As the old year draws to a close and the new one unfolds, the Department of Earth System Science (DESS) at Tsinghua University extends its highest respect, warmest greetings, and sincere gratitude to all faculty, students, and staff who have worked diligently and selflessly; to alumni around the globe and their families who remain devoted to their alma mater; to leaders at all levels who have staunchly supported the development of Tsinghua’s Earth system science, and to friends from all walks of life at home and abroad who have assisted and collaborated with us!

Reflecting on the year 2025, guided by Xi Jinping Thought on Socialism with Chinese Characteristics for a New Era, we thoroughly studied and implemented the spirit of the 20th National Congress of the Communist Party of China and its Fourth Plenary Session. We steadfastly advanced further comprehensive reform, centered on promoting high-quality development, seized opportunities, and forged ahead with determination, achieving a series of remarkable accomplishments.

Professor Zhang Qiang was elected an Academician of the Chinese Academy of Sciences (CAS). The research team on “Atmospheric Composition Change and Carbon Neutrality” was awarded the Excellent Research Group Project (Category B) by the National Natural Science Foundation of China (NSFC). Academician Chen Deliang initiated and led the establishment of the Chinese University Alliance of Earth System Science (CUAESS), with 11 academicians attending the launch ceremony and 22 academicians co-authoring an article on the front page of Science and Technology Daily.

Integrating liberal arts education and specialized training, we have laid a solid foundation for nurturing top-tier talent. The new educational paradigm for the minor in Earth System Science received the Second Prize in the 2025 Tsinghua University Teaching Achievement Award, marking a historic breakthrough for DESS in this category. We completed the pilot program of the “One Department, One Strategy” initiative for curriculum-based ideological and political education. “Fundamentals of Ecological Remote Sensing” was designated a Model Course for Ideological and Political Education. We continued to enhance curriculum quality, with Remote Sensing and Geography recognized as a University-level Quality Course. Doctoral student Sun Yida was awarded the Tsinghua University Special Scholarship (Graduate), and Zhou Shuyi received support from the Basic Research Program for Young Students of the National Natural Science Foundation of China.

We have drawn up a strategic blueprint and fostered a fertile environment for faculty development. Two academicians serve as development advisors, and the Young Faculty Development Advisory Group has played a prominent role in providing comprehensive support for young faculty members. Professor Liu Zhu was awarded the Young Scientists Fund (Category A) of the National Natural Science Foundation of China. Professor Fu Haohuan’s team was honored as one of the “Top 10 Most Contributive Data Teams”. Associate Professor Yu Le was named an Outstanding Communist Party Member of Tsinghua University. A high-caliber faculty team with an optimized structure, vitality, and innovative spirit has become the core engine driving DESS’s high-quality development.

We have expanded international cooperation and deeply engaged in major international science programs. Academician Chen Deliang was invited to serve as an international juror for the first UNIDO “One World Sustainable Development Award”, Chief Academic Advisor for the Chinese version of the World Economic Forum’s Climate Resilience Report, and Chair of the Volvo Environment Prize Jury. The pilot project on Regional Climate Model Intercomparison for the Tibetan Plateau under the World Climate Research Programme, initiated and led by him, was extended, attracting 24 research teams from 13 countries. Academician Chen continued to co-chair the Third Pole Environment (TPE) Program initiated by Chinese scientists, and remained a member of the Council and Editorial Board of Future Earth, participating in the drafting of the global report Ten New Insights in Climate Change Science (2025/2026), which is the most important publication on climate change besides the IPCC Assessment Reports, presented annually to government delegations at the UN Climate Change Conference. This year, DESS participated in the drafting and release of this report for the first time.

In international exchanges, we welcomed 62 visits by foreign experts, a 35% year-on-year increase. We hosted the first side event on “Climate Change and Health” at the China Pavilion of the UN Climate Change Conference (COP30), and organized and successfully held the Asian Youth Innovation Competition on Climate Change and Health, which has been incorporated into the Action Plan of the World Meteorological Organization’s Regional Association II. We successfully convened key events including the Forum on Science, Technology Cooperation and Sustainable Development in the Global South, the China-Sweden Green Innovation Day High-Level Dialogue, the China-UK Science and Technology Cooperation Forum and Dialogue on Carbon Neutrality and Clean Growth under Global Challenges, and the Annual Meeting of the China-France Carbon Neutrality Center, continuously deepening international collaboration.

Innovation fuels transformation, and we have deepened our commitment to national strategic research. Academician Chen Deliang co-initiated and co-chaired the Shuangqing Forum on Earth System Science organized by the National Natural Science Foundation of China; he also joined the founding of the Science and Technology Innovation Consortium for Extreme Weather Disaster Risk Prevention at the National Institute of Natural Hazards, Ministry of Emergency Management, and serves as its Chief Scientist. Responding to the university’s initiative, we have actively expanded cooperation with the Tibet Autonomous Region to advance regional sustainable development. Working with the China Meteorological Administration and the Chinese Academy of Meteorological Sciences, we submitted a proposal for the National Major Science and Technology Infrastructure under the 15th Five-Year Plan (2026–2030): the Super-large Experimental Research Platform for Future Habitable Planets. We organized interdisciplinary collaborative research to further develop the CIESM2.0 model, and preliminarily completed the two-way coupling between the land surface model ORCHIDEE and the atmospheric component of CIESM, as well as the coupled operation of the aerosol module PAM with CIESM. The research initiative Habitability of Extraterrestrial Carbon-Based Life, proposed by Professor Liu Zhu’s team, was selected as part of the global projects under the United Nations International Decade of Sciences for Sustainable Development.

We released the 2025 Lancet Countdown on Health and Climate Change China Report in Beijing and during COP30, which received recognition from leaders of relevant ministries and officials of the World Health Organization. We strengthened internal and external cooperation, expanded the application of artificial intelligence, and actively advocated on multiple platforms to raise societal awareness of climate resilience and drive profound transformation toward low-carbon development.

Academician Zhang Qiang’s team, collaborating with domestic and international research groups, built a near-real-time inversion technology and data product for global wildfire PM2.5 pollution based on an independently developed near-real-time atmospheric composition tracking platform, revealing the global impacts of long-range transport of extreme wildfire smoke. Working with Professor Tong Dan’s team, they established a coupled analysis framework for climate change, extreme events, and energy security, quantifying the impacts of future climate change on the reliability of global high-penetration wind and solar power systems, and developing regionally differentiated climate adaptation and resilience enhancement strategies for such systems. Collaborating with Associate Professor Zheng Bo’s team at the School of Environment and Ecology, Tsinghua University Shenzhen International Graduate School, they revealed the health and climate effects of future global wildfire emissions under climate change, analyzing the potential impacts and key implications of global warming in exacerbating wildfire-related health burdens and reshaping inequality patterns. These findings were published in Nature under the titles “Long-range PM_2.5 pollution and health impacts from the 2023 Canadian wildfires”, “Strategies for climate-resilient global wind and solar power systems”, and “Global warming amplifies wildfire health burden and reshapes inequality”.

Associate Professor Wang Han’s team, in collaboration with international research groups, constructed a global database of plant stem respiration, confirming the widespread thermal adaptation of stem respiration and uncovering its regulatory mechanisms and critical impacts on the global carbon cycle. The findings were published online in Science under the title “Thermal acclimation of stem respiration implies a weaker carbon-climate feedback”.

Professor Cai Wenjia’s team developed a plant-level recursive dynamic optimization model, innovating emission reduction strategies to support low-cost transformation in the coal-fired power industry. The results were published online in Nature Communications under the title “Reducing transition costs towards carbon neutrality of China’s coal power plants”. Additionally, the team systematically reviewed quantitative results of cost-benefit analysis (CBA) at global and regional levels, proposing reference pathways to address bottlenecks in policy implementation. These findings were published online in Nature Climate Change under the title “Improving cost–benefit analyses for health-considered climate mitigation policymaking”.

Associate Professor Li Wei’s team, using independently developed bioenergy crop module in their model, revealed the contribution of bioenergy crop cultivation in countries without a carbon neutrality target to climate change mitigation. The findings were published in Nature Communications under the title “Contributions of countries without a carbon neutrality target to limit global warming”.

Professor Xu Bing’s team, collaborating with domestic and international institutions, constructed a global gridded database covering economic, social, and environmental infrastructure, revealing global inequalities in infrastructure access and their links to health disparities. The results were published in Nature Human Behaviour under the title “Inequality in infrastructure access and its association with health disparities”.

Associate Professor Peng Yiran’s team revealed the global impacts of discrete effects on aerosol-cloud interactions and developed a new cloud droplet spectrum parameterization scheme based on satellite datasets. The findings were published in Nature Communications under the title “Global quantification of the dispersion effect with POLDER satellite data”.

Professor Lu Hui and Academician Chen Deliang’s team focused on water scarcity and transboundary water conflicts in global international rivers under climate change, projecting future changes in transboundary water conflict risks and proposing response strategies. The results were published in Nature Communications under the title “Transboundary conflict from surface water scarcity under climate change”.

Professor Yang Kun’s team identified strong coupling regions and causal pathways between soil moisture and precipitation globally, and applied these findings to evaluate the performance of mainstream climate models in simulating land-atmosphere interactions. The findings were published online in Nature Communications under the title “Causal pathways underlying global soil moisture–precipitation coupling”.

Team Guan Dabo developed the CEADs-Building model for building-scale carbon emission accounting and mitigation pathway analysis, providing actionable scientific tools and decision support for precise carbon reduction governance at the urban level. The research was published in Nature Communications under the title “A building-scale modeling framework for urban net-zero transitions in Nanjing”.

Serving the nation and society, we have lived up to our mission and demonstrated our sense of responsibility. Over the past year, our department has received special letters of appreciation from national ministries and international organizations in recognition of our various efforts. From providing critical support for the country’s flood-season climate prediction to successfully hosting a series of side events at the China Pavilion of the UN Climate Change Conference (COP30); from guiding the climate and health cases in Tianjin and Zunyi to their inclusion in the WHO Global Case Library, to engaging deeply in capacity building at the International Mangrove Center — these efforts not only serve the nation’s major strategy for addressing climate change and help safeguard public health at the local level, but also contribute Chinese wisdom and Tsinghua solutions to the world. Serving the nation, the people, and the building of a community with a shared future for mankind stands as the defining hallmark of the research pursuits of our faculty and students.

Staying true to our path, we forge ahead with resolve to reach greater heights; persisting with diligence, we refine our capabilities to achieve excellence. On the journey ahead, we will resolutely drive forward further comprehensive reform, harnessing the full strength of Tsinghua to contribute to the realization of a strong China and the great rejuvenation of the Chinese nation.

Wishing you warmth and well-being throughout the year, and every success in all your endeavors!

Department of Earth System Science, Tsinghua University

January 1, 2026