Prof. Zhengyu Liu is an intellectual leader at the intersection of climate dynamics, Earth system modeling, and paleoclimate reconstruction who has developed a deep understanding of Earth system interactions and global climate and environmental change. Liu’s work is underpinned by his strong modeling acumen and rich knowledge of the mechanics of the atmosphere and oceans, and their interactions that bear on questions that challenge other disciplines. One example is the Holocene temperature conundrum. Here, most proxy data suggest warmer global temperatures during the early to mid-Holocene and cooler temperatures in the late Holocene, culminating in the Little Ice Age and subsequent anthropogenic warming. Climate models suggest an opposing scenario. Liu is deeply involved in efforts to resolve this important issue, as both cannot be correct. He also applies his modeling expertise to better understand such complex processes as the decadal climate variability, El Niño–Southern Oscillation (ENSO), monsoons, and Atlantic Meridional Overturning Circulation (AMOC) and thereby unravel the dynamical interactions among different regions of Earth’s climate system and examine climate variability over a broad spectrum of timescales ranging from glacial/interglacial to decadal and interannual. His work on the AMOC, one of the most active components of our climate system with the potential to initiate abrupt climate changes over the globe, has profound implications for our projections of future climate change.

Bert Bolin, the Swedish meteorologist for whom this award is named, spent time at Princeton working with Jule Charney, John von Neumann, and others on the first computerized weather forecast. However, his most impactful contributions led to the formation of the Intergovernmental Panel on Climate Change (IPCC) by bringing together numerous scientists with diverse backgrounds. Much like Bolin, Liu collaborates with many of the world’s best climate modelers, climatologists, oceanographers, and paleoclimatologists and crosses disciplinary lines easily and productively. He has been a leader in the application of climate models with isotopes to understand the formation mechanism of oxygen isotopic composition of precipitation preserved in speleothems and, more recently, in ice cores. His leadership in the development and application of the isotope-enabled Earth system model to past climate changes has and will continue to improve our fundamental understanding of the climatic interpretation of stable water isotopes globally. The impact of Prof. Zhengyu Liu’s extensive body of work on the scholarship and productivity of his colleagues in both the modeling and paleoclimate communities has been extensive and transformative.

—Ellen Mosley-Thompson, Ohio State University, Columbu

It is my great honor to receive the 2022 Bert Bolin Global Environmental Change Award and Lecture. I am deeply grateful to Prof. Ellen Mosley-Thompson for nominating me and to my references for their strong support. The study of global climate change is especially exciting due to its transdisciplinary nature: The climate on our planet is a complex system that involves not only the atmosphere, but also the ocean, land, and cryosphere. It is determined by physical as well as biogeochemical processes, it varies in its spatial scale from localized to global, and it spans from daily time frames to those that extend millions of years. Our climate has experienced dramatic changes in the past 4.5 billion years through natural forces and has just recently started a new journey alongside our human beings. This complexity poses a great challenge to all climate scientists, and we must use the lessons learned from the rich history of Earth’s climate to better predict our future. In my journey of exploring global climate change, I have had the great fortune of working with many of the best scientists in the world across various disciplines. The interactions are stimulating and rewarding, and I would like to express my great gratitude and acknowledgment for the tremendous amount I have learned from them. My gratitude extends further back to those who have helped me arrive here, especially my Ph.D. adviser, Joe Pedlosky, who taught me how to think about the fundamentals of climate dynamics; my postdoc mentor, George Philander, who showed me how to view climate from the perspective of a coupled ocean-atmosphere system; and my colleague John Kutzbach, who introduced me to thinking of global climate from both past and future from an interdisciplinary perspective. Finally, but not the least, I owe much to my family, whose love and support have made all my work possible. —Zhengyu Liu, Ohio State University, Columbus