The story so far: El Nino , meaning ‘the little boy’ in Spanish, has emerged as one of this year’s most widely discussed climate phenomena. The exceptional warming of sea surface temperatures in the central and eastern Equatorial Pacific Ocean is already influencing weather disruptions worldwide and is also hitting hard on Indian monsoon.
With the Southwest monsoon beginning to retreat and leaving rainfall deficits across parts of India, El Nino is being closely monitored as meteorologists await its impact during the ensuing northeast monsoon in the southern peninsula, including Tamil Nadu. El Nino is one of the key climate signals being closely watched this year While several weather factors influence the monsoon. Sea surface temperatures across the central-eastern equatorial Pacific are well above average and are continuing to rise. The World Meteorological Organisation has warned that a very strong El Nino can significantly shift rainfall and temperature patterns across the world and fuel extreme weather events. However, strong El Nino conditions alone do not determine the severity of impact over various regions. The significance of El Nino comes against the backdrop of a rapidly warming world. El Nino years are normally associated with fewer weather systems forming over Bay of Bengal, with many of them tending to be less intense. Most systems would have a westwards track towards Tamil Nadu-Andhra Pradesh coasts. However, El Nino may not be the only factor for extreme weather events like prolonged dry period or urban flooding.
The widely used Niño 3.4 index, which measures sea surface temperature anomalies in the central-eastern equatorial Pacific, has strengthened considerably to an average of +2.51 degrees Celsius, which is well above the El Nino threshold. (+0.80 degrees Celsius). Some models indicate that it may peak above +3.0 degree Celsius in the coming months. 2024 was the warmest year in record, with the global temperature exceeding 1.5 degree Celsius threshold set by the Paris agreement. 2023 and 2025 were also some of the warmest years.
Including the Australian government’s Bureau of Meteorology, both oceanic and atmospheric indicators are consistent with a strong El Nino, according to models from various countries. Its effects may vary according to region and seasons and may be altered by other climate drivers like Indian Ocean Dipole and conditions in the Indian and Atlantic Oceans, noted international meteorological agencies. Rising global temperatures and climate change fueled by urbanisation and changes in land use and land cover could amplify its impact, said Mr.Pai.
Why is upcoming monsoon rainfall important?
The Tamil Nadu government has formed an Expert Advisory Committee to monitor and assess the potential impact of a strong El Niño and advise the government on preparedness and mitigation measures. IMD and Tamil Nadu Disaster Risk Reduction Agency are planning to host a northeast monsoon seasonal outlook forum on October 1.
