Warming Arabian Sea Linked to Devastating Landslides in Kerala's Wayanad

Warming of the Arabian Sea is enabling the formation of deep cloud systems, resulting in extremely heavy rainfall in Kerala over shorter periods and increasing the likelihood of landslides, a senior climate scientist stated on Tuesday. The intense rain triggered multiple landslides in Kerala's Wayanad district early on Tuesday, causing at least 123 fatalities and injuring 128 people. Many individuals are feared to be trapped under the debris.

S Abhilash, director of the Advanced Centre for Atmospheric Radar Research at Cochin University of Science and Technology (CUSAT), explained that Kasargod, Kannur, Wayanad, Calicut, and Malappuram districts have been experiencing significant rainfall due to an active monsoon offshore trough impacting the entire Konkan region for the past two weeks. The soil saturation from continuous rainfall led to a deep mesoscale cloud system forming off the Arabian Sea coast on Monday, which resulted in extremely heavy rain in Wayanad, Calicut, Malappuram, and Kannur, causing localised landslides.

Climate Change Impact

Abhilash noted that scientists have observed a trend of very deep cloud systems developing over the southeast Arabian Sea. He added that sometimes these systems intrude into the land, similar to what happened 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 is linked to climate change and allows for the formation of deep clouds. Previously, such 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, which is the primary reason behind such extremely heavy rainfall.

Research Findings

Research by Abhilash and other scientists published in Climate and Atmospheric Science journal in 2022 found that rainfall over India's west coast is becoming more convective. Another study by Abhilash and scientists from IITM and IMD, published in Elsevier in 2021, found that one of the hotspots of heavy rainfall in the Konkan region between 14 degrees north and 16 degrees north seems to have shifted southward with likely fatal consequences.

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 monsoon seasons. According to the India Meteorological Department (IMD), several automatic weather stations in Thrissur, Palakkad, Kozhikode, Wayanad, Kannur, Malappuram, and Ernakulam districts recorded rainfall between 19 cm and 35 cm.

Rainfall Data

Most automatic weather stations of the IMD in the region recorded rainfall above 24 cm within 24 hours. Some stations installed by farmers recorded more than 30 cm of rain. The Met Office indicated that very heavy rainfall could occur in some places within the state over the next two days.

Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology, mentioned it is too early to understand the specifics of the Kerala landslides. "In general, monsoon patterns have become erratic and more rainfall is occurring in a short period. As a result, there are frequent instances of landslides and floods along the Western Ghats from Kerala to Maharashtra," he said.

The clouds were very deep, similar to those seen during the 2019 Kerala floods. This atmospheric instability allows for deep cloud formation linked to climate change. Earlier, this kind of rainfall was more common in northern Konkan belt areas north of Mangalore.

With climate change extending this rain-bearing belt southward, extremely heavy rainfall has become more frequent. Research indicates that this shift has significant consequences for regions like Kerala.

The findings underscore an urgent need for better preparedness against such extreme weather events. Enhanced monitoring and early warning systems could mitigate some impacts on vulnerable communities.