# **Introduction**

An increase in damaging storms will be one of the most significant consequences of climate change.<sup>1</sup> These disasters impose substantial cost on the communities that they impact through asset destruction, human capital losses, and the loss of human life.<sup>2,3,4</sup> However, the incidence of these storms varies over space and while climate change will increase the frequency, severity, and range of these storms, some areas will be more impacted than others.<sup>1</sup> As a consequence of this variation in incidence over space, many have suggested that migration away from areas that will be more impacted by these disasters will be an important form of adaptation to climate change.<sup>5,6,7,8</sup> Indeed, calibrated theory-based modeling of the impacts of climate change suggest that in the coming centuries as much as 5% of the world’s population will relocate because of changes in local amenities driven by climate change, including by increasing hurricane risk.<sup>9</sup> These projected moves are not solely local, with some estimates suggesting large shifts in population from temperate regions into the Arctic circle.<sup>9</sup> There are, however, reasons to be skeptical of the hypothesis that migration will lead to population-level reductions in risk and serve as a form of adaptation, at least in the short to medium-term. For migration to be a societal-level adaptation to a given shock, it is necessary that population-level exposure to that shock decline as a consequence of migration. The empirical evidence we have so far – for example, from Indonesia – suggests that storm events have not led to out-migration in ways that reduce future risk.<sup>10</sup> We advance the existing literature further by using data on the paths of all Atlantic basin hurricanes between 1992 and 2017 to study whether county-to-county migration has reduced risk for migrants in recent history in the United States. In particular, we focus on whether out-migration increases (and net-migration declines) in response to a hurricane and whether migrants relocate to areas that are less exposed to disasters. In doing so, we address a key research challenge to understanding the future of the U.S. Gulf Coast, as articulated by the National Academies of Sciences, Engineering, and Medicine in 2018.<sup>11</sup> Experiencing a storm may lead to adaptive behavior for a variety of reasons. Experiencing a storm that destroys assets may reduce an individual’s connection to a given location and therefore facilitate a move to a location that is less exposed to future storms. Experiencing a storm may also cause an individual to update their expectations about the risk of experiencing future storms and so induce a move to a less risky location. This could occur for classically rational reasons – learning new information about the personal costs of experiencing a disaster, for example<sup>12</sup> – or as a consequence of a variety of behavioral biases. For example, the availability heuristic suggests that salient information, in this case the cost of experiencing a disaster, is overemphasized by people making decisions about the future.<sup>13</sup> Individuals may also move due 2