Sweeping chunks of dust, sounds of tin roofs blowing up, utensils and clothes flying like saucers, tress uprooted, collapsing mud walls, and screaming winds – this was the deadliest dust storm to have hit northern India over decades. The speeding winds that had reached 130 km per hour took a toll on human life and property. As per reports, at least 100 people have lost their lives and the storm left a trail of destruction in six states. Meteorologists who termed the disaster as a ‘freak’ storm are of the opinion that abnormally high temperatures in the past weeks could have caused this dust storm. The Indian Prime Minister Narendra Modi recognised the extent of this disaster and tweeted, “Saddened by the loss of lives due to dust storms in various parts of India.”
Dust storms are caused when strong winds sweep away loose particles of sand and dirt by blowing over dry surfaces. The blown away particles are generally suspended in the air, causing soil erosion and forming slits in places of deposition. The World Meteorological Organisation (WMO) defines dust storms as strong winds, which lift large amounts of sand and dust from bare, dry soils into the atmosphere and transports the dust particles.
But what causes these dust storms? According to WMO, these are common meteorological hazards in arid and semi-arid regions and are usually caused by thunderstorms – or strong pressure gradients associated with cyclones – which increase wind speed over a wide area. Aerosols, particularly mineral dusts, impact weather as well as global and regional climate. Dust particles, especially if coated by pollution, act as a condensation nuclei for warm cloud formation, which indirectly affects the energy reaching the earth’s surface.
The functioning of Airborne dust is akin to the greenhouse effect. It absorbs and scatters solar radiation entering Earth’s atmosphere, reducing the amount reaching the surface and absorbs long-wave radiation bouncing back up from the surface, re-emitting it in all directions. Dr. M. Mohapatra, a scientist associated with the Government of India’s Meteorological Department, told BE, “The condition for formation of thunderstorm in north India was intense heating, availability of moisture, unstable atmosphere and prevalence of conditions enabling the formation of a cyclonic circulation.”
While scientists said high temperatures, moisture and an agitated atmosphere made a perfect combination for storms of this type, meteorologists stated that the easterly winds from the Bay of Bengal brought in moisture that merged with the destructive winds from the west to trigger the havoc dust storms in northern India.
Out of these four conditions, if moisture is not available, it will lead to formation of a dust storm. Usually moisture is low in Rajasthan and adjoining Delhi, Haryana, UP and MP in the month of May-June. Hence, the dust storm occurs in these regions mostly in May and June. In both thunderstorm and dust storm, depending upon the intensity of the favourable parameters, there can be gustiness and squalls as well as lightning. When the wind speed exceeds 32 kmph suddenly, and remains for less than a minute, it is called as gust. If the wind speed exceeds 44 kmph and persists for at least one minute, it is called as squall. Rain may not occur in a thunderstorm. Sometimes, a dust storm gets converted into a thunderstorm as it moves over the area with higher humidity and causes rain. In a dust storm, there is reduced visibility due to a large amount of suspended particles in air. All the above conditions converged to create the dust storm. Mohapatra said, “There was a cyclonic circulation over Haryana which triggered the activity.”
It is alarming that even after the prolonged concerns and several debates held by industry and environmental experts over the on-going environmental hazards, India witnessed an acute dust storm. Even after steps like the ‘odd-even’ system pertaining to private vehicles adopted in Delhi to limit air pollution, there was nothing positive. Oppressive urbanisation, high environmental pollution, soaring temperatures and emission of greenhouse gases could be considered as the major reasons behind the dust storm. Kuldeep Srivastava, a senior official at the India Meteorological Department (IMD) informed The Hindustan Times that a cyclonic circulation, induced by a western atmospheric disturbance, high moisture levels brought by easterly winds and a recent spell of unusually high temperatures that soared to 45 degrees Celsius was responsible for the thunderstorms.
Furthermore, Mahesh Palawat, Chief Meteorologist, Skymet Weather, a private forecaster, said, “It can be called a freak incident. Dust storms are usually not this intense nor do these systems cover such a large area.”
Uttar Pradesh alone confirmed 73 deaths, which were mostly in the Agra district. 36 died in Rajasthan and two each in Uttarakhand, Madhya Pradesh and Punjab. Haryana, too, faced massive storms where trees were uprooted and power supplies were disrupted. At least, 150 animals were reported dead in Uttar Pradesh. Western Uttar Pradesh and neighbouring eastern Rajasthan bore the major brunt of the storms and many houses are reported to have collapsed. Other districts like Kanpur, Hamirpur, Bijnore and Meerut also reported widespread damage and casualties. Climate scientists attributed an increase in the frequency of storms to climate changes stemming from global warming, caused by heat-trapping of the greenhouse gases.
Frequency of dust storms in India
Dust storms have never been a common feature of the Indian climate. It is believed that the dust storm has been created due to lack of poor land and soil management, soil depletion and adoption of newer agricultural practices. The resultant soil erosion has been identified as a major cause of this dust storm.
Priya Pillai, an environmental activist, told BE, “The frequency has increased and the intensity of these calamities are increasing which of course can be attributed to climate change. As Delhi is already highly polluted, the concentration of 2.5 pm and 10 pm is already very high in Delhi because of the pollution. This will further aggravate the situation.
Impact of dust storms
Dust storms carry large amounts of airborne dust and pose serious risks to human health. The WMO states that particles larger than 10 μm are not breathable and can only damage external organs by mostly causing skin and eye irritations, conjunctivitis and enhanced susceptibility to ocular infection. Inhalable particles, those smaller than 10 μm, often get trapped in the nose, mouth and upper respiratory tract and can cause respiratory disorders like asthma, tracheitis, pneumonia, allergic rhinitis and silicosis. However, finer particles may penetrate the lower respiratory tract and enter the bloodstream to cause cardiovascular disorders.
‘‘These kinds of natural calamities or disasters are rising because of the climate change. We all know global temperature is rising, and the frequency and intensity of flood, dust storm, cyclones, and hurricanes has greatly increased. All these factors together can be attributed to the rise in global temperature. Even the IPCC report has predicted that as the global temperatures rise, we will find more of these natural calamities and the frequency of these calamities is increasing and the intensity of each of these becoming much stronger,” added Priya Pillai.
Additionally, dust storms have negative impact on agriculture. They reduce crop yields by burying seedlings, damaging plant tissues, reducing photosynthetic activities and by increasing soil erosion. Indirect dust deposit caused by such storms fill up irrigation canals, cover transportation routes and impact river and stream water quality.