Innovations in International Migration for use in Global Population Projections

Advances in projecting international migration have been hindered by a lack of adequate data. Consequently, international projection-making agencies commonly use simplistic assumptions of net-migration measures derived as residuals from demographic accounting. However, past net migration can be often volatile and are known to introduce inaccuracies when projecting populations (Rogers, 1990). This paper presents a set of global population projections to 2060, focusing on alternative international migration assumptions. Expert-based assumptions about fertility, mortality and migration developed for the new edition of the Wittgenstein Centre (WiC) global population projections are combined to project each country’s population. We overcome the limitations of using net-migration models and zero convergence assumptions by drawing on a first-of-a-kind set of estimated quinquennial bilateral migration flows developed by Abel (2012). Using a multiregional cohort-component projection model, alternative future migration trends are explored based on a set of ‘what-if?’ scenarios. Our results highlight differences in the future level and distribution of populations around the globe between a constant-rates, a convergence to zero-net, a zero flows and two ‘what-if’ scenarios.