La Nina Struggles For Survival
Jan 2025 was the hottest on record—a whole 1.7°C above pre-industrial level. February 2025 seems like a repeat of January. Climate watchers expected the world to cool slightly this year on account of the natural La Niña phenomenon, but then the human-driven ocean warming is increasingly overwhelming these natural climate patterns. Each El Niño/La Niña cycle is unique. However, the equatorial Pacific has been witnessing more La Niña or El Niño cycles and minimal ENSO-neutral conditions. The last ENSO neutral year was 2013. Thereafter, it has been oscillating between El Niño and La Niña. Following the lengthy “triple dip” La Niña starting in 2020, the El Niño that developed in 2023 was also unusual, struggling to stand out against globally warm seas. The switch to a weak La Niña has only slightly cooled a narrow stretch along the equatorial Pacific while surrounding waters have remained unusually hot. It may be construed that the natural cooling phases have been less effective at temporarily offsetting the impact of rising greenhouse gas levels on global temperatures.
ENSO: As of end-February 2025, weak La Niña conditions persist in the equatorial Pacific marked by cooler-than-average sea surface temperature in the Nino 3.4 region. This region—a key indicator of La Niña and marker for the Oceanic Niño Index—has remained below the threshold mark of -0.5°C for the second consecutive week. The IRI ENSO plume forecasts equal chances for La Niña and ENSO-Neutral conditions for Feb-Apr 2025. From Mar-May 2025 onwards to Jun-Aug, ENSO neutral conditions are favoured.
The Nino 3.4 index is below the desired threshold of -0.5°C for the last two weeks. The continuation of this trend may result in the collapse of La Niña earlier than expected. The mean value of the Nino 3.4 index for the month of February is -0.5°C, just about the borderline mark. Despite the rise in the temperature in Nino 3.4, the ONI, or the quarter Dec-Jan-Feb, will come around -0.6°C. It means La Niña conditions continue for the quarter Dec-Feb 2025.
IOD: The Indian Ocean Dipole is neutral. The index had crossed the positive threshold at 0.46°C on 09th Feb 2025. On the expected lines, the IOD has dipped. The latest value of the index for the week ending 23rd Feb 2025 was 0.12°C. Such variations in the index at this point in time are very common and have limited significance.
MJO: The Madden-Julian Oscillation is the largest element of intra-seasonal variability in the tropical atmosphere. Unlike a standing pattern like the ENSO, the MJO is a travelling pattern that propagates eastward at approximately 4-6 m/s through the atmosphere above the warm parts of the Indian and Pacific Oceans. The MJO pulse is likely to shift eastward from the Western Hemisphere and Africa to the Indian Ocean in the next fortnight. The Indian Ocean, south of the equator, is a very active basin. There are five tropical storms, nearly aligned east-west, in the open ocean waters. Two storms are close to Madagascar, two on the peripheral east coast of Australia, and one in the middle of the ocean between Madagascar and the west coast of Australia.
Nino indices are wavering across the tropical Pacific. Two to three more weeks are needed to read of ENSO firmly. La Niña 2025 could be just ‘touch and go.’. This La Niña may go on record as the shortest-duration event since the time records began.
