Mumbai among cities at maximum risk due to rising sea levels: WMO report

The study says sea levels rose by 4.5 mm a year between 2013 and 2022, over three times the rate between 1901 and 1971

India's financial capital Mumbai is among several cities across the globe that would be most affected due to rising sea levels, according to a report by the World Meteorological Organization (WMO).

Other cities at risk include Shanghai, Dhaka, Bangkok, Jakarta, Maputo, Lagos, Cairo, London, Copenhagen, New York, Los Angeles, Buenos Aires, and Santiago.

In its report, the WMO, says sea levels rose by 4.5 millimetres a year on average between 2013 and 2022, over three times the rate between 1901 and 1971. WMO is a specialised agency of the United Nations for meteorology (weather and climate), operational hydrology and related geophysical sciences.

The Global Sea-Level Rise & Implications report released on Tuesday says the rise threatens several low lying small islands, along with countries like India, the Netherlands, Bangladesh and China, which have large coastal populations.

“The speed at which the largest global ice mass, Antarctica, is melting is uncertain. Over the next 2,000 years, global mean sea-level will rise by about 2-3 metres if warming is limited to 1.5°C, 2-6 metres if limited to 2°C and 19-22 metres with 5°C of warming, and it will continue to rise over subsequent millennia,” the report says.

Sea levels also rise due to storm surges and tidal variations. However, human influence was quite likely the main driver at least since 1971, the report adds.

Rising sea levels cause the erosion of coastal ecosystems, worsening the intensity of storm surges and flooding. They can also lead to the contamination of soil and groundwater with salt, further impacting food security.

Anjal Prakash, research director and adjunct associate professor, Bharti Institute of Public Policy, and a lead author of the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC), says, “The WMO report has once again highlighted India’s vulnerability, which has a 7,500-km long coastline, on both the west and the east. India is a hotspot when it comes to coastal impacts because of climate change. Sea-level rise exposes the country to water insecurity due to salinity. It also causes a decline in fish production. This is not a healthy sign for India.”

Prakash stressed on the need for adopting measures to secure the livelihood of fishermen, and providing safe and clean water to coastal populations.

“The problem of climate change-led sea level rise needs more discussion at the policy level, explaining the bottom-up plan at the sub-district level and how we can map climate impact at the local level,” says Prakash.

United Nations Secretary-General, António Guterres, while presenting his remarks to the UN Security Council debate on ‘Sea-level rise: Implications for international peace and security’ cautioned that rising sea levels aren't a standalone threat but a threat-multiplier. “Rising seas are sinking futures,” Guterres says.

According to the report, at sustained warming levels between 2-3°C, the Greenland and West Antarctic ice sheets will almost be completely and irreversibly lost over multiple, millenia causing potentially multimetre sea-level rise. “In case of very high greenhouse gas emissions (total failure of mitigation) there is a risk of sea levels rising by 2 metres by 2100 and even 15 metres by 2300,” the report highlights.

Guterres, cautioned that the Greenland ice cap is melting even faster, losing 270 billion tonnes a year. “We’ve already seen how Himalayan melts worsened flooding in Pakistan in 2022. But as these glaciers recede over the coming decades, over time, the Indus, Ganges and Brahmaputra rivers will shrink,” Guterres says.

Rising seas threaten lives, and jeopardise access to water, food and healthcare. Saltwater intrusion can decimate jobs and entire economies in key industries like agriculture, fisheries and tourism.

It can damage or destroy vital infrastructure such as transportation systems, hospitals and schools, especially when combined with extreme weather events linked to the climate crisis.

The global mean sea-level has risen faster since 1900 than in any preceding century in the past 3,000 years. The global ocean has warmed faster in the past century than since the end of the last deglacial transition (around 11,000 years ago).

“Sea-level rise poses a distinctive and severe adaptation challenge as it implies dealing with slow onset changes and increased frequency and the magnitude of extreme sea level events which will escalate in the coming decades,” says Petteri Taalas, secretary-general, WMO.