  In this study, the global scientific workforce is explored through
large-scale, generational, cross-sectional, and longitudinal approaches. We
examine 4.3 million nonoccasional scientists from 38 OECD countries publishing
in 1990-2021. Our interest is in the changing distribution of young male and
female scientists over time across 16 STEMM (science, technology, engineering,
mathematics, medicine) disciplines. We unpack the details of the changing
scientific workforce using age groups. Some disciplines are already numerically
dominated by women, and the change is fast in some and slow in other
disciplines. In one-third of disciplines, there are already more youngest
female than male scientists. Across all disciplines combined, the majority of
women are young women. And more than half of women scientists (55.02%) are
located in medicine. The usefulness of global bibliometric data sources in
analyzing the scientific workforce along gender, age, discipline, and time is
tested. Traditional aggregated data about scientists in general hide a nuanced
picture of the changing gender dynamics within and across disciplines and age
groups. The limitations of bibliometric datasets are explored, and global
studies are compared with national-level studies. The methodological choices
and their implications are shown, and new opportunities for how to study
scientists globally are discussed.
