On the morning of September 25,2020, Yang Zili, a professor of economics at State University of New York at Binghamton, was invited to give an online "Climate change and externality" academic report. The report was hosted by Professor Yu Biying.

Prof. Zili Yang is Professor of Economics at State University of New York, Binghamton, Adjunct Professor at Beijing Institute of Technology and Doctor of Economics at Yale University, Mainly engaged in resources and environmental economics, energy economics, economic modeling, applied game theory, China's economy and other research work. Professor Yang Zili, in collaboration with Professor William D.Nordhaus Yale University, winner of the 2018 Nobel Prize for Economic Science, developed the most influential comprehensive climate change assessment model worldwide (RICE model), Associated results are published in top journals such as American Economic Review. The RICE model and its derived multiple models have been widely used in the reports of the United Nations Intergovernmental Panel on Climate Change (IPCC) in various countries. In addition, Professor Yang has also independently developed a research method that combines the concept and algorithm of game theory numerical solution with the integrated assessment model of climate economy.

Professor Yang first pointed out in this report that the impact of climate change can be regarded as an externality phenomenon, while the DICE and RICE model is a comprehensive assessment model that explicitly regards climate change as an externality (Intergrated Assessment Model). Then Professor Yang introduced how DICE and RICE models incorporate externalities into models, pointing out the need to integrate the external effects of climate change into our socio-economic understanding of climate change. The key role of externality in IAM modeling is demonstrated from the perspective of neglecting the deviation caused by externalities in climate change economics. The consideration of externalities in DICE and RICE models has also been recognized by the Nobel Committee and is an important reason for its wide influence in the field of climate models.

After the report, participants had a deep exchange with Professor Yang on how to internalize the externality of climate change and how to coordinate the differences of emission reduction targets among different countries, and took a group photo online.