Kochi: The sea level has risen faster than before over the last several years and will continue to rise in the future, warned a report released by the World Meteorological Organization (WMO, a body under the United Nations), on February 14. Small island states and countries with low-lying, densely populated coastal areas – including in India – will bear the brunt of the sea level rise. People in coastal urban areas in least developed and low and middle income countries will also face specific impacts and challenges, the report said.
“Sea-level rise is not only a threat in itself,” remarked UN Secretary-General, António Guterres at the United Nations Security Council on February 14. “It’s a threat-multiplier. For the hundreds of millions of people living in small island developing states and other low-lying coastal areas around the world, sea-level rise is a torrent of trouble.”
Glacial melts, warming waters
Global warming has caused ice loss and glacier melts worldwide. It has also caused thermal expansion of water – the phenomenon by which any object that is subjected to heat expands. The ocean is now heating up faster over the past century than since the end of the last deglacial transition which was around 11,000 years ago, the WMO’s report titled “Global Sea-Level Rise & Implications: Key facts and figures” said.
The report highlighted how the sea level, in turn, has risen over the years. Thermal expansion explained 50% of sea-level rise between 1971 and 2018 and human activities were what most likely drove the increase since 1971. The average rate of sea level rise increased from 1.3 mm per year between 1901 and 1971, to 1.9 mm per year between 1971 and 2006. Between 2006 and 2018, this rose again to 3.7 mm per year. As per the WMO, the sea level rise has been 4.5 mm per year between 2013 and 2022.
“It is virtually certain that global mean sea-level will continue to rise over the 21st century,” the report noted. It also warned that over the next 2000 years, the global mean sea-level would rise by 2 to 3 m if warming is limited to 1.5°C; 2 to 6 m if limited to 2°C; and by 19 to 22 m with 5°C of warming.
“Sea-level rise is unavoidable for centuries to millennia due to continuing deep ocean warming and ice sheet melt, and sea-levels will remain elevated for thousands of years,” it warned.
At risk: Low-lying coasts, people, economies
Coastal regions will be among the hardest hit, apart from small island states; sea-level rise “poses an existential threat” in these areas, per the report.
“Sea-level rise will bring cascading and compounding impacts resulting in losses of coastal ecosystems and ecosystem services, groundwater salinization, flooding and damage to coastal infrastructure that cascade into risks to livelihoods, settlements, health, well-being, food, displacement and water security, and cultural values in the near to long-term,” it read. People experiencing sea-level rise living in coastal urban areas in least developed and low-middle income countries will also face specific impacts and challenges.
According to the report, the threat from sea level rise is a “major economic, social and humanitarian challenge”. Several low lying small islands and countries that have huge coastal populations such as the Netherlands, Bangladesh, India and China would be most affected.
“Several big cities on all continents are threatened,” it read. The cities the report lists here includes Mumbai in India too. Others include Shanghai, Bangkok, London and New York.
A 2022 study by RMSI, a GIS consulting company that analysed the Intergovernmental Panel on Climate Change’s (IPCC) sixth assessment report published in August 2021, had estimated that sea-level rise could submerge some parts of the coastal Indian cities of Mumbai, Kochi, Mangalore, Chennai, Visakhapatnam, and Thiruvananthapuram by 2050. The Deccan Herald reported that Mumbai would be the most affected, with the sea level rise impacting 998 buildings and 24 km of road length in the city.
The WMO report has once again highlighted India’s vulnerability, as it owns a 7,500-km long coastline, said Anjal Prakash, research director and adjunct associate professor, Bharti Institute of Public Policy, Indian School of Business and a lead author of the IPCC reports.
“India is [sic] major hotspot when it comes to coastal impacts because of climate change. Sea level rise exposes country [sic] to water insecurity because of salinity,” he said.
Secondly, sea level rise has also resulted in a decline in fish production which is not a healthy sign for India, he added.
“There is a need for adaptation measures to secure the livelihood of fishermen and water security in terms of providing safe and clean water to inhabitants of coastal areas,” he said. “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 impacts at the local level.”
‘Consequences unthinkable’
Consider the “hundreds of millions of people living in the river basins of the Himalayas”, said Guterres in his remarks during a debate on sea level rise at the UN Security Council. “We’ve already seen how Himalayan melts have worsened flooding in Pakistan. But as these glaciers recede over the coming decades, over time, the Indus, Ganges and Brahmaputra rivers will shrink. And rising sea levels combined with a deep intrusion of saltwater will make large parts of their huge deltas simply uninhabitable. We see similar threats in the Mekong Delta and beyond. The consequences of all of this are unthinkable.”
We must address the climate crisis and broaden our understanding of the root causes of insecurity, Guterres said, highlighting the importance of actively supporting grassroots resilience efforts to tackle climate change and improving early warning systems.