El Nino Current Affairs - 2019

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Impact of global warming on El-Nino

El-Nino disturbs the atmospheric conditions across the world. El-Nino occurs every two-to-seven years with very strong El Niño’s occurring about every 15 years results in droughts, floods, wildfires, dust and snow storms, fish kill, and even elevated risks of civil conflicts.

The El-Nino is measured by studying the averages sea surface temperature anomalies over the central-eastern tropical Pacific. A study which analyses the impact of global warming on El-Nino has been published in the journal Nature in December 2018.

Findings of the Study

The important findings of the study are:

  • The study serves a warning to the countries on all continents that suffer from these extreme weather events during strong El Niño events such as the ones during 1982-83, 1997-98 and 2015-16.
  • The study notes that eagerly-awaited winter rain and snow storms over California did not occur during the latest extreme El Nino. Hence it is unclear whether global warming is already affecting El Nino and its remote impacts.
  • The study argues that it is unclear if the impact of global warming on El Nino can easily be extracted considering its intrinsic tendencies and its dependency on so many factors that are not easily predictable.

The study concludes that various models to study El-Nino deliver a slightly different rendition of El Niño compared to nature. Hence it is imperative that models be held to very stringent standards on their performance of El Niño behaviour during historic periods, especially the 20th century, as a test of their reliability for future projections. As a result it is difficult to conclude how reliably the models can project El Niño response to global warming in addition to how the models perform in reproducing floods and droughts of 20th century.

Conditions normal for 2018 monsoon season: Weather scientists

Weather scientists have predicted normal monsoon in June-September 2018 monsoon season as prevailing conditions as well as neutral ENSO were favourable for good monsoon rainfall. India receives 89 cm of rainfall during four-month monsoon season, which is almost 75% of its annual rainfall. In 2017 monsoon season, country as whole had received rainfall that was 95% of its long-period average.

Key Facts

The most important favourable condition for good monsoon is near-neutral to neutral ENSO (El Nino Southern Oscillation) in equatorial Pacific Ocean, off coast of South America. Global climate models are showing near-neutral conditions prevailing in Pacific Ocean and it will remain this way through most of the year.

Moreover, La Niña conditions are present and equatorial sea surface temperatures (SSTs) are below average across central and eastern Pacific Ocean. The transition from La Niña to ENSO-neutral is most likely during March-May season, with neutral conditions likely to continue into second half of year. SST anomalies in eastern tropical pacific are ENSO-neutral during coming summer and hence normal monsoon is expected this year.

ENSO (El Nino Southern Oscillation)

ENSO refers to anomalies in SSTs in Pacific Ocean off coast of South America which has sometimes been observed to have near-decisive impact on monsoon rainfall. In El Nino, a warmer than usual SST is observed in Pacific Ocean off coast of South America . This condition is associated with suppressed monsoon rainfall in India. La Nina is opposite ENSO and is more favourable for monsoon. It is known to help monsoon rainfall in India. When anomalies (deviations from usual SST in the Pacific Ocean) are too small or absent, monsoon rainfall over India is normal.