"Scientists Call for Study of Severe Incoming El Niño's Ecological Effects"
El Niño
Periodic warming of central and eastern equatorial Pacific Ocean surface waters affecting global weather.
Walker Circulation
East-west atmospheric loop linking rising air over Indonesia and sinking air over the eastern Pacific.
El Niño is the periodic warming of the central and eastern equatorial Pacific Ocean, part of the wider El Niño-Southern Oscillation (ENSO) cycle that also includes the atmospheric pressure changes known as the Southern Oscillation. It recurs roughly every two to seven years and is officially declared once Pacific sea-surface temperature anomalies exceed +0.5°C above the long-term average. When Pacific waters warm, the Walker Circulation, the east-west loop of rising air over Indonesia and sinking air over the eastern Pacific, weakens. This cuts convective activity over the Indian Ocean and suppresses the southwest monsoon. Strong El Niño years have historically coincided with major Indian droughts, including 2002, 2009, 2015-16, and 2023-24.
A related but distinct system, the Indian Ocean Dipole (IOD), measures the difference in sea-surface temperature between the western Indian Ocean, near the African coast, and the eastern Indian Ocean, near Sumatra. A positive IOD phase can offset El Niño's drying effect on the monsoon, while a negative IOD can amplify it. India's actual monsoon outcome in any El Niño year depends on how these two systems interact, not on El Niño alone.
The current episode, developing since mid-2026, is being described by scientists as unusually severe. Pacific sea-surface temperature anomalies crossed the +0.5°C threshold in May 2026 and had risen to +2.6°C by August 2026. Projections point to anomalies reaching +4°C, a level higher than any reconstructed from coral-core records over the past 1,000 years.
Ocean Mean Temperature (OMT), calculated up to the depth of the 26°C isotherm, is one of the tools used to forecast whether Indian monsoon rainfall will fall above or below the long-term mean. When Pacific warming spreads and interacts with the IOD, it changes evaporation and moisture-transport patterns across the tropical Indian Ocean. This combination, not El Niño in isolation, ultimately decides how severe the Indian monsoon deficit will be in a given year.
Beyond agriculture, El Niño events also disturb biological systems whose survival depends on stable temperature and rainfall patterns. …
With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct?
1.OMT is measured up to a depth of 26°C isotherm which is 129 metres in the south-western Indian Ocean during January-March.
2.OMT collected during January-March can be used in assessing whether the amount of rainfall in monsoon will be less or more than a certain long-term mean.
Which of the statements given above is/are correct?
Consider the following statements:
1.In the tropical zone, the western sections of the oceans are warmer than the eastern sections owing to the influence of trade winds.
2.In the temperate zone, westerlies make the eastern sections of oceans warmer than the western sections.
Which of the statements given above is/are correct?
With reference to 'Indian Ocean Dipole (IOD)' sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?
1.IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
2.An IOD phenomenon can influence an El Nino's impact on the monsoon.
Select the correct answer using the code given below:
The World Bank warned that India could become one of the first places where wet-bulb temperatures routinely exceed 35°C. Which of the following statements best reflect(s) the implication of the above-said report?
I.Peninsular India will most likely suffer from flooding, tropical cyclones and droughts.
II.The survival of animals including humans will be affected as shedding of their body heat through perspiration becomes difficult.
Select the correct answer using the code given below.
Consider the following statements about the Indian Ocean Dipole (IOD):
1.The IOD refers to the difference in sea surface temperature between the western Indian Ocean and the eastern Indian Ocean.
2.A positive IOD phase can offset the drying effect of El Niño on the Indian monsoon.
Which of the statements given above is/are correct?
Consider the following statements regarding El Niño and Ocean Mean Temperature (OMT):
1.El Niño is officially declared when sea surface temperature anomalies in the equatorial Pacific Ocean exceed +0.5°C above normal.
2.OMT is measured up to the depth of the 26°C isotherm and is used to assess likely monsoon rainfall performance.
Which of the statements given above is/are correct?
Match the following climatic phenomena with their correct description:
Phenomenon: (1) El Niño (2) La Niña (3) Indian Ocean Dipole (4) ENSO
Description: (a) Combined phenomenon of the Southern Oscillation and El Niño (b) Anomalous warming of eastern Pacific waters off the Peru coast (c) Difference in sea surface temperature between the western and eastern Indian Ocean (d) Anomalous cooling of central and eastern Pacific waters
Select the correct answer using the code given below:
The Walker Circulation, whose weakening during El Niño years suppresses the Indian monsoon, is best described as:
Consider the following statements:
1.El Niño events recur at intervals of roughly two to seven years.
2.Coral reefs typically require at least a decade to show significant recovery after a major bleaching event.
Which of the statements given above is/are correct?
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