傳媒

A new study co-authored by Professor Guy Abel of the Department of Sociology, Faculty of Social Sciences of the University of Hong Kong, alongside researchers from Meta and Harvard University, introduces a groundbreaking approach to measuring international migration. Published in the prestigious journal Proceedings of the National Academy of Sciences (PNAS), the research leverages online data to provide the most comprehensive and timely estimates of global migration flows to date.

The study, titled "Measuring Global Migration Flows Using Online Data," was conducted by Professor Abel in collaboration with Meta researchers Guanghua Chi, Eugenia Giraudy, and Mike Bailey, as well as Drew Johnston from Harvard University. Their innovative approach utilises privacy-protected records from over three billion Facebook users to estimate monthly migration flows between 181 countries, accounting for biases in social media usage to generate reliable and near-real-time insights.

Key findings from the research include:

• An estimation of 39.1 million international migrants in 2022, representing 0.63% of the population in the sampled countries.
• A 64% decrease in migration during the COVID-19 pandemic, followed by a rebound in 2022 to a rate 24% higher than pre-pandemic levels.
• A tenfold increase in migration from Ukraine following the Russia-Ukraine war.

"This work addresses a critical gap in global migration data," said Professor Abel. "Past efforts pieced together various migration and demographic data to provide a tentative glimpse of global migration patterns. This new research takes a more direct approach, leveraging billions of anonymised digital traces to directly estimate when and where people migrate across borders. The estimates provide timely and detailed insights that can guide researchers, policymakers, and humanitarian efforts worldwide."

Access the full study and data:

• Full paper: https://www.pnas.org/doi/10.1073/pnas.2409418122
• Migration data: https://data.humdata.org/dataset/international-migration-flows
• The New York Times article on the estimates, including an interactive data visualization: https://www.nytimes.com/interactive/2025/04/17/opinion/global-migration-facebook-data.html

For media enquiry, please contact: 
Department of Sociology, Faculty of Social Sciences, HKU by email (socidept@hku.hk)