The El Nino phenomenon is characterized by unusual warming of the Pacific Ocean’s surface waters. It is part of the larger El Nino-Southern Oscillation (ENSO), which also encompasses the La Nina phenomenon, which marks cooler than normal temperatures.
Emergence of El Nino Conditions in 2023
Recent news has shed light on an emerging phenomenon along the equatorial Pacific region, indicating the onset of El Nino conditions in 2023. The simultaneous warming of the eastern and western regions of the equatorial Pacific mirrors a pattern last seen in 2009, posing significant threats to marine life worldwide.
The Driving Forces Behind the Phenomenon
Global warming and the transition from a La Nina winter to an El Nino summer form the crux of the factors triggering this phenomenon. The warmer Eastern Pacific should typically cool the western part; however, global warming leads to basin-scale warming across the tropical Pacific.
Basin-Scale Warming in the Equatorial Pacific
In the absence of global warming, the equatorial Pacific experiences basin-scale warming, causing both the eastern and western regions to heat up. This term refers to the spatial extent of a common water outlet or basin, particularly the equatorial Pacific region. Recent analysis of data reveals that ocean temperatures as of May 29, 2023, were unusually warm compared to the average temperatures from 2003-2014.
Potential Consequences of Global Warming and the ENSO Cycle
The conclusion of La Nina implies that the ocean is no longer absorbing heat, which instead disperses into the atmosphere. Consequently, a warmer atmosphere prevents the ocean from losing much of its heat, causing it to warm up at the surface. This could potentially push global warming beyond the 1.5°C mark, albeit temporarily.
Geophysical Effects
This phenomenon can influence cyclones, hurricanes, and typhoons, leading to even stronger storms, such as Typhoon Mawar in the western Pacific. The warming of the ocean waters could intensify marine heatwaves and slow down meridional circulation, spelling disaster for marine biodiversity.
Coral Bleaching
Coral reefs stand at risk of destruction with a 1.5°C rise in temperature, and a 2°C increase may result in a near-total loss. This is a crucial threshold beyond which recovery may be impossible.
Past El Nino Events
The El Nino events of 1982-83 and 1997-98 were the most severe of the past century. The 1997-98 event bore witness to drought conditions in Indonesia, Malaysia, and the Philippines, while severe flooding occurred in Peru and California. Both this event and global warming made 2016 the warmest year on record.
Impact of El Nino 2023 on India
El Nino’s onset in May or June 2023 could weaken the southwest monsoon season, responsible for roughly 70% of India’s total rainfall. Although sub-seasonal factors like the Madden-Julian Oscillation (MJO) and monsoon low-pressure systems can temporarily boost rainfall in certain parts. In addition, it may lead to heatwaves and droughts in India and other regions, including South Africa, Australia, Indonesia, and the Pacific Islands.