Scientists warn of high probability of El Nino onset this year

Early data that shows the high probability of the El Nino climate pattern this year has caused experts to warn of a potentially warmer summer, although they admit that it's premature to assess its impact on the annual monsoon rains.

There is an almost 50% probability of El Nino conditions prevailing during summer months of June, July and August, and a 58% probability in July, August September according to the latest probabilistic estimates of the US National Oceanic and Atmospheric Administration (NOAA) that were released Thursday. Both these numbers are higher than the chances of a neutral condition.

After three successive years of the La Nina effect, scientists around the world have been anticipating the emergence of El Nino conditions . According to the latest data, there is a low probability of this happening in March-April-May, rising to around 15% in April-May-June, and around 37% in May-June-July.

El Nino is characterised by an unusual warming of waters in the eastern equatorial Pacific; its opposite, La Nina is characterised by unusually cooler waters in the same area. Together, the phenomenon is called the ENSO (El Nino Southern Oscillation), and it has a high correlation with warmer summers and weaker monsoon rains in India.

The India Meteorological Department or IMD also has an outlook similar to NOAA's. "La Nina conditions are weakening. There is a high chance of neutral ENSO conditions during the pre-monsoon season. Thereafter there is a 50% probability of El Nino conditions emerging during monsoon. It's difficult to comment on its impact immediately. The forecast is not accurate when there is still three-four months for the El Nino season to begin. We will issue our latest ENSO forecast on 28 February," said M Mohapatra, director general, IMD.

The move from La Nina to El Nino, a given in light of the data, is itself worrying, said an expert.

"An evolving El Nino is more dangerous than El Nino conditions existing for some time. We are seeing El Nino conditions evolve now. Very soon ENSO neutral conditions will be recorded and then El Nino will develop during monsoon. A moderate El Nino is likely to impact the monsoon. It can lead to lower rainfall but we cannot say immediately if the monsoon will be below normal. It is unlikely to be an excess monsoon year. Despite La Nina conditions so far we have seen above normal temperatures and even a severe heat spell last spring. This spring may not be as bad but temperatures are expected to be above normal in February and March is expected to be warm. Summer temperatures may be very high," said Mahesh Palawat, Vice President, Climate and Meteorology, Skymet Weather, a private forecaster.

The current La Niña has been relatively weak but unusually prolonged. It began in 2020 and returned for its third consecutive northern hemisphere winter making it a rare "triple-dip" event.

"A moderate El Nino can impact the monsoon. It can pull down the rainfall volume , but at the moment, it is difficult to say if it will be a below normal monsoon. If there are positive Indian Ocean Dipole conditions during those months then that can help the monsoon. We have to monitor other parameters also closely," said M Rajeevan, secretary, ministry of earth science, referring to another weather phenomenon, this one concerning temperature differentials in the Indian Ocean.

Rajeevan said it is certain that 2023 will see a harsh summer and recommended early adaptation plans. "I am very sure it will be a harsh summer. The warming of the Pacific will have widespread impacts. It's important that we have heat adaptation plans ."