The United Nations University’s Institute for Environment and Human Security (http://www.ehs.unu.edu/) has issues a press release claiming that by the year 2010 the world will need to cope with as many as 50 million people escaping the effects of creeping environmental degradation.
The press release says that “environment-related migration has been most acute in Sub-Saharan Africa, but also affects millions of people in Asia and India.”
The one nuance in the press release is provided by Dr. Janos Bogardi who says “the term “environmental refugee” rankles many experts as simplistic, masking what are often compound motives behind migration and implicitly laying the blame on nature when often the policies and practices of people are the cause of displacement.”
One salient example is New Orleans and Hurricane Katrina. This event has created thousands of U.S environmental refugees. Building on Bogardi’s point, there is a synergy between policies and environmental shocks. If the levees had been in better shape ( a policy), the same natural shock (Katrina) would have caused less damage to New Orleans and there would have been much fewer environmental refugees.
Experts working in this field will face the challenge of disentangling whether observed migration flows are due to economic arbitrage (seeking out higher $ in destination cities) or because environmental shocks push people away from places they wanted to keep living in.
An interesting self selection issue arises, when an environmental shock such as a hurricane takes place --- who leaves? My guess is that it is the skilled and able and motivated. If the right tail of the ability/motivation distribution exits as environmental refugees; then the remaining folks on average will be the “slugs”. Any growth model with human capital would predict that such an area will grow more slowly after the shock if it loses its best people.