India should brace for dry and hot spring-summer, El Nino, say experts

It is too early to predict an El Nino but it is possible, say;meteorologists
United States Global Forecasting System temperature forecast for February 19, 2023, 2 pm
United States Global Forecasting System temperature forecast for February 19, 2023, 2 pm

Very little rainfall and warmer-than-normal temperatures projected for February as well as a declining La Niña indicate a hot and dry spring and summer months for most of India. 

The United States Global Forecasting System data as visualised by the website windy.com showed a spike in maximum temperatures in the northwest and some parts of central, eastern and southern India starting from February 17, 2023. Day time temperatures will be in the range of 35-37 degrees celsius in these regions, the data showed.

On February 15, the maximum temperatures in Jammu and Kashmir, Ladakh, Himachal Pradesh, Rajasthan and some parts of Uttarakhand, Gujarat, Madhya Pradesh and Chhattisgarh were higher by more than 5°C, observed the India Meteorological Department (IMD) on February 15.

IMD has not put out an alert for warmer-than-normal temperatures for any part of India as of February 16. 

The indications of abnormal heat come on the heels of a dry winter season of 2022-23. The season has been dry for most of India, which is indicative of drought-like conditions in many of the regions. 

In December, there was a countrywide rainfall deficit of 14 per cent. The northwest, central and east and northeast India were particularly dry with 83 per cent, 77 per cent and 53 per cent deficit in rainfall respectively. The period is the Rabi cropping season for northwest and central regions. Only the southern peninsular region received 79 per cent excess rainfall in that month.

The dryness has also continued into January and February, with 27 out of the 36 states and Union territories receiving deficient, large deficient or no rainfall from January 1-February 15, 2023. 

The country, as a whole, recorded a rainfall deficit of 30 per cent in this period. Mizoram, Tripura, Jharkhand, Goa, Dadra and Nagar Haveli and Daman and Diu received no rain on these days. In 10 other states the rainfall deficit was greater than 90 per cent. 

The reason for this sudden spike in temperatures is “a strong upper level westerly jet that seems to be setting up lower-level winds that are sweeping in warm ocean and desert winds”, Raghu Murtugudde, a climate scientist at the University of Maryland and Indian Institute of Technology, Bombay, told Down To Earth (DTE).  

Akshay Deoras, a research scientist at the National Centre for Atmospheric Science and Department of Meteorology, University of Reading, told DTE:

The strongest temperature anomaly (both maximum and minimum) on February 15 were observed in plains of northwest India (mainly Rajasthan) and hilly states. There is an anticyclone (a high-pressure region) near the surface level, which is centred over northern parts of the Arabian Sea and adjoining northwestern parts of Gujarat.

“This high-pressure region is causing subsidence of air as well as enhancing the influx of dry winds from the northwest into India,” Deoras added. 

Furthermore, we have not seen a strong western disturbance affecting the plains recently. All these factors are causing the temperature spike, according to Deoras. 

“This high-pressure region will disintegrate by this weekend and a weak western disturbance is expected to impact hills early next week, so temperatures will ease due to these factors,” he added.

During late last year and January this year, there were low temperatures extending from Pakistan and Iran up into Afghanistan and beyond, said Murtugudde. “This low temperature and the associated high pressure were blocking western disturbances and cold air was blowing for the north. This has now changed with a new wind pattern being set up.”

As we go into the spring and summer seasons, there are concerns regarding the decline of the La Niña conditions by March-April and the development of El Niño conditions later in the year, which could mean further rise in temperatures and subsequent heat waves. 

There have even been media reports based on a forecasting model of the United Kingdom Met Agency about the 1.5°C barrier being temporarily breached for the average temperature anomaly for 2024 due to the prospective El Niño. 

During La Niña there are cooler than normal sea surface temperatures (SST) in the equatorial Pacific Ocean, which generally have a cooling effect on temperatures in many regions around the world, including India. In 2022, there were intense heat waves from March to June in 17 states, despite the La Niña, which was highly anomalous. 

The impact of El Niño, during which warmer-than-normal SSTs prevail, is exactly the opposite and many regions experience episodes of intense heat. An intense El Niño event, along with global warming, made 2016 the hottest year on record globally.

“ENSO forecasts are not really reliable this early, especially before spring, due to the spring predictability barrier,” said Murtugudde. 

“But three consecutive La Niñas have loaded up the tropical Pacific with warm water and any little trigger will kickoff an El Niño. So an educated guess should say we are ready for an El Niño,” he cautioned. 

El Niños always cause a mini-global warming by realising the accumulated ocean heat into the atmosphere, the expert noted. “Does that mean we will cross the global threshold of 1.5C? I am not so sure. Even if we did, will anything new and dramatic happen? Don’t count on it.”

“We are already in the middle of all the extremes and so we just have to focus on the heatwave season and the monsoon deficit,” he added. 

A La Niña winter transitioning to a El Niño summer is bad news for the monsoon in general. But again, the seasonal totals may be lower but extremes will do their dance of death anyway, according to Murtugudde.

Related Stories

No stories found.
Down To Earth
www.downtoearth.org.in