Julien Emile-Geay

• 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 –