PhD Project description

 

The cause, consequences and recovery of early Paleogene global warming events.

 

The Paleocene-Eocene thermal maximum (PETM) represents a brief (~200 ka) interval of rapid and profound global warming ~55 Million years ago, when high-latitude surface and deep ocean temperatures increased by 6 to 8 °C (Kennett and Stott, 1991; Zachos et al., 2003).

 

It is characterized by profound changes in environmental conditions (Bowen et al., 2002; Clyde and Gingerich, 1998; Crouch et al., 2001; Kelly et al., 1996; Kennett and Stott, 1991; Koch et al, 1992;  Thomas et al., 2002 ) The base of the PETM corresponds to an extraordinarily large (~2.5 to 4 ‰) negative carbon isotope excursion (CIE) in marine and terrestrial fossil records of carbonate and organic matter (Kennett and Stott, 1991; Koch et al, 1992 (Figure 1)). The magnitude and shape of the isotope excursion indicate a massive injection of at least 1000 Gt of isotopically light CO2 or CH4 to the ocean or atmosphere (Dickens et al., 1997; Dickens et al. 1995; Kurtz et al., 2003; Svensen et al. 2004),  somewhoat comparable to present and future anthropogenic input of CO2 from fossil fuel burning.

  

Figure 1:

Global benthic foraminifer carbon isotope compilation (after Zachos et al., 2001), showing the extreme negative carbon isotope excursion (CIE) at the Paleocene/Eocene boundary at ~55 Ma.

The following questions are the focus of research on the PETM

-         What was the cause of the greenhouse gas injection

-         How much, and which greenhouse gas(ses) were injected into the system

-         How did the climate system react in terms of sea level, temperature change and oceanic and atmospheric circulation

-         Where and how was the excess carbon buried

-         Was the PETM a unique event

-         What can we learn for future climate change in respect to anthropogenic carbon injection

 

Figure 2:

Representative of the genus Apectodinium from the PETM in the North Sea.

One of the most striking biotic signals of the PETM is a global acme of the organic-walled dinoflagellate cyst (resting stages of unicellular plankton) genus Apectodinium (Figure 2; Bujak and Brinkhuis, 1998; Crouch, 2001; Crouch et al., 2003a; Crouch et al., 2003b).This signal is especially significant for providing clues on processes involving continental shelf settings, since those represent the common habitat for cyst producing dinoflagellates. Apectodinium is considered to have had an affinity for warm water, quickly migrating across the globe along continental margins and into high latitudes during the unusual warmth of the PETM (Bujak and Brinkhuis, 1998). In addition, since the Apectodinium motile stage was most probably heterotrophic, therefore requiring a large food supply, the event may reflect the expected onset of nutrient-rich and highly productive surface waters.

In research I am doing in cooperation with a lot of people, I’m trying to elucidate the complete ecological implications of the Apectodinium acme by extracting information from dinoflagellate cyst assemblages (Sluijs et al., 2005) and integrating this with organic and inorganic geochemistry and climate models.

 

With this, I will try and get a grip on nutrient cycling, productivity, sea level, the hydrological cycle and carbon burial across the PETM. For that I predominantly focus on shallow marine deposits recovered from the Arctic Ocean, the New Jersey Shelf, the North Sea and the Tasman Sea. Moreover, using deep sea sediments from the Walvis Ridge, I am also studying ocean chemistry changes (Zachos et al., in press) and additional PETM-like events in the early Paleogene (Figure 3; Lourens et.al, in review).

 

Bowen, G.J., Clyde, W.C., Koch, P.L., Ting, S.Y., Alroy, J., Tsubamoto, T., Wang, Y.Q. and Wang, Y., 2002. Mammalian dispersal at the Paleocene/Eocene boundary. Science. 295: 2062-2065.

Bujak, J.P. and Brinkhuis, H., 1998. Global warming and dinocyst changes across the paleocene/eocene Epoch boundary. In: M.-P. Aubry (Editor), Late Paleocene-early Eocene biotic and climatic events in the marine and terrestrial records. Columbia University Press, New York, pp. 277-295.

Clyde, W.C. and Gingerich, P.D., 1998. Mammalian community response to the latest Paleocene thermal maximum: An isotaphonomic study in the northern Bighorn Basin, Wyoming. Geology, 26: 1011-1014.

Crouch, E.M., 2001. Environmental change at the time of the Paleocene-Eocene biotic turnover. Laboratory of Palaeobotany and Palynology Contribution Series, 14, 216 pp.

Figure 3: Elmo meets Elmo

Crouch, E.M., Brinkhuis, H., Visscher, H., Adatte, T. and Bolle, M.-P.,2003a. Late Paleocene-early Eocene dinoflagellate cysy records from the Tethys: Further observations on the global distribution of Apectodinium. In: S.L. Wing, P.D. Gingerich, B. Schmitz and E. Thomas (Editors), Causes and Consequences of Globally Warm Climates in the Early Paleogene. Geological Society of America Special Paper 369. Geological Society of America , Boulder, Colorado, pp. 113-131.

Crouch, E.M., Dickens, G.R., Brinkhuis, H., Aubry, M.-P., Hollis, C.J., Rogers, K.M. and Visscher, H., 2003b. The Apectodinium acme and terrestrial discharge during the Paleocene-Eocene thermal maximum: new palynological, geochemical and calcareous nannoplankton observations at Tawanui, New Zealand. Palaeogeography, Palaeoclimatology, Palaeoecology, 194: 387-403.

Crouch, E.M., Heilmann-Clausen, C., Brinkhuis, H., Morgans, H.E.G., Rogers, K.M., Egger, H. and Schmitz, B., 2001. Global dinoflagellate event associated with the late Paleocene thermal maximum. Geology, 29: 315-318.

Dickens, G.R., Castillo, M.M. and Walker, J.C.G., 1997. A blast of gas in the latest Paleocene: Simulating first-order effects of massive dissociation of oceanic methane hydrate. Geology, 25(3): 259-262.

 Dickens, G.R., O'Neil, J.R., Rea, D.K. and Owen, R.M., 1995. Dissociation of oceanic methane hydrate as a cause of the carbon isotope excursion at the end of the Paleocene. Paleoceanography, 10: 965-971.

 Kelly, D.C., Bralower, T.J., Zachos, J.C., Premoli Silva, I. and Thomas, E., 1996. Rapid diversification of planktonic foraminifera in the tropical Pacific (ODP Site 865) during the late Paleocene thermal maximum. Geology, 24: 423-426.

Kennett, J.P. and Stott, L.D., 1991. Abrupt deep-sea warming, palaeoceanographic changes and benthic extinctions at the end of the Palaeocene. Nature, 353: 225-229.

Koch, P.L., Zachos, J.C. and Gingerich, P.D., 1992. Correlation between isotope records in marine and continental carbon reservoirs near the Palaeocene/Eocene boundary. Nature, 358: 319-322.

Kurtz, A., Kump, L.R., Arthur, M.A., Zachos, J.C., and Paytan, A., 2003. Early Cenozoic decoupling of the global carbon and cycles. Paleoceanography, 18 (1090, doi:10.1029/2003PA000908).

Lourens, L., Sluijs, A., Kroon, D., Zachos, J.C., Thomas, E., Röhl, U., Bowles, J. and Raffi, I., in print. Astronomical pacing of late Palaeocene to early Eocene hyperthermal events. Nature, June 2005.

Sluijs, A., Pross, J., and Brinkhuis, H., 2005. From Greenhouse to icehouse; organic-walled dinoflagellate cysts as paleoenvironmental indicators in the Paleogene. Earth-Science Reviews, 68(3-4): 281-315.

Svensen, H., Planke, S., Malthe-Sørensen, A., Jamtveit, B., Myklebust, R., Eidem, T.R., and Rey, S.S., 2004. Release of methane froma volcanic basin as a mechanism for initial Eocene global warming. Nature, 429: 542-545.

Thomas, D.J., Zachos, J.C., Bralower, T.J., Thomas, E. and Bohaty, S., 2002. Warming the fuel for the fire: Evidence for the thermal dissociation for methane hydrate during the Paleocene-Eocene thermal maximum. Geology, 30(12): 1067-1070.

Thomas, E. and Shackleton, N.J., 1996.  The Palaeocene-Eocene benthic foraminiferal extinction and stable isotope anomalies. In: R.W.O.B. Knox, R.M. Corfield and R.E. Duney (editors), Correlation of the Early Paleogene in Northwestern Europe, Geological Society LOndon Special Publication, 101, pp 401-441.

Wing, S.L., 1998. Late Paleocene-early Eocene floral and climate change in the Bighorn Basin, Wyoming. In: M.-P. Aubry, S.G. Lucas and W.A. Berggren (Editors), Late Paleocene-early Eocene climatic and biotic events in the marine and terrestrial records. Columbia University Press, New York, pp. 380-400.

Zachos, J.C., Röhl, U., Schellenberg, S.A., Sluijs, A., Hodell, D.A., Kelly, D.C., Thomas, E., Nicolo, M., Raffi, I., Lourens, L.J., Kroon, D. and McCarren, H., in press. Rapid Acidification of the Ocean during the Paleocene-Eocene Thermal Maximum. Science, June 2005.

Zachos, J.C., Wara, M.W., Bohaty, S., Delaney, M.L., Petrizzo, M.R.. Brill, A., Bralower, T.J. and Premoli Silva, I., 2003. A transient rise in tropical sea surface temperature during the Paleocen-Eocene thermal maximum. Science, 302: 1151-1154.

Last update: 01-Nov-2006
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