Global bilateral migration projections accounting for diasporas, transit and return flows, and poverty constraints

Abstract

BACKGROUNDAnticipating changes in international migration patterns is useful for demographic studies and for designing policies that support the well-being of those involved. Existing forecasting methods do not account for a number of stylized facts that emerge from large-scale migration observations and theories: existing migrant communities -diasporas -act to lower migration costs and thereby provide a mechanism of self-amplification; return migration and transit migration are important components of global migration flows; and poverty constrains emigration. OBJECTIVEHere we present hindcasts and future projections of international migration that explicitly account for these nonlinear features. METHODSWe develop a dynamic model that simulates migration flows by origin, destination, and place of birth. We calibrate the model using recently constructed global datasets of bilateral migration. RESULTSWe show that the model reproduces past patterns and trends well based only on initial migrant stocks and changes in national incomes. We then project migration flows under future scenarios of global socioeconomic development. CONCLUSIONSDifferent assumptions about income levels and between-country inequality lead to markedly different migration trajectories, with migration flows either converging towards net zero if incomes in presently poor countries catch up with the rest of the world; or remaining high or even rising throughout the 21st century if economic development is

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“…However, these can become insignificant once bilateral migrant networks are explicitly accounted for by including a diaspora variable ([ 52 ], p. 508). This is also the case for the present model specification, where these dyadic variables were estimated to be insignificant, and therefore neglected [ 26 ]. Moreover, the geographical distance in particular shows up more significantly in log-transformed models, while untransformed models such as ours predict more limited effects of distance [ 53 , 54 ].…”

“…The data is not disaggregated by country of birth, and therefore does not report transit and return migration flows separately. On the other hand, return and transit migration are included explicitly in our model, following the methods in ref [ 26 ].…”

“…We use a global model of international migration that is calibrated on historical bilateral flow data [ 25 ], and has been shown to represent current patterns of bilateral migration well, despite relying on just a small number of predictor variables [ 26 ]. Note that refugee movements are not accounted for in the model, as these are assumed to have different causes and dynamics than regular migration [ 34 ].…”

“…First we estimate the parameters that shape the emigration rate through the term F ( G i ) on the right-hand side of Eq 6a . To this end we follow the method used in ref [ 26 ]. That is, where possible, we exclude return and refugee migration flows from the reported bilateral flows.…”

“…Reproducing the approach in ref. [ 26 ] we fit the reported [ 25 ] bilateral migration flows M i , j to the sum of emigration from country of birth and return migration flows defined in our model in Eq 6a and 6b : Due to computational costs, we do not include the transit flows. These flows have been shown to have a very small share in the total emigration compared to return and emigration from country of birth flows [ 38 ].…”