The impact of large natural disasters on economic growth

In the aftermath of the earthquakes in Haiti and Chile it is natural to wonder what impact these two terrible events will have on these countries' future economic growth. Will the damage permanently lower output and burden future generations with the reconstruction bills? Or will the post-disaster construction boom and opportunity for structural change act as an economic stimulus, ushering in a new period of rapid growth?

Well, the folks over at the Inter-American Development Bank have clearly pondered these two questions more than I have. And their results are not exactly what one would expect.

Using a large comparative sample of severe natural disasters, the authors take advantage of the fact that natural disasters are a random event to tease out their causal effects on growth. In other words, the paper attempts to approximate a laboratory setting by also putting together a "synthetic" counterfactual of what would have happened in disaster countries if the natural disaster had never happened (they do this by grabbing a bunch of similar countries and weighting them to approximate the initial conditions of the disaster countries).

The results can basically be summarized with the graph below. It shows the path of real GDP per capita in actual disaster cases and in the counterfactual cases. Real GDP per capita is set to zero on the year of the crisis.

So what does this tell us? Well, disasters appear to have no effect on per capita income. In fact, the path of real GDP per capita following disasters perfectly mirrors the counterfactual index.

There were, however, two exceptions to the rule:

"Contrary to previous work, we find that natural disasters, even when we focus only on the effects of the largest events, do not have any significant effect on subsequent economic growth. Indeed, the only two cases where we found that truly large natural disasters were followed by an important decline in GDP per capita were cases where the natural disaster was followed, though in one case not immediately, by radical political revolution, which severely affected the institutional organization of society. Thus, we conclude that unless a natural disaster triggers a radical political revolution, it is unlikely to affect economic growth."

So there you have it. From the perspective of GDP per capita, a profoundly flawed but nevertheless indispensable measure of economic welfare, even the most severe natural disasters do not have an effect. So what's the moral of the story here? Is this a tale about human resilience in the face of calamity? Or is it another sobering lesson in the perils of statistical abstraction?