Internationally mobile researchers contribute to scientific production far beyond their share in the population

Scientists move internationally in search of opportunities, because of push factors in the origin countries, for family-related, personal, or other reasons. Regardless of what prompts international relocations of researchers, mobility (or lack of it) has macro-level implications for scientific production that are often not fully visible because they have not been quantified. We analyzed bibliometric data on 30+ million publications, indexed by Scopus, and written by 19+ million scholars between 1996 and 2021, to measure the contribution of internationally mobile scholars to scientific production in their country of residence. We found that, across countries, scientific fields, and genders, internationally mobile scholars consistently contribute far more publications than their share of the population of scientists would imply. In advanced economies, mobile scholars account for approximately 20% of all publications, compared to 14--15% in non-advanced economies; in both cases their contribution far exceeds their share of the scholarly population. Smaller countries show a distinct pattern of hosting a larger fraction of scholars with international mobility experience (up to 60%) who are highly productive (in some cases contributing to up to 80% of the publications of the country). Standard bibliometric metrics of national scientific production are analogous to Gross Domestic Product (GDP) accounting: they capture what is produced within a country's borders regardless of who produced it. Our results quantify a dimension invisible in such metrics---the contribution of internationally mobile scholars---and motivate complementary measures of scientific production that account for scholar's country of origin and mobility history.