2023 Arthur L. Day Medal

Presented to Isabel Patricia Montañez

Isabel Patricia Montañez

Isabel Patricia Montañez
University of California, Davis


Citation by Judith Parrish

Professor Isabel P. Montañez’ research is application of geochemistry, especially isotope geochemistry, to past climates, ranging across a broad range of topics. Her research has ranged from the oceans to the continents and across geologic time from the Cambrian to the Holocene. She recognized early on that the deep-time climate, ocean, and paleobiological records are fundamentally salient to the modern climate crisis. Montañez and her collaborators understood the importance of learning the full range of climate responses, and that meant tracking major warming transitions and disruptions from the last time Earth was as cold as the recent preindustrial period. To do so, they had to dig deep in geologic time. These studies involve careful and innovative application of carbon, oxygen, and strontium isotope geochemistry and development of geochemical proxies of past atmospheric CO2 concentrations and climate and calibration of proxy approaches in modern systems (Montañez, 2013; Oster et al., 2015; Wortham et al., 2022).

Prof. Montañez’ earliest work (Montañez, 1994, AAPG Bulletin) revealed the step-wise nature of dolomite recrystallization and documented the complex geochemical signatures that result. She extended her studies in the marine realm to carbonate stratigraphy and diagenesis (e.g. Montañez and Osleger, 1993, AAPG Memoir; Sadler et al., 1996, JSR; Montañez et al., 2018, EPSL), and low-temperature marine isotope geochemistry (e.g. Montañez et al., 2000, GSA Today; Montañez et al., 1996, Geology). Prof. Montañez revealed the highly dynamic environmental conditions of the Cambrian early metazoan world and offered the highest temporal resolution for this early period of Earth history (Montañez et al., 1999, AJS). Thus, she helped make advances in our understanding of the oxygenation history of the deep ocean and its role in the establishment of Burgess Shale-type, early marine ecosystems.

Expanding to the terrestrial realm, Prof. Montañez and her colleagues worked to provide a better understanding of the processes and their linkages that governed climate, surface conditions, and carbon cycling during the late Paleozoic Ice Age (Ekart et al., 1999, Geology; Royer et al., 2004, GSA Today). They documented a higher background level of CO2, helping to explain a long-standing radiative-forcing conundrum, as well as an underappreciated role for terrestrial vegetation-CO2 feedbacks in driving eccentricity-scale climate cycles (Montañez et al., 2007, Science; DiMichele et al., 2009, Geobiology; Montañez et al., 2016, Nature Geoscience; Wilson et al., 2017, New Phytologist; Matthaeus et al., 2021, PNAS). In this work, she and her colleagues tied together changes in temperature, CO2 levels, plant communities and their dependent ecosystems, sea level soil moisture, and weathering. Part of this work was an effort to determine the physiology of late Paleozoic plants to understand how they could be used as proxies for past CO2 and how these now-extinct plants influenced their environment, in the process developing an entire new scientific frontier, leading to a complete rethinking of how past plants function (e.g. Wilson et al., 2017, New Phytologist; Richey et al., 2020, Paleo3) and interacted with the climate and hydrologic cycle (Matthaeus et al., 2021, PNAS). In addition, Prof. Montañez and her colleagues have contributed substantively to the science of using paleosols to interpret climate. Paleosols are among the few proxies for determining ancient CO2 concentrations so deep in geological time. To take advantage of them requires careful field work to understand the spatial relationships in terrestrial deposits, careful petrographic observations to know what to measure, and careful geochemical and stable isotope measurements to be able to have data to make interpretations. This work is exacting and time consuming, and Prof. Montañez’ is extraordinary in its scope.

She and her colleagues more than doubled the high-precision U-Pb ages for glacial and interglacial deposits in paleo-high-latitude regions (Gulbransen et al., 2010, GSA Bulletin; Tierney et al., 2020, Science), allowing development of detailed stratigraphic studies in North America, Europe, and China; and developed geochemical proxy records within the cyclostratigraphic frameworks (Eros et al., 2012, Palaeo3; Chen et al., 2018, Geology; 2021, EPSL). These studies have been integrated with data-climate model comparisons (Montañez and Poulsen, 2013, Ann. Rev. EPS), revealing dynamic glaciation history (Montañez et al., 2018, EPSL). Prof. Montañez contributed to one of the most consequential review papers to draw the connection between past and future climates (Tierney et al., 2020, Science).

Prof. Montañez also has worked on Late Quaternary linkages between megadroughts and North Atlantic sea temperature fluctuations using soil and speleothem geochemistry, with implications for how water resources might evolve in the arid West with continued climate warming.

Prof. Montañez has performed extensive service to the Geological Society of America, including as President Elect (2016-2017), President (2017-2018), Immediate Past President (2018-2019). Her unparalleled list of professional service runs from local to international. She has been recognized with the SEPM Francis J. Pettijohn Medal, the Jean Baptiste Lamarck Medal of the European Geosciences Union, GSA Sedimentary Geology Division Lawrence L. Sloss Award, AAPG J. “Cam” Sproule Award, and membership in the National Academy of Sciences, to name just a few of the awards she has received.

Her efforts advancing diversity within the geosciences are remarkable, including serving on GSA’s President’s Diversity Task Force and Committee on Diversity in the Geosciences, and as one of four PIs on the recently NSF-funded Women of Color in the Geosciences (WinG) Collective. Prof. Montañez is deeply committed to strengthening diversity in the geoscience community, and she puts her strong shoulder to the effort.

In her career, Prof. Montañez has advised and mentored dozens of early career researchers from undergraduate students to post-docs; garnered teaching awards; and won numerous research grants. She is an outstanding mentor for the next generation and role model for all of us and highly deserving of the Day Medal.


Response by Isabel Patricia Montañez

Thank you Judy for believing in me and for initiating this nomination, as well as to those who supported it. You have all been inspirational colleagues to me over the years and I am humbled and deeply appreciative of the many ways that you have supported my career.

Many have gambled on my potential as a researcher when they could have been more agnostic. Starting as an undergraduate, Bruce Saunders who was my senior thesis advisor, encouraged me to pursue graduate school even when my GPA did not. Fred Read, at VA Tech, took me on as his first female Ph.D. student – not a small endeavor for a western Australian ‘mate’ — and provided me the latitude to fail, the support to recover and succeed, tolerated my insistence that I absolutely had to look at 1200 thin sections, and helped me to build the tough skin that has served me well since then. That two of my dissertation chapters won best-publication awards from journals is testament to his support. Krishna Sinha, a radiogenic isotope geochemist at VA Tech, recognized and nurtured my curiosity and gave me the confidence to apply geochemistry to address sedimentary geology questions. My career as an academic at the University of California was launched fortuitously when the faculty in the Department of Earth Sciences at UC Riverside hired the underdog. An opportunity spearheaded by Jeff Mount, then the Chair of the Department of Geology at UC Davis, greatly boosted my research trajectory.

But the biggest gambler is my ‘enabler’, David Osleger, who 35 years ago thought it was a good idea to ‘hitch his wagon to mine’ (his words). Every step of my career since then has been in some way a reflection of his unwavering support and encouragement of my passion for my work and his tolerance of my inability to keep time and my addiction to ‘just one more thing’.

I also have been extremely fortunate to have had many talented graduate students and postdoctoral scholars and they have been the protagonists of my career narrative. Over 34 years, these young researchers, who have come from a diversity of scientific and cultural backgrounds, have expanded my thinking through their keen curiosity about the Earth system and its climate history and by their willingness to challenge and not blindly accept ideas. Their dedication to the simple but profound proposition that the past matters has been, and continues to be, an endless source of inspiration for me. And a special word of appreciation for all the colleagues with whom I have collaborated and who have continued my education well beyond graduate school.

Thank you The Geological Society of America for this wonderful honor. I accept the Arthur L. Day Medal on behalf of all these many people who have been instrumental in building my career over the past four decades.