When enviromentalists tell us that the melting of the polar caps would cause the sea level to raise by 20 feet

Are they taking into account that 9/10th of the ice is submerged in the water and therefore already contribuiting to the current sealevel, or are they falsely assuming that all of the ice in the polar caps including the part that is submerged, if melted, adds up to the current sea level ?
Update: well yah if extremist fit or not in this case would depend on if the answer to my question is 1 or 2
Update 2: Parrot enviromentalists arent necessarily scientists. Actually some scientists say the maximum increase would be around 28 inches.
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