The formation of deep cloud systems caused by the warming of the Arabian Sea is resulting in extremely heavy rainfall in Kerala over shorter periods, increasing the risk of landslides, according to a senior climate scientist's statement on Tuesday,
At least 89 people were killed in a series of landslides in Kerala's Wayanad district as a result of the heavy rain on Tuesday, with many feared to be trapped under debris.
S Abhilash, director of the Advanced Centre for Atmospheric Radar Research at Cochin University of Science and Technology (CUSAT), mentioned that Kasargod, Kannur, Wayanad, Calicut, and Malappuram districts have been experiencing abundant rainfall for the past two weeks due to the active monsoon offshore trough affecting the entire Konkan region.
Following two weeks of rain, the ground was already saturated. On Monday, a deep mesoscale cloud system developed off the coast of the Arabian Sea and led to exceptionally heavy rain in Wayanad, Calicut, Malappuram, and Kannur, resulting in localized landslides, as reported to PTI.
"The clouds were very deep, similar to those seen during the 2019 Kerala floods," Abhilash said.
He said scientists have noticed a trend of very deep cloud systems developing over the southeast Arabian Sea, adding that sometimes, these systems intrude into the land, like in 2019.
"Our research found that the southeast Arabian Sea is becoming warmer, causing the atmosphere above this region, including Kerala, to become thermodynamically unstable," Abhilash said.
"This atmospheric instability, allowing the formation of deep clouds, is linked to climate change. Earlier, this kind of rainfall was more common in the northern Konkan belt, north of Mangalore." With climate change, that rain-bearing belt with deep clouds is extending southward, and this is the main reason for such extremely heavy rainfall, he said.
Research conducted by Abhilash and other researchers and documented in the NPJ Climate and Atmospheric Science journal in 2022 indicates that there is an increase in convective rainfall over the west coast of India.
Another research paper authored by Abhilash and scientists from IITM and IMD, which was published in Elsevier in 2021, reveals that a region known for heavy rainfall in the Konkan area (between 14 degrees north and 16 degrees north) appears to have shifted southwards, potentially leading to fatal repercussions.
"An increase in rainfall intensity may suggest a rising probability of landslides in the high to mid-land slopes of the Western Ghats in eastern Kerala during the monsoon seasons," the study said.
According to the India Meteorological Department, several automatic weather stations in Thrissur, Palakkad, Kozhikode, Wayanad, Kannur, Malappuram, and Ernakulam districts recorded rainfall between 19 cm and 35 cm.
"Most automatic weather stations of the IMD in the region recorded rainfall above 24 cm in 24 hours. Some stations installed by farmers recorded more than 30 cm of rain," Abhilash said.
The Met Office said very heavy rainfall could occur in some places in the state over the next two days.
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