Just about a year after one of the strongest-ever El Niño events ended in 2016, there is a possibility of another later in 2017, though not of the same strength. El Niños have a cycle of about 3 to 5 years — and the event repeating itself so soon is unusual, though not unprecedented. The June to September monsoon season might escape the impact of the El Niño if, as expected, it develops after August — but its effects can be felt in other ways in the post-monsoon months in the country.
El Niño refers to an unusual warming of waters in the equatorial Pacific Ocean off the coast of Chile and Peru. It is known to impact weather events across the world, resulting in excessive rainfall in some areas, while causing dry spells in regions like India, Indonesia and Australia. In India, an El Niño event is strongly linked to suppressed rainfall in the monsoon season. The droughts of 2014 and 2015 were blamed on one of the longest and strongest El Niño events ever recorded, nicknamed “Godzilla”.
Not surprisingly, therefore, El Niños are tracked very closely by Indian meteorologists, especially in the run-up to the monsoon season during which India gets about 75% of its annual rainfall.
Global climate models are predicting a 50% chance of a “weak” El Niño developing in the Pacific Ocean in the latter half of this year, most likely after August. Never before in the last 40 years has the El Niño returned so soon.
“Over the past 35 years, El Niño events happened in 1972, 1977, 1982, 1987, 1991, 1997, 2002, 2009, 2012, and 2015. If an El Niño appears again in 2017, it would be unusual,” said J Srinivasan of the Divecha Centre for Climate Change at the Indian Institute of Science, Bengaluru.
But it is not impossible, he added. El Niños have returned after a gap of 2 years earlier, and sometimes they have not happened for 7 years at a stretch. “Whether El Niño will emerge during the monsoon will become obvious by the end of May,” Srinivasan said.
In any case, predictions of El Niño events made in March and early April are not very reliable due to what is known as the “Spring Predictability Barrier”. The El Niño phenomenon is in the process of transition during this time of the year; besides, it is always tougher to predict a weak El Niño than a strong one.
Even so, the Australian Bureau of Meteorology in its latest El Niño outlook issued Wednesday said that while current conditions in the Pacific Ocean continue to be “neutral”, there was “around 50 per cent chance” of an El Niño developing later this year. The Bureau said this chance was “twice the normal likelihood”.
“International climate models suggest the tropical Pacific Ocean is likely to continue warming in the coming months, though in recent weeks some models have reduced the expected extent of warming. Five of eight models indicate that sea surface temperatures will exceed El Niño thresholds during the second half of 2017; a reduction of two models since the last release (bulletin),” it said.
Scientists at the India Meteorological Department believe that an El Niño, if it develops any time after August, is unlikely to have much of an impact on monsoon rainfall. But as the “Godzilla” El Niño showed, suppressed rainfall is not the only way the phenomenon influences weather in India. The winter of 2015-2016 was unusually warm; in the first week of January last year, temperatures were 5-8 degrees Celsius above normal in many parts of the country.
Winters following El Niño events are, in fact, known to be slightly warmer. If an El Niño event does reappear this year, India could be looking at another warm winter.