John,
Fortunately, the barrier reef does protect us on the cayes from extreme surges and tsunamis, at least in hurricanes. And Belize is implementing a Climate Change/Global Warming program. Being at sea level, this country is well aware of the impact of a rising sea. We do see it in the erosion. But Belize is a very small country. We don’t make much of a carbon footprint in Belize. But the country will be impacted by what the world’s major countries do, or don’t do, to stave off climate change and the resultant rise in sea level.
I am an environmental engineer by training. I do have no doubt that climate change is already occurring. But no one really knows how fast the sea will rise. From my perspective I’d rather spend 5-10 wonderful years in paradise, on the Caribbean Sea, then skip this wonderful experience due to a sea that will rise, but who knows when? My environmentally trained friends did ask me this same question 10 years ago, when I decided to move to the island of Ambergris Caye.
That being said, personally, my husband and I prefer to live off the beach, for many reasons, aggressive beach erosion being one of them. Since you are worried about the longterm effects of the rise in sea level you may prefer to live inland, not right on the water. For instance, the 4 Mile Lagoon, west of Corozal, is really lovely, and not that far from the sea. You could live there, on an inland fresh water lagoon, but still be very near the Caribbean Sea and have access to it.
Also, since you are concerned about the rising sea level, it makes sense for you to only rent. These are all things to consider, based on your personal concerns and preferences.