Examining the Role of International Migration in Global Population Projections

Guy J. Abel, Wittgenstein Centre (IIASA, VID/ÖAW, WU)
Samir K.C., Wittgenstein Centre (IIASA, VID/ÖAW, WU)
Nikola Sander, Vienna Institute of Demography

Advances in projecting international migration are hindered by a lack of adequate data. Consequently, international projection-making agencies use simplistic assumptions of net-migration measures. However, past net migration can be often volatile and are known to introduce inaccuracies when projecting populations (Rogers, 1990). This paper presents sets of global population projections to 2060, focusing on two alternative specifications of international migration. First we assume net migration at constant levels as done so by the UN. Second, we specify a bi-regional projection model based on estimated immigration and emigration rates for all countries. Assumptions on rates of other demographic factors, namely fertility and mortality, are held constant allowing an examination of the role of international migration in global population projections models. Our results highlight differences in the future level of populations around the globe and numbers of migrant flows via alternative specifications of migration in projection models.