Julien Emile-Geay - USC Dornsife
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Julien Emile-Geay
Professor of Earth Sciences
Pronouns
He / Him / His
Email
julieneg@usc.edu
Office
ZHS 275
Office Phone
(213) 740-2945
Links
My Website
LinkedEarth
Research & Practice Areas
Climate Science, Paleoclimatology, Data Analysis, Data Science
Center, Institute & Lab Affiliations
Center for Applied Mathematical Sciences, Fellow
Information Sciences Institute, Affiliated Faculty
Video
Biography
My lab studies how climate varies on timescales comparable to a human lifetime: the
bassline of climate
. We blend data and models (both deterministic and probabilistic) to shed light on climate system behavior, with a particular focus on constraining how much of climate variations arise from within, or are being triggered by external factors, natural or human.
Beyond climate science, I also teach the art of making reliable inferences from data, which is increasingly needed to cut through the cloud of misinformation, and provides economic opportunities for underrepresented groups. I am passionate about educating people of all levels of scientific literacy to the reality of man-made global warming, using evidence-based knowledge to empower individuals to generate positive change. Press
here
for a detailed CV. For a recent presentation on paleoclimate data science, see
this video
.  For recent publications, see my
Google Scholar profile
I am always looking for motivated students, whether for a sumemr internship or a 5-year PhD program, so don’t be shy about emailing me!
Education
Ph.D. Climate Dynamics, Columbia University, 2006
M.S. Dynamics of Atmospheres and Oceans, Ecole Normale Supérieure, 2001
B.S. Earth Sciences, Ecole Normale Supérieure, 1999
Postdoctoral Scholar, Georgia Institute of Technology, 12/01/2006 – 11/30/2008
Tenure Track Appointments
Professor, University of Southern California, 2023 –
Associate Professor, University of Southern California, 2016 – 2023
Assistant Professor, University of Southern California, 2008 – 2016
PostDoctoral Appointments
Postdoctoral Fellow, Georgia Insitute of Technology, 2007-2008
Postdoctoral Fellow, Georgia Insitute of Technology, 2006-2007
Summary Statement of Research Interests
The climate system’s natural modes of variability are known to modulate its response to external stimuli (e.g. greenhouse gas emissions), in ways that either amplify or minimize societal impacts at the local scale. My work aims to better characterize such modes over the long term, test their theoretical understanding and their representation in climate models (GCMs), with the ultimate goal of reducing uncertainties in twenty-first century model projections. It requires the construction of new tools and their application to new data syntheses. My work lies at the interface between climate modeling, data analysis, and geoinformatics. Here are some of the topics my group is working on:
1) Reconstructing climate conditions over the past 2 millennia. This we do by co-developing cutting-edge databases (PAGES2k), new statistical tools (e.g. Gaussian graphical models), or applying data-assimilation techniques to fuse models and observations
2) Understanding and representing uncertainties in climate proxy records, by modeling the processes giving rise to what we observe in corals, stalagmites, lake & sediment cores, or trees.
3) Understanding tropical climate, using an array of climate models with varying degrees of complexity. I am particularly interested in the climate sensitivity to natural (solar and volcanic) forcing and what it teaches us (or not) about climate sensitivity to anthropogenic greenhouse gas emissions.
4) Developing smart codes (GeoChronR, Pyleoclim) and databases (LiPverse) that allow to make optimal use of the data that my amazing colleagues spend so much time collecting and analyzing in the lab.
Research Keywords
climate dynamics, El Niño, data science, visualization, model/data fusion
Research Specialties
Climate Science, Paleoclimatology, Data Analysis, Data Science
Contracts and Grants Awarded
Last Millennium Reanalysis Project, (NOAA (Dept of Commerce)), Greg Hakim (UW), Julien Emile-Geay (USC), David Noone (U. Colorado), Eric Steig (UW), $1,488,473, 08/2014 –
GeoChronR – open-source tools for the analysis, visualization and integration of time-uncertain geos, (National Science Foundation), N. McKay (Northern Arizona University), Julien Emile-Geay, Ken Collier, $566,000, 07/01/2014 –
LinkedEarth: Crowdsourcing Data Curation & Standards Development in Paleoclimatology, (National Science Foundation), J. Emile-Geay, Y. Gil (ISI), Nick McKay (NAU), $798,000, 09/2015 – 08/2017
Conference Presentations
Probabilistic Models of Past Climate Change , Society for Industrial and Applied MathematicsTalk/Oral Presentation, Invited, Anaheim, CA, Spring 2012
The solar-ENSO connection: detection and implications , AGU Fall Meeting 2011Talk/Oral Presentation, AGU, San Francisco, CA, Fall 2011
Pacific Decadal Variability in the view of linear equatorial wave theory , AGU Ocean SciencesTalk/Oral Presentation, Portland, OR, 2010-2011
Variance-preserving, data-adaptive regularization schemes in RegEM. Application to ENSO reconstructions. , International Meeting in Statistical ClimatologyTalk/Oral Presentation, Edinburgh, Scotland, 2010-2011
New mathematical tools for the analysis of incomplete climate data. Theory and applications , International Congress on Industrial and Applied MathematicsTalk/Oral Presentation, SIAM, Invited, Vancouver, CA, Spring 2011
Data-adaptive truncation in RegEM: potential for multiproxy reconstructions over the Common Era , AGU Fall Meeting 2010Poster, San Francisco, CA, Fall 2010
Low-frequency tropical Pacific SST of the past millennium , American Geophysical UnionTalk/Oral Presentation, San Francisco, Fall 2009
Other Presentations
paleoclimate constraints on tropical Pacific dynamics, USC Paleoenvironment seminar, Los Angeles, CA, 2011-2012
paleoclimate constraints on tropical Pacific dynamics , Paleoclimate Modeling Inctercomparison Project, Villefranche-sur-mer, France, 2011-2012
The mathematics of paleoclimate reconstructions, CAMS weekly seminar, Los Angeles, CA, 2011-2012
Statistics for the Past Millennium The mathematics of climate change reconstructions, Statistics department seminar, Pittsburgh, PA, 2010-2011
ENSO over the past millennium: reconstruction and error estimates, CalTech ESE seminar, Pasadena, CA, 2009-2010
ENSO over the past millennium: reconstruction and error estimates, AOS seminar, Los Angeles, CA, 2009-2010
Extracting the dynamical essence of geophysical timeseries, Quaternary Paleoecology Short Course, Minneapolis, MN, 2009-2010
Geothermal Heating : the Unsung Hero of the Abyssal Circulation, Earth Science Colloquium, Zumberge Hall of Science, 2008-2009
Imputation of missing values in geophysical datasets: An improved, data-adaptive regularization scheme , Probability and Statistics Seminar, Center for Applied Mathematical Sciences, 2008-2009
JOUR 440: Environmental Journalism Guest lecture on climate change communication, Spring 2012
GEOL505: Climate Dynamics @ USC, Fall 2011
ENST150: Anthropogenic Global Warming: science and politics Guest lecture for Jim Haw, Fall 2010
Journal Article
Zhu, F., Emile-Geay, J., Anchukaitis, K. J., Hakim, G. J., Wittenberg, A. T., Morales, M. S., Toohey, M., King,Zhu, J. ,., Emile-Geay, J., Anchukaitis, K. J., Hakim, G. J., Wittenberg, A. T., Morales, M. S., Toohey, M., King, J. (2022). A re-appraisal of the ENSO response to volcanism with paleoclimate data assimilation. Nature communications. Vol. 13 (1), pp. 747.
PubMed Web Address
Power, S., Lengaigne, M., Capotondi, A., Khodri, M., Vialard, J., Jebri, B., Guilyardi, E., McGregor, S., Kug, J. S., Newman, M., McPhaden, M. J., Meehl, G., Smith, D., Cole, J., Emile-Geay, J., Vimont, D., Wittenberg, A. T., Collins, M., Kim, G. I., Cai, W., Okumura, Y., Chung, C., Cobb, K. M., Delage, F., Planton, Y. Y., Levine, A., Zhu, F., Sprintall, J., Di, E., Zhang, X., Luo, J. J., Lin, X., Balmaseda, M., Wang, G., Henley,Power, B. J., Lengaigne, M., Capotondi, A., Khodri, M., Vialard, J., Jebri, B., Guilyardi, E., McGregor, S., Kug, J. S., Newman, M., McPhaden, M. J., Meehl, G., Smith, D., Cole, J., Emile-Geay, J., Vimont, D., Wittenberg, A. T., Collins, M., Kim, G. I., Cai, W., Okumura, Y., Chung, C., Cobb, K. M., Delage, F., Planton, Y. Y., Levine, A., Zhu, F., Sprintall, J., Di, E., Zhang, X., Luo, J. J., Lin, X., Balmaseda, M., Wang, G., Henley, B. J. (2021). Decadal climate variability in the tropical Pacific: Characteristics, causes, predictability, and prospects. Science (New York, N.Y.). Vol. 374 (6563), pp. eaay9165.
PubMed Web Address
Kaufman, D., McKay, N., Routson, C., Erb, M., Davis, B., Heiri, O., Jaccard, S., Tierney, J., Dätwyler, C., Axford, Y., Brussel, T., Cartapanis, O., Chase, B., Dawson, A., de, A., Engels, S., Jonkers, L., Marsicek, J., Moffa-Sánchez, P., Morrill, C., Orsi, A., Rehfeld, K., Saunders, K., Sommer, P. S., Thomas, E., Tonello, M., Tóth, M., Vachula, R., Andreev, A., Bertrand, S., Biskaborn, B., Bringué, M., Brooks, S., Caniupán, M., Chevalier, M., Cwynar, L., Emile-Geay, J., Fegyveresi, J., Feurdean, A., Finsinger, W., Fortin, M. C., Foster, L., Fox, M., Gajewski, K., Grosjean, M., Hausmann, S., Heinrichs, M., Holmes, N., Ilyashuk, B., Ilyashuk, E., Juggins, S., Khider, D., Koinig, K., Langdon, P., Larocque-Tobler, I., Li, J., Lotter, A., Luoto, T., Mackay, A., Magyari, E., Malevich, S., Mark, B., Massaferro, J., Montade, V., Nazarova, L., Novenko, E., Paril, P., Pearson, E., Peros, M., Pienitz, R., Plóciennik, M., Porinchu, D., Potito, A., Rees, A., Reinemann, S., Roberts, S., Rolland, N., Salonen, S., Self, A., Seppä, H., Shala, S., St-Jacques, J. M., Stenni, B., Syrykh, L., Tarrats, P., Taylor, K., van, V., Velle, G., Wahl, E., Walker, I., Wilmshurst, J., Zhang, E., Zhilich, S. (2020). A global database of Holocene paleotemperature records. Scientific data. Vol. 7 (1), pp. 115.
PubMed Web Address
Dee, S. G., Cobb, K. M., Emile-Geay, J., Ault, T. R., Edwards, R. L., Cheng, H., Charles, C. D. (2020). No consistent ENSO response to volcanic forcing over the last millennium. Science (New York, N.Y.). Vol. 367 (6485), pp. 1477-1481.
PubMed Web Address
PAGES, C. o., Neukom, R., Barboza, L. A., Erb, M. P., Shi, F., Emile-Geay, J., Evans, M. N., Franke, J., Kaufman, D. S., Lücke, L., Rehfeld, K., Schurer, A., Zhu, F., Brönnimann, S., Hakim, G. J., Henley, B. J., Ljungqvist, F. C., McKay, N., Valler, V., von, L. (2019). Consistent multi-decadal variability in global temperature reconstructions and simulations over the Common Era. Nature geoscience. Vol. 12 (8), pp. 643-649.
PubMed Web Address
Zhu, F., Emile-Geay, J., McKay, N. P., Hakim, G. J., Khider, D., Ault, T. R., Steig, E. J., Dee, S., Kirchner, J. W. (2019). Climate models can correctly simulate the continuum of global-average temperature variability. Proceedings of the National Academy of Sciences of the United States of America. Vol. 116 (18), pp. 8728-8733.
PubMed Web Address
Cheetham, M., Feakins, S., Kirby, M., Emile-Geay, J., Lund, S., Zimmermann, S. (2011). 3000 Years of Interannual to Millennial Variability in Californian Runoff. Geophysical Research Letters.
Khider, D., Stott, L., Emile-Geay, J. (2011). Salinity influence on the Globigerinoides ruber Mg/Ca thermometer: assessing resulting uncertainties in paleoceanographic reconstructions. Paleoceanography.
Khider, D., Stott, L. D., Emile-Geay, J., Thunell, R., Hammond, D. (2011). Assessing El Niño Southern Oscillation Variability During the Past Millennium. Paleoceanography. Vol. 26, pp. 20.
Cross ref
Emile-Geay, J., Cobb, K. M., Mann, M. E., Wittenberg, A. T. (2011). Estimating Tropical Pacific SST variability over the Past Millennium. Part 1: Methodology and Validation. Journal of Climate (American Meteorological Society).
Emile-Geay, J. T., Cobb, K. M., Mann, M. E., Wittenberg, A. T. (2011). Estimating Tropical Pacific SST variability over the Past Millennium. Part 2: Reconstructions and Uncertainties. Journal of Climate (American Meteorological Society).
Thompson, D. M., Ault, T. R., Evans, M. N., Cole, J. E., Emile-Geay, J. (2011). Comparison of observed and simulated tropical climate trends using a forward model of coral d18O. Geophysical Research Letters. (38)
Cross ref
Introduction to Atmospheric Science, Earth Sciences, Fall 2010
Data Analysis in the Earth & Environmental Sciences, Earth Sciences, Fall 2009
Media, Alumni, and Community Relations
ABC News interview on heat waves, 2012-2013
Other Service to the University
Hosted a screening of award-winning documentary “Carbon Nation’, a Dornsife Commons event. , Fall 2011
Panelist in the Global College Briefing on “What We Know about Climate Change”, Spring 2011
Editorships and Editorial Boards
Associate Editor, Scientific Data, 2018 –
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