One reader responded, "Ain't no way I'd live in either of those places without appropriate structure. Then again, people don't want to, and maybe shouldn't, always plan for 100 year events."
He raises a good point. Traditional actuarial science does demonstrate the relative benefit-cost of overbuilding as perhaps more expensive than rebuilding following the occasional natural event. And that's one way of looking at it.
On the other hand, there are perhaps three reasons why it's worth constructing for the worst case scenario. I'd offer the following:
1. The trend seems to be that these events are happening more frequently. What was once an infrequent disaster may become more frequent. No matter who (or what) you believe is causing climate change, it's hard to avoid believing something is happening.
2. The cost is only marginally more expensive (if at all). When you're rebuilding anyway (as those in these areas will be doing), it's probably worth taking the time to build more safe habitation. In this blog, I've discussed various techniques for better housing that can be done using indigenous materials. It makes sense to use the best knowledge you have at the time.
3. The costs aren't always calculable. Traditional benefit-cost analysis looks at the monetary loss of property and the effect a disaster has on the long-term economy of a region. The real purpose of this blog is to emphasize the loss of life associated with these major events and to try to find ways to minimize that loss. Human lives cannot be quantified--at least not in any reasonable way.
Obviously, we can't predict the future, but if we can better prepare, it makes sense to do so. As an article in The Economist wisely points out, if it's not doing any harm, it's worth doing just in case.
And I'd add that I don't want anyone else to have to live there without them either.
A more recent article in The Economist describes some of the roadblocks to rebuilding (physical, economical, and political) in the Caribbean:
"Three main barriers get in the way. The first is that weather patterns are changing faster than scientists and policymakers expected.... The second obstacle is short-term thinking, which encourages fast economic growth but neglects climate-change planning....The third barrier is lack of money. Most Caribbean islands are not poor... But most have high levels of public debt and many have suffered from a decline in prices of agricultural goods. Their small populations mean that the cost per person of building and upgrading infrastructure is high."
Sadly, this article was published post-Irma, but before Maria devastated the region for the second time in as many weeks. The following post-Maria photo was published of the same area of Old San Juan:
The photo source and accompanying article is here.