As Michael Crichton says, there are still too many unanswered questions to be spending billions, if not trillions of dollars to prevent a problem that may not even exist.
This is a very contentious issue, especially in environmental circles where the precautionary principle is popular.
There are some instances in which prevention is obviously the best strategy: oil slicks, radiation leaks, exposure to lead and pathogens. Thus the conversion to double-hull tankers and vaccination. It all makes sense. But inevitably things still go wrong. And when they do, we adapt. Indeed, we're so adaptable that we often demand a crisis in order to address the root cause of a problem.
So, over time, I have actually developed an affinity for adaptation, as opposed to prevention, both as a coping mechanism and as a policy predicate. I believe it's the better strategy. As Mark Twain said, "I've seen a heap of trouble in my life, and most of it never came to pass."
In addition, I remind you of the work of the late Aaron Wildavsky, who argued, in a very complicated analysis that you can find in "Searching for Safety," that the strategy of prevention favors the elite; adaptation favors the average person. Certainly if you look at who is advocating which strategy, it seems clear that Wildavsky was right.
The debate isn't anywhere near over.