The “Big Four” venomous snakes of India, namely the Indian cobra (Naja naja), common krait (Bungarus caeruleus), Russell’s viper (Daboia russelii), and saw-scaled viper (Echis carinatus), are likely to see their habitats shift significantly due to climate change, a new study has found.
For record’s sake, the four are responsible for most snakebite deaths in the country.
Published in the journal PLOS Neglected Tropical Diseases, the study, titled ‘Future of snakebite risk in India: Consequence of climate change and the shifting habitats of the big four species in next five decades,’ warns that while southern states may see a reduction in suitable habitats, northern and northeastern regions could experience a sharp rise in risk, exposing new populations to snakebite-related health concerns.
The research has been carried out by Imon Abedin, Hey-Eun Kang, Hemanta Saikia, Won-Kyo Jung, Hyun-Woo Kim, and Shantanu Kundu.
The risk index developed in the study combined three main elements including overlap of snake habitats with croplands and built-up areas, socio-economic deprivation and access to healthcare.
Researchers noted that most snakebites occur in farming or settlement regions where humans and snakes are likely to encounter each other. To measure socio-economic vulnerability, they used the Global Gridded Relative Deprivation Index (GGRDI), which incorporates factors such as education, healthcare, infrastructure, and housing. Data on healthcare facilities were sourced from the UN Office for the Coordination of Humanitarian Affairs.
At present, southern states, particularly Karnataka, Tamil Nadu and Kerala, record the highest overlap between croplands and snake habitats. Districts in Karnataka such as Chikkaballapura, Haveri and Chitradurga are identified as high-risk zones. Gujarat and Maharashtra also show considerable overlap with agricultural lands and human settlements. These overlaps indicate greater chances of snakebite incidents in these regions.
The study, however, warns that climate change will likely cause a northward and northeastward shift in snake habitats. Rising temperatures and changing rainfall patterns are expected to reduce suitable habitats in parts of southern and western India, while creating new favourable areas in northern and northeastern states. For example, Karnataka is projected to lose a significant share of its highly suitable habitats, but Assam and Manipur may experience a large increase. Assam could see its cobra-related risk index rise by more than seven times under extreme climate scenarios between 2061 and 2080. The projections also highlight species-specific changes. The common krait and Russell’s viper, for instance, are expected to expand into new regions where they are not currently found in large numbers. Conversely, the saw-scaled viper is likely to retain more of its existing range, with comparatively smaller declines.
Overall, suitable habitats for all four species are projected to shrink by 40 per cent to 80 per cent in southern states, while northeastern states such as Nagaland, Meghalaya and Arunachal Pradesh - currently unsuitable - may record more than 100 per cent increases in habitat suitability.
The researchers emphasised that risk is not determined by habitat alone. “Socio-economic conditions and healthcare access strongly influence outcomes of snakebite incidents. Areas with poor healthcare facilities and high deprivation scores face higher mortality and morbidity. East Kameng district in Arunachal Pradesh currently records one of the highest risk scores due to poor infrastructure and limited services, despite relatively lower habitat overlap,” the study noted.
The study recommends expanding healthcare networks, raising awareness in newly vulnerable regions, and developing targeted mitigation strategies to reduce the health burden of snakebites in a changing climate.