El Niño is a meteorological phenomenon that occurs every few years as a result of unusually warm ocean conditions along the tropical west coast of South America. This event is associated with adverse effects on local fisheries, agriculture and climate from Ecuador to Chile and with far-field weather anomalies in the equatorial Pacific and occasionally in Asia and North America as well.
The deviation from normal sea surface temperature in the east-central Pacific Ocean is measured by the Oceanic Niño Index (ONI), the standard means by which each El Niño event is determined, measured and forecast. El Niño events are indicated by increases in sea surface temperature of more than 0.5 ° C during at least five successive three-month seasons.
As well; New research led by scientists at the University of Texas estimates that global warming is approaching a tipping point that could awaken an ancient El Niño-like climate pattern in the Indian Ocean this century. If it does happen, floods, storms and droughts are likely to worsen and become more regular, disproportionately affecting populations most vulnerable to climate change.
As a tool to make this prediction, the researchers designed computer simulations showing that global warming could disrupt Indian Ocean surface temperatures , causing them to rise and fall year after year much more abruptly than they do today.
According to this scientific team, this ‘seesaw’ pattern is strikingly similar to E Niño, and would affect the global climate.
Lead author Pedro DiNezio, a climate scientist at the University of Texas Institute of Geophysics: “Our research shows that raising or lowering the average global temperature by just a few degrees makes the Indian Ocean work exactly the same as the other tropical oceans. , with less uniform surface temperatures throughout the equator, a more variable climate and its own El Niño. “
There was already an El Niño in the Indian Ocean 21,000 years ago
The results, which were published on May 6 in the journal Science Advances, are based on a 2019 article by many of the same authors, who already found evidence of a past El Niño-like phenomenon in the Indian Ocean, taking place. 21,000 years ago, at the peak of the last ice age, when the Earth was much colder.
The air physicist, disseminator and meteorologist at Meteored José Miguel Viñas, a regular contributor to Muy Interesante, explains: “What this study indicates is that an episode similar to El Niño could have occurred in the Indian Ocean during the last ice age, producing very anomalous periodic heating of the SST (temperature of the water of the sea surface) “.
Could another El Niño be born in the Indian Ocean on a much hotter planet? To verify this, the scientists analyzed the climate simulations, grouping them according to how well they matched current observations. When global warming trends were included, the most accurate simulations predicted an emerging Indian Child in 2050 at the earliest and 2100 at the latest.
In other words, “according to the study, in a scenario of global warming such as that of high emissions, a phenomenon similar to that of El Niño could be triggered in the Indian Ocean, which is known to have occurred during the last ice age,” Viñas clarifies.
The consequences of an El Niño in the Indian Ocean
As we pointed out, the consequences of a phenomenon like El Niño unleashed in the Indian Ocean could be disastrous for the populations of this region of the planet.
This is how José Miguel Viñas warns: “Any change in the atmospheric circulation in the Indian Ocean could have important repercussions in this vast region, one of the most populated on Earth. Many millions of people in India and other riparian countries are highly dependent on monsoon rains , which irrigate the area generously and regularly every year ”.
In addition, Viñas recalls: “Now in June the southwest monsoon begins in India (the one that leaves the rains), which will last until September-October”.
How is the situation in the Indian Ocean?
The Indian Ocean today experiences very mild climate changes from year to year because the prevailing winds blow gently from west to east, keeping oceanic conditions stable. However, according to simulations, global warming could reverse the direction of these winds, destabilizing the ocean and turning the climate into warming and cooling changes similar to the El Niño and La Niña weather events in the Pacific Ocean. The result would be new extreme climates throughout the region, including the interruption of monsoons over East Africa and Asia.
For Michael McPhaden, physical oceanographer at the National Oceanic and Atmospheric Administration, this new study highlights the potential for how human-driven climate change can unevenly affect vulnerable populations: Current trends, by the end of the century, extreme weather events will affect the countries surrounding the Indian Ocean, such as Indonesia, Australia and East Africa with increasing intensity. ” In addition, he adds: “Many developing countries in this region are at greater risk of these types of extreme events.”
And in the Pacific?
According to José Miguel Viñas, an El Niño event is not expected to take place in the Pacific in the coming months : “In fact, the prediction of the hurricane season in the Atlantic is more active than normal, among other reasons. due to the absence of El Niño. Between now and summer, neutral ENSO conditions are expected (El Niño-Southern Oscillation, a climatic pattern that consists of the oscillation of the meteorological parameters of the equatorial Pacific) ”.
Referencias:
Science Advances (2020). DOI: 10.1126/sciadv.aay7684 , advances.sciencemag.org/content/6/19/eaay7684
Kaustubh Thirumalai et al. An El Niño Mode in the Glacial Indian Ocean?, Paleoceanography and Paleoclimatology (2019). DOI: 10.1029/2019PA003669
