The Intergovernmental Panel on Climate Change predicts that climate change will intensify during the 21st century. The exact distribution of impacts will likely be complex in nature. Although some areas may exhibit benefits, many areas will likely experience environmental decline. The objective of this article is to answer the following question: What are the potential implications of deteriorating environmental conditions for human migration? This is not an easy question to answer because the full effects of climate change are not yet completely evident. Yet by studying the impact of environmental forces on migration in recent decades, we can offer some insight to this question. Methods. In implementing this approach, we employ theoretical and empirical methods. Our theoretical model suggests that environmental degradation should promote out-migration from affected areas, all other things being equal. To test this prediction empirically, we conduct a large-N statistical analysis focusing on the role of several environmental factors in emigration to developed countries. Our empirical sample covers the late 1980s and the 1990s. Results. The empirical results suggest that environmental decline plays a statistically significant role in out-migration, pushing people to leave their homes and move to other countries. Conclusions. In the conclusions section of this article, we evaluate the policy implications of these findings for developed countries in the context of climate change and national security.