Whether we are dealing with risks to our health or risks to the continuity of our business or risks to the safety and security of our society, the age-old wisdom of prevention being better than cure is easy to recall but difficult to cost-justify. Even when there is adequate evidence that points to a statistically significant probability that disaster may strike us, most people would rather spend time, energy and even money, sometimes, on debating the need for investing in preventive measures. People on the side of the debate that call for investments in prevention would be treated by those on the other side of the debate as alarmists, and would be challenged to prove not only that it is highly likely that a disaster of the type they are anticipating could happen, but also that it would wreak the kind of havoc they are forecasting it would. These are the people who would bet good money that it won't happen, and lose, rather than invest the same money on preventive measures. Typically, these are also the people who benefit from the status quo, and who therefore would resist changes that acceptance of the likelihood of disaster would entail. In the context of climate change, these would also be the people with vested interests who would spend a lot of time and money on climate change denial and avoidance, because accepting the reality of climate change would mean far more changes to their business models than they can handle.
The current 'best practice' approach on disaster management is broadly stratified into 4 'levels' that deal with strategic and tactical planning, and implementation of various types of measures and countermeasures. These levels are: Prevention, Containment, Mitigation and Recovery. To a rational mind, it is fairly logical and self-evident that you would first try to prevent a disaster from happening, and if you just can't prevent it you'd try to restrict any damage that might be done to as narrow an impact zone as possible, try to minimize the damage done even within that narrow impact zone, and try to recover the situation and restore normalcy to the extent possible, as quickly as possible. Attempts to tackle disasters at any of these 4 levels need careful planning and skilled execution, and cost money. While investments at all 4 levels have their own pay-offs, the best RoI comes from investments at the level of Prevention, as opposed to the other 3 levels. It is not difficult to see why, as the following example illustrates. For a marathon runner, a fractured leg (resulting from some accident, let's say) even when mended will never be the same again. In the case of this athlete, money spent on averting the accident that resulted in the broken bone will pay back far more than large sums of money spent on post-accident treatment (which, incidentally, may not even ensure a full return to pre-accident normalcy). The problem is that such wisdom usually occurs in hindsight, and for the most part the athlete is likely to believe that it won't happen, simply because believing that it might happen would mean investment in Prevention, which in turn would involve too much of a change in lifestyle as also an outflow of cash.
If planned and executed properly, preventive measures can be quite effective in averting disasters. In all likelihood most people would not even be aware that a disaster could have struck them but was successfully prevented. And that is precisely where the problem lies, in terms of justifying the investment. When successful, preventive measures don't even let you know that they have delivered results. Most people would barely see the ghost of the disaster looming over them, if at all they do, and then disappearing - it would barely be a blip on the smooth surface of their daily routine. Only a few would know anything about the magnitude of the disaster that was averted and how close they came to being hit - and these would be the people who are closest to the apparatus that monitors the leading indicators of the disaster and triggers / oversees the preventive measures that should kick-in. Other people would, over a period of time, when the public memory of the disaster that never struck has faded, sceptically ask as to why so much is being spent on prevention. The ones who confidently bet that it would not happen will continue to believe that it hasn't and that it never will, while the few in the know will try to point out that it almost did, on at least one occasion, and is likely to happen again in future - and would promptly be called alarmist. And the same debates would continue.
By very definition, investments in Prevention will not tell you that they are working for you. If indeed disaster does strike, in spite of preventive measures, then it points to the underestimation of the probability and/or the scope and impact of the disaster, or else the effectiveness of the preventive measures. In such cases a common mistake would be to consider the investment in Prevention to be a waste. ("What's the use of spending so much if it had to hit us anyway" would be the line that sceptics would take.) Quite to the contrary, investments in Prevention should be directly proportional to the cross product of probability and impact. If it did hit you finally, and hit you badly, it most likely means that you got the probability and/or the impact wrong. (Of course, other reasons could be failure of execution / technology, but again that would most likely be due to inadequate investments.) And now it is the turn of investments at those other 3 levels - Containment, Mitigation and Recovery to work for you and deliver returns on those investments. However, even if they do work out as planned, they will never take you back to the way things were just a moment before the disaster struck. There is no resetting to normal, once disaster strikes: there is only adapting to the 'new normal' - a term that comes into vogue in the aftermath of a disaster, as it has in the wake of the global economic crisis.
Prevention works at the fork in the path of reality unfolding around the disaster - at the point in the eternally streaming flow of cause and effect, where things could turn left and towards disaster, or turn right and away from it. If the preventive measures are effective, things will take the right turn (quite literally). To justify the investment beyond doubt, you have to go back in time to the fork, as it were, take the other route to the left, and witness the alternative reality. Unfortunately, the laws of physics, as known to mankind up until now don't permit time travel. And so you have to settle for conjecture and speculation as to what might have happened, and whether the investment was worth it - there would never be any solid proof that it was. In science fiction, concepts like the 'Butterfly Effect' and movies like the Terminator series explore the possibility of going back in time to specific moments, where the outcome of a single seemingly insignificant event changes the course of history. The need for investment in Prevention would be obviated only if and when such time travel becomes possible in our real world, and not before. As of now, there is no going back - the only hindsight allowed to us is foresight. Which is why we need to make sure that we get this sustainability thing right the first time around. There will be no second time, and no world to get it right in, if we don't.