Little-understood western disturbances have been blamed for most of the freak weather events in India in the past decade. With 50 per cent of its foodgrain production at risk, can India afford to ignore the phenomenon?
The sight of wheat, mustard, gram and fenugreek crops spread over 10 hectares (ha) would fill Vidyadhar Olkha’s heart with joy. It was end of February and the crops were almost ready to be harvested. A week later, all he had was a mat of leaves and stalks lying on the ground. The rain and hailstorm in the first week of March destroyed 70 per cent of his crops in Jhunjhunu district of Rajasthan.
Olkha has no idea what brought so much rain this March. Neither do scientists and weather forecasters, who attribute the rain to western disturbances and have different theories on what made the disturbances so severe this year.
Western disturbances are low-pressure areas embedded in the Westerlies, the planetary winds that flow from west to east between 30°-60° latitude. They usually bring mild rain during January-February, which is beneficial to the rabi crop. But in the past few years western disturbances have been linked to disasters. The cloud burst in Leh in 2010, the floods and landslide in Uttarakhand in 2013 and the excessive rain in Jammu and Kashmir in 2014 were all linked to these disturbances. This year, as per the India Meteorological Department (imd), the average rain received between March 1 and March 18 was 49.2 mm—197 per cent above normal. This caused severe damage to crops in several states of the country. According to a statement by Union agriculture minister Radha Mohan Singh in the Rajya Sabha on March 19, crops in over 5 million hectares have been damaged. But despite the destruction the disturbances have been causing, there have been very few studies to understand them.
Scientists agree that western disturbances are formed naturally. They originate in the Mediterranean region and travel over Iran, Iraq, Afghanistan and Pakistan to enter India loaded with moisture, where the Himalayas obstruct them, causing rain and snow in western Himalayas. The snow adds to the glaciers which provide water to India’s major perennial rivers. But what is it that is making this beneficial weather phenomenon increasingly disastrous?
There is no unanimity among scientists on the reasons behind the changes in the phenomenon. They offer a number of explanations:
Easterly wave: According to IMD, the severe rain this year is the result of the confluence of western disturbance and easterly wave from the Bay of Bengal. Easterly wave, or Easterlies, blow throughout the year from east to west. The confluence of the two winds happens throughout the year, but the results vary. They generally bring rain only to the northern part of the country but this year states in central and south India also received rain, says B P Yadav, head of IMD’s National Weather Forecasting Centre. Western parts of Madhya Pradesh, for instance, received over 2,025 times more than usual rainfall during March 1-18, while the rainfall in central Maharashtra was 3,671 times above normal, says IMD data. Yadav says the change in rain pattern is part of natural weather variation.
Pacific Decadal Oscillation: Jason Nicholls, senior meteorologist and manager of international forecasting at AccuWeather Inc, a global leader in weather information services, offers a more complicated reason. He says a phenomenon called Pacific Decadal Oscillation (PDO) contributed to the severity of this year’s rainfall. PDO is the name given to long-term fluctuations in the surface temperature of the Pacific Ocean. In areas above 20° north off the western coast of North America, cooling is observed during the negative phase of PDO while warming is observed during the positive phase. This shift from one phase to another happens every 10 years or in multiples of 10 years and is yet to be understood properly. PDO influences the placement and intensity of ridges (high-pressure areas) and troughs (low-pressure areas) over the northern hemisphere. Nicholls says that the wet winter seen this year and in 2013-14 was caused due to the impact of a “very strong positive PDO”. The warm waters in the west coast of North America led to a strong ridge over the Gulf of Alaska and western Canada. Another ridge prevailed over the central Atlantic Ocean which allowed storm systems to move through Europe into southeast Europe and the Middle East. A weakness between a couple of such ridges allowed storm systems to move into Afghanistan, Pakistan and northern India over the past couple of winters/springs, he explains.
- R Krishnan, scientist, Indian Institute of Tropical Meteorology, Pune
"The confluence of Westerlies and eastern currents brought rain to far off states such as Maharashtra"
- B P Yadav, head, National Weather Forecasting Centre, IMD
"A phenomenon called Pacific Decadal Oscillation made the rains so excessive this time"
- Jason Nicholls,senior meteorologist, AccuWeather Inc
"The rain can be mostly explained by natural short-term weather events. There is nothing too unusual or any sign of climate change"
- Thomas Reichler, scientist, University of Utah, USA
Jet streams: Akshay Deoras, an independent weather expert based in Maharashtra, says that widely used weather models, such as the Global Forecast System, are consistently showing the movement of new upper air troughs into India. Such troughs in the jet streams (narrow bands of strong winds flowing in the upper troposphere) could be affecting the western disturbances which, imd says, are present in the lower and middle troposphere. One such trough started forming in the upper troposphere over Iran, Afghanistan and Pakistan on February 26 and intensified and moved towards north-western parts of India on February 28. This led to the formation of a low-pressure region in the lower troposphere over northwest India, causing an incursion of moisture from Arabian Sea, and produced heavy rains. The rainfall on March 14-16 was also caused by a similar upper air weather set-up. This shows how problematic the combination of western disturbances and upper air troughs can be for India, says Deoras.
But all these explanations are based on climatic phenomena that have always existed. What is making their impact increasingly severe now? A few studies say that global warming holds the clues.
Heating of the Tibetan plateau: A study by the Indian Institute of Tropical Meteorology (IITM), Pune, has directly linked western disturbances to global warming. In a paper published in Climate Dynamics in February 2015, the researchers say global warming is impacting air currents and causing freak weather events. Pronounced warming over the Tibetan plateau in recent decades has increased the instability of the Westerlies and this has increased the variability of the western disturbances. According to the study, the western Himalayan region has seen a significant rise in surface temperatures since the 1950s. Observations from the area show a significant increase in precipitation in recent decades. The researchers looked at a variety of climate data to understand the increasing frequency of heavy precipitation. They say temperatures have risen in the middle- and upper-tropospheric levels over the sub-tropics (area between the Tropic of Cancer and the Tropic of Capricorn) and the middle latitudes. “Our study suggests that human-induced climate change is the reason for the increased variability of western disturbance,” says R Krishnan, one of the researchers. “The findings are based on direct observations and we are now using climate models to confirm if the impact is human-induced,” says Krishnan.
Arctic warming: Another study which blames global warming is by Jennifer Francis of Rutgers University, New Jersey, and S J Vavrus of University of Wisconsin- Madison, both in the US. The study, published in the January issue of Environment Research Letters, suggests that heating up of the Arctic has weakened the jet streams in the northern hemisphere. The west to east flow of jet streams in the northern hemisphere is maintained by the “gradient of heat” between the cool Arctic and warmer areas near the equator. But the Arctic has been warming since the past 20 years due to which the jet streams have become weaker. Rather than circling in a relatively straight path, jet streams now meander. This is making the South colder and the North warmer. Francis says western disturbances could definitely be affected by these jet streams.
Regional factors at play'
There are also those who believe that climate change is not the culprit. Scientists like Thomas Reichler from the department of atmospheric sciences, University of Utah, USA, do not link global warming and abnormal weather events. “These can be mostly explained by natural short-term weather events. There is nothing too unusual or any sign of climate change,” says Reichler.
Newly appointed IITM director M Rajeevan also does not subscribe to the theory of global warming and says that such events are regional.
“There does seem to be an increase in western disturbances, but it appears to be part of natural variability. A variety of factors could be at play and a detailed analysis is needed,” he says (see ‘Enigmatic disturbances’). Dieter Scherer, chair of climatology, Technische Universität Berlin, Germany, holds a similar view. “It is well-known that precipitation is a highly complex phenomenon caused by processes on a wide range of spatial scales. These highly complex multi-scale atmospheric processes are yet not fully understood and need more research,” says Scherer.
Rajesh Kapadia, a meteorology enthusiast who writes on weather trends in his blog ‘vagaries of the weather’, points out that there is nothing extraordinary about the event and India has witnessed similar weather events. “In March 1915, Delhi received 78 mm of rain while in March 1945, the temperature recorded in the city was as low as 4.4°C. We have had cold weather even in May,” he says, giving the example of May 14, 1982, when the temperature dipped to 25°C. “There is nothing to worry about as of now, but if this weather continues it might affect monsoon in north India. However, it is too early to know,” he says.
There is not much data on western disturbances. According to A P Dimri, professor, school of environment science, Jawaharlal Nehru University, New Delhi, there has been very little research on western disturbances because most researchers prefer to study the monsoon which is considered lifeline of Indian agriculture. R Krishnan,a scientist at the Indian Institute of Tropical Meteorology, says that even defining or counting a disturbance is tricky because when western disturbance moves over a long distance, its strength changes and one can never be sure when a new disturbance gets formed or an existing one undergoes change. These disturbances originate thousands of kilometres away and travel over countries where data collection is sparse. India has facilities to study the weather but observational data from Afghanistan and Pakistan is virtually non-existent, says A Jayaraman, director, National Atmospheric Research Laboratory, Department of Space.
B P Yadav, head of IMD's National Weather Forecasting Centre, says that more disturbances are being observed these days because the technology to detect, monitor and predict has improved. IMD is now undertaking studies to understand western disturbance, Yadav adds.
The trends are likely to continue and the country could see a few more disturbances in March and April. “The peak activity of western disturbances is usually seen in January. This year they were delayed and the cold, wet weather could spill over to April too,” says G P Sharma, vice-president, meteorology, Skymet Weather Services, a Noida-based forecasting company. “Rains in April could have huge implications for agriculture,” Sharma says.
Rabi crop accounts for 51 per cent of the country’s grain output and sustains India’s requirements till October till the kharif crop is harvested. Therefore, the winter crop has a significant bearing on food inflation. The fact that kharif yield in 2014 was below normal makes the situation even more grim. And the impact of crop damage has already started percolating to consumers. Vegetable prices increased by 30-40 per cent after rains in Delhi’s wholesale markets.
Losses and government aid
As states calculate crop loss, there are reports of farmer suicides in Maharashtra and Uttar Pradesh. Protests have also reached Delhi, where farmers have been holding an indefinite demonstration at the Jantar Mantar from March 18, demanding compensation. While the Union government has assured all help, states too have been announcing relief packages. Maharashtra, which has been struggling with drought and is now faced with excessive rain and hailstorm, has announced a compensation package of Rs.7,000 crore. Of this, Rs.4,000 crore have already been credited to the bank accounts of 78 per cent farmers in the state, said a state government press release on March 16. The state has also demanded Rs.6,000 crore from the Central government.
In Rajasthan, Chief Minister Vasundhara Raje announced on March 16 that if the crop loss is over 50 per cent, farmers will get aid and exemption from paying electricity bill. “However, the survey to assess the damage has not been completed. It should end by March 25 and compensation should be available thereafter,” Rajasthan agriculture minister Prabhu Lal Saini told Down To Earth. For the families of the 25 people who died due to the calamity in the state, Raje has announced a compensation of Rs.3 lakh. Relief packages have also been promised by states such as Gujarat and Uttar Pradesh.
However, Rakesh Tikait, national spokesperson of the Bhartiya Kisan Union, says governments always underestimate losses to avoid giving compensation to farmers. “Compensation is paid only if the losses are more than 50 per cent,” he says.
"We will revolt against the Rajasthan government. Instead of hiking the electricity rate, it should make it free, like in Punjab"
|"The agitation will go on till the government agrees to a dialogue. Bhartiya Kisan Union wants to talk to the prime minister"
- Rakesh Tikait, national spokesperson, Bhartiya Kisan Union
|"I am ready to go to jail if the police come and beat us, but I will not go back without getting compensation"
- Rajpal Sharma, farmer and national general secretary, Bhartiya Kisan Union
|"Instead of helping farmers with aid and relief package, the government is trying to take our land"
- Lal Singh, farmer from Ludhiana district, Punjab
Ill-prepared for disasters
This raises the question of what could have been done to prevent the loss of crops, particularly at a time when India is witnessing a spate of extreme weather events. According to World Bank, between 1996 and 2000, direct losses from natural disaster cost India over 2 per cent of its gross domestic product (GDP). Without adequate measures to mitigate climate change, these costs could amount to 10 per cent of the gdp by 2100, warns an Asian Development Bank report released in 2014. A few weeks ago, the 14th Finance Commission recommended a whopping Rs.55,000 crore allocation for disaster risk reduction. This is more than double the amount recommended by the 13th Finance Commission.
The situation needs to be dealt with at two levels: a proper scientific analysis of western disturbances to make accurate forecast and a long-term adaptation plan for farmers. Yadav says imd can predict a disturbance a week or 10 days in advance. But there is little one can do to prepare for the effects of the disturbance. The most farmers can do is to ensure that the fields are well-drained and, if time allows, set up nets for protection from hailstorms.
The grimmest aftermath of the weather event is the surge in farmer suicides. And while the disturbances cannot be avoided, effective planning can definitely help contain the loss of lives. For starters, the Centre must prioritise crop insurance and ensure that the existing schemes are implemented effectively. Recent experiences have shown that many of these freak weather events are localised and affect some farmers more than others. By taking averages of crop loss over large areas, as stipulated in the existing schemes, the government fails to help the people who need help the most. Farmers are worried. It is no longer acceptable to consider these weather events normal. The scientists and the government need to meet the challenge.
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