Kolkata: Kolkata could face a future of devastating downpours and prolonged water shortages as global warming increases atmospheric moisture by as much as 25% by the end of the century, according to an IIT Kharagpur study warning of an increasingly volatile global water cycle.
By 2100, atmospheric water vapour over Kolkata and West Bengal could increase by roughly 15% under a moderate-emission pathway and 25% under a high-emission pathway, said Prof Jayanarayanan Kuttippurath of IIT Kharagpur’s Centre of Ocean, River, Atmosphere and Land Sciences (CORAL), who led the research. Using CMIP6 climate models, researchers examined atmospheric moisture changes between 1980 and 2020 and projected their evolution through 2100. The study found that atmospheric moisture could increase by 5–18 mm under moderate emissions and 7–28 mm under high emissions across different regions.
The warning follows a study titled “Global changes in precipitable water vapour during 1980–2100 and its spatial, temporal, radiative and causal insights for enhanced climate warming,” published in the Journal of Hydrology. “West Bengal’s agriculture could face a difficult water paradox in the coming decades: more water in the atmosphere, but not necessarily more water available to crops,” Kuttippurath said. The projections suggest that Kolkata could experience heavier rainfall and severe waterlogging even as rising temperatures and erratic rainfall put greater pressure on freshwater availability. Kuttippurath clarified that the research was global in scope and did not involve separate city-specific modelling for Kolkata. The estimates for Kolkata and Bengal are regional interpretations of its broader findings. However, a wetter atmosphere does not necessarily mean more evenly distributed rainfall. For Bengal, the implications extend beyond Kolkata’s waterlogged streets to its agricultural heartland. Rice cultivation could become particularly vulnerable to both excessive rainfall and prolonged dry spells. In the Sundarbans, rising salinity and limited freshwater availability could further threaten agriculture.