A warming El Nino event may develop in the coming months after three consecutive years of La Nina, the World Meteorological Organization (WMO) said on Wednesday while warning of a likely spike in temperatures globally this year.
El Nino is characterised by an unusual warming of waters in the eastern equatorial Pacific. Its opposite, La Nina, is defined by unusually cooler waters in the same area. The phenomenon together is called the ENSO (El Nino Southern Oscillation). It has a high correlation with warmer summers and weaker monsoon rains in India.
La Nina, which began in September 2020 with a brief break in the boreal summer of 2021, usually has the opposite impact on weather and climate as El Niño. It has been associated with persistent drought in the Greater Horn of Africa and parts of South America as well as above-average rainfall in South East Asia and Australasia.
In a statement, WMO secretary-general Petteri Taalas said, “If we do now enter an El Niño phase, this is likely to fuel another spike in global temperatures…”
Taalas said the first triple-dip La Niña of the 21st century is finally coming to an end. “La Niña’s cooling effect put a temporary brake on rising global temperatures, even though the past eight-year period was the warmest on record.”
WMO’s warning comes a day after IMD’s on Tuesday said March to May are likely to be severe in most parts of India.
The return of El Nino will be preceded by a period of ENSO-neutral conditions (90% probability) from March to May. The likelihood of the conditions beyond May decreases slightly but remains high, according to the model predictions and assessment from WMO experts.
Long-lead forecasts from June to August indicate a much higher chance (55%) of El Niño developing.
The year 2016 was the warmest on record because of the combination of El Niño and climate change.
A UK Met Office study last year concluded that there is a 93% likelihood of at least one year until 2026 being the warmest on record. It added there is a 50:50 chance of the global temperature temporarily reaching 1.5°C above the pre-industrial era.
A regional climate outlook issued on February 22 warned the drought in the Horn of Africa would worsen.
A return to near-normal ENSO conditions is predicted for the equatorial central and eastern Pacific and warmer-than-average sea-surface temperatures for other oceanic regions. This is likely to lead to above-normal temperatures, WMO warned.
Even though La Niña is coming to an end, likely latent impacts may continue for some time. Therefore, some of the canonical rainfall impacts of La Niña may still continue. The lingering impacts of multi-year La Niña are basically due to its long duration, and continuous circulation anomaly, which is different from the single-peak La Niña event.
IMD on Tuesday said a transition from La Niña to ENSO-neutral was likely from February to April. It added the ENSO-neutral will persist through the northern hemisphere in early summer this year.
IMD indicated a near 50% chance of El Nino conditions from June to August followed by a 60% chance from July to September.
Experts said India should focus on developing heat action plans as soon as possible. “Responding to this forecast, state governments should prepare immediately. Some states have already done this. Heat can have deadly impacts on the vulnerable population,” said former earth sciences ministry secretary M Rajeevan.
