Strong El Nino receding; will monsoon be spared?
2023-24 El Nino, one of the five strongest on record, to impact global climate for at least half of the year, with above-normal temperatures and possible heatwaves.
The 2023-24 El Nino has peaked as one of the five strongest on record and will continue to impact global climate for at least half of this year despite a gradual weakening trend, the World Meteorological Organisation said on Tuesday. Indian experts separately said they saw it as a positive development, with likely no impact on the monsoon as the El Nino usually does.
In its Global Seasonal Climate Update, the UN agency has predicted above-normal sea-surface temperatures over much of the global oceans leading to above-normal temperatures over most land areas in the next three months. These temperatures are also likely to influence regional rainfall patterns, WMO said.
“There is about a 60% chance of El Nino persisting during March-May and a 80% chance of neutral conditions (neither El Nino or La Nina) in April to June,” the agency said.
Typically, an El Nino has the greatest impact on the global climate in the second year of its onset — which is 2024 this time.
“Our studies confirm heat wave frequency is more the year following an El Nino. We should expect above normal temperatures and heat waves during this summer. Even though El Nino is waning we should expect its impact till June this year,” said M Rajeevan, former secretary, ministry of earth sciences and climate scientist.
“But it will not have any adverse impact on Indian monsoon,” he added.
The El Nino phenomenon refers to a warm phase of ENSO, which has a major influence on weather and climate patterns. In India, El Nino is associated with harsher summer and weaker monsoon.
La Nina, meanwhile, is associated with strong monsoon and above average rains and colder winters. It has a cooling influence in India and brings about unusual spring and summer.
El Nino, a naturally occurring climate pattern, occurs every two to seven years and typically lasts nine to 12 months.
“It is… associated with warming of the ocean surface in the central and eastern tropical Pacific Ocean. It influences weather and storm patterns in different parts of the world,” the WMO update said, as it went on to explain that the 2023-24 onset happened “in the context of a climate being changed by human activities”.
The WMO update came months after 2023 ended as the warmest year on record. But experts have maintained that despite the El Nino contributing to the record temperatures, heat-trapping greenhouse gases remain the main culprit.
“Every month since June 2023 has set a new monthly temperature record — and 2023 was by far the warmest year on record. El Nino has contributed to these record temperatures, but heat-trapping greenhouse gases are unequivocally the main culprit,” WMO Secretary-General Celeste Saulo said.
“Ocean surface temperatures in the equatorial Pacific clearly reflect El Nino. But sea surface temperatures in other parts of the globe have been persistently and unusually high for the past 10 months. The January 2024 sea-surface temperature was by far the highest on record for January. This is worrying and cannot be explained by El Nino alone,” Saulo said.
The current El Nino event, which developed in June 2023, was at its strongest between November and January. It displayed a peak value of about 2°C above the 1991 to 2020 average sea surface temperature for the eastern and central tropical Pacific Ocean. This made it one of the five strongest El Nino events ever, though it was weaker than the 1997/98 and 2015/2016 events.
While El Nino is weakening now, above normal temperatures are predicted over almost all land areas between March and May.
There is also a chance of La Nina developing later in the year, but the odds are currently uncertain, WMO said.
HT, on February 4, reported that India is likely to experience a short-lived spring followed by a harsh summer this year according to meteorologists and that El Nino conditions will gradually transition to neutral conditions by June, making way for the onset of La Nina by September.
“We are in complete agreement with the WMO outlook and our seasonal forecast has taken this ENSO outlook in to account,” M Mohapatra, director general, India Meteorological Department, said following the WMO update.
Earlier on Friday, IMD forecast hotter than usual summer months of March to May across most of the country, predicting El Nino conditions to persist for most of this period. This could also result in a higher number of heatwave days.
IMD declares a heatwave if the maximum temperature reaches at least 40°C or more for plains, 37°C or more for coastal regions and at least 30°C or more for hilly areas at two stations for at least two days.
Some regions, however, including the northwest that covers Delhi, could record normal to below normal night-time lows and daytime peaks, especially over the first 15 days of March when a series of western disturbances are predicted to bring rain in these regions.
IMD customarily puts out a forecast for the summer season in the first week of March every year, with the temperatures in the 12-week period from then having significant implications for public health and agriculture. For instance, unusually hot weather or excessive spells of rain in March could hurt a number of winter crops that are close to harvest in April and May.