As climate change continues to cause an escalation in climate disasters, several experts are trying to establish a link between the growing temperature of the Indian Ocean and the incidences of cloudbursts in the Himalayas.
However, the Centre has told Parliament "there is no established study for India" regarding climate change triggering cloudburst.
"Manifestations of extreme events, including cloudbursts, and their incidence are modelled and projected in various scientific assessments. However, there is no established study for India estimating the quantified contribution of climate change in triggering such cloudbursts," Minister of State for Environment, Forests and Climate Change, Ashwini Kumar Choubey told the Rajya Sabha in a written reply on August 2.
He added that the science of the attribution of such extreme events to climate change is far more complex and currently an evolving subject and is being closely studied by the Ministry of Earth Sciences, through the Indian Institute of Tropical Meteorology and the India Meteorological Department.
The issue perhaps lies with the definition of cloudbursts set by the India Meteorological Department (IMD). Cloudbursts are events wherein a small geographical area receives an intense amount of rainfall, usually caused by tall cloud formations that accumulate in mountainous areas.
The IMD defines a cloudburst as any event where 100 millimetres of rainfall pours down in a km² region in an hour. The stringent definition implies that IMD often doesn't characterise heavy rainfall events as cloudbursts even when local authorities and other experts do.
At least 26 cloudbursts occurred in the Himalayan region from January through July 29, 2021, according to an analysis by Down to Earth. However, none of these events were classified as cloudbursts by the IMD. The weather body has classified only 30 events as cloudbursts between 1970 and 2016.
Scientists have suggested a more reasonable cloudbursts parameter of rains of more than 50mm over a couple of hours in a limited area.
But as cloudbursts' exact definition remains muddled, experts have pointed to the link between a global rise in temperature with increasing frequency and the intensity of cloudbursts.
The reason behind this is the warming of the Indian Ocean, along with the Bay of Bengal and Arabian Sea. As water bodies get warmer, they produce water vapours and moisture that is carried by the monsoon winds inland. When the moisture-laden winds meet the impassable Himalayas, they start to accumulate in cloud formations that later result in cloudbursts.
Munir Ahmad of the Indian Institute of Technology, Srinagar said, "it (cloudburst) is likely to occur more with an increase in moisture from the Indian Ocean."
Meanwhile, Raghu Murtugudde, a climate scientist at the University of Maryland, told Down to Earth, "What is unusual in the current scenario is the very warm temperature anomaly to the west of north India over Iran, Pakistan and Afghanistan. The Arabian heat low pumps winds into the northern Arabian Sea and there has been a strong wind along the coast of Oman and going straight over Gujarat into Uttarakhand. I guess that this is raising the chances of cloudbursts there.”
With the rise in temperatures, the amount of moisture created and carried will in turn increase, leading to more frequent and intense cloudburst event
“As temperatures increase the atmosphere can hold more and more moisture and this moisture comes down as a short very intense rainfall for a short duration probably half an hour or one hour resulting in flash floods in the mountainous areas and urban floods in the cities,” said Vimal Mishra, from IIT Gandhinagar.
Mishra added there is evidence suggesting that globally short duration rainfall extremes are going to become more intense and frequent. With warming climate or climate change, the frequency of cloudburst events is likely to increase in the future.