I thought it might be interesting to see what happens to some familiar coastal areas with moderate increases in ocean levels.  The areas in red in the following maps are the areas that become ocean, under conditions of rising sea levels.  Here is Ocean City with a 2 meter rise:

Here's lower Manhattan with a 3 meter rise.

You can create your own maps for any area of the world here:
  http://geongrid.geo....

(Hint: drawing rectangles with mouse clicks is the fast way to zero in on selected land areas.)

I have contacted some of the modeling researchers, and while I am by no means an expert on the subject some people are predicting sea level increases of 2 meters within 20 to 30 years, and also saying the change will occur fairly rapidly.  (Of course, there is no consensus on timing or the amount of the rise.)  But then if enough cold water flows into the Atlantic and disrupts the Gulf Stream, glaciers in Europe might build up again.

I did a map of Florida, and Jeb could basically be Governor of Disneyland

Seriously, this is alarming

The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) is the fourth in a series of reports on climate change.  As to sea level increases, the general view is:

Based on a model that excludes ice sheet flow due to a lack of basis in published literature, it is estimated that sea level rise will be, in a low scenario, 18 to 38 cm (7 to 15 inches) and in a high scenario, 26 to 59 cm (10 to 23 inches).

http://www.scienceda...

From what I understand, some scientists think the consensus model is too conservative, and the IPCC report states:

"The now published text gives a warning that the new estimation of sea-level could be too low: "Dynamical processes related to ice flow not included in current models but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea level rise."

http://en.wikipedia....

Among experts who think the likely scenario is worse,  Arizona U. Prof. Jonathan Overpeck says:

"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."

http://www.eurekaler...

Other IPCC conclusions:

"As a result it is predicted that, during the 21st century the following will occur. Regarding surface air warming in the 21st century, the best estimate for a "low scenario" is 1.8 degrees Celsius with a likely range of 1.1 to 2.9 degrees Celsius (3.2 degrees Fahrenheit with a likely range of 2.0 to 5.2 degrees Fahrenheit). The best estimate for a "high scenario" is 4.0 degrees Celsius with a likely range of 2.4 to 6.4 degrees Celsius (7.2 degrees Fahrenheit with a likely range of 4.3 to 11.5 degrees Fahrenheit)."

"It is more than 90% certain that there will be frequent warm spells, heat waves and heavy rainfall. It is more than 66% certain that there will be an increase in droughts, intensity of tropical cyclones (which include hurricanes and typhoons) and extreme high tides. " 

(Note: I have no expertise in this area, and am merely reporting others' views.)

"We will pay for this one way or another," stated retired Marine Corps General Anthony C. Zinni, former commander of U.S. forces in the Middle East. "We will pay to reduce greenhouse gas emissions today, and we'll have to take an economic hit of some kind. Or, we will pay the price later in military terms. And that will involve human lives."

Watch the appropriations bills and you will see the choices that have been made.