  Major shifts in the global system of science and technology are destabilizing
the global status order and demonstrating the capacity for emerging countries
like China and India to exert greater influence. In order to measure changes in
the global scientific system, we develop a framework to assess the hierarchical
position of countries in the international scientific collaboration network.
Using a machine-learning model to identify the leaders of 5,966,623 scientific
teams that collaborated across international borders, we show that Chinese
scientists substantially narrowed their leadership deficit with scientists from
the US, UK, and EU between 1990 and 2023 in absolute terms. Consequently, China
and the US are on track to reach an equal number of team leaders engaged in
bilateral collaborations between 2027 and 2028. Nevertheless, Chinese progress
has been considerably slower in per-collaborator terms: after adjusting for the
number of non-leaders from each country, our models do not predict parity
between the US and China until after 2087. These dynamics extend to 11 critical
technology areas central to ongoing diplomacy between the two nations, such AI,
Semiconductors, and Advanced Communications, and to China's scientific
leadership with respect to the European Union and the United Kingdom. Thus,
while China's elite scientists are achieving leadership in the international
scientific community, China's scientific enterprise continues to face
developmental constraints. We conclude by reviewing several steps that Chinese
science is taking to overcome these constraints, by increasing its engagement
in scientific training and research in signatory nations to the Belt and Road
Initiative.
