Increasing geopolitical tensions between the US and China are having a noticeable effect on the two countries’ research and may be harming global science, according to recent analysis from the US National Bureau of Economics Research (NBER).

The report concludes that the US Department of Justice’s investigations into ethnically Chinese scientists under the now defunct China Initiative – created during the Trump administration to crack down on Chinese state-backed espionage – may have damaged their productivity.

The study finds that ethnically Chinese graduate students became 16% less likely to attend a US-based PhD programme between 2016 and 2019. Those that did were 4% less likely to stay in the US after graduation. In both instances, these students were more likely to move to a non-US anglophone country instead.

The NBER report also documents a sharp decline in Chinese usage of US science as measured by citations of research papers. Among Chinese publications, the share of references citing US research fell by about 4–6% after 2016, and among recently published articles the share of citations on Chinese publications to US research papers dropped by 10–12%. At the same time, however, no decrease was observed in the likelihood of US scientists to cite Chinese studies.

Moreover, the data indicates that China’s avoidance of US science does not appear to affect the average productivity of China-based researchers. The report’s authors found no statistically significant decrease in the scientific output of previously ‘US-reliant’ scientists in China relative to those who had heavily relied upon UK science.

The paper concludes, however, that heightened anti-Chinese sentiment in the US seems to have reduced the productivity of ethnically Chinese scientists in the US by 2–6% after 2016, when compared with non-ethnically Chinese researchers.

‘Our results do not suggest any clear “winner,” but instead indicate that increasing isolationism and geopolitical tension lead to reduced talent and knowledge flows between the US and China, which are likely to be particularly damaging to international science,’ the authors write. ‘The effects on productivity are still small but are likely to only grow as nationalistic and isolationist policies also escalate.’

Its authors warn that their findings as a whole ‘strongly suggest’ a ‘chilling effect’ for ethnically Chinese scholars in the US, affecting that country’s ability to attract and retain scientific and technological talent, as well as the productivity of its ethnically Chinese scientists.

Meanwhile, the 45-year-old Science and Technology Cooperation Agreement between the US and China to facilitate research cooperation between the two countries is still up in the air. The agreement, which is renewed every five years, was set to lapse in late August 2023 but in March the Biden administration temporarily extended it for six months to determine how to proceed.