Sea-surface temperatures are expected to reach ‘record levels’ as forecasters warn this El Niño could be one of the strongest since at least 1950
El Niño is “strengthening rapidly” just weeks before its expected peak in December, forecasters say.
El Niño, a climate phenomenon that happens every two to seven years when temperatures in the tropical eastern Pacific rise 0.5C above the long-term average, influences weather patterns across the world. It can increase the chances of wetter and stormier conditions across north-west Europe, including the UK, in autumn and early winter, and may also increase the risk of cold spells in late winter.
The World Meteorological Organization (WMO) said in its latest update that sea-surface temperatures in the central and eastern tropical Pacific are expected to rise to “record levels” in October, November and December, “reflecting the strengthening of the El Niño event”.
WMO Secretary-General Celeste Saulo said last week: “El Niño is firmly established and strengthening rapidly. WMO forecasts indicate a near-100 per cent likelihood that it will persist through February 2027, potentially being one of the strongest since at least 1950.”
She said the near-certainty figure reflects a consensus among 13 national and international centres – from Washington to Tokyo to London to Pune – built on real-time exchange of ocean buoy, satellite and radiosonde data.
For October, November and December, the seasonal average sea-surface temperature anomaly is forecast to reach approximately +3.7C, peaking around December. This would be the highest on record, surpassing the previous record of +2.6C, recorded between November 2015 and January 2016.
Following its peak, El Niño “tends to promote the breakdown of the polar vortex, especially in late winter”, the US government’s NOAA Chemical Sciences Laboratory states.
The weakening of the polar vortex – a band of strong westerly winds surrounding a pool of cold air high in the stratosphere – “may raise the chance of Sudden Stratospheric Warming events, which can increase the potential for cold weather”, the Met Office says.
The national weather service says several extreme cold and winter snow events have been linked to the surface effects of sudden stratospheric warmings, including those in 2009-10 and 2013, and the “Beast from the East” in 2018.
The so-called “Big Freeze of 2010”, which saw the winter of 2009-10 become the coldest in three decades at the time, coincided with an El Niño event. However, some scientists say past evidence is mixed, noting that 2006-2007 was also an El Niño winter but was unseasonably warm.
Strong El Niño events are typically associated with a rise in global average temperatures because additional heat is released from the ocean into the atmosphere, which then spreads around the globe, further warming other ocean basins, the Met Office says.
Exceptionally strong El Niño events can therefore contribute to record-breaking global temperatures in the year following their peak.
The current event is developing against a backdrop of long-term human-induced climate change, meaning its effects are superimposed on an already warming climate, the Met Office notes.
