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Ph.D. in Geology, University of California, Davis, (2005)

M.Sc. in Geology, University of South Florida, (1997)

B.S. in Geology, Vanderbilt University, (1993)

Expertise

Research Interests

Reconstructing Mean State and ENSO Variability in the Eastern Equatorial Pacific under Glacial Forcing: A Combined Geochemical and Organic Proxy ApproachOne of my current NSF funded projects involves reconstructing how the Eastern Equatorial Pacific (EEP) mean state and ENSO varied across the Dansgaard-Oeschger (D-O) cycles of Marine Isotope Stage 3 (MIS 3). The magnitude, duration, and number of these abrupt climate events make them the ideal natural experiment to test how the system will evolve in the near future. By utilizing a unique combination of multi-proxy methods together in a single study, this project will generate records of surface and subsurface temperature, thermocline temperature variance, upper-water column hydrography and upwelling variability from eight time slices in the EEP between 30 to 65 kyr. These objectives will be achieved by using a high-sedimentation rate core recovered from the heart of the cold-tongue EEP upwelling region during R/V Melville cruise MV1014 in 2010. Sedimentation rates in this core are among the highest in ENSO-sensitive regions of the tropical Pacific, ~10.5 cm/kyr, allowing for the resolution of millennial-scale climate events. The project will use a combination of foraminiferal stable isotope and trace metal geochemistry to reconstruct long-term changes in the EEP mean state across MIS 3. Next, 8 time slices spanning the extremes of MIS 3 climate (D-O interstadials, stadials and Heinrich Events) will be selected for further analyses. For each time slice, ENSO variability will be determined using thermocline temperature variance derived from single shell foraminiferal Mg/Ca analyses. In addition, upwelling intensity and nutrient variability will be characterized by the Diol Index and the Long Chain Diol Index. Together, this multi-proxy approach will allow for the most complete characterization of how the EEP varied across millennial-scale climate events of MIS 3 and will provide critical insight into how ENSO is related to extreme climate states of the past. This study will also provide climate modelers with critical information needed to simulate future climate change. Atmospheric CO2 and the Relationship to Millennial Changes in Atmospheric and Oceanic Circulation in the Eastern Equatorial Pacific Ocean over the Past 100,000 yearsI am working with my colleague Franco Marcantonio from Texas A&M University on another NSF funded project focused on answering questions related to:1) where and how atmospheric carbon dioxide was sequestered from the atmosphere, or ventilated from the ocean, on millennial timescales, and 2) how these carbon dynamics are related to both changes in atmospheric and oceanic circulation over the last glacial period. To address these objectives, an integrated suite of multiple proxies will be measured on several high accumulation rate sediment cores previously collected from the EEP. For my part of the project, my students are measuring Boron/Calcium (B/Ca) ratios in planktic and benthic foraminifera as a proxy for carbonate ion concentration in surface and bottom waters of the EEP. By investigating the storage of a respired carbon pool in the deep ocean and how it altered the pH of surface and bottom waters during cold periods of the last glacial period (i.e., from ~71,000 to 14,000 years ago), in conjunction with probing how this storage relates to changes in export production and potential iron fertilization, this collaborative research will shed light on the mechanistic links between ocean (stratification/ventilation) and atmospheric (wind belt shifts) circulation and the modification of atmospheric CO2 levels.

Articles

Bahr, A., Hoffmann, J., Schönfeld, J., Schmidt, M., Nürnberg, D., Batenburg, S. J. and Voigt, S. (2018). Low-latitude expressions of high-latitude forcing during heinrich stadial 1 and the younger dryas in northern south america. Global and Planetary Change 160 , pp. 1-9.

Schmidt, M., Ping, C., Parker, A. O., Ji, L. and He, F. (2017). Deglacial Tropical Atlantic subsurface warming links ocean circulation variability to the West African Monsoon. Scientific Reports 7 (15390) , pp. 1-6.

Loveley, M. R., Marcantonio, F., Lyle, M., Ibrahim, R., Heltzberg, J. E. and Schmidt, M. (2017). Sediment redistribution and grainsize effects on 230Th-normalized mass accumulation rates and focusing factors in the Panama Basin. Earth & Planetary Science Letters 480 , pp. 107-120.

Loveley, M. R., Marcantonio, F., Wisler, M. M., Hertzberg, J. E., Schmiodt, M. W. and Lyle, M. (2017). Millennial-scale iron fertilization of the eastern equatorial Pacific over the past 100,000 years. Nature Geoscience 10 , pp. 760-764.

Parker, A. O., Schmidt, M. and Slowey, N. C. (2016). A New Perspective on West African Hydroclimate During the Last Deglaciation. Earth and Planetary Science Letters 449 , pp. 79-88.

Hertzberg, J. E., Schmidt, M., Smith, R. K ., Shields, M. R., Bianchi, T. S. and Marcantonio, F. (2016). Comparison of eastern tropical Pacific TEX86 and Globigerinoides ruber Mg/Ca derived sea surface temperatures: Insights from the Holocene and Last Glacial Maximum. Earth and Planetary Science Letters 434 , pp. 320-332.

Parker, A. O., Schmidt, M. W. and Chang, P. (2015). Tropical North Atlantic Subsurface Warming Events as a Fingerprint for AMOC Variability During Marine Isotope Stage 3. Paleoceanography 30 , pp. 1-12.

Them, T. R., Schmidt, M. and Lynch-Stieglitz, J. (2015). Millennial-scale Atmospheric and Ocean Circulation Change from the Last Glacial Maximum and Marine Isotope Stage 3. Earth and Planetary Science Letters 427 , pp. 47-56.

Lynch-Stieglitz, J., Schmidt, M., Henry, L. Gene., Curry, W. B., Skinner, L. C., Mulitza, S., Zhang, R. and Chang, P. (2014). Muted change in Atlantic overturning circulation over some glacial-aged Heinrich events. Nature Geoscience 7 , pp. 144-150.

Xie, R., Marcantonio, F. and Schmidt, M. (2014). Reconstruction of intermediate water circulation in the tropical North Atlantic during the past 22,000 years. Geochimica et Cosmochimica Acta 140 , pp. 455-467.

Hertzberg, J. E. and Schmidt, M. (2013). Refining Globigerinoides ruber Mg/Ca paleothermometry in the Atlantic Ocean. Earth and Planetary Science Letters 383 , pp. 123–133.

Xie, R. C., Marcantonio, F. and Schmidt, M. (2012). Deglacial variability of Antarctic Intermediate Water penetration into the North Atlantic from authigenic neodymium isotope ratios. Paleoceanography 27 (3).

Schmidt, M., Chang, P., Hertzberg, J. E., Them, T. R., Ji, L. and Otto-Bliesner, B. L. (2012). Impact of abrupt deglacial climate change on tropical Atlantic subsurface temperatures. Proceedings of the National Academy of Sciences 109 (36) , pp. 14348–14352.

Schmidt, M., Weinlein, W. A., Marcantonio, F. and Lynch-Stieglitz, J. (2012). Solar forcing of Florida Straits surface salinity during the early Holocene. Paleoceanography 27 (3).

Schmidt, M. and Hertzberg, J. (2011). Abrupt climate change during the last ice age. Nature Education Knowledge 3 (10) , pp. 11.

Lynch-Stieglitz, J., Schmidt, M. and Curry, W. B. (2011). Evidence from the Florida Straits for Younger Dryas ocean circulation changes. Paleoceanography 26 (1).

Schmidt, M. and Lynch-Stieglitz, J. (2011). Florida Straits deglacial temperature and salinity change: Implications for tropical hydrologic cycle variability during the Younger Dryas. Paleoceanography 26 (4).

Schmidt, M. and Spero, H. J. (2011). Meridional shifts in the marine ITCZ and the tropical hydrologic cycle over the last three glacial cycles. Paleoceanography 26 (1).

Wan, X., Chang, P. and Schmidt, M. (2010). Causes of tropical Atlantic paleo-salinity variation during periods of reduced AMOC. Geophysical Research Letters 37 (4).

Cléroux, C., Lynch-Stieglitz, J., Schmidt, M., Cortijo, E. and Duplessy, J. (2009). Evidence for calcification depth change of G loborotalia truncatulinoides between deglaciation and Holocene in the Western Atlantic Ocean. Marine Micropaleontology 73 (1) , pp. 57–61.

Wan, X., Chang, P., Saravanan, R., Zhang, R. and Schmidt, M. (2009). On the interpretation of Caribbean paleo-temperature reconstructions during the Younger Dryas. Geophysical Research Letters 36 (2).

Nürnberg, D., Ziegler, M., Karas, C., Tiedemann, R. and Schmidt, M. (2008). Interacting Loop Current variability and Mississippi River discharge over the past 400 kyr. Earth and Planetary Science Letters 272 (1) , pp. 278–289.

Schmidt, M., Vautravers, M. J. and Spero, H. J. (2006). Rapid subtropical North Atlantic salinity oscillations across Dansgaard–Oeschger cycles. Nature 443 (7111) , pp. 561–564.

Schmidt, M., Vautravers, M. J. and Spero, H. J. (2006). Western Caribbean sea surface temperatures during the late Quaternary. Geochemistry, Geophysics, Geosystems 7 (2).

Schmidt, M., Spero, H. J. and Lea, D. W. (2004). Links between salinity variation in the Caribbean and North Atlantic thermohaline circulation. Nature 428 (6979) , pp. 160–163.

Book Chapters

Hertzberg, J. E . and Schmidt, M. (2017). Paleotemperatures Encyclopedia of Geochemistry, Earth Science Series (pp. 8) Springer International Publishing.

Presentations

Loveley, M., Marcantonio, F. and Schmidt, M. (December 15, 2016). Millennial-scale Iron Fertilization of the Eastern Equatorial Pacific over the last 100 kyr Poster Fall American Geophysical Union Meeting San Francisco.

Glaubke, R. and Schmidt, M. (December 15, 2016). Tropical North Atlantic Subsurface Temperatures: A Proxy for AMOC Variability Poster Fall American Geophysical Union Meeting San Francisco.

Schmidt, M., Parker, A. O. and Chang, P. (September 2, 2016). Tropical Atlantic subsurface warming links ocean circulation change to West African Monsoon Poster International Conference of Paleoceanography Utrecht, NE.

Schmidt, M. W., Parker, A. O. and Chang, P. (December , 2015). Millennial-Scale Subsurface Temperature Change in the Niger Delta Linked to AMOC Variability During the Last Deglacial Oral Presentation American Geophysical Union Fall Meeting San Francisco.

Hertzberg, J. E. and Schmidt, M. W. (December , 2015). Multi-species temperature and proxy reconstructions of the tropical Pacific mean state across Marine Isotope Stage 3 Oral Presentation American Geophysical Union Fall Meeting San Francisco.

• 2006: Allen G. Marr Prize, University of California, Davis
• 2005: NOAA Global Climate Change Postdoc, UCAR