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Aaron Diefendorf

Title: Associate Professor, Organic and Isotope Geochemistry
Office: 610 Geology-Physics Building
Tel: 513-556-3787
Email: aaron.diefendorf@uc.edu
Web: http://aarondiefendorf.weebly.com

My research uses stable isotope and organic biogeochemical tools to solve critical questions in the areas of global climate change, carbon cycling, Earth’s climate sensitivity, paleoclimatology, and paleoecology.


  • Ph.D., Pennsylvania State University, 2010 (Geosciences and Biogeochemistry).
  • M.S., University of Saskatchewan, Canada, 2005 (Geological Sciences).
  • B.S., University of Tennessee, 2002 (Honors Geology).
  • B.F.A., University of Tennessee, 2002 (Studio Art Ceramics).

Research Information

Research Interests

Earth’s climate is warming at a pace and magnitude unprecedented in recent times, with profound consequences for terrestrial ecology and hydrology. My research aims to contribute to our understanding of future global change by examining Cenozoic changes in climate, ecology, and the carbon cycle. Fossil chemical signatures—biomarkers—and their carbon isotope ratios integrate and track the ancient carbon cycle and provide unique paleoecological information in sediments where other proxies are not often preserved. The combination of biomarkers and carbon isotopes provides new insights into the feedbacks between global change, terrestrial ecology, and the carbon cycle.

Please see my website for current information, a curriculum vitae, information about our organic and isotope geochemistry facilities.

Research Support

  • (PI), Diefendorf, MRI: Acquisition of Stable Isotope Instrumentation for Biogeochemistry Research and Teaching at the University of Cincinnati , NSF. (EAR-1229114), $400,000 ($571,428 total). 09/15/2012 to 08/31/2015. Status: Active.
  • (PI), Diefendorf, In support of NSF Grant., Ohio Board of Regents Action Fund. (OBR AF), $85,714. 09/15/2012 to 08/31/2015. Status: Active.
  • (PI), Diefendorf, Aaron, Terrestrial Biomarker Transport Mechanisms and Implications for Interpreting Terrestrial Signals in Oils and Bitumens, American Chemical Society - National Chapter. (PRF 5187-DN12), $100,000.00. 01/01/2012 to 08/31/2016. Status: Active.
  • (PI), Diefendorf, Aaron, North Hemisphere mid-latitude paleovegetation response to moisture changes during the late Quaternary, Korea Institute of Geoscience and Mineral Resources. (KIGMR 2015-2016), $29,000.00. 07/01/2015 to 04/30/2016. Status: Awarded.
  • (Collaborator), Diefendorf, Aaron; Havig, Jeff, Agouron Small Grant in Aid conference funds for 10/15/16 event (Grant No.AI-SGIA-203.16.1), Agouron Institute. (AI 010348-002), $8,000.00. 06/01/2016 to 05/31/2017. Status: Awarded.
  • (PI), Diefendorf, Aaron, Evaluating plant carbon isotope fractionation as a pCO2 proxy for the geologic record, National Science Foundation. (EAR-1636546), $138,189.00. 09/01/2016 to 08/31/2018. Status: Active.
  • (PI), Diefendorf, Aaron; Lowell, Thomas, Collaborative Research: Identifying basin-specific controls on isotopic and chronological offsets of lake sediment leaf wax hydrogen isotope records, National Science Foundation. (EAR-1636740), $124,332.00. 08/01/2016 to 07/31/2018. Status: Active.
  • (PI), Diefendorf, Aaron, Hydrologic conditions in western North America during the Last Interglacial , Korea Institute of Ocean Science and Technology. (KIGMR 2016-2017), $31,284.71. 06/01/2016 to 04/30/2017. Status: Active.
  • (Collaborator), Czaja, Andrew; Diefendorf, Aaron; Hamilton, Trinity; Havig, Jeff, Midwest Geobiology Conference , National Aeronautics and Space Administration. (OSGC Student-Innovative-Creative-Hands-on Project (SICHOP) grant), $2,000.00. 06/06/2016 to 12/31/2016. Status: Awarded.


Peer Reviewed Publications

  • Diefendorf, A.F., Freeman, K.H., Wing, S.L., 2014. A comparison of terpenoid and leaf fossil vegetation proxies in Paleocene and Eocene Bighorn Basin sediments. Organic Geochemistry 71, 30-42. 
  • Marin-Spiotta, E., Chaopricha, N.T., Plante, A., Diefendorf, A.F., Muller, C.W., Grandy, S., Mason, J.A., 2014. Rapid climate change leads to stabilization of soil carbon by fire and burial. Nature Geoscience 7, 428-432. 
  • Clyde, W.C., Gingerich, P.D., Wing, S.L., Röhl, U., Westerhold, T., Bowen, G., Johnson, K., Baczynski, A.A., Diefendorf, A.F, McInerney, F., Schnurrenberger, D., Noren, A., Brady, K., and the BBCP Science Team, 2013. Bighorn Basin Coring Project (BBCP): a continental perspective on early Paleogene hyperthermals. Scientific Drilling, 16, 21–31.
  • Close, H.G., Shah, S.R., Ingalls, A.E., Diefendorf, A.F., Brodie, E.L., Hansman, R.L., Freeman, K.H., Aluwihare, L.I., Pearson, A., 2013. Export of submicron particulate organic matter to mesopelagic depths in an oligotrophic gyre. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.1217514110 
  • Diefendorf, A.F., Freeman, K.H., Wing, S.L., 2012. Distribution and carbon isotope patterns of diterpenoids and triterpenoids in modern temperate C3 trees and their geochemical significance. Geochimica et Cosmochimica Acta 85, 342-356
  • Cui, Y., Kump, L.R., Ridgwell, A.J., Charles, A.J., Junium, C.K., Diefendorf, A.F., Freeman, K.H., Urban, N.M., Harding, I.C., 2012. Reply to 'Constraints on hyperthermals'. Nature Geoscience 5, 231-232.
  • Freeman, K.H., Mueller, K.E., Diefendorf, A.F., Wing, S.L., & Koch, P.L. (2011). Clarifying the influence of water availability and plant types on carbon isotope discrimination by C3 plants. 108, E59-E60, Proceedings of the National Academy of Sciences.
  • Cui, Y. Kump, L.R., Ridgwell, A.J., Charles, A.J., Junium, C.K., Diefendorf, A.F., Freeman, K.H., Urban, N.M., Harding, I.C., (2011). Slow release of fossil carbon during the Paleocene-Eocene Thermal Maximum. Nature Geoscience. 4, 481-485.
  • Diefendorf, A.F., Freeman, K.H., Wing, S.L., and Graham, H.V. (2011). Production of n-alkyl lipids in living plants and implications for the geologic past. Geochimica et Cosmochimica Acta. 75, 7472-7485.
  • Mueller, K.E., Diefendorf, A.F., Freeman, K.H. & Eissenstat, D.M. (2010). Appraising the roles of nutrient availability, global change, and functional traits during the angiosperm rise to dominance. Ecology Letters, 13, E1-E6.
  • Diefendorf, A.F., Mueller, K.E., Wing, S.L., Koch, P.L., & Freeman, K.H. (2010). Global patterns in leaf 13C discrimination and implications for studies of past and future climate. Proceedings of the National Academy of Sciences, 107, 5738-5743.
  • Wing, S.L., Bloch, J.I., Bowen, G.J., Boyer, D.M., Chester, S., Diefendorf, A.F., Harrington, G.J., Kraus, M.J., Secord, R., Smith, F.A. (2009). Coordinated sedimentary and biotic change during the Paleocene-Eocene Thermal Maximum in the Bighorn Basin, Wyoming, USA, in: Crouch, E.M., Strong, C.P., Hollis, C.J. (Eds.), Climatic and Biotic Events of the Paleogene (CBEP 2009). GNS Science Miscellaneous Series, 18, 156-162.
  • Schouten, S., Hopmans, E.C., van der Meer, J., Mets, A., Bard, E., Bianchi, T.S., Diefendorf, A., Escala, M., Freeman, K.H., Furukawa, Y., Huguet, C., Ingalls, A., Menot-Combes, G., Nederbragt, A.J., Oba, M., Pearson, A., Pearson, E.J., Rosell-Mele, A., Schaeffer, P., Shah, S.R., Shanahan, T.M., Smith, R.W., Smittenberg, R., Talbot, H.M., Uchida, M., Van Mooy, B.A.S., Yamamoto, M., Zhang, Z.H., Damste, J.S.S. (2009). An interlaboratory study of TEX86 and BIT analysis using high-performance liquid chromatography-mass spectrometry. Geochemistry Geophysics Geosystems, 10, 13.
  • Diefendorf, A.F., Patterson, W.P., Holmden, C., Mullins, H.T. (2008). Carbon isotopes of marl and lake sediment organic matter reflect terrestrial landscape change during the late Glacial and early Holocene (16, 800 to 5, 540 cal yr BP): a multiproxy study of lacustrine sediments at Lough Inchiquin, western Ireland. Journal of Paleolimnology, 39, 101-115.
  • Tibert, N.E., Patterson, W.P., Diefendorf, A.F., Martini, A., Stanton, C. (2007). Holocene temperature variability in western Ireland: Evidence from limnic ostracode assemblages and stable isotope values. Stratigraphy, 4, 353-361.
  • Diefendorf, A.F., Patterson, W.P., Mullins, H.T., Tibert, N., Martini, A. (2006). Evidence for high-frequency late Glacial to mid-Holocene (16, 800 to 5500 cal yr B.P.) climate variability from oxygen isotope values of Lough Inchiquin, Ireland. Quaternary Research, 65, 78-86.
  • Diefendorf, A.F., & Patterson, W.P. (2005). Survey of stable isotope values in Irish surface waters. Journal of Paleolimnology, 34, 257-269.

Experience & Service

Work Experience

  • 2011 to Present, Assistant Professor, University of Cincinnati.

Other Experience and Professional Memberships

  • Geological Society of America
  • American Geophysical Union
  • Sigma Xi
  • American Association for the Advancement of Science

Courses Taught

    Level: Undergraduate
    Term: 11S

    Level: Graduate
    Term: 11S