The 2024 monsoon season in India recorded the highest number of heavy rainfall events in the last five years, a consulting agency Climate Trends has said in a report.
The effects of climate change had increased the longevity of the monsoon systems, the report added.
Citing data from the India Meteorological Department, the agency found that the southwest monsoon this year concluded with above-normal rainfall, reaching 108% of the long period average rainfall.
The measure is the mean rainfall during the four-month monsoon season over the last 50 years. The southwest monsoon season generally begins in June and starts to retreat by September.
“Between June 1 to September 30, India recorded 934.8 mm of rain, surpassing the seasonal norm of 868.6 mm,” the report said.
It said that out of the 729 districts it had analysed, 340 districts recorded normal rains during the four-month season, 158 districts experienced excess rainfall and 48 districts saw large excess rainfall.
However, while 167 districts faced a rainfall deficit, 11 districts had a large deficit, the report added.
There were 2,632 events of “extremely heavy rainfall”, which is defined as more than 204 mm in 24 hours, and 473 events of “very heavy rainfall”, or 115 mm to 204 mm in 24 hours, the researchers pointed out citing data from the weather department.
“During the last five to six years, weather systems have been travelling through central India, which used to follow the northward trend,” the report quoted KJ Ramesh, former director general of the India Meteorological Department, as saying.
“Changes of rainfall patterns are driven by global warming and at the same time driven by El Niño, IOD [Indian Ocean Dipole] and MJO [Madden Julian Oscillation],” he said. “High intensity and short duration precipitation is driven by climate change.”
The El Niño phenomenon involves warming of ocean surface temperatures in the eastern and central Pacific that typically occurs every few years and has been linked to crop damage, fires and flash floods.
The Indian Ocean Dipole is the difference in the surface temperatures of the sea between the western parts of the Indian Ocean near Africa and the eastern parts of the ocean near Indonesia. Positive conditions are good for rainfall over India.
The Madden-Julian Oscillation is a weather pattern that causes changes in atmospheric pressure over the Indian Ocean and Pacific Ocean. It creates alternating areas of low and high pressure, which can increase or decrease rainfall, and moves eastward along the equator.
“The longevity of monsoon systems has increased because of back-to-back systems,” Ramesh said.
The general link with climate change is that when conditions are favourable for rain, the chance of getting intense rainfall would be more than it was several years ago, the report quoted Akshay Deoras, a research scientist at the United Kingdom’s University of Reading, as saying.
Deoras added: “As the planet warms, the monsoon would get more and more variable. Longer dry spells and periods of more intense rainfall. Huge variation was seen in the rainfall among different districts.”
Aarti Khosla, the founder and director of Climate Trends, said that the rise in extreme weather events was constant due to a persistent rise in the average temperatures.
“We should now focus on building a comprehensive adaptation strategy to safeguard the lives, livelihood and ecosystems from overlapping climate impacts affecting the country's diverse geography,” she said.
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