So raising the sea wall another 5-7 meters would be no big problem?  How high are they now?  6C is not an unreasonable average ambient increase, given the collective ability of our species to respond to what are perceived as distant threats.  I understand that 6C is what we can expect unless current actual trends are significantly altered, and these trends have not yet really begun to be altered, especially outside of Europe.

Even if we reach 6C there is no certainty as to how long it will take for the ice cap to melt.  But there is also no certainty that the ice cap will not have already melted by then.  And then large scale ice melt from Greenland could conceivably alter the deep saline current and the Gulf Stream.  This could cause ice sheets to begin accumulating in northern Europe.  It might slow down the melting of Greenland, but it would hardly be an advantage to northern Europe.

There is only really one way to verify if the models are accurate and we don't want to go there.  To me the prudent thing is to assume a worst case and work to avoid it.  At worst we will have given people employment doing things that turned out not to have been necessary, but the world as we know it will have survived substantially.  But that is not how finance operates and, as we know, finance runs the world.

"It is not necessary to have hope in order to persevere."