controls sufficient to reduce the difference between developing country and global wage rates by 10 percent generates a welfare gain of the order of $774 billion per year, in 1998 US dollars (assuming unitary elasticities of substitution in production in all regions).

More recently, the Linkage model used for the above Doha analysis has been used by the World Bank in a study of the potential gains from a one-off expansion over a 25-year period in international migration (World Bank 2006, Chapter 2). That study builds on earlier work by Winters et al. (2003) and draws on a new bilateral migration and remittances database involving no less than 226 countries (Parsons et al. 2007), thereby capturing the past patterns of migration between different countries (including the profile of accompanying family members if any). It simulates the impacts of an increase in migrants per year from developing to high-income countries that accumulates to a 3 percent boost in the latter’s labor force (both skilled and unskilled) by 2025, a total of 14.2 million workers and their families coming at the rate of 568,000 extra migrant workers per year over the 25 years beginning in 2001. To put that in context, in 2000 a net total of 2.4 million people migrated from developing to high-income countries (UN Population Division 2002, Table 1). That extra 3 percent gain in the high-income countries’ workforce by 2025 represents a loss of merely 0.4 percent to the developing countries’ workforce, and even in the developing countries’ skilled category it represents only a 1.7 percent loss of workers (final column of Table 9).

That comparative static migration study estimates the global gains by 2025 would amount to $674 billion per year in 2001 US dollars. Of that, $624 billion would be enjoyed by current citizens of developing countries. That includes those who migrate, whose share is estimated to be $481 billion in after-tax income (net of what the model assumes they remit back to their country or origin, based on past bilateral remittance patterns of existing migrants, the average of which is 17 percent of the migrant’s earnings). The small residual gain to the host country comprises a nontrivial gain to natives ($138 billion), but a loss to earlier migrants (of $88 billion or 6 percent) because they would face stronger competition in the workplace from the new migrants than would natives (even though the proportional increase in skilled migrant workers is much higher than in unskilled migrants to get the same 3 percent increase in both groups of workers in host countries). That is, their good fortune from being an earlier migrant would be shared somewhat with the newest migrants as the stock of migrants grows (see Table 10).

That comparative static aggregate global gain of $674 billion per year represents just over 1 percent of the projected global income for 2025. We assume the annual migration numbers return to normal after 2025, and that the on-going comparative static gain for the rest of this century from this accelerated program remains at just over 1 percent of global GDP. It is difficult to say how those gains would be shared between groups over a whole century (four generations), but if they were shared in the same proportions between migrants and natives as in 2025 (see final column of Table 10) then most would go to current citizens of developing countries, particularly the migrants themselves. To err on the conservative side, we also assume there are no additional dynamic gains from migration, even though they may well be a similar order of magnitude to those from product trade reform.

That proportional comparative static gain is more than five times the proportional gain reported above for the ‘Central’ Scenario of the Doha Round. Or to put it another way, if the extent of increased migration was only one-fifth as large (a 0.5 instead of 3.0 percent increase in the recipient countries’ labor force by 2025) it 22