The Future of International Migration

Migration is a key means by which human beings act to preserve or enhance their well-being. Since Homo sapiens first emerged in Africa about 200,000 years ago, geographic mobility has been a prominent strategy for human adaptation and improvement (Cavalli-Sforza et al., 1994). In modern societies, people most commonly migrate to further their economic position or to join family members who migrated before them (Massey et al., 1993). Yet, many others move, both temporarily and permanently, with the more explicit purpose of reducing social, economic, political, or environmental vulnerability (Bardsley and Hugo, 2010; Hunter, 2005; Lundquist and Massey, 2005). All of these forms of human mobility frequently span international borders, oftentimes despite substantial barriers to transborder movement. Estimates of migration flows are the expression of these heterogeneous motivations. As the drivers of migration also vary conspicuously across nations (Clark et al., 2004; Massey and Sana, 2003) and evolve over time within countries (Lindstrom and Ramírez, 2010; Massey, 1990; Massey et al., 1994), they are particularly difficult to forecast. As we show in this chapter, even developing a homogeneous series of baseline estimates at a global level is very complex (Abel, 2013a), further complicating forecasting efforts. Reliable baseline estimates are hard to obtain, for instance, given differences in the definitions across countries of what is an international migrant (Kupiszewska and Nowok, 2008) and owing to the presence of sizable irregular or unauthorized flows in some nations (e.g. Passel et al., 2009). Notwithstanding these difficulties, international migration has increasingly become, and will remain, a crucial component of the population dynamics of many sending and receiving nations. While only 2 per cent of the world’s population lives outside of their country of birth, this figure is above 10 per cent for nationals of countries like Mexico and El Salvador. Foreign-born shares are also substantial relative to the population of many migrant-receiving countries, with levels above 10 per cent (in some cases well above) in North America, most of Western Europe and Oceania, and parts of South East Asia. At the extreme, this share has reached levels of 60–80 per cent in some age groups in the oil-producing nations of the Gulf Cooperation Council (GCC).