Rob Knight in the lab with a colleague

Credit: Erik Jepsen/UC San Diego Publications

Rob Knight, left, UC San Diego professor of pediatrics and computer science and engineering, and postdoctoral researcher Daniel McDonald, right, discuss data from The American Gut Project. Knight is the only person out of the entire list of 6,602 people to be highly cited in four or more disciplines.

More than 300 University of California researchers from across the UC system have been named among the most influential in their fields, according to the 2021 Highly Cited Researchers list released last month by Clarivate.

A snippet of the 2021 Highly Cited Researchers bar graph with UC as the top bar
The University of California is the global leader in cited scholarship, according to Clarivate. (Click to view full-size infographic)
Credit: UC Office of the President

The annual list identifies a virtual “who’s who” in the sciences and social sciences from around the world. Clarivate’s 2021 list identified 6,602 researchers who had significant influence in their chosen field or fields, as evidenced by the publication of multiple highly cited papers during the last decade.

Across the UC system, faculty and researchers accounted for 317 of those listed — or nearly 5 percent of the global total — with four UC campuses among the top 15 institutions globally for their number of highly-cited researchers. UC Berkeley was 7th, UC San Diego was 9th, while UCLA and UC San Francisco were 13th and 14th respectively.

“This list identifies and celebrates exceptional individual researchers at the University of California who are having a significant impact,” said David Pendlebury, senior citation analyst at the Institute for Scientific Information at Clarivate. “The research they have contributed is fueling the innovation, sustainability, health and security that is key for our society’s future.”

Clarivate’s list of standouts included four UC-affiliated researchers who won Nobel Prizes in October: UC Berkeley economist David Card, UC San Francisco physician David Julius, UCLA alum Ardem Patapoutian and UC Irvine alum David McMillan.

It also included UC San Diego’s Rob Knight, the only person out of the entire list of 6,602 people to be highly cited in four or more disciplines. Knight, the founding director of the Center for Microbiome Innovation and a professor of pediatrics and computer science and engineering was named a highly cited researcher in the fields of biology and biochemistry, environment/ecology, microbiology, and molecular biology and genetics.

He was one of 54 UC San Diego researchers recognized for having significant influence in their various fields of study.

“Having over 50 highly cited researchers from diverse fields of research on the 2021 Clarivate list is the mark of a great research university,” said UC San Diego Vice Chancellor for Research Sandra A. Brown. “We’re excited to see our faculty and researchers get the recognition they deserve for their groundbreaking and impactful research.”


Clarivate, formerly known as Clarivate Analytics and Thomas Reuters, provides analytics on scientific and academic research. Its 2021 list contains 6,602 highly cited researchers in 21 fields from more than 70 countries and regions.

Highly cited researchers were identified using data and analysis performed by bibliometric experts from Clarivate’s Institute for Scientific Information at the Web of Science Group.

The fields are defined by sets of journals and, in the case of multidisciplinary journals such as Nature and Science, a paper-by-paper assignment to a field based on an analysis of cited references in the papers. This percentile-based selection method removes the citation advantage of older papers relative to those more recently published since papers are weighed against others in the same annual cohort. The full 2021 Highly Cited Researchers list, executive summary and methodology can be found at Web of Science.

Editor's note: Minor discrepancies between counting in this story and campus stories can be attributed to whether or not campuses included secondary affiliations in their count. This story includes primary and secondary institutional affiliations to reach its 317 researchers number.