And that's just based on the sea level rise scientists can calculate.
Even as scientists and engineers around the globe scramble to figure out ways to mitigate global warming (to stop it from reaching much above the additional two degrees Fahrenheit scientists say Earth will experience by about 2050) they are also trying to get the word out to people everywhere that humanity must at the same time learn to adapt to the irreversible changes it is now too late to prevent.
"Everybody is going to have to learn to adjust and adapt to climate change because it's going to be warmer no matter what," Princeton University climate scientist Michael Oppenheimer told ABC News.
"But at the same time," he said, "we have to combine that with a program for sharply reducing emissions, because adaptation alone can never be enough."
The scientists in Paris did agree -- unanimously -- that that even if humanity soon makes drastic cuts in greenhouse emissions, sea level -- partly because of long slow delays in its global circulation of heat -- will keep rising for centuries.
What humanity may be able to control, they say, is how much and how fast.