Warming of waters in the Arabian Sea has led to the formation of deep cloud systems, leading to extremely heavy rainfall in Kerala in a shorter span and that has increased the possibility of landslides, climate scientists say.

Extremely heavy downpour led to a series of landslides in the hilly areas of Wayanad district in Kerala early on Tuesday. At least 45 people have been reported killed. Many were feared trapped under the debris at various places.

The director of the Advanced Centre for Atmospheric Radar Research at Cochin University of Science and Technology (CUSAT) S Abhilash has said Kannur, Wayanad, Kasargod, Calicut, and Malappuram districts have been receiving heavy rains due to the active monsoon affecting the entire Konkan region for the last 15 days.

The soil was saturated after two weeks of rainfall. A deep mesoscale cloud system formed off the coast in the Arabian Sea on Monday which led to extremely heavy rain in Calicut, Wayanad, Malappuram, and Kannur, resulting in localised landslides, he said.

“The clouds were very deep, similar to those seen during the 2019 Kerala floods,” S Abhilash said. He said scientists have witnessed a trend of very deep cloud systems developing over the southeast Arabian Sea, he said, adding that sometimes, these systems intrude into the land. The same had happened in 2019 as well.

“Our research has found that the southeast Arabian Sea is becoming hot, 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 behind such extremely heavy rainfall, he said.