unprecedented heat waves, scientists have warned.

Early predictions suggest that El Niño will return in late 2023, exacerbating extreme weather around the world and making it “very likely” that global warming will exceed 1.5°C. The hottest year on record, 2016, was driven by a major El Niño.

It is part of a natural oscillation driven by ocean temperatures and winds in the Pacific, alternating between El Niño, its cooler counterpart La Niña, and neutral conditions. Over the past three years, there has been an unusual string of back-to-back La Niña events.

This year is already forecast to be warmer than 2022, which global data ranks as the fifth or sixth warmest year on record. But El Niño occurs during the Northern Hemisphere’s winter and its warming effect takes months to be felt, meaning 2024 is much more likely to set a new global temperature record.

Greenhouse gases emitted by human activities have raised the average global temperature by about 1.2°C to date. This has already led to catastrophic impacts around the world, from heat waves in the United States and Europe to devastating floods in Pakistan and Nigeria, injuring millions of people.

The next big El Niño and unprecedented heatwaves

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Heat wave in the city with the bright sun background. heat wave concept

The next big El Niño is very likely to take us above 1.5°Csaid Professor Adam Scaife, head of long-range forecasting at the UK Met Office. “The probability of having the first year at 1.5°C in the next five year period is now about 50:50“.

We know that with climate change, the impacts of El Niño will be stronger, and this must be added to the effects of climate change itself, which are growing more and more.“, said. “Put those two things together and we’re likely to see record heat waves during the next El Niño.”.

The fluctuating impacts of the El Niño-La Niña cycle can be seen in many regions of the world, Scaife said. “Science can now tell us when these things will happen months in advance. So we really need to use it and be more prepared, from having prompt emergency care to which crops to plant.”.

Professor James Hansen of Columbia University in New York and his colleagues recently said: “We suggest that 2024 is likely to be the hottest year on record. The current La Niña is unlikely to continue for a fourth year. Even a little El Niño should be enough for a record global temperature”. China’s decline in air pollution, which blocks the sun, has also added to warming, he said.

The debate in the scientific community about heat waves

Although El Niño supercharges extreme weather, the degree of exacerbation has been the subject of debate among scientists.

Professor Bill McGuire, University College London, UK, said: “When [llegue El Niño]the extreme weather that devastated our planet in 2021 and 2022 will become insignificant“. While Professor Tim Palmer of the University of Oxford said: “The correlation between extreme weather and average global temperature is not that strong. [pero] the thermodynamic effects of climate change will make the anomalies we get from an El Niño year even more extreme.”

The results of climate models published in early January by the Australian Bureau of Meteorology They indicated the country could go from three years of above-average rainfall to one of the hottest and driest El Niño periods on record, increasing the risk of severe heat waves, droughts and wildfires. In December, the US National Oceanic and Atmospheric Administration put the chances of an August-October El Niño at 66%.

The scale of the probable El Niño was not yet clear. Professor Andy Turner of the University of Reading said: “Many seasonal forecast models suggest the arrival of moderate El Niño conditions from summer 2023 onwards.“. The picture would be much clearer by June, the scientists said.

The El Niño-La Niña phenomenon responsible for climate differences

The El Niño-La Niña phenomenon is the main cause of climate differences from one year to the next in many regions. In La Niña years, the east-west trade winds from the Pacific are strongest, pushing warm surface waters to the west and pulling deeper, colder waters to the east. El Niño events occur when the trade winds subside, allowing warm waters to spread eastward, smothering cooler waters and causing global temperatures to rise.

Nations bordering the western Pacific, including Indonesia and Australia, experience hotter and drier conditions. “They tend to have a lot of droughts, a lot of forest fires.Scaife said, although China may experience flooding in the Yangtze basin after El Niño.

Indian monsoons and southern African rains can also be suppressed. Other regions, such as East Africa and the southern United States, which have suffered recent droughts, could experience more rain and flooding. In South America, the southern regions are wetter, but the Amazon, already approaching a dangerous tipping point, is drier.

The effects of El Niño can also be felt up to mid-latitudes in the Northern Hemisphere, with wetter conditions likely in Spain starting in the summer and drier conditions on the US East Coast in the following winter and spring.“, said. Turner.

The biggest unanswered question

Palmer said the biggest unanswered question is whether climate change has favored more El Niño or La Niña events: “This is vitally important for countries seeking long-term adaptation, and they will need much higher resolution climate models. This can only happen with larger computers.”.

Palmer and his colleagues have called for the establishment of a billion-dollar international climate modeling center, similar to the Large Hadron Collider, that allows international particle physicists to do together what no nation can do alone.

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