The early February heat and the prediction of an El Niño later this year have been hogging the headlines over the past few days — raising concerns over their likely impact on the weather, monsoon and agriculture.
So, what exactly is an El Niño year? And why did we see April-May-like temperatures in a month that is generally way cooler than it was in the last two-three weeks?
First, let’s look at the El Niño phenomenon and what it means for India.
What is El Niño?
On February 9, the US National Oceanic and Atmospheric Administration (NOAA) had forecast the possibility of El Niño, which is known to have a negative impact on the monsoon system, over the tropical eastern Pacific after three straight La Niña years.
The NOAA is an American scientific agency within the United States department of commerce that focuses on the conditions of the oceans, major waterways, and the atmosphere.
In simple terms, the warming of the central and eastern tropical Pacific Ocean is referred to as El Niño, which means little boy in Spanish. Such a phenomenon could impact weather across the world, including the southwest monsoon in India. An El Niño, which typically peaks towards the end of the year, could lead to drier conditions and cause a deficit in the monsoon.
In contrast, a La Niña, or little girl in Spanish, has the opposite effect. It would cause cooling, leading to more precipitation and rainfall. We are presently in La Niña conditions for the third straight year.
The forecast of an El Niño year has generated a lot of buzz and caused anxiety over its likely effect on the southwest monsoon, which is crucial for the farming sector and the entire economy.
The Maharashtra government has reportedly warned about the possibility of a drought-like situation and industry bodies fear a bad monsoon could hit rural recovery, which could have a negative impact on other sectors. Ratings agency CRISIL has called for constant monitoring of the forecasts.
“It is a bit early but global agencies indicate a transition from La Niña to El Niño this year. The latest forecasts indicate that the likelihood of El Niño emerging by July has a more than 60% chance,” said Roxy Mathew Koll, senior scientist at the Indian Institute of Tropical Meteorology, an autonomous institute of the Ministry of Earth Sciences.
No need to panic yet
Other weather scientists, while admitting that an El Niño may be brewing, say it is too early to draw any definite inference so early on as a clearer picture would emerge only by April or so.
According to India Meteorological Department (IMD) director general Mrutyunjay Mohapatra, El Niño is a major parameter for the monsoons and there have been instances of below-normal or normal rain during El Niño years. But at the same time, he cautioned that the prediction of an El Niño summer so early on may not be so accurate. For that matter, any forecast of an El Niño beyond three-four months needs to be dealt with caution, he said.
“We are emerging from a La Niña winter, which will slowly decrease and become neutral by April or May and continue in that state for some time. Per the forecasts, the second half may see an El Niño but to be more sure and for an accurate prediction, we have to wait till April,” Mohapatra told Moneycontrol.
Speaking along similar lines, SN Mishra, former director of climate science and weather, Indian Air Force, explained that we are currently under La Niña conditions, where the average sea surface temperatures are below normal over the east Pacific Ocean, especially the coastline of Peru.
Mishra said though El Niño is considered to have a negative impact on precipitation, there have been years of good rainfall even in El Niño years, prompting weather scientists to consider other parameters to predict the monsoon, including the Indian Ocean dipole (which influences from the Indian Ocean).
Mishra, a guest faculty at TERI University for Climate Change Mitigation, said any prediction about monsoon 2023 would be very premature at this stage and one has to wait for two more monthly (March and April) updates that take into account parameters such as ENSO (El Niño and southern oscillation), the Indian Ocean dipole, etc.
“Let us be cautious and watchful of the developing situation for at least the next 45 days before commenting,” Mishra said.
Effect on monsoon
El Niño conditions, Koll explained, generally weaken the monsoon circulation and can potentially result in drier conditions and so there is a need to keep a watch on the emerging conditions in the Pacific this time.
But regardless of the El Niño-La Niña effect, there is a clear shift in monsoon patterns, Koll explained. Widespread extreme rainfall events, he said, have increased threefold across India — particularly over parts of the Western Ghats, central India, and northeast India.
At the same time, the total amount of rainfall has decreased over many regions, particularly central and north India, he said. “We need urgent measures to ensure water and agricultural security in the light of these changes.”
Climate scientist Raghu Murtugudde also cautioned that the monsoon may see a deficit in an El Niño summer. An El Niño tends to produce a monsoon deficit and is generally the highest at ~15% going from a La Niña winter to an El Niño summer, he said.
“That means we will have a weaker circulation of monsoon winds, so (it will be) warmer and drier. But, of course, the extreme wet and dry events play havoc anyway,” Murtugudde, a visiting professor at IIT Bombay and emeritus professor at the University of Maryland, told Moneycontrol.
Mahesh Palawat, vice-president of private forecaster Skymet, said if data of the last 50 years is taken into account, the southwest monsoon reported below-normal rainfall during most El Niño years. Considering this, the monsoon could be slightly weaker this year, he said, but cautioned that it was too early to come to a conclusion. “We will come up with a forecast in April.”
India, Murtugudde said, would have to wait for an updated El Niño forecast and hope for the best but prepare for the worst. An unfavourable prediction, Murtugudde stressed, will test the Met office’s forecast products, and efforts to translate its forecasts to usable advisories for fishing, farming, flood alerts, etc.
A hot February
Coming to the warm weather, after a cold January, the tables suddenly turned in February, which turned out to be warmer than usual — leading to the spectre of a rerun of last year’s heatwave in March that damaged the wheat crop during harvest time.
Temperatures 8-9 degrees above normal were reported from across the west and northwest, prompting the IMD to issue heatwave warnings in Gujarat and warn that the high temperatures could affect the wheat crop.
If Delhi recorded 33.6 degrees Celsius on February 20, the highest since 2006, Mumbai reported 36.5 degrees Celsius a day before. Parts of Bhuj in Gujarat experienced 40 degrees Celsius. The mercury also rose across the hill states.
Why so warm?
There are two main reasons behind this unusual phenomenon: an anti-cyclonic formation that brought warm winds from the west into India and feeble western disturbances that did not produce enough rain to negate the warm effect, weather experts said.
Mohapatra said the anticyclone circulation, which moves clockwise, transported warm winds to Gujarat, Kutch, Maharashtra and parts of northwest India, leading to above-normal temperatures. He said that in such conditions, the air gets compressed and goes down, and the temperature rises.
“Conditions have eased and the temperatures have come down from 8-9 degrees above normal to 4-5 degrees above normal. But as summer approaches, the mercury will eventually rise,” Mohapatra said.
According to Mishra, during mid-January and the beginning of February, anticyclone conditions led to a spike in pollution in Mumbai, Pune and other areas as pollutants could not escape. “A similar situation is again responsible for the rising temperatures. But this is temporary. In meteorology, such episodes keep occurring but the frequency has increased due to climate change,” he said.
Palawat admitted that such high temperatures in February are unusual. Apart from the anticyclone over the Arabian Sea, feeble western disturbances over the western Himalayas, which are not capable of producing any significant rain or snow to check the mercury, are leading to warm conditions, he explained.
“We do not foresee any significant relief from the hot weather conditions over northwest, central India and parts of the west coast in the coming week,” Palawat said, adding that the warm temperatures could affect crops.
Changing weather patterns
Murtugudde said upper-level winds in the westerly jet are driving a low-level flow of warm air from the Middle-East, Persian Gulf and northern Arabian Sea into India. The jet is a seasonal feature but the Middle East is warming very rapidly and that provides the source for warmer air early on. “We have to wait and see if this indicates more heatwaves this spring.”
Almost every year and every month are now warmer than the earlier ones, Koll explained; 2022 was one of the warmest years despite having a La Niña with cool waters in the East Pacific. “La Niñas typically have a cooling effect on global temperatures, but this is now offset by global warming due to greenhouse gas emissions. As a result, La Niña years are warmer than years with El Niño events of the past.”
Regardless of all this, the world needs to be prepared for an increase in the frequency, intensity and area covered by heatwaves in the coming years, as carbon emissions and urbanisation continue unabated, Koll said. “Instead of waiting for forecasts, we need long-term measures to reduce the impact of these heatwaves and be prepared every year.”
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