@b7e93d67 (As you know Mumbai is in India, not Bangladesh). Still, it's a good example. Almost every goddamn major port on the planet is at or close to sea level. Singapore, Shenzhen, Rotterdam, Hamburg, and so on. Human residents can be relocated, but rebuliding/relocating the infrastructure on which our sea-going containerized global supply chain depends is going to be beyond painful. And if we don't retain global food distribution billions will starve as climate instability hits harvests. 

 @0c1a9324 also large heavily populated areas of Vietnam, Tokyo... it's really not good. 

 @b7e93d67 If the West Antarctic ice sheet collapses, we're going to see hundreds of millions to billions of refugees. Most of whom will stick near the new coastlines, but many of whom will be completely displaced.

In these parts it'll be an age of migrations the like of which Europe hasn't seen outside of the late Roman empire and the end of WW2.