Every year,  millions of people leave their homelands to start their lives somewhere else. Some seek to find a promising new job, strengthen family ties, or engage in new cultural opportunities. Some are seeking relief from crushing poverty or a lack of economic prospects. Others are fleeing war or persecution. Still others are escaping the effects of a long-term drought, a devastating hurricane, or some other kind of climate change–related disaster.

Although individuals’ reasons for wanting to resettle vary,  steadily rising numbers of migrants over the past two decades suggest that migration management is becoming one of the  most pressing issues of this century. And there are no signs that  this trend is slowing. Thus, many host and home communities  and countries are urgently revisiting or developing new  migration policies.