MSL - Advance Planning Required.
Mean Sea Level seems to have increased by about ten inches (250 mm) since 1870 - 3.5 inches of that in the last thirty years. The rest of the century will probably see something like another 1 to 3 feet of sea level rise, enough to seriously threaten or destroy many low-lying islands and ocean front areas. Endangered cities will cost many billion, or perhaps trillions of dollars to defend or relocate. There is every prospect that sea level rise will continue long after CO2 additions to the atmosphere stop.