More extreme El Niño, La Niña events could drive global warming, study finds INQUIRER.net
El Nino may trigger frequent extreme weather events from 2040s: Study
In less than two decades from now, extreme weather events like intense heat waves and rainfall events triggered by El Nino are set to increase, a new study has shown.
El Nino is the unusual warming of ocean waters along the eastern equatorial Pacific Ocean. It is known to affect the monsoon and cause intense heat and droughts globally. In recent years, the 2015 El Nino event has significantly affected India’s rainfall, crop output and, thus, the overall economy.
In this study, researchers from the University of Exeter, UK have tried to calculate the ‘time of emergence’ of changes along the tropical Pacific Ocean under four possible carbon emissions scenarios. They concluded that drastic rainfall changes were on the cards starting in the 2040s.
“When looking at changes in El Nino rainfall patterns, the best estimate of the time of emergence of changes converges on 2040 in all of the four emissions scenarios considered,” the study published in the peer-reviewed scientific journal Nature Climate Change noted.
Normally, the India Meteorological Department (IMD) observes a weaker monsoon over India during El Nino years, even though the Met agency says that there is no one-on-one association between the two.
During 1951 – 2021, 15 years have been dominated by El Nino, including 2015, 2009, 2004, 2002, 1997, 1991, 1987, 1982, 1972, 1969, 1965, 1963, 1957, 1953 and 1951. Of these, nine summer monsoon seasons over the country recorded deficient rain by more than 90 per cent (of the Long Period Average or LPA of 88cm for the country for June-September). During one of the strongest El Nino years in 1997, however, India’s seasonal rain was over 100 per cent of the LPA, the IMD data showed.
Earlier this month, the IMD said that a weak La Nina – the opposite phenomenon of El Nino when the equatorial Pacific remains cooler than normal – has been shown to favour Indian summer monsoons. As per the latest forecasts, the existing La Nina will turn the El Nino Southern Oscillation (ENSO) neutral sometime during the upcoming monsoon season.
Increasing frequency of El Niño events expected by 2040
Global weather fluctuations called El Niño events are likely to become more frequent by 2040, a new study shows.
El Niño—the unusual warming of surface waters in the eastern tropical Pacific Ocean—affects climate, ecosystems and societies worldwide.
The study examined four possible scenarios for future carbon emissions, and found increased risk of El Niño events in all four.
This means El Niño events and associated climate extremes are now more likely “regardless of any significant mitigation actions” to reduce emissions, the researchers warn.
Lead author Dr. Jun Ying, from the Second Institute of Oceanography, Ministry of Natural Resources in China and the University of Exeter, says that “we know from previous studies that, when measuring El Niño changes in terms of rainfall shifts in the eastern equatorial Pacific, models predict an increase in the frequency of events.”
“This study shows that those changes could happen after the next two decades.”
The study, published in Nature Climate Change, examines the “time of emergence” of changes in the tropical Pacific using state-of-the-art climate models.
The time of emergence is defined as when the signal of climate change emerges from the usual background noise of natural climate variability.
When looking at changes in El Niño rainfall patterns, the best estimate of the time of emergence of changes converges on 2040 in all of the four emissions scenarios considered.
Co-author Professor Mat Collins, from the University of Exeter and part of the Global Systems Institute, added that “what surprised us is that changes emerge regardless of the scenario we look at.”
“Because rainfall in the tropics is associated with the warmest sea surface temperatures (SSTs), it is the relative changes in SST that are more important than the absolute change.
“This leads us to the rather stark conclusion that these changes are essentially unavoidable.”
Jun Ying, Emergence of climate change in the tropical Pacific, Nature Climate Change (2022). DOI: 10.1038/s41558-022-01301-z. www.nature.com/articles/s41558-022-01301-z
University of Exeter
Increasing frequency of El Niño events expected by 2040 (2022, March 7)
retrieved 7 March 2022
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