Unusual even for El Nino: What's kept this winter so warm?

“We don’t have any rain, we don’t have any snow, we don’t have any chilling,” said Ravinder Chauhan from Shimla. Chauhan is the president of the Apple Growers Association of India and has been watching the winter weather closely. So far, the news is not good. Since mid-October the hills have been uncharacteristically hot. Typically, temperatures should range between a daily minimum of zero degree Celsius and a maximum of less than 15 degree Celsius – ideal for a good apple crop.

“Temperature these days is above 20[degree Celsius] and in the nighttime it is around 7-8 [degree Celsius]," Chauhan said. "There is a great fluctuation, which is harmful for the crop. It was very hot during the daytime and above normal, more like Delhi, Chandigarh and other parts of the plains.”

Further south in Mahabaleshwar, strawberry farmers like Nitin Bhilare are already seeing the effects of the almost non-existent winter. “In this area there will be more than 2,000 farmers who are into losses because of this winter," said Bhilare, president of the Strawberry Growers Association of India. "Last year we had rates of about Rs 140-Rs 150 per kilogram. Right now it has dropped below Rs 100. Last year, I produced 600 kilograms-700 kilograms per day. Right now I am not crossing even the 100 kg figure.”

The winter weather is affecting rabi crop sowing across the Indo-Gangetic plain. According to numbers released by the agriculture ministry, wheat output could fall for the second consecutive year with sown area till December-end lagging by 2 million hectares from last year. The trend extends to pulses, oilseeds and rice.

Cities like Delhi, Chandigarh and Kanpur have been reporting unusually high temperatures for the winter months. Delhi had a “pleasant” New Year’s Eve at 25 degree Celsius, surprising even for a year that has been declared the hottest on record.

“Delhi had a minimum average of 9 degree Celsius for December, when the normal average is 8.4 for the month. So 0.6 of the normal is fairly significant when the average is taken over 31 days,” said GP Sharma, meteorologist with private weather forecaster Skymet. “The maximum temperature was also on the higher side.”

Weather or climate?

Winter temperature in north India are mostly the outcome of a weather systems called Western Disturbances, which are extratropical storms driven by the winds called the Westerlies that bring winter rain and snow to the north western part of the country. A strong Western Disturbance brings a lot of rain and a lot of cooling to the region.

“Right now, there is a Western Disturbance that is not very strong and earlier, for the last 10 days and even before that, there was not much Western Disturbance activity so no cooling or rainfall,” said Anand Kumar Sharma, deputy director general at the regional centre for North India of the Indian Meteorological Department.

Sharma doesn’t consider the current weather to be an anomaly, yet. “December maximum [in 2015] did not go beyond 28 degree Celsius but in 2013 it went to 30 degree Celsius. This does happen when we have minimal activity of Western Disturbances,” he said. “It is above normal but not unusual.”

Meanwhile, long-term data shows that winters around the world have been getting warmer. Vimal Mishra, scientist at the water and climate laboratory at the Indian Institute of Technology – Gandhinagar, who has been studying cold waves noted that since the 1970s, winter nighttime temperatures risen more than winter daytime temperatures have. "In our study we have seen globally the number of cold waves has declined over the years. If you look at long-term data from 1973 onwards, in majority of cities, the frequency of cold waves have declined because winter temperatures are increasing more rapidly than those in summer,"he said.

Is it the El Nino?

But Mishra, Sharma and other climate experts are also keeping their eye on the monster El Nino that has been forming in the Pacific for most of the past year.

The El Nino is a phase of the weather phenomenon called the El Nino Southern Oscillation during which a warm band of ocean water forms in the central and east Pacific Ocean. An El Nino occurs every two to seven years, can last for between 9 months to a year or occasionally for a couple of years and typically affects weather systems across the world.

That the El Nino has a strong bearing on the Indian monsoon has been established. Most often an El Nino causes a deficient monsoon or a drought, depending on other weather phenomena in play. The correlation between El Nino and winter weather in India is not established but meteorologists have seen signals that an El Nino might cause warming in winter. The reasoning is this. After a drought, such as one caused by an El Nino, there is little moisture in the soil. Therefore, when the monsoon rains end there is little cooling from water evaporating from the soil during daytime, which leads to generally higher temperatures.

The El Nino is being held responsible for a lot of freak weather already being experienced around the world. Most of the United States experienced an unusually mild Christmas followed by torrential rain in some southern states. Missouri experienced its worst flooding in two decades as rivers overflowed their banks. There have been tornados in southern United States, bush fires in Australia and flooding in the United Kingdom and the El Nino is suspected to have had a hand in each.

“This is not only in India but more or less across the northern hemisphere. When something of this scale and this magnitude happens, I think the El Nino is the only thing that could be related,” said Mishra. “There might be some contribution from local effects like the Western Disturbances, but the El Nino is so strong that the overall effects will be dominated by the El Nino rather than regional-scale processes.”

For Indian Institute of Tropical Meteorology scientist Ramesh Kumar Yadav, the current weather is contrary to what his research on the El Nino shows. Yadav’s paper on how the El Nino influences winter precipitation in north west India shows that an El Nino sets off warming in the equatorial Indian Ocean, which in turn triggers the formation of Western Disturbances that bring rain and cold to north India.

“Even though this is an El Nino year, maybe there is not much warming over the Indian Ocean, so the temperature gradient between land and sea causing the Western Disturbances may not be there,” said Yadav.

Freak weather globally

But this El Nino is not normal as far as El Ninos go.

For example, an El Nino usually brings rain to California in December but the state has remained dry, almost parched, till this first week of January when a string of El Nino storms have just begun. The powerful cyclone that brought tornados and flooding to the US also caused a storm that blanketed the North Pole in warm air and made temperatures rise to between -1 degree Celsius and 1 degree Celsius. That’s a mind-boggling 30 degrees Celsius above what North Pole temperatures normally are at this time of year.

“Usually when there is an El Nino we get warming in the tropical Pacific,” explained Raghu Murtugudde, an earth systems scientist at the University of Maryland. “But this time we have also warming in almost the entire north Pacific. Basically, the shift that should happen with the sun moving south in October, November and December – many of those things don’t seem to have happened.”

Is it 'the Blob'?

Another reason why the 2015 El Nino, which has already earned monikers like Godzilla El Nino and Darth Nino, has not been behaving quite like previous El Ninos is because of “the Blob”.

The Blob is a large, persistent, dynamic mass of warm water that has been lurking in the north Pacific Ocean just south of Alaska for most of 2015 and though to be the result of a long-term cycle of the Pacific Ocean switching from heating to a cooling phase.

Interactions between the Godzilla El Nino and the Blob seem to be making weather around the world aggressive and unpredictable even for an El Nino year.

“This is El Nino plus,” said Murtugudde about the factors responsible for India’s warm winter. “I suspect the warmth in the north Pacific held some things in place unusually that means we didn’t get enough cold air coming in. It’s definitely to do with the El Nino but there seems to be some other factor two.”

The winter chill might not have disappeared but just be delayed. Skymet has predicted that a western disturbance will bring rain to parts of Haryana and Punjab in the next few days and also lead to a drop in the mercury in Delhi. A second system is likely to hit around January 13th, with the possibility for more rain and cooler weather.

Skymet's Sharma expects that the western disturbance activity will pick up and linger till the end of winter. “By the end of February the systems starts shifting northward and get confined in the hilly areas. But now you could see that they keep affecting the plains beyond February and even in March. The absence of activity now could get compensated a little later but will be unseasonal at that point of time,” he said.

But little or delayed rain is still bad news for apple farmer Chauhan. The lack of winter precipitation will only aggravate the need for irrigation water that will be difficult to access after a deficient monsoon year. “It is too early to talk about losses but our past experience shows that if these types of temperatures persist it is always harmful for the crop,” Chauhan said.

Scientist Mishra is worried about the longer term. “If this warming is caused by the El Nino, then next year could be normal. But in another 15-20 years, every year could be like this. How will we then manage our crops, how will we manage water resources, how will we manage energy demands? That is the more pressing question.”