Jubilee Post News & Views
Dr. Seema Javed
According to the latest Sea-level rise report – rising sea level is a major threat for countries like Netherlands, Bangladesh, India and China some of which comprise large coastal populations.
Several big cities on all continents are threatened, such as Shanghai, Dhaka, Bangkok, Jakarta, Mumbai, Maputo, Lagos, Cairo, London, Copenhagen, New York, Los Angeles, Buenos Aires and Santiago.
Human influence was very likely the main driver of these Sea-level increases since 1971. due to this The global ocean has warmed faster over the past century than since the end of the last deglacial transition (around 11,000 years ago).
Over the next 2000 years, global mean sea-level will rise by about 2 to 3 meter if global warming is limited to 1.5°C as per Paris agreement . The sea level rise will be 2 to 6 meter if global warming is limited to 2°C and 19 to 22 meter with 5°C of warming.
Sea-levels will continue to rise over the 21st century. Relative to 1995–2014. The average rate of sea level rise was 1.3 mm yr–1 between 1901 and 1971, increasing to 1.9 mm yr–1 between 1971 and 2006, and further increasing to 3.7 mm/yr between 2006 and 2018. WMO has reported that during the period 2013-22 sea level rise has been 4.5 mm/yr . Human influence was very likely the main driver of these increases since at least 1971.
Sea-level rise is not globally uniform and varies regionally.
The speed of the melting of the largest global ice mass Antarctica has uncertainties. There is a risk of a much higher sea-level rise due to potential intrusion of sea water under the Antarctic glaciers, as NASA has demonstrated in its recent published scientific studies.
In case of greenhouse gas emissions (total failure of mitigation) there is a risk of sea-level rise by of 2 m by 2100 and even 15 m by 2300.
At sustained warming levels between 2-3 C, the Greenland and West Antarctic ice sheets will be almost completely and irreversibly lost over multiple millenia causing potentially multi- meter sea-level rise. The mass loss is higher with higher warming rates.
Thermal expansion of sea level due to global warming explained 50% of sea-level rise during 1971–2018. Global mean sea-level increased by 0.20m between 1901 and 2018.
Ice loss from glaciers contributed 22%, ice sheets 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.
Sea-level rise poses a distinctive and severe adaptation challenge as it implies dealing with slow onset changes and increased frequency and magnitude of extreme sea-level events which will escalate in the coming decades.
Scenarios for the future
It is virtually certain that global mean sea-level will continue to rise over the 21st century. Relative to 1995–2014, the likely global mean sea level rise by 2100 is 0.28–0.55 m under the very low GHG emissions scenario (which equals about 1.5 C of global warming target). 0.32–0.62 m under the low GHG emissions scenario (equals about 2 C of global warming target); 0.44–0.76 m under the intermediate GHG emissions scenario (equals about4.5C of global warming target).
Over the next 2000 years, global mean sea-level will rise by about 2 to 3 m if warming is limited to 1.5°C, 2 to 6 m if limited to 2°C and 19 to 22 m with 5°C of warming, and it will continue to rise over subsequent millennia. Projections of multi-millennial global mean sea-level rise are consistent with reconstructed levels during past warm climate periods: likely 5–10 meter higher than today around 125,000 years ago, when global temperatures were very likely 0.5°C– 1.5°C higher than the temperatures of 1850–1900. It was very likely 5–25 m higher from roughly 3 million years ago, when global temperatures were 2.5°C–4°C higher. Sea-level rise is not globally uniform and varies regionally.
