to changes in the benefits or costs of living in a given location. Amenities destroyed by a storm may not be fully rebuilt and insurance rates may be adjusted upwards after a storm, both of which could induce individuals to relocate.<sup>14</sup> Despite theoretical reasons why migration might respond to the occurrence of disasters in an adaptive way, it is not clear that realized migration patterns will be adaptive. The drivers of migration are complex.<sup>15,16,17</sup> The hypothesis that migration will be adaptive gives primacy to reducing risk from climate change over many other potential motivations – many of which may be countervailing – for migration.

It is well known, for example, that most migration is driven by existing social networks and takes place over relatively short distances.<sup>18,19</sup> Even long-distance migratory responses to hurricanes are driven by existing social networks.<sup>20</sup> To the extent that social and family networks are geographically concentrated, and the risk of exposure to storms only changes slowly over space, migration along these existing networks may offer little protection from future storms.<sup>21</sup> A clear example of this occurred after Hurricane Katrina, when the majority of migrants from New Orleans fled to Houston,<sup>22</sup> a city that is also highly exposed to hurricanes.<sup>23,24</sup> More broadly, migration intended to reduce flood risk exposure – encouraged by government buy-outs – has been found to be highly local.<sup>25</sup> The evidence for whether these local moves are adaptive is mixed,<sup>25,26</sup> and whether a local move is adaptive depends on how risk profiles change over space. In localities with significant topographical variation, local moves may be highly effective at reducing flood risk. But whether this migration is truly adaptive or not, its local nature suggests more generally that local ties are important in migration decisions.

The process of migration is also expensive. Individuals impacted by disasters have often suffered a substantial negative shock to their wealth and thus may not be able to incur the substantial costs of a significant relocation.<sup>18,27,28</sup> This is exacerbated by the fact that housing costs in less vulnerable areas may be bid up precisely because these areas are less vulnerable.<sup>29</sup> In the United States there are also a variety of economic and policy conditions that incentivize people to stay put or migrate in non-adaptive ways. While storms lead to destruction of property, federal or state-subsidized insurance often reduces the costs of these losses. Take-up of these policies increases after the occurrence of a disaster – a form of adaptation in and of itself .<sup>30,31</sup> Economic activity in the United States is also disproportionately concentrated along the coasts. More than 50% of GDP in 2014, the last year for which data are available from the National Oceanic and Atmospheric Administration (NOAA), was generated within 50 miles of the coasts.<sup>32</sup> Because of this pattern of economic activity, moving to opportunity may require moving into at-risk areas.

Despite these theoretical reasons to believe that migration may not be an adaptive response to future storms, and evidence from Indonesia that it has not historically served this role,<sup>10</sup> both 3