On the waterfront: Cities at risk
Some of India’s richest and most populous cities sit squarely in the path of rising seas. Already, there are intensifying floods here, as well as cyclones and dry spells, receding groundwater levels and subsiding land. See what the latest IPCC report predicts for Mumbai, Surat, Kolkata, Chennai, Kochi, and see what these cities are doing to prepare
Indonesia is shifting its capital, partly in an attempt to get away from the sea. Jakarta, its current capital city, sits on the island of Java, a narrow strip in an increasingly stormy sea. The island is home to rivers that are flooding more frequently, as monsoon patterns change. Parts of the island are sinking as groundwater reserves are over-used. And Java is ceding land to a rising sea.
While it is alarming to see a country make such a move partly as a result of the climate crisis, it is even more concerning to note that many of the issues plaguing Jakarta are those that affect India’s coastal cities too.
India’s 7,500 km of coastline is home to some of the country’s largest cities by population and economy. Mumbai, the commercial capital, is an island city built largely on reclaimed land. Surat, a hub of the lucrative diamond and textile trades, is built along a river and is flood-prone.
Kochi is being lashed by storms from both coasts. Chennai’s water reserves are being depleted even as its population booms. Kolkata, already disaster-prone, is seeing land subside, seas rise, and the buffer offered by the Sunderbans weaken.
These five are among the coastal Indian cities at risk of being submerged by 2100, according to the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC); two of the report’s four parts have been released so far, in August 2021 and February 2022.
Other major at-risk cities in India include Ahmedabad, Kandla, Okha and Bhavnagar in Gujarat; Bhubaneswar and Paradip in Odisha; Patna and Lucknow; Mormugao in Goa; Mangaluru, Visakhapatnam and Tuticorin. In terms of potential economic impact from floods, Mumbai, Chennai and Kolk- ata also featured, alongside Guangzhou and Bangkok, on the IPCC’s list of 20 coastal cities around the world that stand to lose the most.
Rising sea levels are part of the reason these cities are at risk. Other key factors are already visible.
Warming seas are causing storms to intensify and super-storms to become more frequent. Cyclone Amphan, which hit West Bengal in May 2020, was one of the fiercest to hit the state in 100 years. On the cooler, calmer western coast, Cyclones Ockhi in 2017 and Tauktae in 2021 would once have been considered rare. Researchers at the Indian Institute of Tropical Meteorology have observed a 52% increase in the number of cyclones in the Arabian Sea over four decades, along with an increase in intensity and duration.
Altered monsoon patterns are causing flooding in cities that didn’t flood and worsening flooding in cities that did. The same is true of water scarcities. As the rains become more erratic and less predictable, they are dumping more of their volumes in single large events that cannot be absorbed effectively.
This depletes groundwater levels, already low on account of human use. Depleting groundwater levels cause land to subside. Meanwhile, as more land is covered with concrete in prime cities, more rainwater runs off into the sea.
“As cities grow taller and more concretised, turning into urban heat islands, the climatic behaviour within the city becomes erratic, with pockets of intense heat that cannot escape and rainfall that does not move,” says climate scientist Subimal Ghosh, convener of the interdisciplinary programme in climate studies at the Indian Institute of Technology (IIT) - Bombay, and one of the lead authors of the IPCC report.
For the purposes of this report, the focus is the coastlines. But it must still be said that much of India stands smack in the fallout zone of another major eco-sensitive and vulnerable land mass: the Himalayas.
As flash floods strike and glaciers recede, the impact of the climate crisis on the Himalayas is so significant, for India and globally, that the Hindu Kush-Karakoram-Himalayan mountain system is being referred to as the third pole.
Back to the coasts, what does the action plan look like? See what’s unfolding on the ground in five key cities.