Sea level rise over the last century was 4-8 inches on average depending on location. Which means some locations saw much less and some much more. You can always find exceptions, skeptics tend to focus on those. For example certain valleys in the arctic regions are showing cooling while the overall arctic trend is toward warming. In Montana Glacier National Park will be glacier free in the next 20 years, it is a high impact area of the globe in terms of warming. It was likely going to happen anyway...the problem is when changes happen very quickly the impact is much greater.
The average rise in temperature and sea levels are accelerating. Sea rise will likely be 2x-3x as much over the next century. This is not the sort of change people will notice in a low change area over 10-20 years, unless they are really looking with specific equipment. In terms of Ambergris I worry more about nutrient loads, acidification and water temps adversely impacting the reef. Yes it is possible these changes could lead to even better coral growth if they can evolve quickly enough...the problem is that if life fails to adapt it goes extinct under adverse changing conditions.
Hysterics and hysteria are pretty insulting and dismissive words to use regarding a global phenomenon that is very well documented just because the impact is less in your corner of the world.