Global Sea-Level Rise and Implications

Global Sea-Level Rise and Implications

News: According to the World Meteorological Organization ‘s (WMO) Report “Global Sea-level Rise and Implications”, India, China, Bangladesh and the Netherlands face the highest threat of sea-level rise globally.

Which big cities are threatened by sea-level rise?
 Big cities in all continents are threatened by rise of sea-level which includes Shanghai, Dhaka, Bangkok, Jakarta, Mumbai, Maputo, Lagos, Cairo, London, Copenhagen, New York, Los Angeles, Buenos Aires and Santiago.

Key Findings:
Contributors to Sea-level Rise
 Thermal expansion contributed to 50% of sea level rise during 1971-2018, while ice loss from glaciers contributed to 22%, ice-sheet loss to 20% and changes in land-water storage 8%.
 The rate of ice-sheet loss increased by a factor of four between 1992-1999 and 2010-2019. Together, icesheet and glacier mass loss were the dominant contributors to global mean sea level rise during 2006- 2018.

Key Trends and projections
 Between 2013 and 2022, Global mean sea-level was 4.5 mm/year and human influence was likely the main driver of these increases since at least 1971.
 Global mean sea-level increased by 0.20m between 1901 and 2018,
 1.3 mm/ year between 1901 and 1971,
 1.9 mm/year between 1971 and 2006
 3.7 mm/year between 2006 and 2018.
 Even if global heating is limited to 1.5 degrees Celsius over pre-industrial levels, there will still be a sizable sea level rise.
 But every fraction of a degree counts. If temperatures rise by 2 degrees, that level rise could double, with further temperature increases bringing exponential sea level increases.

Impact
 At sustained warming levels between 2-3 degree Celcius, the Greenland and West Antarctic ice sheets will be almost completely and irreversibly lost over multiple millennia causing potentially multimeter sea-level rise.
 Consequences will result in losses of coastal ecosystems and ecosystem services, groundwater salinization, flooding and damage to coastal infrastructure that can further lead to risks to livelihoods, settlements, health, well-being, food, displacement and water security, and cultural values in the near to long-term.

What will be the impact on India?
 India is most vulnerable to compounding impacts of sea level rise.
 In the Indian ocean half of sea level rise is due to the volume of water expanding since the ocean is warming up rapidly The Indian Ocean is the fastest warming ocean in terms of surface warming.
 According to the Ministry of Earth Sciences, on average, the sea level along the Indian coast was observed to be rising at a rate of about 1.7 mm/year during the last century (1900-2000).
 A 3 cm sea level rise could cause the sea to intrude inland by about 17 meters. At future rates of 5 cm/decade, this could be 300 metres of land taken by the sea in a century.
 Cyclones are intensifying rapidly due to more moisture and heat from ocean warming. The amount of flooding also increases as storm surges are compounding sea level rise decade by decade.
 Cyclones are bringing more rain than earlier. Super Cyclone Amphan (2020) caused large-scale flooding and inundated tens of kms inland with saline water intruding.
 Over time, the Indus, Ganga and Brahmaputra rivers may shrink, intrusion of saltwater will make large areas inhabitable.