Scientists have issued a warning that the return of the El Niño climate phenomenon later this year will lead to an unprecedented rise in global temperatures and bring about extreme heatwaves.
Early forecasts indicate that El Niño is expected to return in 2023, exacerbating extreme weather events worldwide and making it highly probable that global warming will surpass 1.5°C. The record-breaking year of 2016 was driven by a significant El Niño event.
El Niño is part of a natural oscillation influenced by ocean temperatures and winds in the Pacific, transitioning between El Niño, its cooler counterpart La Niña, and neutral conditions. The past three years have witnessed an unusual series of consecutive La Niña events.
2023 is already projected to be hotter than 2022, which was ranked as the fifth or sixth hottest year on record by global datasets. However, since El Niño typically occurs during the northern hemisphere winter and its heating effect takes months to be felt, it is much more likely that 2024 will establish a new global temperature record.
The greenhouse gases emitted by human activities have already caused the average global temperature to rise by approximately 1.2°C, resulting in catastrophic consequences worldwide, including scorching heatwaves and devastating floods that have affected millions of people.
According to Prof Adam Scaife, the head of long-range prediction at the UK Met Office, it is highly probable that the next significant El Niño event will push global temperatures beyond the 1.5°C threshold. He emphasizes that the impacts of El Niño events will intensify under climate change, further exacerbating the effects already caused by ongoing global warming. Consequently, unprecedented heatwaves are expected during the next occurrence of El Niño.
The fluctuating impacts of the El Niño-La Niña cycle will be observed in various regions worldwide, highlighting the importance of utilizing scientific predictions that can identify these events months in advance. This knowledge should be used to enhance preparedness, from emergency services readiness to informed agricultural practices.
Prof James Hansen from Columbia University, along with colleagues, recently suggested that 2024 is likely to be the warmest year on record, surpassing previous records. It is unlikely that the current La Niña will continue for a fourth year, and even a minor El Niño event would be sufficient to establish a new global temperature record. Additionally, declining air pollution in China, which previously blocked the sun, is contributing to increased heating.
There is ongoing debate among scientists regarding the extent to which El Niño would intensify extreme weather events.
According to Prof Bill McGuire from University College London, when El Niño arrives, the extreme weather experienced in 2021 and 2022 will seem insignificant. On the other hand, Prof Tim Palmer from the University of Oxford argues that while the correlation between extreme weather and global mean temperature may not be strong, the thermodynamic effects of climate change will amplify the anomalies experienced during an El Niño year.
Climate modeling results released by Australia’s Bureau of Meteorology in early January indicated the possibility of a shift from three years of above-average rainfall to one of the hottest and driest El Niño periods on record. This would increase the risk of severe heatwaves, droughts, and fires. The US National Oceanic and Atmospheric Administration estimated a 66% chance of El Niño formation by August-October.
The magnitude of the anticipated El Niño event is still uncertain. Prof Andy Turner from the University of Reading suggests that many seasonal forecast models predict the emergence of moderate El Niño conditions from summer 2023. A clearer picture is expected to emerge by June.
The El Niño-La Niña phenomenon significantly influences weather patterns in many regions. During La Niña years, strong east-to-west Pacific trade winds push warm surface waters westward and bring up cooler water from the depths in the east. El Niño events occur when these trade winds weaken, allowing warm waters to spread eastward, overpowering the cooler waters and leading to global temperature increases.
Countries bordering the western Pacific, such as Indonesia and Australia, typically experience hotter and drier conditions, with increased risks of droughts and wildfires. China may face flooding in the Yangtze basin after significant El Niño events. India’s monsoons and rainfall in southern Africa can be suppressed, while other regions like east Africa and the southern US may experience more rain and flooding. South America’s southern regions tend to become wetter, while the Amazon, already at a critical tipping point, becomes drier.
Turner explains that the effects of El Niño could also extend to the northern hemisphere mid-latitudes, resulting in potentially wetter conditions in Spain from summer onward and drier conditions on the eastern seaboard of the US in the subsequent winter and spring.
One crucial unanswered question is whether climate change favors more El Niño or more La Niña events. Answering this question is essential for countries planning long-term adaptation strategies, requiring higher-resolution climate models that can only be achieved with more powerful computers.
Palmer and his colleagues propose the establishment of an international center for climate modeling with a budget of $1 billion, similar to the Large Hadron Collider, to enable collaboration among scientists from different nations and address climate modeling challenges.
