Science behind global sea level and sea level rise for global warming and polar ice-melt: myths and reality

Document Type : Original Article


Dept. of Oceanography and Hydrography, Faculty of Earth and Ocean Science, BSMR Maritime University, Dhaka, Bangladesh


Global sea level rise of 1.5 meter by 2100 AD due to global warming and polar ice-melt has emerged as a concept and not a science. Ocean thermal expansion responsible for sea level rise has also emerged as a myth. Warming of ocean surface can produce water vapor by evaporation which is not the volumetric expansion of ocean water to raise sea level. More the thermal heating of the ocean surface water more will be the evaporation from the ocean that negates volumetric expansion of the ocean water. Global warming can alleviate ocean temperature not to expand ocean water. Global scale ocean temperature measures 28oC upto the depth of 40 m only. Below this depth temperature drastically decreases almost to 6oC at 1000 m depth trending further decrease. Science behind melting of the polar floating ice-blocks supports reoccupation of the same occupied volume of the floating ice without sea level rise. Ice-melting further reduces load from the crust of the Earth to elastically rebound for attaining isostatic equilibrium preventing sea level rise. Paleo-sea level markers in the sediment deposits occur due to the crustal subsidence and uplift for transgression and regression respectively. Prograding delta can result in apparent sea-level drop showing retreat of the sea. Geophysical spheroidal shape of the earth with equatorial bulge and polar flattening maintain a perfect hydrostatic equilibrium condition. Maximum centrifugal force and minimum gravity attraction can allow sea level to occur at about 21 km higher in the equatorial region than in the polar region preventing sea-level fluctuation. 


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