Study links monsoon changes, cloud shifts to rising flash flood threats

With IMD predicting above-normal monsoon in 2025, new studies reveal sharp rise in intense short-duration rainfall and changing cloud patterns due to warming

A new paper by some eminent scientists shows that sub-daily rainfall extremes have been steadily rising over the country that could precipitate the threat of flash floods. 

 

The paper, published in a journal of ‘Nature’, sometime back has been written by former secretary in the ministry of earth sciences Madhavan Nair Rajeevan along with eminent scientists Kadiri Saikranthi and Basivi Radhakrishna.The India Meteorological Department (IMD) yesterday predicted “above normal” monsoon across India in 2025.

 

The research used hourly self-recorded rain gauges’ data from 1969 to 2010 from IMD to arrive at the conclusions.

 

It said that the frequency of short-duration, heavy rainfall events over Central India and long-duration heavy rainfall events over North-Western Coasts of the country has risen considerably in the last few decades as compared to the previous decades.

 

Meanwhile, another recent study by Saloni Sharma, along with researchers Piyush Kumar Ojha, Vaibhav Bangar, Chandan Sarangi, Ilan Koren, Krishan Kumar, and, Amit Kumar Mishra from the School of Environmental Sciences, at Jawaharlal Nehru University, in collaboration with IIT Madras and Weizmann Institute of Sciences, Israel, showed how global warming is reshaping India’s monsoonal cloud patterns. 

 

The research, published in Science of the Total Environment some months back, used 20 years of radiosonde data from 16 locations across India to conclude that the number of cloudy days during the monsoon season has increased by around 13 per cent per decade.

 

However, this doesn’t mean more low level, rain-heavy clouds.

 

In fact, low-level clouds have decreased by 8 per cent, while high-level clouds-- which often trap heat-- have increased by about 11 per cent per decade.

 

This shift in cloud types is significant, the paper said.

 

It said that low-level clouds are typically thicker and more effective at reflecting sunlight, helping to cool the Earth’s surface. High-level clouds, by contrast, tend to trap heat. The study found that not only are these higher clouds becoming more common, but they are also forming at greater altitudes as the atmosphere warms and expands.