Chris Reinhard is an outstanding young geochemist who has made critical advances across numerical, analytical and experimental approaches to understanding the impact of life on Earth’s elemental cycles. He gained early notoriety as a Ph.D. student through his pioneering research on chemical fingerprints for the rise of oxygen in the atmosphere. Specifically, Chris took trace metal data, iron speciation measurements and sulfur isotope data from 2.5-billion-year-old shales to demonstrate that the juxtaposition of hydrogen sulfide maximum zones in coastal marine settings was a response to a rise in production of biogenic oxygen (O2 ). That study, however, presented the community with a small problem. How could there be atmospheric O2 when the mass-independent fractionation of sulfur isotopes (MIF-S) — our most reliable indicator for an ancient reducing atmosphere — persisted until around 2.45 billion years ago? This is where Chris’ ingenuity shines through because he offered an elegant solution to this paradox: MIF-S signatures were simply recycled long after the MIF-S process in the atmosphere ceased to exist. In effect, there was a “crustal memory effect” that could be removed only through successive stages of weathering, dilution and burial on an oxygenated surface. Chris’ subsequent work on phosphorus biogeochemistry and its implications for the evolution of bacterial phytoplankton and the rise of eukaryotic life forms remains at the forefront of the discipline. His compilation of phosphorus abundances in marine sedimentary rocks spanning the last ~3.5 billion years provided evidence for phosphorus biolimitation in the oceans until ~800 million years ago. By incorporating that phosphorus record into a quantitative biogeochemical framework Chris hypothesized that a combination of enhanced phosphorus scavenging in anoxic, iron-rich oceans and a nutrient-based bistability in atmospheric O2 levels could have resulted in a stable low-oxygen world that would have restricted the spread of multicellular life. The broader reach of Chris’ work has included extrapolations of Earth’s early atmospheres to fundamental questions about life detection in the atmospheric gases surrounding exoplanets. Chris is among the very best in a new subfield of exoplanetary science populated by researchers gifted with deep biological and biogeochemical understandings of planetary ocean-atmosphere systems. In doing so, he has embraced the full suite of models required to propose entirely novel ways of linking atmospheric compositions to life in the oceans on early Earth and their relevance beyond. Chris’ trajectory over a relatively short amount of time from geochemist, to leading geobiologist and paleoceanographer, to astrobiologist/exoplanetary scientist is nothing short of astonishing. I am simply honored to be Chris’ nominator, colleague and friend. 

— Kurt Konhauser University of Alberta Edmonton, Alberta, Canada

Response

I’d like to express my deepest thanks to Kurt Konhauser, all of those who supported my nomination and AGU for honoring me with this award. There are many whose influence I would like to acknowledge, and I hope you will accept my sincerest apologies for any oversight.

I'd first like to thank my mother, Christine Reinhard, and my late father, Jeff Reinhard, who passed away 20 years ago this year. They stoked my curiosity tirelessly and taught me to always remain mindful of how fortunate I am.

I’d also like to thank my mentors, colleagues and friends from my time at the University of California, Riverside. I would particularly like to thank Nigel Hughes, Mary Droser and my Ph.D. adviser, Tim Lyons, all of whom helped me navigate the first years of graduate school with a patience and grace that I will always struggle to pay forward.

I am more or less useless on my own, and to the extent I’ve ever accomplished anything it is because I have been lucky enough to be surrounded by incredible collaborators, students and mentors. I owe a particular debt of gratitude to Noah Planavsky, who has been my closest collaborator and colleague over the years. It has been inspiring and fun to work together.

I would also like to thank the Georgia Institute of Technology for giving me a chance and the many people who have made me feel at home there, especially the phenomenal staff in School of Earth and Atmospheric Sciences — thank you for all that you do and for your patience with me.

Most importantly, I am grateful to my partner, Katy Zimmermann. You are a brilliant scientist and educator and a truly remarkable person. I don’t know where I’d be without you.

— Christopher Reinhard
Georgia Institute of Technology
Atlanta, Georgia