We're headed towards an ice-free planet. According to James Hansen that means sea levels 82 feet higher than today. When sea levels rise 82 feet, the Arlington Library will become ocean front property and most of Boston and Cambridge will be completely under water.
In a recent paper, James Hansen and Makiko Sato make the remarkable finding, that sea level rise will be highly nonlinear this century based on our current business-as-usual [BAU] emissions.
BAU scenarios result in global warming of the order of 3-6°C. It is this scenario for which we assert that multi-meter sea level rise on the century time scale are not only possible, but almost dead certain.
That takes us through the Eemian interglacial period of about 130,000 years ago when sea levels were 15 to 20 feet higher, when temperatures had been thought to be about 1°C warmer than today. Then we go back to the "early Pliocene, when sea level was about 25 m [82 feet] higher than today," as NASA's James Hansen and Makiko Sato explain in a new draft paper, "Paleoclimate Implications for Human-Made Climate Change."