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. further progress in global economic integration should not be taken for granted, however. geopolitical concerns, including international tensions and the risks of terrorism, already constrain the pace of worldwide economic integration and may do so even more in the future. and, as in the past, the social and political opposition to openness can be strong. although this opposition has many sources, i have suggested that much of it arises because changes in the patterns of production are likely to threaten the livelihoods of some workers and the profits of some firms, even when these changes lead to greater productivity and output overall. the natural reaction of those so affected is to resist change, for example, by seeking the passage of protectionist measures. the challenge for policymakers is to ensure that the benefits of global economic integration are sufficiently widely shared - for example, by helping displaced workers get the necessary training to take advantage of new opportunities - that a consensus for welfare - enhancing change can be obtained. building such a consensus may be far from easy, at both the national and the global levels. however, the effort is well worth making, as the potential benefits of increased global economic integration are large indeed. references bloom, nick, raffaella sadun, and john van reenen ( 2006 ). " it ain't what you do it's the way that you do i. t. - investigating the productivity miracle using the overseas activities of u. s. multinationals, " unpublished paper, centre for economic performance, march. bordo, michael, barry eichengreen, and douglas irwin ( 1999 ). " is globalization today really different than globalization a hundred years ago? " nber working paper no. 7195, june. some of the key empirical papers in this literature are doms and jensen ( 1998 ) ; criscuolo and martin ( 2005 ) ; corrado, lengermann, and slifman ( 2005 ) ; bloom, sadun, and van reenen ( 2006 ), and kurz ( 2006 ). see, for example, bordo, eichengreen, and irwin ( 1999 ). corrado, carol, paul lengermann, and larry slifman ( 2005 ). " the contribution of mncs to u. s. productivity growth, 1977 - 2000, " unpublished paper, board of governors of the federal reserve system, july. criscuolo, chiara, and ralf martin ( 2005 ). "