Kolkata: Cyclone Arnab’s rapid intensification highlights growing risks to Sundarbans and coastal Bengal as unusually warm seas create favourable conditions for recurrent and powerful storms and extreme rainfallUnusually warm sea surface temperatures in the Bay of Bengal, coupled with the evolving El Nino phenomenon, could create conditions favourable for more powerful cyclones, raising fresh concerns over the vulnerability of West Bengal’s coastline. While scientists have not established that these conditions will necessarily bring more cyclones ashore in Bengal, they warn that storms developing over increasingly warm waters could intensify faster, unleash heavier rainfall and leave coastal communities with less time to prepare.Cyclone Arnab, which made landfall along the Andhra Pradesh and Yanam coasts early on Wednesday, has reinforced these concerns. The storm developed into a depression on Oct 24, strengthened into a cyclonic storm within 36 hours and subsequently intensified into a very severe cyclonic storm, packing sustained winds of 125–135 kmph and gusts reaching 150 kmph.For Bengal, still grappling with the consequences of Amphan and Yaas, Arnab is a reminder that the warming Bay of Bengal remains a breeding ground for potentially destructive cyclones, particularly during the post-monsoon season.Meteorologists attribute the rapid strengthening of tropical cyclones partly to the increasing heat stored in ocean waters. Warmer seas provide the energy and moisture necessary for storms to intensify, while a warmer atmosphere can hold more water vapour, increasing the potential for extreme rainfall.“Warmer-than-normal sea surface temperatures and potential influence of El Nino conditions may have contributed to its intensity,” said former India Meteorological Department director general KJ Ramesh. “While global warming does not cause El Nino, the background warming adds to the extra heat and intensifies the impacts of extreme weather systems.”The latest ocean temperature analysis cited in the assessment shows that global sea surface temperatures in September 2026 were 1.10°C above average, setting a record for the fourth consecutive month.Scientists believe such warming could have serious implications for the North Indian Ocean, where cyclones have shown an increasing tendency towards rapid intensification.According to research cited in the assessment, 38% of North Indian Ocean cyclones since 2000 have undergone rapid intensification, compared with 22% in the northwest Pacific. The eastward shift in cyclone formation over the Bay of Bengal may also allow some storms to spend longer over warm waters, drawing additional energy before approaching the coast.“Present conditions in the Bay of Bengal are extremely favourable for cyclogenesis. El Nino can play a significant role in amplifying the impacts of Cyclone Arnab,” said Akshay Deoras, research scientist at the University of Reading, UK. He warned that higher sea temperatures and increased atmospheric moisture could lead to more spells of intense rainfall.For Bengal, the implications extend well beyond coastal landfall. The Sundarbans, already exposed to rising sea levels, saline intrusion and erosion, face the possibility of repeated damage to embankments, agriculture and settlements. Kolkata and its surrounding urban areas also remain vulnerable to intense rainfall, waterlogging and disruptions to essential services.National Disaster Management Authority member Kirishna S Vatsa said improved forecasting and preparedness had significantly reduced cyclone mortality, but economic losses remained substantial. “Cyclones, these days, are no longer limited to coastal hazards, as we can now see them impacting inner parts of the states as well,” he said.IPCC author Anjal Prakash called for climate-resilient housing, stronger electricity grids, flood-proof roads and better insurance protection for farmers and informal workers. For Bengal, the emerging challenge is not simply to count how many cyclones approach its coast, but to prepare for storms that may intensify more rapidly and inflict greater damage in an increasingly warmer world.
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