MELBOURNE, Australia – El Niño continues and is near its end. Climate models indicate sea surface temperatures in the central tropical Pacific are expected to return to ENSO-neutral later in autumn 2024, reports the Bureau of Meteorology (BoM) of the Australian government in its latest update released on March 19th.
Atmospheric indicators are consistent with a decaying El Niño. Cloudiness near the equatorial Date Line is slightly below average. The 90-day Southern Oscillation Index (SOI) is currently −3.7, indicative of ENSO-neutral conditions.
International climate models suggest the central tropical Pacific Ocean will continue to cool in the coming months, with four out of seven climate models indicating the central Pacific is likely to return to neutral El Niño–Southern Oscillation (ENSO) levels by the end of April (i.e., neither El Niño nor La Niña), and all models indicating neutral in May.
While three out of seven international models are predicting a La Niña by late winter, El Niño and La Niña predictions made in early autumn tend to have lower accuracy than predictions made at other times of the year.
This means that current forecasts of the ENSO state beyond May should be used with caution. ENSO forecasts have historically had their lowest skill for forecasts issued in April, with skill increasing from May.
The oceans have been the warmest on record globally since April 2023. Sea surface temperatures continue to increase with temperatures in February 2024 setting a record for that month, and March 2024 on track to be the warmest March on record. The Atlantic Ocean in particular is showing exceptional and prolonged warmth in sea surface temperatures.
This global pattern of warmth is affecting the typical, historical global pattern of sea surface temperatures associated with ENSO variability. Since we have never observed global sea surface temperatures like this before, inferences of how ENSO may develop in 2024 that are based on past events may be less useful.
Although the most recent value of the Indian Ocean Dipole (IOD) index (+0.86 °C) is above the positive IOD threshold, the IOD is neutral. Sustained values of the IOD index above the threshold are required for an IOD event to form. The eastern Indian Ocean has cooled in recent weeks, due to increased monsoonal activity in the area, including tropical low 08U.
The Southern Annular Mode (SAM) is currently negative, as of 17 March. Forecasts indicate SAM will return to neutral during the coming week.
A strong Madden–Julian Oscillation (MJO) is currently in the Western Pacific. The majority of climate models indicate that the MJO will move east to the Western Hemisphere in the coming days, then likely weaken significantly in the equatorial Africa in late March.
The annual global mean temperature for the 12 months from February 2023 to January 2024 was the highest on record, with Copernicus reporting that it was 1.52 °C above the 1850–1900 pre-industrial average. However, this does not mean that the 1.5 °C target referred to in the Paris Agreement has been exceeded as the magnitude of global warming is assessed using multi-year averages, and this is only one 12-month period.
