James P. Kennett

James P. Kennett
Born1940
Wellington, New Zealand
NationalityAmerican
Other namesJim
EducationVictoria University of Wellington
Scientific career
FieldsPaleoceanography
InstitutionsUniversity of California, Santa Barbara
Thesis The Kapitean Stage (Upper Miocene) of New Zealand  (1965)
Websitekennett.faculty.geol.ucsb.edu

James P. Kennett is a New Zealand-American paleoceanographer, marine geologist, and climate scientist.[1]

Early life and education

James P. Kennett received a BS with honors in 1963, a Ph.D. in 1965, and later a DSc in 1976, all from Victoria University of Wellington, Wellington, New Zealand[1]. His dissertation focused on late Miocene to early Pliocene marine sediment sequences throughout New Zealand, with emphasis on the latest Miocene Kapitean Stage.[2]

He was one of the first workers to employ planktonic foraminiferal microfossil assemblages as a proxy for marine temperature changes during the Cenozoic. Specifically, these records revealed a history of significant, widespread cooling during the late Miocene that implied an expansion of an Antarctic Ice Sheet, previously unknown to exist prior to the Pleistocene ice ages. Accordingly, these studies were the first to recognize this major ice sheet as a crucial part of the earth’s changing climate system.[3]

Academic career

He immigrated to the United States in 1966 to take a postdoctoral position with Orville Bandy at the University of Southern California, Los Angeles. This was followed by faculty positions at Florida State University (1968–1970) and the University of Rhode Island (1970–1987). In 1987 Professor Kennett made his final move to the University of California, Santa Barbara as Director of the Marine Science Institute and Professor of Geological Sciences.[1]

Professor Kennett has published over 300 research papers and 14 books and edited volumes.[4][5] He initiated "Paleoceanography" as a new field of science,[1] coined this term for the first time in scientific journals,[1][6] and in 1986, became the founding editor of the journal Paleoceanography. He is the author of the textbook "Marine Geology",[7] the first textbook integrating plate tectonics and Earth’s environmental evolution as recorded in ocean sediments.

Awards and honors

Professor Kennett is the recipient of numerous awards. Most notably, he was elected a Member of the National Academy of Sciences in 2000.[1][8] He is also an elected Fellow of the American Geophysical Union,[9] the American Association for the Advancement of Science,[10] and the Geological Society of America.[11] He is an Honorary Fellow of the Royal Society of New Zealand[12] and the European Union of Geosciences[13] among many other honors.[5]

Mentorship and legacy

Professor Kennett supervised 20 PhD students, many of whom later became distinguished professors and researchers in paleoceanography and related fields.[5]

Scientific contributions

Glacial Development & Ocean Circulation

Professor Kennett’s research has spanned a wide spectrum of subjects. He was the first to demonstrate the presence of an Antarctic Ice Sheet millions of years before the Pleistocene ice ages, with consequent global climate and sea-level influences.[3][14][15][16] and the development of the Circum-Antarctic Current and its consequences.[17] These contributions documented that fundamental changes in ocean circulation resulted from continental drift and plate tectonics and led Earth’s climatic development; namely that tectonic isolation of Antarctica produced the Circum-Antarctic Current, climatic isolation of Antarctica, and major expansion of Antarctic Ice Sheets at the Oligocene onset (38 my BP). This also triggered major shifts in the marine and terrestrial environments including the development of the deep, cold ocean sphere (psychrosphere)[18]. Overall, his contributions provided the first evidence connecting glacial developments in Antarctica with global changes in climate and sea level.

He pioneered studies of Earth’s Cenozoic step-like climatic and glacial development (60 million years ago to present)[19][20][21] and discovered the Paleocene – Eocene Thermal Maximum (PETM), representing peak Cenozoic warmth 56 million years ago.[20][22]. He and his students presented carbon isotopic evidence for methane hydrate instability in marine sediments during late Quaternary interstadials[23] and hypothesized the role of methane hydrates in Quaternary climatic change: the Clathrate Gun hypothesis.[24] He also highlighted and championed the importance of Marine Tephrochronology (volcanic tephra deposits) for the dating and correlation of marine sediments.[25]

Foraminifera & Biostratigraphy

Professor Kennett is known as a pioneer and world expert on planktonic foraminifera and their applicability as markers of climatic change, He produced the first mid-latitude planktonic foraminiferal biostratigraphy and related datum horizons for the Cenozoic Era.[26] His many papers also deal with foraminiferal evolution[26][27][28] and related environmental change, foraminiferal biology, species characteristics, new species descriptions and species identification.[5][29][30]

Younger Dryas

He co-authored the first paper to recognize that the Younger Dryas cool episode (12.8 – 11.5 ka) occurred widely in the Northern Hemisphere oceans.[31] He discovered that “plumbing changes” (changing directions of outburst flooding from major lakes produced by the melting ice sheets) occurred on the North American continent at the onset of the Younger Dryas climatic cooling episode (12.8 ka), and that this, in turn, triggered fundamental change in ocean thermohaline circulation and Northern Hemisphere cooling.[31][32][33][34] His work has shown that climate cycles shorter than 1000 years, earlier discovered in the Greenland and North Atlantic, were also synchronously recorded in the Pacific Ocean.[35] demonstrating that many such climatic shifts were global to hemispheric in scope.

Professor Kennett participated, with many other workers, in the discovery and documentation of a widespread layer marking the onset of the Younger Dryas climate episode dating to ~12,800 years ago at over 60 sites in the Americas and elsewhere.[36][37] This layer is often carbon rich and contains melt glass, spherules, nanodiamonds, shocked quartz, high concentrations of platinum and iridium, and numerous other proxies in support of an extraterrestrial impact with Earth, likely from a disintegrating comet.[36][38] These works have suggested that impacts by fragments of this extraterrestrial body produced high temperatures, massive biomass burning, destabilization of the North American ice sheet and associated major plumbing shifts of glacial meltwaters.[37][38] Abrupt environmental degradation caused by this impact led to the Younger Dryas extinction of ~ 35 genera of megafauna (giant ground sloths, mammoths, saber tooth cats, dire wolves, horses, camels, short-faced bear, etc.) in North America and ~50 megafaunal genera in South America.[37][38][39][40][41]

The Younger Dryas Impact Hypothesis has been challenged,[42] although a more balanced, independent evaluation of this hypothesis than currently available on Wikipedia is provided by Sweatman[43] and Powell[44], and a list of papers, both supporting and challenging this hypothesis, can be found at https://cometresearchgroup.org/publications/.

References

  1. ^ a b c d e f Tinsley H Davis (6 February 2007). "Profile of James P. Kennett". Proceedings of the National Academy of Sciences of the United States of America. 104 (6): 1751–3. Bibcode:2007PNAS..104.1751D. doi:10.1073/PNAS.0609142104. ISSN 0027-8424. PMC 1794309. PMID 17267607. Wikidata Q28763669.
  2. ^ Kennett, James (1965). The Kapitean Stage (Upper Miocene) of New Zealand (Doctoral thesis). Open Access Repository Victoria University of Wellington, Victoria University of Wellington. doi:10.26686/wgtn.16945609
  3. ^ a b Kennett, J. P. (1967). Recognition and Correlation of the Kapitean Stage (Upper Miocene), New Zealand. N.Z.J. Geol. Geophys.. 10(4): 1051–1063. https://doi.org/10.1080/00288306.1967.10423208
  4. ^ James P. Kennett, Google Scholar, https://scholar.google.com/citations?user=exIxX5cAAAAJ
  5. ^ a b c d Kennett Website, UC Santa Barbara, https://kennett.faculty.geol.ucsb.edu/Books.php
  6. ^ Kennett, J. P. (1968) Paleo-oceanographic Aspects of the Foraminiferal Zonation in the Upper Miocene-Lower Pliocene of New Zealand. Committee Mediterranean Neogene Stratigraphy Proc. IV Session. Giornale di Geologia Annali Del Museo Geologico de Bologna 35: 143-156.
  7. ^ Marine Geology (1982) Prentice Hall. Englewood Cliffs, New Jersey https://openlibrary.org/books/OL21996019M/Marine_geology
  8. ^ "National Academy of Sciences Elects New Members". Science. 288 (5468): 957-957. 12 May 2000. https://doi.org/10.1126%2FSCIENCE.288.5468.957 . ISSN 0036-8075. Wikidata Q113533760.
  9. ^ AGU Fellow: https://www.agu.org/user-profile?cstkey=b429cf26-bbe6-4d0e-b6e6-f6c522b26383
  10. ^ AAAS Fellow, https://www.aaas.org/fellows/listing
  11. ^ GSA Fellow, https://www.geosociety.org/GSA/GSA/Awards/Fellows.aspx#K
  12. ^ Royal Society of New Zealand Honorary Fellows, https://www.royalsociety.org.nz/who-we-are/our-people/our-fellows/view-our-honorary-fellows
  13. ^ European Union of Geosciences Honorary Fellow, https://www.egu.eu/eug/fellows.htm#kennett
  14. ^ Margolis, S. V. and J. P. Kennett. (1970). Antarctic Glaciation during the Tertiary Recorded in Subantarctic Deep-Sea Cores. Science 170: 1085–1087. https://doi.org/10.1126/science.170.3962.1085
  15. ^ Kennett, J. P. and S. V. Margolis. (1971) Cenozoic Paleoglacial History of Antarctica Recorded in Subantarctic Deep-Sea Cores.American Journal of Science. 271(1): 1–36. https://doi.org/10.1016/0025-3227(77)90050-0
  16. ^ Kennett, J. P. (1987) Glacial History of Antarctica. Nature. 328(6126): 115–116. http://dx.doi.org/10.1038/328115a0
  17. ^ Kennett, J. P. et al. (1971). Australian-Antarctic Continental Drift, Paleocirculation Changes and Oligocene Deep-Sea Erosion. Nature Physical Science. 239(91): 51–55
  18. ^ Kennett, J. P. and N. J. Shackleton. Oxygen Isotopic Evidence for the Development of the Psychrosphere 38 M yr Ago. Nature 260 (5551): 513-515
  19. ^ Shackleton, N. J. and J. P. Kennett. (1975) Late Cenozoic Oxygen and Carbon Isotopic Changes at DSDP Site 284: Implications for Glacial History of the Northern Hemisphere and Antarctica. In: Kennett, J.P., Houtz, R.E., et al., Initial Reports of the Deep Sea Drilling Project, Vol XXIX, Washington, D.C. (U.S. Government Printing Office): 801-807.
  20. ^ a b Shackleton, N. J. and J. P. Kennett. (1975) Paleotemperature history of the Cenozoic and the Initiation of Antarctic Glaciation: Oxygen and Carbon Isotope Analyses in DSDP Sites 277, 279, and 281. In: Kennett, J.P., Houtz, R.E., et al., Initial Reports of the Deep Sea Drilling Project, Vol. XXIX, Washington, D.C. (U.S. Government Printing Office): 743-755.
  21. ^ Kennett, J. P., R. G. Houtz, P. B. Andrews, A. R. Edwards, V. A. Gostin, M. Hajos, M. Hampton, D. Graham Jenkins, S. V. Margolis, A. T. Ovenshine and K. Perch-Nielsen.(1975) Cenozoic Paleoceanography in the Southwest Pacific Ocean Antarctic Glaciation and the Development of the Circum-Antarctic Current. In: Kennett, J.P., Houtz, R.E., et al., Initial Reports of the Deep Sea Drilling Project, Vol. XXIX, Washington, D.C. (U.S. Government Printing Office): 1155-1169.
  22. ^ Kennett, J. P. and L. D. Stott. (1991) Abrupt Deep-Sea Warming, Paleoceanographic Changes and Benthic Extinctions at the End of the Paleocene. Nature 353: 225-229.
  23. ^ Kennett, J. P., K. G. Cannariato, I. L. Hendy, and R. J. Behl. (2000) Carbon Isotopic Evidence for Methane Hydrate Instability During Quaternary Interstadials. Science 288: 128-133
  24. ^ Kennett, J. P., K. G. Cannariato, I. L. Hendy, R. J. Behl. (2003) Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis, Am. Geophys. Union, 216 pps
  25. ^ Kennett, J. P. Marine Tephrochronology. In: Emiliani, C. ed., The Sea, Vol. 7: 1373- 1436, The Oceanic Lithosphere, John Wiley and Sons, Inc.
  26. ^ a b Kennett, J. P. and M. S. Srinivasan. (1999) Neogene Planktonic Foraminiferal Datum Planes of the South Pacific: Mid to Equatorial Latitudes. In: Tsuchi, R., and Ikebe, N. eds., Pacific Neogene Datum Planes - Contribution to Biostratigraphy and Chronology: 11-25, University of Tokyo Press.
  27. ^ Wei, K.-Y. and J. P. Kennett. (1986) Taxonomic Evolution of Neogene Planktonic Foraminifera and Paleoceanographic Relations. Paleoceanography 1(1): 67-84.
  28. ^ Wei, K.-Y. and J. P. Kennett. (1988) Phyletic Gradualism and Punctuated Equilibrium in the Late Neogene Planktonic Foraminiferal Clade Globoconella. Paleobiology, Vol. 14(4): 345-363.
  29. ^ Kennett J.P. and Srinivasan.M.S. (1983) Neogene Planktonic Foraminifera: A Phylogenetic Atlas. Hutchinson Ross Publishing Company, Stroudsburg, Pennsylvania, 230 pages.
  30. ^ Srinivasan, M. S. and J. P. Kennett. A Review of Neogene Planktonic Foraminiferal Biostratigraphy: Applications in the Equatorial and South Pacific. In: Douglas, R., and Winterer, G., “A Decade of Ocean Drilling” SEPM Special Publication No. 32: 395-432.
  31. ^ a b Kennett, J. P. and N. J. Shackleton. (1975) Laurentide Ice Sheet Meltwater Recorded in Gulf of Mexico Deep Sea Cores. Science 188: 147-150.
  32. ^ Leventer, A., D. F. Williams and J. P. Kennett. (1982) Dynamics of the Laurentide Ice Sheet During the Late Deglaciation: Evidence from the Gulf of Mexico. Earth and Planet. Sci. Letts. 59: 11-17.
  33. ^ Broecker, W. S., M. Andree, W. Wolfli, H. Oeschger, G. Bonani, J. Kennett and D. Peteet. (1988) The Chronology of the Last Deglaciation: Implications to the Cause of the Younger Dryas Event. Paleoceanography Vol. 3(1): 1-19.
  34. ^ Broecker, W. S., J. P. Kennett, B. P. Flower, J. T. Teller, S. Trumbore, G. Bonani and W. Wolfli. (1989) Routing of Meltwater from the Laurentide Ice-Sheet During the Younger Dryas Cold Episode. Nature 341: 318-321.
  35. ^ Behl, R. J. and J. P. Kennett.(1996) Brief Interstadial Events in the Santa Barbara Basin, NE Pacific, During the Past 60 kyr. Nature 379: 243-246.
  36. ^ a b Firestone R.B., West, A., Kennett, J. P., Becker, L., Bunch, T. E., Revay, Z. S., Schultz, P. H., Belgya, T., Kennett, D. J., Erlandson, J. M., Dickenson, O. J., Goodyear, A. C., Harris, R. S., Howard, G. A., Kloosterman, J. B., Lechler, P., Mayewski, P. A., Montgomery, J., Poreda, R., West, A., Wolbach, W. S. (2007). Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. Proceedings of the National Academy of Sciences, 104(41), 16015–16021.
  37. ^ a b c Kennett, J.P, Kennett, D.J., Culleton, B. J., Aura Tortosa, J.E., Bischoff, J. L., Bunch, T.E., Daniel, J., Erlandson, J. M., Ferraro, D., Firestone, R. B., Goodyear, A. C., Israde-Alcántara, I., Johnson, J. R., Jordá Pardo, J. F., Kimbel, D.R., LeCompte, M. A., Lopinot, N. H., Mahaney, W. C., Moore, A. M. T., ... West, A. (2015). Bayesian chronological analyses consistent with synchronous age of 12,835-12,735 Cal B.P. for Younger Dryas boundary on four continents. Proceedings of the National Academy of Sciences, 112(32), E4344-E4353.
  38. ^ a b c Bunch T.E. , Hermes, R. E., Moore, A. M. ., Kennett, D. J., Weaver, J. C., Wittke, J. H., DeCarli, P. S., Bischok, J. L., Hillman, G. C., Howard, G. A., Kimbel, D. R., Kletetschka, G., Lipo, C. P., Sakai, S., Revay, Z., West, A., Firestone, R. B., & Kennett, J. P. (2012). Very high-temperature impact melt products as evidence for cosmic airbursts and impacts 12,900 years ago. (2012) Proceedings of the National Academy of Sciences, 109(28), E1903–E1912.
  39. ^ Wittke J. H., Weaver, J. C., Bunch, T. E., Kennett, J. P., Kennett, D. J., Moore, A. M. T., Hillman, G. C., Tankersley, K. B., Goodyear, A. C., Moore, C. R., Daniel, I. R., Ray, J. H., Lopinot, N. H., Ferraro, D., Israde-Alcantara, I., Bischok, J. L., DeCarli, P. S., Hermes, R. E., Kloosterman, J. B., Firestone, R, B,. (2013). Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago. Proceedings of the National Academy of Sciences, 110(23), 9199–9199.
  40. ^ Wolbach W. S., Ballard, J. P., Mayewski, P. A., Adedeji, V., Bunch, T. E., Firestone, R. B., French, T. A., Howard, G. A., Israde- Alcántara, I., Johnson, J. R., Kimbel, D., Kinzie, C. R., Kurbatov, A., Kletetschka, G., LeCompte, M. A., Mahaney, W. C., Melott, A. L., Maiorana-Boutilier, A., Mitra, S., West, A., Kennett, J. P. (2018). Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago. 1. Ice Cores and Glaciers. The Journal of Geology, 126(2), 165–184.
  41. ^ Moore, C. R., LeCompte, M. A., Kennett, J. P., Brooks, M. J., Firestone, R. B., Ivester, A. H., Ferguson, T. A., Lane, C. S., Duernberger, K. A., Feathers, J. K., Mooney, C. B., Adedeji, V., Batchelor, D., Salmon, M., Langworthy, K. A., Razink, J. J., Brogden, V., van Devener, B., Perez, J. P., Polson, R., Martínez-Colón, M., Rock, B. N., Young, M. D., Kletetschka, G., Bunch, T. E., & West, A. (2024). Platinum, shock-fractured quartz, microspherules, and meltglass widely distributed in Eastern USA at the Younger Dryas onset (12.8 ka). Airbursts and Cratering Impacts, 2(1), 31 pages.
  42. ^ Holliday, Vance T.; Daulton, Tyrone L.; Bartlein, Patrick J.; Boslough, Mark B.; Breslawski, Ryan P.; Fisher, Abigail E.; Jorgeson, Ian A.; Scott, Andrew C.; Koeberl, Christian; Marlon, Jennifer; Severinghaus, Jeffrey; Petaev, Michail I.; Claeys, Philippe (26 July 2023). "Comprehensive refutation of the Younger Dryas Impact Hypothesis (YDIH)". Earth-Science Reviews. 247: 104502. Bibcode:2023ESRv..24704502H. doi:10.1016/j.earscirev.2023.104502 . S2CID 260218223 .
  43. ^ Sweatman, M.B. (2021) The Younger Dryas Impact hypothesis: Review of the impact evidence. Earth-Science Reviews 218: 103677 https://doi.org/10.1016/j.earscirev.2021.103677
  44. ^ Powell, J. L. (2022) Premature rejection in science: The case of the Younger Dryas Impact Hypothesis. Science Progress105:1-43
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