A new rapid attribution study has identified climate change as a significant factor in the deadly landslides that devastated Kerala's ecologically fragile Wayanad district. The landslides, triggered by an intense burst of rainfall, resulted in the deaths of at least 231 people and caused widespread destruction. The study, conducted by a global team of 24 scientists from India, Sweden, the US, and the UK, revealed that the rainfall was 10 percent heavier due to the impacts of human-induced climate change.
The researchers, part of the World Weather Attribution (WWA) group, analyzed climate models to measure the influence of climate change on the rainfall that occurred in Wayanad. Their findings indicated that more than 140 mm of rainfall fell in just one day on already saturated soils, leading to the catastrophic landslides and floods. The models showed that the intensity of the rainfall was 10 percent greater than it would have been without the effects of climate change. Furthermore, the study predicts a further increase in rainfall intensity by an additional four percent if global temperatures rise by two degrees Celsius above pre-industrial levels.
The study acknowledged the complexities involved in accurately predicting rainfall in such a small and mountainous area as Wayanad, leading to a "high level of uncertainty" in the model results. However, the increase in extreme one-day rainfall events is consistent with a growing body of scientific evidence on climate change's role in intensifying extreme weather, including in India. Scientists have noted that a warmer atmosphere holds more moisture, which leads to heavier and more frequent downpours. The atmosphere’s capacity to hold moisture increases by about 7 percent for every one-degree Celsius rise in global temperature. Currently, the earth's global surface temperature has increased by around 1.3 degrees Celsius due to the rapidly rising concentration of greenhouse gases, primarily carbon dioxide and methane. This warming is driving more frequent and severe extreme weather events, such as droughts, heatwaves, and floods, worldwide.
The WWA scientists also pointed to land-use changes as a contributing factor to the increased landslide risk in Wayanad. The relationship between land cover changes and landslide susceptibility is complex, but factors such as quarrying for building materials and a 62 percent reduction in forest cover over the past several decades have likely made the slopes more vulnerable during heavy rainfall. Other researchers have linked the landslides to a combination of forest cover loss, mining in fragile terrains, and prolonged periods of rain followed by intense precipitation.
S. Abhilash, director of the Advanced Centre for Atmospheric Radar Research at Cochin University of Science and Technology (CUSAT), highlighted the role of the warming Arabian Sea in the formation of deep cloud systems, which contribute to extremely heavy rainfall in Kerala within short periods. This phenomenon, he said, increases the risk of landslides.
According to the landslide atlas released by ISRO's National Remote Sensing Centre last year, 10 out of the top 30 landslide-prone districts in India are in Kerala, with Wayanad ranking 13th. A 2021 study published by Springer identified landslide hotspots in Kerala, concentrated primarily in the Western Ghats region, including Idukki, Ernakulam, Kottayam, Wayanad, Kozhikode, and Malappuram districts. The study revealed that about 59 percent of all landslides in Kerala have occurred in plantation areas.
A 2022 study on forest cover depletion in Wayanad showed a staggering 62 percent reduction in forests between 1950 and 2018, while plantation cover rose by approximately 1,800 percent during the same period. These changes in land use have significantly contributed to the region's vulnerability to landslides, especially in the face of increasingly erratic and extreme weather patterns driven by climate change.
