Why in news?

Just about a year after one of the strongest-ever El Nino events ended in 2016, there is a possibility of another later in 2017, though not of the same strength.

What is the significance of El Nino?

  • El Nino 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 Nino 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 Nino events ever recorded, nicknamed “Godzilla”.
  • El Nino events have a 3-5 year cycle.
  • El Ninos 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 Nino developing in the Pacific Ocean in the latter half of this year, most likely after August.
  • Over the past 35 years, El Nino events happened in 1972, 1977, 1982, 1987, 1991, 1997, 2002, 2009, 2012, and 2015.
  • El Ninos have returned after a gap of 2 years earlier, and sometimes they have not happened for 7 years at a stretch.
  • Never before in the last 40 years has the El Nino returned so soon.
  • In any case, predictions of El Nino events made in March and early April are not very reliable due to what is known as the “Spring Predictability Barrier”.
  • The El Nino phenomenon is in the process of transition during this time of the year; besides, it is always tougher to predict a weak El Nino than a strong one.

What are the chances of El Nino this year?

  • Australian Bureau of Meteorology in its latest El Nino outlook said that while current conditions in the Pacific Ocean continue to be “neutral”, there was “around 50% chance” of an El Nino 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 Nino thresholds during the second half of 2017.
  • Scientists at the India Meteorological Department believe that an El Nino, if it develops any time after August, is unlikely to have much of an impact on monsoon rainfall.
  • But as the “Godzilla” El Nino showed, suppressed rainfall is not the only way the phenomenon influences weather in India.
  • The winter of 2015-2016 which followed after El Nino was unusually warm, with were 5-8 degrees Celsius above normal in many parts of the country during January.
  • If an El Nino event does reappear this year, India could be looking at another warm winter.