Mumbai faces increasing storm surges

Many older citizens of Mumbai vividly recall the cyclone that hit the metropolis in 1948. As strong winds and rain lashed the city incessantly, the sky was completely overcast for a few days and a sense of menace pervaded the city. Trees were uprooted in large numbers and there was extensive property damage.

Indelible memories of that cataclysmic event came back to the mind as this reporter attended a full-day workshop on Cyclones & Storm Surges: Building a Framework for Evaluating the Climate Risk to Mumbai, organised by Columbia University’s Global Centre in Mumbai recently. It was led by Adam Sobel, a meteorologist who heads a new Initiative on Weather Risk and Climate at the New York-based university.

Sobel is familiar to some Indian readers because he is cited by Amitav Ghosh in his recent non-fiction book, The Great Derangement: Climate Change and the Unthinkable, for detailing how Hurricane Sandy, which hit New York in 2012, was frequently described as an “unprecedented” phenomenon and wasn’t expected, like many repercussions of climate change.

Sobel wrote a book titled Storm Surge: Hurricane Sandy, Our Changing Climate, and Extreme Weather of the Past and Future in 2014. A surge is the rise in sea level as the winds whipped up by a storm propel ocean water on to the shore. He states how losing one’s life to a hurricane is “something that happens in faraway places” and Ghosh began to wonder if a storm of this magnitude could hit Mumbai, also a coastal megacity and a commercial hub, and contacted Sobel. That started the New Yorker thinking.

In 2013, Mumbai was listed by the journal Nature Climate Change as the fifth coastal city in the world to be most affected by flooding in the future, measured by economic losses. The first four are Guangzhou, Miami, New York-Newark and New Orleans.

Link with climate change

In his presentation in Mumbai, Sobel raised the possibility of linking Mumbai being the landfall in the event of a severe storm in the future and low-lying areas being flooded with climate change. He hastened to assert that investigations were at a very preliminary level and his team was embarking on a two-year study. They displayed a hypothetical model of how a cyclone would impact Mumbai and will resort extensively to modelling to assess possible impacts.

According to a recent unpublished paper by R. Mani Murali from the National Institute of Oceanography (NIO) in Goa, Mumbai has some coastal areas as low as 6-8 metres above sea level, with an average elevation of 14 metres. It is well known that Bombay originally consisted of seven islands, which were reclaimed. Many low-lying areas in what is still known as the island city are those that were inadequately reclaimed from the 19th century onwards.

At the Mumbai workshop, the former Director General of the India Meteorological Department, R. R. Kelkar, outlined how the first reclamations were by a private company, followed by the Bombay Port Trust and lastly by the state government till campaigns by environmentalists halted it in 1974.

In July 2005, Mumbai got a premonition of what lies ahead if a storm hits it when 94.4 cm of rain fell in 24 hours in the northern suburbs, while the island city was relatively unscathed. The official fact-finding committee, headed by the well-known hydrologist Madhav Chitale, published maps identifying vulnerable areas throughout Mumbai.

While all experts point out that one can’t attribute cyclones and storms in the Arabian sea directly to climate change, it is incontrovertible that as temperatures rise both in the ocean and on land, with each year breaking new records, weather patterns throughout the globe are getting erratic and the possibility of torrential downpours, accompanied by fierce winds, is increasing.

See: Indian Ocean warming: a curious case

Cyclonic activity will rise

According to Ghosh, the most recent research shows that the Arabian Sea is one of the world’s regions where cyclonic activity is likely to rise. He cites a 2012 paper by a Japanese research team, which predicts a 46% rise in tropical cyclones by the end of the next century, with a corresponding 31% decrease in the Bay of Bengal. 2015 was the first year in which the Arabian Sea is known to have more storms than the Bay of Bengal, while the latter has historically been hit by far more and fiercer storms.

Cyclones are more likely to occur during and after the monsoons. American researchers show that cyclonic activity in the Arabian Sea is likely to intensify due to the suspended particulate matter over the Indian subcontinent and its surrounding waters, all of which contribute to altering the region’s wind patterns.

In an article in the Times of India newspaper in 2015, Sobel wrote: “Between 1998 and 2001, three cyclones struck the west coast of the subcontinent, not far from Mumbai. Just in the past few weeks, Yemen was struck by two cyclones in the space of a single week. One of them, Chapala, was the strongest to make landfall there in known history. El Nino may be a factor this year, but the unusual Arabian Sea cyclone activity has been going on for a longer period.”

Ghosh adds that these three cyclones claimed over 17,000 lives. “Then in 2007, the Arabian Sea generated its strongest ever recorded storm: Cyclone Gonu, a Category 5 hurricane, which hit Oman, Iran and Pakistan in June that year, causing widespread damage,” he writes.

Because these have taken place north of India, they didn’t attract much attention. However, there were two severe cyclones, which hit the Gujarat coast between 1972 and 2015. The 1998 event was very severe, with over 10,000 deaths and losses amounting to $290 million.

Preparing for storms

Experts believe that given this increasing risk, coastal cities must prepare for such eventualities. Sobel pointed out that the administration should identify which areas are prone to flooding, which is already available for Mumbai.

Secondly, what is the threat to lives and property? As many as 447 people lost their lives in the city in 2005, as detailed by the report titled Mumbai Marooned: An Enquiry into the Mumbai Floods by the Concerned Citizens’ Commission, on which this writer served.

The total economic loss was put at INR 28 billion (USD 41 million), of which INR 10 billion was of infrastructure. The airport, which was on reclaimed land where the Mithi River, was bent twice at right angles to permit runways, was inundated for three days.

One has only to realise that Mumbai — and Chennai, which was hit by cyclones in 2015 and 2016 – are hubs for international IT firms and can’t tolerate a disruption in communications.

Evacuation plans

Evacuation plans should be put in place. In 2005, no Mumbaikars could access higher ground because the roads and railway tracks were under water. Boats, which could have worked, were not provided for rescue or relief.

While the influence of climate change on cyclonic storms lies in the realm of uncertainty, the same doesn’t hold true of sea level rise. Due to the melting of polar ice caps because of global warming, ocean levels throughout the world are rising.

At the launch of his book in Mumbai, Ghosh unsettled his audience by pointing out that some of the most expensive real estate in the world lies along the west coast of Mumbai. According to the unpublished paper by Murali of NIO, as much as 40% of Greater Mumbai – a staggering 190 sq km – could be under water within a century.

“Going by previous studies by NIO researchers, we considered a 3 mm rise (annually) in sea levels along Mumbai’s coast. That, coupled with factors such as natural calamities and tidal changes, will result in an approximate increase of 3 metres,” Murali told the Hindustan Times newspaper.

Another multidisciplinary study in 2012 by 220 Indian scientists from 120 institutes forming part of India’s second communication to the UN Framework Convention on Climate Change (UNFCCC) stated: “It is estimated that sea level rise by 3.5 to 34.6 inches (8.89 – 87.88 cm) between 1990 and 2100 would result in saline coastal groundwater, endangering wetlands and inundating valuable land and coastal communities. The most vulnerable stretches along the western Indian coast are Khambat and Kutch in Gujarat, Mumbai and parts of the Konkan coast and south Kerala.”

Ironically, such submergence would hit two extremes — the very wealthy living in high-rises along the coast and the poorest shanty dwellers who live on mudflats, given the astronomical real estate values. Mumbai is unique in that nearly 60% of its 13 million inhabitants are slum dwellers who, however, only occupy around 9% of the area.

Rising sea levels

The geography department of SP College in Pune has been studying sea level rise in the Konkan coast from Dahanu, just north of Mumbai, to Vengurla to the south. Over 20 years, levels have risen by 5-6 cm. On a full moon night in 2009, the high tide rose by 4 cm near Ratnagiri, which was much higher than previously recorded. In recent years, sea levels were rising at a much faster pace.

A 5-6 cm rise has led to the ingress of sea water up to 1 km inland, eroding beaches, harming mangroves and coconut and cashew plantations. The geographers find that tidal patterns are getting increasingly erratic.

The standard response of the authorities only when the situation gets too serious is to construct bunds to keep the sea at bay. These cost as much as Rs 60,000 per metre and are only built at certain stretches.

In their extensively researched 2016 book, How the World Breaks: Life in Catastrophe’s Path, from the Caribbean to Siberia, Stan and Paul Cox cite the 2005 Mumbai floods. “The sheer scale of this disaster and the fact that it brought an entire metropolis, India’s biggest and richest, to its knees was enough to send storm drainage straight to the top of Mumbai’s long list of urgent issues,” they write.

The authors quote Aromar Revi, Director of the Indian Institute of Human Settlements in Bangalore: “It was clear to many million people in Mumbai that life may never be quite the same again. An exceptional rainstorm finally put to rest the long-prevailing myth of Mumbai’s indestructible resilience to all kinds of shocks.”

They conclude on a sombre but truthful note: “In the minds of many, an event that overwhelming should have served as a wake-up call. But while it unmasked Mumbai’s increasing vulnerability, the flood appeared to stiffen the city’s resistance to any policy changes that might undermine its famed moneymaking prowess.”

“Heedless maldevelopment has continued. Meanwhile, sea level rise combined with increased rainfall will dramatically increase the extent and depth of flooding, doubling the likelihood that a flood on the scale of the 2005 catastrophe will recur.”