We know when the sea level was that high in the past, and we know how much warming is necessary to get that amount of sea level rise from both Greenland and Antarctica.
We need to start serious measures to reduce greenhouse gases within the next decade. If we don't do something soon, we're committed to four to six meters (13 to 20 feet) of sea-level rise in the future.
Although ice-sheet disintegration and the subsequent sea-level rise lags behind rising temperatures, the process will become irreversible sometime in the second half of the 21st century unless something is done to reduce human emissions of greenhouse-gas emissions.
After that we'll be committed to multiple more meters of sea level rise that will occur at rates of up to a meter?or three feet?per one hundred years.