and none of the asteroids were projected to end all life on Earth, there would no doubt be an equal amount of disagreement.

Without arguing the anthropological aspect of the problem, there are going to be some losses of habitable real estate. New Orleans is sinking as fast as the water is rising and I don't think it can be saved beyond the end of this century, even if we spend tons of money on the problem.

Carbon Brief

I picked this link because it was the first site that Google listed for "best guess on rising water levels from global warming". It is not to my knowledge a conservative site. There are many other sites that predict way more and way less.

Your numbers are not outrageous at 8 ft but nonetheless that number and the effect of that rise, should it happen, is open to a lot of conjecture.

Assuming that humans are directly responsible for 90% of the rise in sea level, I don't think we will be able to mitigate the rise, to any great extent, in the next 200 years but I am confident that we can and will deal with the problem technologically to avert any major loss of life, (if not property).