Kolkata and the Sundarbans two regions separated by just 100 km, are now being seen as climate twins. At a recent meet in Kolkata, experts said that the air and water pollution from the city is damaging the Sundarbans mangroves an ecosystem that, in turn, acts as a vital buffer protecting Kolkata from extreme weather. The loss of these mangroves is making the city more vulnerable to climate shocks.
At the heart of the meet was the Kolkata Declaration 2025, a five-point agenda focused on a shared climate security strategy. Experts stressed the need for an integrated approach rather than treating Kolkata and the Sundarbans as separate climate cases.
The event, a citizen assembly, was organised by Tramjatra an international tram-lovers’ movement involving activists from Kolkata and Melbourne. Over a hundred people attended, including scientists, environmentalists, and public figures.
From Local Action to Global Stage
The declaration called for reducing emissions by promoting eco-friendly transport like trams, getting civil society and politicians more involved, and seeking climate justice for those already suffering the worst impacts.
Michael Douglas from RMIT University, along with Australian activist Roberto D’Andrea and filmmaker Mahadeb Shee, said a white paper will be presented to both Indian and global decision-makers. Sanjay Vashist of CANSA added that his group is already working on climate-linked migration from the Sundarbans and plans to highlight these issues internationally.
Former bureaucrat and MP Jawhar Sircar admitted that most governments, regardless of political stance, don’t prioritise the environment. Dr. Kunal Sarkar blamed the global slowdown in climate action on political setbacks like Donald Trump’s presidency.
Deep Link Between City + Delta
Bose Institute’s Abhijeet Chatterjee explained that even a 1% rise in Kolkata’s emissions can reduce mangrove photosynthesis by 15%, weakening their ability to store carbon an alarming trend since Sundarbans’ mangroves hold nearly 270 million tonnes of carbon.
Toxic metals and microplastics from city effluents are also degrading water quality in the Sundarbans, according to Punyaslok Bhadury from IISER-Kolkata. While mangroves tend to bounce back after cyclones within weeks, the constant pollution pressure is another story.
Oceanographer Tuhin Ghosh flagged climate-induced migration as a growing issue in the Sundarbans. He, along with botanist Krishna Ray, warned against artificial mangrove plantations, saying they often fail to provide the same ecological services as naturally grown ones.
Environmental lawyer Ritwick Dutta emphasized the need for legal pathways to climate justice, especially for those who are suffering without contributing to the crisis. “The legal system may not support this yet, but we’re pushing for it,” he said.
Tramways = Climate Lifeline
The panel also made a strong case for saving Kolkata’s iconic tram system not just for heritage, but as a real climate solution. With increasing private vehicles and shrinking road space, experts said sustainable transport like trams and ferries are the only way forward.
Transport expert Bhargab Maitra of IIT-Kharagpur warned that mobility in the city will collapse without action. Anumita Roychoudhury of CSE added that the city’s clean air targets are unattainable without reviving and modernising trams an official requirement under the NCAP.
Despite this, the state government plans to shut down all tram routes except one heritage line, a move that’s facing stiff opposition from green groups and civic bodies.
Urban planner Tathagata Chatterjee pushed for a data-driven, long-term development strategy rooted in climate resilience. Mahalaya Chatterjee, an urban economist, criticised past decisions to prioritise buses over trams, calling it a “suicidal move.”