Environmental factors have shaped human migration since the origin of Homo sapiens. Indeed, the relationship between migration and the environment has been at the core of population-environment studies. Further, fueled by contemporary concerns with the impacts of global climate change on human populations, substantial public and policy dialogue has inspired additional scholarship on the migration-environment connection. This collection of manuscripts has been crafted to add to the intellectual foundation underpinning that dialogue.This issue of Population & Environment presents new research on the complex and layered links between human migration and the environment, examining the effects of environmental change on migration patterns as well as the impacts of migration dynamics on environmental conditions in sending and receiving regions.Papers in this special issue address such topics from a number of different theoretical and methodological perspectives. The contributions also interrogate other important dimensions of this association such as those related to gender, ethnicity, and social, economic and cultural institutions. In addition, a variety of geographic settings and social contexts is represented, focusing on push and pull factors in sending and receiving areas through examination of both internal and international migration. We are convinced that contributions on internal migration represent a revitalizing view calling attention to the fact that, without denying the relevance of international movements, much environmental displacement takes place within countries. Further, we argue that more research attention must be paid

El artículo trata sobre la importancia del agua para la sustentabilidad de la Ciudad de México; presenta una breve referencia a sus características ecológicas y a las principales transformaciones que sufrió a lo largo del tiempo, modificando su ecosistema natural de origen lacustre para convertirse en una de las ciudades más grandes del planeta. Se analizan los problemas vinculados al abasto de agua, especialmente los relacionados con la creciente dependencia del líquido que proviene de cuencas vecinas; también se examinan los efectos de la explotación del acuífero, las fugas en las redes de suministro, el acceso diferencial del recurso y el tratamiento de aguas servidas. Finalmente, se presentan algunas reflexiones sobre los retos que enfrentará la ciudad para abastecer de agua a la población futura.

No abstract

SUMMARY: This paper describes the interrelationships between migration, environmental degradation and perceptions of the environment, by comparing the responses of middle-income and low-income, both native and in-migrant, households to the worsening environmental conditions in Mexico City. Migration to secondary centres by middle-class households is explained as a response to both increasing economic opportunities in intermedi-

This paper examines migratory flows in and out of Mexico City between 1995 and 2000, and discusses the social and economic characteristics of the individuals involved. Over recent decades, there have been changes in migratory patterns, as the earlier influx of migrants to Mexico City appeared to decrease, and to be overtaken in 1990 by net out-migration. However, figures from the 2000 Mexican census indicate that there is now relative migratory equilibrium. The city continues to be a destination for migrants from poorer states in the country, but it is also an important source of migration to the central and northern states. An examination of the characteristics of the migrants demonstrates that migratory processes are dynamic and complex, responding to a range of economic, environmental, social, cultural and political factors at both origins and destinations.