Appy Sluijs

Utrecht University

2016 James B. Macelwane Medal Winner

Appy Sluijs was awarded the 2016 James B. Macelwane Medal at the AGU Fall Meeting Honors Ceremony, held on 14 December 2016 in San Francisco, Calif. The medal is for “significant contributions to the geophysical sciences by an outstanding ­­early-­career scientist.”


It is my honor to introduce Appy Sluijs, a recipient of the 2016 James B. Macelwane Medal. Appy, a geobiologist, is being recognized for his prolific and ­­leading-­edge contributions to resolving the nature of extreme climate change and impacts on marine biota in Earth’s past.

Appy’s scientific achievements come as no surprise. His deep passion and aptitude for his craft were evident early on when, as an undergraduate at Utrecht, he participated in Ocean Drilling Program (ODP) Leg 208 to the South Atlantic. Despite his inexperience, he made the most of the opportunity, becoming a valued member of the scientific party and eventually contributing to several seminal publications that defined the scale and timing of Eocene hyperthermals and ocean acidification, including the ­­Paleocene-­Eocene Thermal Maximum (PETM). Building on this foundation, as a graduate student under the tutelage of Henk Brinkhuis and later as a postdoc, he produced a series of landmark papers involving dinoflagellate taxonomy and geochemical proxies to constrain changes in ocean temperatures, salinity, and ecology of the Arctic and ­­lower-­latitude coastal oceans. Key to this effort was his creative use of organic biomarker proxies which he and colleagues at the Royal Netherlands Institute for Sea Research, J. Sinninghe Damsté and S. Schouten, began to apply to Paleogene archives across the globe. This work not only established the extreme warmth and stratification of the Arctic during the PETM but also served as a cornerstone for subsequent reconstructions of global meridional temperature gradients for the Paleogene. In addition to the landmark work on Eocene hyperthermals, Appy contributed to ­­high-­impact studies of several other key climate events of the Paleogene, including the middle Eocene Climatic Optimum and the ­­Eocene-­Oligocene transition.

Not long after these very early career accomplishments, Appy was appointed full professor, one of the youngest to achieve the rank at Utrecht University. He has since established a major research program and continues to address fundamental issues on the character and impacts of major changes in climate during the Cenozoic. He is also recognized for his extensive service to the scientific community and for exceptional public outreach and education, particularly his work with students in the Young Academy of the Royal Society of the Netherlands.

—James C. Zachos, University of California, Santa Cruz


Thank you, Jim, for this generous citation. I also thank you and my colleagues who wrote letters for the nomination. I thank the members of the Macelwane Medal Committee and AGU for this great honor.

Similar to many of us, my story is one of remarkable serendipity. Coming from a ­­nature-­loving family and focusing on biology during my undergraduate studies, I miraculously ran into Henk Brinkhuis at Utrecht University, who introduced me to the wonderful world of dinoflagellates, micropaleontology, and paleoceanography. I would not be where I am without his generosity and inspiration. After my first micropaleontological work, Henk sent me to University of California, Santa Cruz to work with Jim and Stephen Schellenberg, who introduced me to geochemistry. During my graduate work I had the pleasure to collaborate with a set of truly unique, diverse, and creative scientific innovators. Along with Henk and Jim, these were Jerry Dickens, Jaap Sinninghe Damsté, Stefan Schouten, Lucas Lourens, Matt Huber, Ellen Thomas, and many others, discovering, describing, and understanding ­­Paleocene-­Eocene transient global warming events. Later on, ­­Gert-­Jan Reichart helped me design biogeochemical culturing experiments for dinoflagellate proxy development. I consider all of these people to be incredible scientists and great friends. I also thank my parents and the rest of my family and friends for their unconditional support and Margriet for being who she is.

I cannot name all colleagues who inspired me and with whom I have had the pleasure to work (even Scopus stops counting at 150 collaborators). I would, however, like to mention that much of my work was driven by two institutes: the International Ocean Discovery Program and the Urbino Summer School on Paleoclimatology, dominantly initiated by Henk and Simone Galeotti, which by now has taught over 800 international graduate students.

Our field of science, multidisciplinary paleoclimatology and paleoceanography, had barely started when Father James Macelwane was the AGU president. Now it is a crucial field in improving projections of future change. The rapid progress over the past decades is the accomplishment of a critical but constructive community with excellent leadership in the past and the present. I therefore feel that this medal, although awarded to me, rather marks the success of this research community as a whole, which includes students, postdocs, and faculty, all standing on the shoulders of past giants. And as many grand scientific and societal challenges lie ahead of us, I’m proud to be part of it.

—Appy Sluijs, Utrecht University, Netherlands