Citation for Rajdeep Dasgupta

Rajdeep Dasgupta
Rajdeep Dasgupta

It is fitting that one of this year’s Macelwane awards is being given to Rajdeep Dasgupta. There are but a handful of people who have accomplished so much and have had such an impact on the scientific community at such a young age.

Together with his students, he has published a series of papers that have defined him and his laboratory at Rice University as one of the world leaders in understanding the role of volatiles in phase equilibria. His work is now the gold standard for the melting of rocks in carbon dioxide–rich systems, and he has provided new models and data for carbon dioxide solubility in melts. He has also provided new constraints on carbon solubility in the core and has given us a deeper understanding of how melting happens in the mantle, with implications for the physical properties of the astheno­sphere.

On top of all the experimental work, he has still managed to find time to synthesize observations with experiments, providing the community with comprehensive and, at times, provocative views of how the whole Earth carbon cycle operated, from magma oceans in the Hadean to the plate tectonics at present. These are clearly hot topics in the Earth science community right now, but it is clear that Raj has played a dominant role in defining these research directions, rather than being someone who follows fads. Thus, it is no surprise that he is continuing to push new frontiers as we speak. He is currently working on sulfur solubility in a variety of petrologic systems in order to understand sulfur transport in subduction zones and even during Martian magmatism.

On top of his research accomplishments, Raj has also carved a niche for himself as a great mentor and educator, inspiring and working with numerous graduate students and undergraduates. His ability to pay attention to important details and, at the same time, maintain the big picture is a skill that all desire but few have. Raj is the quintessential role model for a new generation of petrologists.

—Cin-Ty Lee, Rice University, Houston, Texas


Thank you, Cin-Ty, for the kind and generous citation and thanks to the Macelwane committee and those who contributed toward my nomination for their time and consideration. I am deeply honored to receive this recognition from AGU. Especially, looking at the list of illustrious scientists who received this award in the past, I feel humbled.

It is usual for the honorees to thank some key people and recall a few defining moments in occasions like this, and my response, in many ways, is not going to be different. Without the tutelage and encouragement of Somnath Dasgupta, Pulak Sengupta, Sudipta Sengupta, Pradip Bose, the late Prasanta Bhattacharya, Subir Ghosh, and many others at Jadavpur University during my B.Sc. and M.Sc. days; the guidance of Marc Hirschmann at University of Minnesota during my Ph.D. work; and the supervision of Dave Walker during my postdoc research at Lamont, I would not be standing here. In particular, getting a taste of the full course of geological sciences at Jadavpur, learning how to ask important questions and connect small-scale experiments to big-scale processes from Marc, and the out-of-the-box and free thinking under the support of Dave were all essential for me.

When I wrote similar responses even 2–3 years ago, I could have stopped with more or less what I have written thus far. But for this particular recognition, I feel it is really my time at Rice University since 2008 that made this happen. I am grateful to the Department of Earth Science for providing me with the much-needed support to build my experimental lab and group plus supportive colleagues. Not too many young investigators can say with confidence that it is the work of their current and past advisees that brought them the recognition. But it is certainly the hard work, dedication, and accomplishments of Ananya Mallik, Kyusei Tsuno, Justin Filiberto, Veronique Le Roux, Han Chi, Megan Duncan, Echo Ding, Sébastien Jégo, Laura Carter, Yuan Li, James Eguchi, Sriparna Saha, and several undergraduate researchers that made my scientific career flourish in recent years. So I am standing here simply on behalf of all of them, and they should feel as proud as I do today.

Finally, the adventure with geology and life would have been impossible without Sushmita and so much less fun to look forward to without Pritthij, Aurno, and Odri. So this is to all of you as well.

—Rajdeep Dasgupta, Rice University, Houston, Texas

Citation for Christian Frankenberg

Christian Frankenberg
Christian Frankenberg

Christian Frankenberg is pioneering the development and use of satellite remote sensing for new and original scientific research coupling ecology with the ­larger-​scale physical processes of the Earth system carbon and water cycles. He is one of the discoverers of the new remote sensing technique for solar-induced fluorescence that is providing new global data on the terrestrial biosphere. This is one of the most important discoveries in remote sensing in recent years.

He began his early research as an undergraduate and graduate student in Germany, moving from geoecology to remote sensing. He provided algorithms to derive atmospheric carbon monoxide and methane from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) spectral observations and analyzed these data to estimate global emissions. When he moved to the Institute of Environmental Physics in Heidelberg and then the Netherlands Institute for Space Research in Utrecht, he continued developing new satellite data products, extending them to water vapor and the important isotopologue, HDO. His research on the fractionation of HDO provided new insights into the dynamical processes regulating water vapor in the lower troposphere and thus the global water cycle.

Currently at the Jet Propulsion Laboratory at the California Institute of Technology, Christian has been an integral part of the Orbiting Carbon Observatory 2 (OCO-2) team involved in the challenge of measuring atmospheric carbon dioxide concentrations from space with the sensitivity to infer patterns of the underlying exchange of carbon dioxide with the surface. In analyzing the Japa­nese Greenhouse Gases Observing Satellite (GOSAT) high spectral resolution data intended for greenhouse gas measurements, he and others discovered that the fluorescence photons emitted by chlorophyll during photosynthesis, even though small in number, could be detected as the filling in of the solar Fraunhofer lines. This unexpected by-product offers new information about global plant primary productivity, complementing existing light interception observations.

An impressive characteristic of Christian’s research is his ability to bring together an understanding of fundamental atmospheric radiative transfer, spectroscopy, and nuances of the performance characteristics of the instruments to first tease out these new data sets and then later to analyze them for new understanding of global biophysical processes. He has more than 64 peer-reviewed multidisciplinary publications to his credit since 2004, an impressive body of work that will no doubt continue to expand. These publications have already had both high impact factors as measured by their frequent citation and the more telling impact of stimulating new directions for satellite observations of the Earth system.

—Michael Gunson, California Institute of Technology, Pasadena, Calif.


Thank you, Mike, for your kind words, and thank you, AGU, the Macelwane committee, and my nominators, for this unexpected and overwhelming honor. Going through the list of previous recipients is stimulating and intimidating at the same time. I feel very lucky and honored.

Like life itself and the Earth system, careers are often nonlinear, and I am indebted to many scientists and friends who shaped mine. I was fortunate to start my Ph.D. work at the University of Heidelberg at a time when the ENVISAT satellite was just launched and the SCIAMACHY instrument started shaping my research path. After working with the inspirational Ulrich Platt at Heidelberg, I continued my research in Utrecht with a Veni postdoc fellowship and enjoyed working with a great group of scientists under Ilse Aben.

For various reasons, I may not have made the big jump across the pond to the Jet Propulsion Laboratory (JPL) but for my childhood friend Kai Buchholz. Working for the United Nations, he died tragically during the earthquake in Haiti, just when I started working for JPL in the United States. In many ways, he was the most extraordinary person I knew and has always been an inspiration and moral compass for me. I would not be standing here without him.

I came to JPL about half a year after the OCO launch failure, but we were lucky to be able to work with the Japanese GOSAT satellite and the National Institute for Environmental Studies and Japan Aerospace Exploration Agency teams. Kuze-san, Yokota-san, Dave Crisp, and Mike, thank you for all your support. Again, I was somewhat lucky and at the right place at the right time. Over the last few years, I drifted back to the roots by studying chlorophyll fluorescence from space. This not only was an exciting topic but also gave me the chance to meet and collaborate with great scientists, such as Joe Berry, who probably is one of the most original and knowledgeable yet humble scientists I know. Over the last few years I had the pleasure of working work with and being influenced by many others, including Chris O’Dell, Luis Guanter, Andre Butz, Joanna Joiner, and many others. I learned a lot from many more people than I could possibly mention here.

Last but not least, I want to thank my parents for providing me all the freedom I could wish for; my wife, Suniti, for all her support; and my son, Neal, for teaching me again how powerful curiosity is.

—Christian Frankenberg, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, Calif.

Citation for J. Taylor Perron

J. Taylor Perron
J. Taylor Perron

Pioneering research in geomorphology requires breadth and deep physical insight. The puzzles to be solved extend over vast ranges of spatial and temporal scales and include a wide spectrum of surface features on Earth and other planets. Finding solutions requires mathematical analysis, numerical modeling, field observations, laboratory experiments, and ­high-​­resolution remote sensing. This complexity is motivating a new generation of remarkably talented planetary scientists, and J. Taylor Perron’s elegant and transformative research has placed him at the forefront of that group.

Innovation builds on fundamentals. After receiving undergraduate degrees in Earth and planetary sciences and in archeology at Harvard, Taylor moved to University of California, Berkeley, to join Dietrich’s and Kirchner’s legendary geomorphology groups. Working in this thriving intellectual community—with fellow graduate student Mike Lamb and Professors Manga, Fung, Richards, De Pater (astronomy), and others—he developed the extraordinary breadth of interest and skill that remains a defining character of his research. As a graduate student, Taylor worked on problems as varied as hillslope erosion, valley formation by methane rain and rivers on Titan, polar wander on Mars, and topographic signatures of life. These interests broadened while he was a Daly Postdoctoral Fellow at Harvard, where he explored (with Professor Huybers) the possibility that polar deposits on Mars record Milankovitch cyclicity and continued his seminal study of the regular spacing of ridges and valleys.

Taylor returned to the latter problem after joining the faculty of the Massachusetts Institute of Technology (MIT). In a remarkable study published in 2012, he demonstrated how competition between soil transport and river incision controls the spatial scale of river networks, one of the most striking and pervasive features on Earth’s surface. His work elucidated how these networks record the influences of rock strength, rainfall, and even life and provided a universal framework for understanding drainage networks on other terrestrial bodies. Many other important contributions could be mentioned, but we end by looking back a century, to Darwin’s classic model of the progression from coral reef to atoll. Many islands do not follow this sequence, and providing an alternative has long been a goal in geomorphology. Taylor and his group resolved this enigma by using a model that links reef accretion with island vertical motion and by establishing that coral reefs bear the imprint of ice age sea level cycles—a perturbation to the Earth system of which Darwin was unaware.

This medal recognizes Taylor’s landmark achievements and the promise of discoveries yet to come.

—Jerry X. Mitrovica, Harvard University, Cambridge, Mass.
—Robert D. van der Hilst, Massachusetts Institute of Technology, Cambridge, Mass.


Thank you, Rob and Jerry, for the kind words. I am grateful to AGU for this honor and also for shining a light on the field of geomorphology. It is remarkable that landscapes, which are so eminently observable, can be so full of mystery. And there is no shortage of mysteries: from the ancient Appalachians to the spidery networks of methane rivers on Titan, there are many landscapes we have yet to fully explore.

But I didn’t realize at first how many stories the geological landscape has to tell. As an undergraduate, I spent a lot of time wondering how and when humans migrated to the Americas. Through a stroke of luck, I migrated from the east side of North America to the west side. There, in Berkeley, Jim Kirchner, master analyst, and Bill Dietrich, insightful questioner, found a kid with an archaeology degree on their doorstep and taught him to think quantitatively about Earth’s surface. Around the same time, Alan Howard, Jerry Mitrovica, and Michael Manga sparked my interest in planetary landscapes, which never fail to surprise.

In the years since, new institutions have brought new friends. Colleagues at MIT and Woods Hole have drawn my attention to new problems, introduced me to stellar students, and made time to learn about my work. I especially thank Dan Rothman, Rob van der Hilst, Maria Zuber, Leigh Royden, Sam Bowring, Andrew Ashton, John Southard, Paul O’Gorman, Tanja Bosak, and Ben Weiss. Many others have helped me as collaborators, kindred spirits, or both. I am particularly indebted to Mike Lamb, Kelin Whipple, Paul Myrow, Peter Huybers, Ken Ferrier, Sean Willett, Steve Martel, Sujoy Mukhopadhyay, Devon Burr, Josh Roering, Noah Snyder, Sergio Fagherazzi, John Grotzinger, Mike Church, and Tom Dunne.

I will end by mentioning three groups who deserve their own medals. First, to the students and postdocs who have fueled our work, I look forward to counting you as colleagues for many years to come. Second, I thank my parents, who fostered my curiosity, invested in my education, and kept open minds about what they would get in return. Finally, and most importantly, I thank my wife, Lisa, who makes all my work possible, and our daughters, Mia and Ada, who have inspired me in ways I never anticipated.

—J. Taylor Perron, Massachusetts Institute of Technology, Cambridge, Mass.

Citation for David L. Shuster

David L. Shuster
David L. Shuster

It is with great delight and surprise that I introduce David Shuster as a recipient of the Macelwane Medal—it is a great delight to recognize a young scientist who has brought unique gifts to the emerging field of thermochronology but also a great surprise to be David’s citationist after having contributed essentially nothing to his intellectual growth. My role instead appears to have been that of his number one fan. I became aware of David’s work while reviewing his early manuscripts, but we didn’t meet until years later when I approached him at a meeting to say how profoundly impressed I was with his thoughtful approach and extraordinary experimental skills. I mention this here to underscore my deep admiration of David as, to the best of my recollection, I have never done that before or since.

The development of (U + Th)/He dating of accessory minerals provided new thermochronometers for investigations of tectonic and landscape evolution but was notably limited by near-surface recoil effects and the need for bulk analysis. The former interferes with recognition of ­high-​­frequency diffusion information, and the latter precludes obtaining continuous thermal histories. David’s pioneering development of 4He/3He profiling transcended both limitations, opening up entirely new avenues of research. His investigations of time-varying erosion rates in orogenic terranes have provided the clearest views of how tectonics and climate may be linked. His discovery of proton-induced neon during sample irradiation led to a novel method to determine Ne diffusion in silicates—data essential to understanding the thermal behavior of cosmogenic chronometers. He made significant contributions to developing dating methods to assess the timing of pedogenic processes with a view to better understanding past changes in environmental conditions at the Earth’s surface. In particular, his pioneering application to iron oxides opened up the possibility of directly dating soil formation and thus the calibration of paleosol records with which to examine evidence of past climate change. Although it would have been tempting to simply reproduce the tools he had already developed when commissioning his Berkeley laboratory, David adopted the complimentary capabilities of 40Ar/39Ar dating for revealing intragrain thermochronological variations. His clever application of this method to reveal thermal histories of lunar and Martian samples resulted in standout papers documenting impact events, the effects of solar heating, and timing constraints on the lunar dynamo that are revitalizing the field.

David’s career is characterized by a unique style: an idea for a novel or refined dating method is realized through an equally inspired laboratory development that yields data understood by sophisticated application of physical modeling, ultimately leading to a new view of how a planetary body works. Thus, I believe that this award both recognizes David Shuster’s outstanding early career achievements and presages his emergence as the leading international figure in his field. Congratulations, Professor Shuster!

—Mark Harrison, University of California, Los Angeles, Calif.


Thank you, Mark, for your generous citation. I am grateful to those who nominated me and to the members of AGU for this honor. I am humbled to be in the company of four outstanding scientists who are also receiving the Macelwane Medal this year and many of my academic heroes who are past recipients.

The science I pursue is an interdisciplinary and collaborative endeavor, which benefits from colleagues and mentors too numerous to fully acknowledge here. My friend and colleague Don DePaolo first introduced me to isotope geochemistry and the joys of scientific inquiry as an undergraduate at the University of California (UC), Berkeley. Don taught me how to simplify a problem’s complexity to gain an intuitive understanding of it and the importance of the words “I don’t understand.” Don then enabled me to freely pursue my curiosity as a 21-year-old, with a research position at Lawrence Berkeley National Laboratory, where I learned noble gas geochemistry and mass spectrometry from Mack Kennedy while studying geothermal fluids and volcanic gases. Those early experiences with noble gases defined the trajectory of my career.

As a graduate student at the California Institute of Technology (Caltech), I received mentorship of outstanding geochemists, including John Eiler, Don Burnett, Ed Stolper, Jerry Wasserburg, Jess Adkins, and, of course, my Ph.D. advisor, Ken Farley. I will always appreciate their influence, and I especially thank Ken for teaching me to be rigorous, fearless, and persistent with my science. To this day, Ken is my close colleague, my friend, and always my advisor. And since we began studying meteorites and lunar rocks together as graduate students, I’ve learned much about thermochronology in trying to answer Ben Weiss’s seemingly limitless questions beginning with the word why.

Since my return to UC Berkeley, my work has benefited from the creativity of outstanding graduate students and postdocs in my research group, the penetrating questions of undergraduates in my classes, the creativity and generosity of Greg Balco, and my exceptional colleagues in the Department of Earth and Planetary Science, most especially Kurt Cuffey and Bill Dietrich. I am grateful to the Berkeley Geochronology Center and the Ann and Gordon Getty Foundation for continuing to support my laboratory at a level that is essential but increasingly uncommon and to Tim Becker for world-class laboratory support.

Finally, the love of my wife, Erin, and our beautiful daughter, Nora, provide the most gratifying balance to my life that anyone could hope for. However, when we first met in middle school, Erin could not have predicted that she would later in life become so inadvertently knowledgeable in geochemistry.

—David L. Shuster, University of California, Berkeley, Calif.

Citation for Jessica Tierney

Jessica Tierney
Jessica Tierney

Jess Tierney has made lasting contributions to paleoclimate research through the development, testing, and application of organic biomarkers in key regions of the tropics. Her records provide valuable estimates of past hydrological variability in areas where traditional paleoclimate records are sparse, best illustrated by her extensive work in tropical Africa. Such reconstructions serve to constrain the bounds of natural climate variability while characterizing the sensitivity of the climate system to past climate forcings—information of vital interest to society under continued climate change.

During her graduate work at Brown, she generated several important tropical paleoclimate records and began to work through the complexities of multiproxy records in earnest. Seeking to increase the utility of organic biomarker records like those she generated during her dissertation research, she completed an ambitious effort to refine the community’s understanding of such records. It was during her postdoctoral tenure that she began to work with climate model output, collaborating with a range of top climate modelers on questions at the interface of paleoclimate and climate dynamics.

Early investments in expanding her conceptual and analytical tool kits has equipped Jess to tackle the most pressing questions in paleoclimate, which often require collaborations with climate modelers. Her latest achievements include a sophisticated comparison of paleoclimate data with output from models, demonstrating the potential for paleoclimate data to provide much-needed tests of model accuracy. Increasingly, climate scientists are turning to paleoclimate data sets to test the accuracy of the complex numerical climate models that are used to simulate future climate trends. Jess is a true pioneer in such data-model comparisons and has already made seminal contributions in this rapidly evolving field. In this regard, the quantification and representation of uncertainty in paleoclimate data lie at the core of her research endeavors, and her contributions in this area are helping to define best practices across the field. The fact that much of her published work has appeared in high-profile journals is a testament to the excellence and relevance of her research.

Jess combines a strong vision for paleoclimate science with the skills and leadership qualities necessary to move the field to its next level of evolution—one focused on delivering rigorous constraints on climate variability and change in sensitive areas of the Earth’s climate system.

—Kim Cobb, Georgia Institute of Technology, Atlanta, Ga.


Thank you, Kim, and my thanks to the Macelwane committee and to AGU. It is truly an honor to receive this award and to join the company of the many prestigious colleagues who are past recipients of this medal.

My love of studying past climate change began with a deep appreciation for history. Historical precedence and legacy can explain the present state of world affairs and can shed light on the future evolution of society. Similarly, Earth history reveals much about the present behavior and future state of the climate system. Through my research, I strive to understand past climates, with an eye toward placing the fate of our Earth in a greater context. I believe that new and evolving techniques, geochemical and statistical, can move us forward in this respect.

I would not be receiving this award without the encouragement and support of many wonderful mentors and collaborators. During my time as a postdoctoral scholar at the Lamont-Doherty Earth Observatory, I was fortunate to be mentored by Peter deMenocal, who went above and beyond to support me, to help me meet top researchers in the field, and to engage me in interesting questions in paleoclimatology. While at Lamont, I also had the privilege to collaborate with Ben Cook, Allegra LeGrande, Gavin Schmidt, Richard Seager, and Jason Smerdon, who expanded my knowledge of climate dynamics and climate modeling. I continue to learn new things from my research with my talented collaborators and friends Pedro DiNezio and Martin Tingley.

I owe a huge debt to the organic geochemistry field, a discipline that has been so welcoming to young researchers. In particular, I want to thank Kate Freeman and Ann Pearson—two visionary scientists who, as leaders in the field, are role models for me. I also want to thank Rich Pancost, Jaap Sinninghe Damsté, and Mark Pagani, who have always generously provided analytical resources, their unique insights, and invaluable advice.

I also want to thank my family, in particular my wonderful husband and fellow paleoclimatologist, Kevin Anchukaitis, with whom I am truly blessed to share my life and science.

Finally, I would like to thank all of the women in science who have made it possible, through their perseverance, strength, and example, for me to receive this award. I hope that AGU will continue to recognize, support, and honor the extraordinary achievements of women in the geosciences.

—Jessica Erin Tierney, Woods Hole Oceanographic Institution, Woods Hole, Mass.

Citation: AGU (2015), Dasgupta, Frankenberg, Perron, Shuster, and Tierney receive 2014 James B. Macelwane Medals, Eos, 96, doi:10.1029/2015EO021713.

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