Migration may be increasingly used as adaptation strategy to reduce populations’ exposure and vulnerability to climate change impacts. Conversely, either through lack of information about risks at destinations or as outcome of balancing those risks, people might move to locations where they are more exposed to climatic risk than at their origin locations. Climate damages, whose quantification informs understanding of societal exposure and vulnerability, are typically computed by integrated assessment models (IAMs). Yet migration is hardly included in commonly used IAMs. In this paper, we investigate how border policy, a key influence on international migration flows, affects exposure and vulnerability to climate change impacts. To this aim, we include international migration and remittance dynamics explicitly in a widely used IAM employing a gravity model and compare four scenarios of border policy. We then quantify effects of border policy on population distribution, income, exposure, and vulnerability and of CO₂ emissions and temperature increase for the period 2015 to 2100 along five scenarios of future development and climate change. We find that most migrants tend to move to areas where they are less exposed and vulnerable than where they came from. Our results confirm that migration and remittances can positively contribute to climate change adaptation. Crucially, our findings imply that restrictive border policy can increase exposure and vulnerability, by trapping people in areas where they are more exposed and vulnerable than where they would otherwise migrate. These results suggest that the consequences of migration policy should play a greater part in deliberations about international climate policy.

移民可能越来越多地被用作适应战略，以减少人口对气候变化影响的暴露和脆弱性。相反，由于缺乏有关目的地风险的信息，或者作为平衡这些风险的结果，人们可能会迁移到比原籍地更容易受到气候风险的地方。气候损害的量化有助于理解社会暴露和脆弱性，通常通过综合评估模型（IAM）进行计算。然而，迁移几乎不包含在常用的 IAM 中。在本文中，我们研究了边境政策（对国际移民流动的关键影响）如何影响气候变化影响的暴露度和脆弱性。为此，我们采用引力模型将国际移民和汇款动态明确纳入广泛使用的 IAM 中，并比较了四种边境政策情景。然后，我们根据未来发展和气候变化的五种情景，量化 2015 年至 2100 年期间边境政策对人口分布、收入、暴露和脆弱性以及 CO ₂排放和气温升高的影响。我们发现，大多数移民倾向于迁移到比原籍地更少暴露和脆弱的地区。我们的研究结果证实，移民和汇款可以为适应气候变化做出积极贡献。至关重要的是，我们的研究结果表明，限制性边境政策会将人们困在比他们原本会迁移的地方更容易暴露和脆弱的地区，从而增加暴露和脆弱性。这些结果表明，移民政策的后果应该在国际气候政策的审议中发挥更大的作用。