20 million people in Mumbai at risk due to cyclones, sea level rise: Study – Hindustan Times

The threat of increasing cyclonic events, storm surges and sea level rise could paralyse the financial capital, affecting the lives of more than 20 million people, a study has revealed. It further warned that coastal cities with high population density and delicate infrastructure were left with no more than 10 years to act against the impacts of climate change.

Findings for Mumbai city and the Maharashtra coastline by not-for-profit policy research institute Council on Energy, Environment and Water (CEEW) as a part of its recent report assessing patterns of extreme climate events through district-level profiling showed that south Mumbai was highly vulnerable to the combination of sea-level rise and storm surge.

“Storm surge and cyclone trends across the west coast are worrying because of their compounding effects. The storm surge often leads to an abnormal rise of sea level threatening the safety of citizens. Through spatial maps we were able to estimate that around 20 million people were at risk in Mumbai owing to this threat,” said Abinash Mohanty, programme lead, CEEW and author of the study.

According to data used from National Disaster Management Authority, India Meteorological Department, Press Information Bureau, and international bodies such as World Meteorological Organisation, the study found that the decadal increase in cyclone events had increased six times from two cyclones in 1970-1979 to 12 during 2010-19 that had impact along the Maharashtra coast.

At the same time, the number of affected districts increased from two during 1970-79 to six during 2010-19, an addition of another three in 2020 (including the impact of severe cyclone Nisarga), taking the tally to nine for the 2010-20 period. South Mumbai witnessed a threefold increase in the frequency of extreme flood events over the past five decades with two flood events per decade from 1980-2009 that shot up to six in 2010-19.

Mumbai, Thane, Ratnagiri, and Raigad were identified as the cyclone hotspot districts in Maharashtra. “Cyclones of various categories have severely hit the eastern coast but on the contrary, the west coast has also witnessed a fivefold increase in cyclonic storms’ frequency and intensity making these districts susceptible to annual pre and post monsoon extreme climate events,” said Mohanty.

A similar analysis report by McKinsey & Company Inc, released in February, showed almost three million people living within a kilometre of Mumbai’s coastline were under threat from coastal flooding, storm surges and sea-level rise from now till 2050 with extreme weather events and storm surges accelerating by 1.5 times with 100 km/hour wind speed being the new normal.

The Maharashtra government said it was aware of the increase in cyclonic events and associated threats from sea level rise to coastal cities. “Maharashtra’s climate action policy has factored in these threats and our focus is to protect natural ecosystems, climate resilience for new constructions and linear infrastructure, and effective implementation of coastal protection norms. All state departments are in the process of preparing their own climate policies through the state’s action plan, and simultaneous implementation is being done at district and region-wise levels,” said Manisha Mhaiskar, principal secretary, state environment and climate change ministry, adding that the department will be hosting a climate action summit in February-March 2021 to address these and many other such issues.

The Intergovernmental Panel on Climate Change (IPCC) of the United Nations has said warming of oceans (rising sea surface temperature) has been triggering sea-levels to rise faster. Since 2005, the sea-level rise has risen by more than 2.5 times during the last century, posing a serious threat to communities, livelihoods, and economies. Studies have estimated that the rate of rising seas over the Arabian Sea is about 0.5–3 mm/year, whereas it is 0.75–6 mm/year over the Bay of Bengal. “Considering IPCC’s projections of a 1m rise across by 2050 under a high emissions scenario, many cities of Mumbai’s size can be inundated,” said Mohanty.

Dr Anjal Prakash, research director and adjunct associate professor with Bharti Institute of Public Policy at the Indian School of Business and lead author, IPCC’s 6th Assessment Cycle report, said, “Mumbai as a prominent hotspot, facing challenges of frequent cyclonic storms and sea level rise, coastal green space (mangroves) is vital to be protected under a city-specific policy banning construction, waste dumping and ensuing sustainable utilisation of the sea resource.”

Among solutions, the study said that apart from limiting our emissions and retrofitting the existing infrastructures, restoring natural shock absorbers like mangroves and wetlands could fetch triple dividends of climate-proofing. “It will help halt micro-climate changes, and generate green economic opportunities. We are left with only a decade to act against devastating impacts of climate change,” said Mohanty.