La Niña to trigger more extreme events, intense cold waves, lesser snowfall in India

Mercury across North India has already started dipping, with a cold wave expected to engulf the region very soon

For the second consecutive winter, La Niña is set to make its presence felt and experts are blaming climate change for it. India should expect a drop in snowfall, a prolonged and colder winter season and more extreme weather events. 

What is La Niña?

La Niña is defined as an oceanic-atmospheric phenomenon, El Niño-Southern Oscillation (ENSO), wherein water temperatures in the Equatorial Pacific Ocean become cooler than normal because of the upwelling of cold water from the bottom of the sea. La Niña has the capacity to alter direction as well as velocity of trade winds, which trigger the winter season in India.

What should India expect? 

Experts believe La Niña has an impact primarily on winter rain over North India. The region should expect less rainfall this winter, say meteorologists. Other effects include less snowfall over Western Himalayas, a drop in winter temperatures along with an extended season, and more rain in the second half of the Northeast Monsoon. 

“We know that warming is not going to reduce and whenever there would be poor rainfall during the winter season, it would increase the stress on Himalayan ecology. There would be enhanced climate effects on the vegetation. The situation would be quite troublesome be it for agro-forestry, vegetation or fruit production, etc. There is also a probability of glaciers retreating but at what rate is uncertain,” said Dr Jagdish Krishnaswamy, Dean, School of Environment and Sustainability, Indian Institute of Human Settlements.

This will be the second winter in a row with La Niña. Last year, La Niña developed in August and dissipated in April 2021. North India had a particularly harsh winter last year and a lot of winter precipitation such as freezing rain, snow or sleet.

The effect of global warming on La Niña 

Sea surface temperatures (SST) variability and extreme ENSO events are projected to increase with global warming. According to a research paper, while the possibility of large changes in ENSO cannot be ruled out, current research does not yet precisely say what changes could occur. However, global warming may lead to changes in the characteristic amplitude or frequency of ENSO events. 

If global temperatures continue to rise unchecked, the climate of the Pacific is likely to undergo significant changes. The trade winds will weaken, the pattern of SSTs will change that is likely to be zonally-symmetric with maximum warming on the equator and the thermocline is likely to flatten and become shallow. A thermocline is the transition layer between the warmer mixed water at the surface of the ocean and the cooler deep water below. According to a report by Nature, global warming has increased the frequency of extreme El Niñ that provides a favourable condition for extreme La Niña.