IIASA researchers again recognized among the world’s most highly cited

IIASA researchers have been consistently featured on the annual Clarivate Highly Cited Researchers™ list, reflecting the lasting influence of the Institute’s work and its role in shaping knowledge and solutions for global sustainability challenges.

Of the world’s population of scientists and social scientists, Highly Cited Researchers are 1 in 1,000. They are individuals who have demonstrated significant and broad influence in their field(s) of research, having authored multiple Highly Cited Papers which rank in the top 1% by citations for their field(s) and publication year in the Web of Science Core Collection over the past eleven years. The method of identifying Highly Cited Researchers, however, includes not only publication and citation counts but also other considerations such as researchers’ community-wide impact, their contemporary influence, and the production of original research.

The following IIASA researchers were included on the 2025 list for their extraordinary influence and performance in the fields of environment and ecology research, cross-field research, and social sciences:

• Oliver Fricko, Research Scholar in the Integrated Assessment and Climate Change and Sustainable Service Systems research groups of the Energy, Climate, and Environment Program.
• Petr Havlik, Biodiversity and Natural Resources Program Director.
• Zbigniew Klimont, Pollution Management Research Group Leader in the Energy, Climate, and Environment Program.
• Volker Krey, Integrated Assessment and Climate Change Research Group Leader in the Energy, Climate, and Environment Program.
• Michael Obersteiner, Principal Research Scholar in the Exploratory Modeling of Human-natural Systems Research Group of the Advancing Systems Analysis Program.
• Keywan Riahi, Energy, Climate, and Environment Program Director.
• Yusuke Satoh, Water Security Research Group, IIASA Biodiversity and Natural Resources Program.
• Hans Joachim (John) Schellnhuber, IIASA Director General.
• Carl-Friedrich Schleussner, Integrated Climate Impacts Research Group Leader in the Energy, Climate, and Environment Program.

Havlik and Riahi are among only 227 researchers recognized in two fields of research this year (environment and ecology and social sciences).

Four researchers with IIASA listed as their secondary affiliation are also included on the list: 

• Shinichiro Fujimori, Senior Guest Research Scholar in the Energy, Climate, and Environment Program primarily associated with Kyoto University, Japan.
• Andreas Richter, a Senior Guest Research Scholar in the Advancing Systems Analysis Program primarily associated with the University of Vienna, Austria.
• Joeri Rogelj, a Researcher in the Energy, Climate, and Environment Program primarily associated with Imperial College London, UK.
• Chris Smith, Guest Research Scholar in Energy, Climate, and Environment Program primarily associated with Vrije Universiteit Brussel, Belgium.

“That our colleagues at IIASA continue to be named among the world’s most highly cited speaks both to the quality of their work and to the relevance of systems-based research in tackling global challenges,” says Schellnhuber. “The world needs both deep disciplinary insight and integrative thinking. It is gratifying to see that such efforts are resonating broadly and enduringly.”

We extend our warmest congratulations to all colleagues included on this year’s list and look forward to the next phases of scientific work and impact that this recognition inspires.

Explore the full 2025 list of Highly Cited Researchers.