Environmental constraints have always had and will always have important consequences for human development. It has sometimes contributed to or even caused the reversal of such development. The possibility that such constraints will grow significantly throughout this century raises the concern...

China has witnessed the largest labor migration since the reform and opening up policies were implemented. According to the most recent statistics, the total number of rural to urban migrant workers reached 136 million. Migrants are defined as persons who have left out of township for more than...