What’s in store for India’s coastal cities?
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, Lucknow, Khidirpur; Mormugao in Goa, Mangaluru, Visakhapatnam and Tuticorin.
In terms of potential economic impact from floods, Mumbai, Chennai and Kolkata 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 itself becomes erratic, with pockets of intense heat that cannot escape and rainfall that does not move,” says climate scientist Submal 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.
MUMBAI: A coast-benefit analysis
Old maps of Mumbai are collectors’ items because of how the shape of the city has changed, as it was claimed, colonised, reclaimed and built up over about 250 years. A clump of seven marshy islands has turned into one of the world’s most densely populated megalopolises, the city and suburbs alone home to an estimated 12.4 million people.
Today’s maps could soon be collectors’ items too. The sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC) estimates that large parts of the city could vanish under the sea by 2100, as sea levels rise. In 30 years, about 70% of south Mumbai could be underwater, the city’s municipal commissioner Iqbal Chahal said last August, while announcing that the city was beginning work on a Mumbai Climate Action Plan.
This is a megalopolis that juts into the sea, is built in large parts on reclaimed land, and has a coastline under constant attack from construction (it has some of the world’s most highly priced real-estate), and from infrastructure projects such as the coastal road, which the IPCC report terms “maladaptive”.
Now, as storms intensify on the western coast and cyclones begin to form in the Arabian Sea, this will have a cascading effect. In June 2020, Mumbai was hit by Nisarga, its first cyclone in over 70 years. In May 2021, Cyclone Tauktae became the first extremely severe cyclonic storm to affect Mumbai in 130 years.
“Mumbai is in a unique location, where huge moisture surges generated from the very warm western Indian Ocean enter the landmass, and move towards central India, causing extreme rainfall along the way,” 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. “It acts as sort of a gateway for these events.”
In terms of mitigation efforts, the municipal corporation last month launched the Mumbai Climate Action Plan, a 30-year strategy aimed at readying the city for the coming crises.
It identifies priority areas such as air pollution, urban greening, water resource management and sustainable mobility, with the aim of reaching net-zero carbon emissions by 2050. The plan includes building flood resistant infrastructure, increasing solar power capacity, and improving the century-old stormwater drains that flood even in a normal monsoon.
“The plan ticks all the boxes, but it’s not clear how it is all going to be carried out on the ground,” says Anjal Prakash, research director at the Bharti Institute of Public Policy of the Indian School of Business, Hyderabad, and one of the lead authors of the recent IPCC report. “Coordination, implementation and accountability are where the major issues are. I would say there has to be a special purpose vehicle that reports directly to the chief minister’s office, with the power to implement even at the ward level, with transparency. The role of civil society in monitoring and evaluating the programmes must also be accommodated.”
Without such a special vehicle or some extraordinarily new approach, the Mumbai Climate Action Plan risks ending up like the ambitious Brimstowad (Brihanmumbai Stormwater Disposal System), a project that dates back to 1985, got a boost after the deluge of 2005, but remains mired in litigation and delays nearly 40 years on.
- Natasha Rego
KOLKATA: Heat, drought, storms, cyclones. Could a bio-shield be the answer?
Cyclone Amphan, which hit West Bengal in May 2020, was the first super-cyclone in the Bay of Bengal since 1999, and one of the fiercest to hit the state in 100 years. Exactly a year on, Cyclone Yaas hit.
West Bengal has always had more than its share of hydro-meteorological disasters — floods and cyclones, downpours and lightning strikes. It has the highest death toll from such events of any state in India, according to 2021 data from the Union ministry of earth sciences, with an estimated 964 deaths between April 2018 and March 2021.
Kolkata, the state’s capital, sits at sea level, along the Hooghly river, 125 km from the coast. It has been listed as one of the seven megacities in Asia most vulnerable to disaster-related mortality. It is now at risk from fiercer storms , more intense heat waves, flooding, drought, outbreaks of vector-borne diseases, distress migrations into the city, and a further dipping of land levels as groundwater levels plummet.
For centuries, the city and the state were protected by the Sunderbans, the world’s largest mangrove delta. But the Sunderbans has been losing its very dense mangrove cover, as a result of intensifying storms and rising salinity.
In one sweep, 1,600 sq km of mangrove forest were damaged by Cyclone Amphan. “Amphan has definitely taken a toll on the Sunderbans,” says Debal Roy, chief wildlife warden for West Bengal.
While an IPCC report from 2019 states that sea level is rising by 3.6 mm every year, the Sunderbans delta is subsiding by 2.9 mm every year. “These two figures put together show that water is gobbling up land at the rate of 6.5 mm per year,” says Kalyan Rudra, river expert and chairperson of the West Bengal Pollution Control Board.
Intensifying heat waves are set to raise the risk of drought. “With rising temperatures, cases of vector-borne diseases such as malaria and dengue are also expected to rise,” says Tuhin Ghosh, director of the School of Oceanographic Studies at Jadavpur University. Storms, drought and land loss will force climate migrants to move to cities such as Kolkata, which will further stretch their resources.
Is Kolkata prepared to handle the crises? Human activity continues to eat away at carbon sinks and natural aquifers. “Unbridled development has obstructed the natural drainage system into the East Kolkata Wetlands, which act like the kidneys of the city. As groundwater levels across the city plunge, this may result in gradual subsidence of land,” Ghosh says. Even the city’s drainage systems haven’t been updated; its stormwater drains, like Mumbai’s, date back a century, to colonial times.
The state’s forest department is now working to create a “bio-shield”, a sort of sea wall made up of various plant species that can absorb the impact of storms and protect coastal areas, including the Sunderbans.
“There has to be a combination of strengthening green and blue infrastructure. While green infrastructure includes more focus on urban greening and biodiversity protection for different climate anomalies, blue infrastructure refers to protecting and enriching waterbodies, cascading lake systems, streams and rivers across the city,” says Anjal Prakash, a climate scientist and co-author of the recent IPCC report. “It is important going forward for Kolkata and other cities in West Bengal to focus on resilience plans.”
- Joydeep Thakur
SURAT: Booming population, record floods
Surat sits a mere 13 m above sea level, with the Tapi river, and a network of creeks flowing through it. This makes it vulnerable to flooding. Now, the effects of the climate crisis are being felt too.
In 2006, a deluge combined with high tides to inundate 80% of Surat for four days. It was the third major flood in 12 years, in a city that saw 20 notable floods in the century preceding. “With every 1 degree rise in temperature, we should expect a 7% intensification of extremes,” says Udit Bhatia, a climate scientist working on critical infrastructure resilience at the Indian Institute of Technology (IIT) - Gandhinagar.
As the city works to build a resilience plan, it doesn’t help that Surat’s population is booming. The city, a hub of the lucrative diamond and textile trades, has one of the fastest-growing populations of any city in India. It jumped from 2.4 million to 4.4 million between 2001 and 2011, according to census figures — a rise of over 50% at a time when the national average was 17%. The population is currently 6.9 million and is expected to grow at a rate of 9% until 2035, according to a 2018 report by Oxford Economics, making it the fastest growing city in the world.
What does the resilience plan look like? In 2008, Surat was one of 10 Asian cities (two others from India were Gorakhpur and Indore) selected to join the Asian Cities Climate Change Resilience Network, a joint effort to develop resilience strategies for the years ahead. Under it, the Surat Municipal Corporation (SMC) set up the Surat Climate Change Trust, with climate experts and researchers on board to help analyse patterns and predictions, strategise and help formulate mitigation plans, especially for flooding.
“One of the finest projects that we worked on was establishing an early flood warning system, with the help of IIT-Delhi, in 2013,” says Kamlesh Yagnik, a founder trustee of the Surat Climate Change Trust and chief resilience officer with the SMC. “The integrated system gives us forecasting results from the IMD, lets us know how much rain is going to fall where, and how much is essentially going to have to be released from the dam. It lets us know which areas of the city will be inundated. Of course, it requires continuous fine-tuning, because every year newer real estate developments take place.”
The city has other projects in the works too. One is a proposed 68-hectare biodiversity park, an urban forest that would act as a lung of the city. The other is a proposed water plaza, an idea borrowed from the Netherlands. “It is essentially a multipurpose, transit storage space within the city, with provisions to store water when there is heavy inflow, until it can be pumped out later,” says Yagnik. “At other times, the same space can be used for community engagement, sports, and it can act as a park also.”
If maintained and sustained right, these initiatives could certainly add to the local mitigation efforts, especially in reducing urban heat island effect, says Bhatia.
Meanwhile, construction continues along the banks of the Tapi. A report filed by retired justice BC Patel, former chief justice of the Delhi high court, before the National Green Tribunal, reads: “The law pertaining to Land Acquisition has not been followed, the land was not acquired and the land appears to have been allowed to develop.”
- Natasha Rego
KOCHI: In the path of more storms
Cyclone Ockhi hit Kochi, with devastating effect, in 2017. At least 300 people were killed; hundreds are still missing. In 2021, Cyclone Tauktae travelled parallel to the western coast of India, before making landfall in Gujarat. It caused heavy rainfall in Kerala in May, and delayed the onset of the monsoon. That same year, Cyclone Yaas, which originated in the Bay of Bengal, added to the havoc, and the impact on the monsoon.
Cyclones used to be an unusual phenomenon on the west coast, because of the historically cool waters of the Arabian Sea. In recent decades, that’s changed. “Temperatures in the Arabian Sea have been rising gradually since the early 1900s, with an accelerated increase since the 1980s,” says Roxy Koll, a climate scientist at the Centre for Climate Change Research at the Indian Institute of Tropical Meteorology (IITM) in Pune.
Researchers at IITM have observed a 52% increase in the number of cyclones in the Arabian Sea over the past four decades, along with an increase in intensity and duration. “As we saw with Tauktae, cyclones now spend a long time in the sea, building up a lot of moisture, increasing the chances of destruction along the coast,” Koll says.
Kochi’s position between the Lakshadweep archipelago and Sri Lanka, in the tapering southern end of peninsular India, makes it susceptible to cyclones formed in the Bay of Bengal too.
Kochi’s vulnerabilities are compounded by its location between a sea whose levels are rising and the ravaged hills of the Western Ghats, which send monsoon runoff rushing into the city. “We are seeing that total rainfall during the monsoon period is actually decreasing,” says Koll, who contributed to the recent IPCC report. “We’re having long dry periods, with intermittent heavy-rain events. When the rain does come, it can bring a month’s worth of rainfall in a few days.”
What is the mitigation plan? The short answer is that there isn’t one. At a virtual conference organised last year by the World Resources Institute — the non-profit global research institute that also helped formulate the Mumbai Climate Action Plan — experts and stakeholders from the state discussed the need for a robust action plan to integrate disaster management, nature-based solutions and the involvement of local communities.
The most noteworthy project currently on the table is a two-year-old one that seeks to upgrade some of the city’s 18 canals, to prevent flooding and promote water transportation.
“Restoring these canals is also an important step in tackling water logging, as the drainage system is not capable of accommodating such huge quantities of precipitation appearing these days,” says Sunny George, director of the SCMS Water Institute, an educational institute that provided technical support to the Kochi Municipal Corporation in formulating the city’s 2015 water policy.
- Natasha Rego
CHENNAI: Nascent struggle to stem the flow
As sea levels rise, climatologists watching Chennai are expecting to see flooding, drought and water shortages.
This is a city whose population is growing so fast that estimates have shot up from 4.6 million in the 2011 census to 10.7 million according to Statista, as of 2019. Meanwhile, rampant urbanisation and poor urban planning have seen the total area occupied by water bodies shrink from nearly 12.6 sq km in 1893 to about 3.2 sq km in 2017, according to a 2019 study by the department of geology at Chennai’s Anna University.
In June 2019, after three consecutive deficient monsoons, the city’s four main reservoirs ran dry. Amid uneven rainfall and the shrinking and pollution of water bodies and aquifers, Chennai now leans heavily on desalination plants and groundwater.
Meanwhile, flooding is intensifying. In December 2015, a downpour of 494 mm — the heaviest one-day rainfall in Chennai since 1901 — wreaked havoc in the city. November 2021 went down as the third-wettest November in the city’s recorded history.
“Population growth, drastic changes in land-use patterns, loss of green cover, and inundation due to sea-level rise all make the city exceedingly vulnerable to climate change,” says Palanivelu Kandasamy, professor of environmental sciences at the Centre for Environmental Studies at Anna University. “Climate change action must shift from mitigation to adaptive strategies, and the state must accelerate the pace of the efforts.” Coastal embankments must be constructed where necessary, Kandasamy adds. Instead, marshlands and wetlands are being filled in for construction.
The Pallikaranai marshland, the only urban wetland in Chennai city and one that acted as a sponge in times of flooding, has shrunk by about 90% over less than half a century. A dumping ground as well as developments on and around the wetland have reduced its area from about 5,500 hectares in 1965 to about 600 hectares in 2013, according to a 2019 report by an amicus curiae, senior counsel P S Raman, appointed by the Madras High Court.
Last year, the court directed the state government to declare Pallikaranai a protected Ramsar wetland; the proposal is awaiting a nod from the centre.
For now, the biggest immediate concerns are the increasingly intense storm surges on the cyclone-prone eastern coast, says SA Sannasiraj, professor of ocean engineering at the Indian Institute of Technology (IIT) - Madras. “The frequency of cyclones in the Bay of Bengal is growing. In 2020, there were four major cyclones affecting India — Amphan, Nisarga, Nivar and Burevi,” Sannasiraj says.
In terms of adaptation and mitigation strategies, last August the Tamil Nadu government began formulating a Climate Change Mission aimed at focusing on sustainable agriculture, water resources, forest and biodiversity, strategic knowledge, enhanced energy efficiency and solar power. The plan is to “carry out 199 projects in these sectors” by 2030.
- Vanessa Viegas