To me, the theme in this thread is as valuable as discussing the next ice age and its impact on famous courses. A number of ice ages have covered large portions of North America, and not all that long ago. It's only a matter of time before another strikes: some theory suggests fairly soon. As per the OP, lets not discuss the merits of this aspect of climate change, but instead take it as given.
Right off the bat we lose the great Canadian courses. Banff. Jasper Park. The new masterpieces at Cabot, along with Highland and Stanley Thompson's other great layouts.
But the damage could be far more widespread than that. In the last ice age much of Michigan was buried under 3-4 km of ice. That would mean no more Crystal Downs or Kingsley. The new courses at Sand Valley turn into cross country ski tracks. The Bandon courses are in danger, and so are NGLA, Shinnie, Fishers, the other Long Island greats and virtually everything in New England. Several of Doak's best courses, such as Rock Creek and Ballyneal, probably disappear. We don't have room here to list all the courses this will destroy, but you get the idea.
Another important aspect to this. According to Wikipedia, during the last glaciation around 12,000 years ago, sea level lowered by 120 meters. That would mean many of today's top ocean-side courses will no longer be seaside, but inland, miles from the shore. TOC, if it's not at the bottom of a 2 mile high glacier, could be radically transformed. Same with many other GBI greats, plus those in Holland, not to mention Sweden and Germany.
In short, most of the world's top 100 courses will likely disappear. Clearly a critical issue golf must address, or face radical change.