Global climatic anomalies allied with local weather conditions produced the most freakish hailstorms in central and north India in February and March. Tennis ball-size hailstones put an end to farmers’ dream of a good harvest. Preliminary estimates show loss of about 5.5 million hectares of crop. Was it the doing of climate change? Does India have a contingency plan to tackle such events? Aparna Pallavi, Kundan Pandey and Jitendra brought ground reports from Maharashtra, Madhya Pradesh and Punjab as Soma Basu investigated the causes of the untimely hailstorms…
Raghveer Lal was 22 and full of life. Standing amid the fast ripening crops of peas, pigeon pea and black gram in village Ramgadha in Damoh district of Madhya Pradesh, he would often dream of a bumper harvest and a better life. He was confident he would be able to repay the Rs 1.5 lakh borrowed from a usurious moneylender for taking 4 hectares (ha) on lease and buying seeds and fertilisers. But on the ill-fated night of 10 March, it suddenly started raining. The rain was accompanied by hailstorm and gusty winds. His entire crop flattened within a couple of hours. At around 9 pm, as the rain ceased, Raghveer stepped out of the house to take stock of the situation, but did not return. His father Bhajje Lal went out looking for him, only to find his only son hanging from a tree in the farm. Dismayed, he too hanged himself from another tree. Having lost her husband and son, Nanhi Bai is in a state of shock. “Kuchh samajh me nahi aa raha hai (I am unable to understand anything),” is the only sentence she is able to mumble.
The freak weather event that battered the country’s six States—Punjab, Uttar Pradesh, Rajasthan, Madhya Pradesh, Maharashtra and Andhra Pradesh—for an unprecedented 20 days, from 24 February to 14 March, has left millions of farmers in a similar state of shock. It came just as farmers were getting ready to harvest rabi crops such as wheat, pulses, potato, sugarcane, maize, groundnut and mustard, and horticultural crops like grapes, papaya, mango, banana, onion and other vegetables. …Farmer leaders say about 100 farmers in this arid region have taken their lives in within one month of the hailstorms. The Maharashtra Government has registered suicide by 47 farmers. Most of them were tenant farmers and counting on the harvest to repay their loans.
The erratic weather has not spared big farmers either…Those who have survived are yet to come to terms with the unexpected disaster…
Why the hail?
Scientists blame changing wind patterns near the Arctic for the freak weather. In the seven decades of his life, Kunwarman Patel of Ramgadha village in Madhya Pradesh had never witnessed such bizarre weather events. “It looked as if the rainy season would stretch till summers,” he says. Bhopal and Gwalior in the State recorded heaviest ever rains in February, with Bhopal receiving 40 mm rainfall and Gwalior 69.9 mm on February 27.
Hailstorm, which is never heard of in Maharashtra in this season, extensively damaged crops. “This rabi season, we experienced at least eight hailstorms,” says Ramdas Damle of Sagar, Madhya Pradesh. February is essentially a dry month. Some rainfall in March can be expected, but hailstorm and rain in February is unusual, says J R Kulkarni, senior scientist at the Indian Institute of Tropical Meteorology (IITM) in Pune. “This must be treated as a rare event,” says Medha Kolhe, deputy director general (weather forecasting), Indian Meteorology Department, Pune. “Nothing even resembling this has ever been reported.” Excessive hailstorm was last reported in 1907 and that, too, was limited to one day and one village in Maharashtra’s Satara district, says Ramchandra Sable, retired head of climate change department at Mahatma Phule Agriculture University in Rahuri, Maharashtra. The hailstorms were caused because of an unusual movement of cold westerly winds that come from the north and cause snowfall over the Himalayan region in January, says Kulkarni.
Western disturbances over India originate either from the Atlantic Ocean or from the Mediterranean Ocean, says Air Vice Marshall (retd) G P Sharma, head of Skymet, a private weather forecasting firm. He was earlier principal director, Directorate of Meteorology, Indian Air Force. “A specific climatic condition in the Atlantic could also influence westerlies in the country,” he says. “The cold westerlies usually blow around 30 degree latitude, where Kashmir is located. But this year, they came down to about 15 degree latitude, bringing hailstorms. Mumbai falls on 18.9 degree latitude,” says Kulkarni. The situation intensified when the cold westerlies, after picking up moisture from the Arabian Sea, met the south westerlies, which, too, were moisture-laden. The winds could not move beyond the Bay of Bengal because of the presence of high pressure belt and started blowing clockwise over the central, western and part of northern India. They characteristically moved upwards and precipitated the moisture in the form of hail, says Kulkarni.
Explaining the unusually large size of the hailstones, he says, “Usually, moisture in the atmosphere freezes at 5 km from ground level. But due to the presence of cold westerlies, moisture froze at 4 km. This reduced the hailstones’ travel distance, and hence the melting speed reduced.”
But the question is: what caused the cold westerlies to change their path?
Looking for answers
The root of all problems is the weak polar vortex over the Arctic, say many scientists. Polar vortex is low pressure wind formation which blankets the planet’s poles. Below it flows the jet stream, or a pattern of very strong winds, which saves the earth from the freezing cold air of the two poles. In early January this year, polar vortex in the Arctic weakened and collapsed, allowing cold air to escape down to the mid-latitudes. The disturbed jet stream further pushed down cold air from the Arctic. The US and the UK experienced record breaking cold wave during this time, explains M Rajeevan, senior scientist and adviser to the Ministry of Earth Sciences. Weak polar vortex and meandering jet stream most likely have a connection with the freak weather India is grappling with, he says. These caused the cold westerlies, which normally flow across the Himalayas, to come down to peninsular India. Rajeevan has analysed the causes of hailstorms and excessive rains in central Asia and India from February to March. Weakening of the polar vortex is being attributed to reduced snow cover and sea ice on the northern hemisphere of the earth. Less snow and ice means less reflection of sunlight and, therefore, more evaporation and transpiration. These reduce the air pressure and increase temperature of the polar vortex, causing it to weaken.
Climate scientists also attribute the weakened polar vortex to El Nino—abnormal warming of surface water in the equatorial Pacific accompanied by atmospheric pressure fluctuations. During El Nino events, polar jet stream diverges from its usual path. According to Rajeevan, when El Nino develops, more mid-latitude westerly troughs move across north India. Its presence could bring major changes in the atmospheric pressure and temperature. This year its frequency has been more, indicating presence of conditions favouring El Nino. North Atlantic Oscillation (NAO) also has an impact on a jet stream. NAO is a climatic phenomenon over the North Atlantic Ocean. It involves oscillation of air pressure from Central North America to Europe. The air pattern over Central North America has a strong low pressure system called positive mode. Air pattern over Europe is negative mode where weak high and low pressure systems are found over the same locations. Negative NAO results in a weak jet stream below the polar vortex. Weather anomalies due to cold winds from the Arctic could accentuate due to NAO. Fluctuations of high and low pressure systems control the strength and direction of Westerly winds and storm tracks across the North Atlantic.
Is this climate change?
Over the last decade, there has been an increase in the phenomenon of Arctic air being pushed down leading to unusual regional climate anomalies across the Northern Hemisphere. In 2010, Pakistan witnessed record floods while Russia suffered intense heat waves and forest fires. The year 2012 witnessed record surface melting of the Greenland Ice Sheet, wettest summer ever in England, heat waves in the US and Russia. In 2010 and 2011, there were some enigmatically cold winter spells on both sides of the Atlantic and in eastern Asia. December of 2010 was the coldest December since 1890 in central England records, says German oceanographer and climatologist Stefan Rahmstorf, in his research paper ‘A decade of weather extremes’. Rahmstorf is one of the lead authors of the Inter-Governmental Panel on Climate Change (IPCC) Fourth Assessment Report.
“Weather anomalies greatly increase the intensity and frequency of extreme events,” he says. “There are strong indications that some types of extreme event, most notably heat waves and precipitation extremes, will greatly increase in a warming climate, and have already done so,” he says. Tough road lies ahead for India, says the Inter Governmental Panel on Climate Change (IPCC) report. It warns the country of severe food crisis due to extreme weather events, and estimates countrywide agricultural loss of over US $7 billion in 2030. This will severely affect the income of 10 per cent of the population with increasing weather extremities.
So what can the changes in weather conditions be attributed to? Is this natural variability in climate, or climate change? Most Indian climate scientists say the unprecedented and untimely weather events were yet another sequence in the chain of freak weather events India has been witnessing in the last few decades. But many shy away from attributing it to climate change. R Krishnan, executive director, Climate Change Centre, IITM, says it is premature to attribute it to climate change. More samples are required for the attribution, he says. “Temperatures are rising in the world everywhere and every year, so we can say it is a symptom of climate change. But the current event is an isolated one and has not been witnessed in the last 25-30 years. Also, such hailstorms have not occurred worldwide. So it is difficult to link it to climate change. It may be a part of natural variability of weather conditions,” he says. But J Srinivasan, climatologist with Indian Institute of Science, Bengaluru, differs. “We may not be able to attribute an isolated event to climate change directly, but a series of unprecedented freak events is certainly due to climate change and global warming.” It is well established that there has been an increase in extreme weather events. Only 20 per cent of these are due to natural causes; 80 per cent are human-induced changes, he says. B K Bandyopadhyay, deputy director general of meteorology at the India Meteorological Department, says because of absence of good recording systems earlier extreme events may have gone unnoticed. “How can we say that this was the first ever hailstorm in Maharashtra? May be hailstorm occurred but over a small locality, or in an uninhabited area,” he says.
The sheer magnitude of the event merits it a climate change tag, says Sable. “It occurred due to unnatural and drastic fluctuations in temperatures, which are symptomatic of climate change,” he says. Sable, who has been campaigning for a climate change helpline mechanism for farmers, says extreme and unprecedented weather events have to be accepted as climate change phenomenon regardless of their frequency. Denial among the Indian scientific institutions regarding climate change is delaying action that needs to be taken to help farmers and the poor, he says.
IITM has analysed data of more than 1,800 weather stations in central India from 1951 to 2000. It did not find any significant change in the seasonal mean rainfall in the area, comprising well over a million square kilometres. But it found that the number of extreme events—rainfall exceeding 150 mm per day—has doubled since the early 1950s. Heavy rainfall, exceeding 100 mm per day, shows a 10 per cent increase per decade, says Bhupendra Goswami, director, IITM.
– Excerpts from ‘Flat in 20 days’/ DTE