I have my views and you have yours, so I ask a question, what was the average sea level in Athens, Greece 2,720 years ago? What was the average sea level in ancient Rome 2,420 years ago? https://en.wikipedia.org/wiki/History_of_theatre

Ancient towns have been found that were built thousands of years ago when the towns were above sea level. My bet is the average sea level was at its lowers 2,720 years ago when most of the planet was covered in ice. The sea will continue to rise until the ice caps melt.

Will New York be under water then? When the caps/glaciers melt, what will the average world sea level be considering the volume of the known ice caps/glacier smelt?

At the rising rate of the seas, when will New York, Miami, and other coastal lined cities be underwater---- Anyone care to calculate the year when NY will be completely submerged? https://www.nationalgeographic.com/news/2010/3/100304-snowball-earth-ice-global-warming/

  • $\begingroup$ Where I live the 100 year flood lines are published on the internet for insurance purposes. Can the sea level be determined when the ice caps/glaciers melt? $\endgroup$ Jun 7 '20 at 17:36
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    $\begingroup$ Hi. Unfortunately, some of your assumptions are wrong. "most of the planet" was most decidedly NOT covered in ice a mere 2720 years ago; you have to go back another 7000 years or so, and even then the ice cover was less than half of the planet's surface. $\endgroup$
    – Spencer
    Jun 7 '20 at 17:47
  • $\begingroup$ If you approach the question correctly, it's an interesting question to ask, but it's not a simple matter of calculating how far the bathtub will fill if you put more water it -- there are other factors such as thermal expansion, isostasy, and even plate tectonics to consider. $\endgroup$
    – Spencer
    Jun 7 '20 at 17:52
  • $\begingroup$ There's also no guarantee, even given anthropogenic climate change, that ALL of the polar ice will melt. $\endgroup$
    – Spencer
    Jun 7 '20 at 17:53
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    $\begingroup$ Without links, but can easily be researched: global sea level ~2,700BP was silghtly higher (a few decimeters) than today, because climate (holocene climatic optimum can be searched). 7kyBP it was ~1.4m higher than today. When Antarctica melts, sea level rises by 60m. Greenland contributes 6m (I believe, check), the rest a few decimeters. During the last glacial maximum ~20kyBPit was ~130m lower than today. On geological scales, sea level varies by several hundred meters. $\endgroup$
    – user20217
    Jun 7 '20 at 18:20