There are four atoll states in the world: The Republic of Kiribati, the Maldives, the Republic of the Marshall Islands (RMI), and Tuvalu. These countries are comprised entirely of low-lying land approximately 2 m above sea level. The Intergovernmental Panel on Climate Change (IPCC) has recognized that atoll countries are highly vulnerable to rising sea levels due to climate change. This study aimed to clarify the relative advantages and disadvantages of possible alternatives compared to the present livelihoods of the Marshallese in their home country. We also attempted to identify the best plausible option, using few sets of possible value judgements over the evaluation criteria. The following four alternatives were examined in this study: (i) migration to the developed world, (ii) migration to other island states, (iii) land reclamation and raising, and (iv) development of floating platforms. To evaluate the performance of the four alternatives, we selected 16 criteria representing the societal conditions that would result from each alternative. The performance of each alternative per criterion was rated from 1 to 5 by a literature survey, interviews with researchers who worked on the livelihood of Marshallese immigrants in the U.S. states of Arkansas, Hawaii, and Oregon, and interviews with people knowledgeable about the behavior of the Marshallese both in their home country and in the United States as immigrants. The “migration to the developed world” alternative proved the best choice, followed by “developing floating platforms,” “land reclamation and raising,” and “migration to other island states.” We also found that “migration to the developed world” offered the most change to immigrants, while the alternative of “land reclamation and raising” resulted in the smallest change. The magnitude of anticipated change should be considered. We employed the Analytic Hierarchy Process (AHP) to experimentally evaluate four alternatives in an integrated manner and about three cases were “all the criteria are equally important,” “social environment is more important,” and “personal environment is more important.” With AHP, the “migration to the developed world” alternative yielded the highest point for all three cases examined. Notably, climate migrants do not suddenly emerge, because climate change is a slow-onset process. The Marshallese should make wise use of the available lead time to prepare for migration in the future.

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