Countries with high coastal city populations, including India and China, are among several countries faced with major challenges by the sea level rise, a new report by the World Meteorological Organisation (WMO) said on Tuesday.
While the small islands and low-lying coasts face an existential threat, the population potentially exposed to a 100-year coastal flood is projected to increase by about 20% if the global mean sea level rises by 0.15 metre relative to 2020 levels. The exposed population doubles at 0.75 m rise and triples at 1.4 m without population change and additional adaptation.
The report, 'Global Sea-Level Rise and Implications' is based on the GLobal State of the Climate 2020 and other reports, including the IPCC 2021: Summary for Policymakers. The number of people exposed to risks may increase from 896 million to potentially 1 billion by 2050, it added.
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Describing the development as a "major economic, social and humanitarian challenge" the report said sea-level rise was a "major threat" for countries like Netherlands, Bangladesh, India and China some of which comprise large coastal populations. "Several big cities on contents are threatened, such as Shanghai, Dhaka, Bangkok, Jakarta, Maputo, Lagos, Cairo, London, Copenhagen, New York, Los Angeles, Buenos Aires and Santiago," it said, noting that the negative impacts will be exacerbated by storm surges and tidal variations.
Climate change, the report said, will increasingly put pressure on food production and access, especially in vulnerable regions, undermining food security and nutrition and increases in frequency, intensity and severity of droughts, floods and heatwaves, and continued sea level rise will increase risks to food security in vulnerable regions between 1.5 C and 2 C Global warming level.
It said the global mean sea-level will rise by about 2 to 3 metres if warming is limited to 1 degrees Celsius, 2 to 6 metre if limited to 2 degrees Celsius and 19 to 22 metres with 5 degrees Celsius of warming.
The global mean sea-level has risen faster since 1900 than in the last 3000 years and the ocean has warmed faster over the past century than since the end of the last deglacial transition, around 11,000 years ago, it added.
The frequency and magnitude of extreme sea-level events will escalate in the coming decades, the report warned, calling for early implementation of adaptation measures.
The present response of the government, from relocation of people to ecosystem-based approaches, can be more effective if combined with sociocultural values and development priorities. Such measures should be underpinned by inclusive community engagement, it added.