New constraints on massive carbon release and recovery processes during the Paleocene-Eocene Thermal Maximum

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doi: 10.1088/1748-9326/aae285
Author(s): Penman, Donald E.; Zachos, James C.
Author Affiliation(s): Primary:
Yale University, Department of Geology & Geophysics, New Haven, CT, United States
University of California at Santa Cruz, United States
Volume Title: Environmental Research Letters
Source: Environmental Research Letters, 13(10). Publisher: IOP Publishing for Institute of Physics, Bristol, United Kingdom. ISSN: 1748-9326
Note: In English. 47 refs.; illus., incl. 3 tables
Summary: Recent geochemical and sedimentological evidence constrains the response of seawater chemistry to carbon injection during the Paleocene-Eocene Thermal Maximum (PETM): foraminiferal boron-based proxy records constrain the magnitude and duration of surface ocean acidification, while new deep sea records document a carbonate compensation depth (CCD) over-shoot during the recovery. Such features can be used to more tightly constrain simulations of the event within carbon cycle models, and thus test mechanisms for carbon release, buffering, and sequestration. We use the LOSCAR carbon cycle model to examine first the onset of, and then recovery from the PETM. We systematically varied the mass, rate, and location of C release along with changes in ocean circulation patterns as well as initial conditions such as pre-event pCO2 and the strength of weathering feedbacks. A range of input parameters produced output that successfully conformed to observational constraints on the event's onset. However, none of the successful scenarios featured surface seawater aragonite or calcite undersaturation at even peak PETM conditions (in contrast to anthropogenic acidification projections), and most runs featured approximately a doubling of pCO2 relative to pre-event conditions (suggesting a high PETM climate sensitivity). Further runs test scenarios of the body and recovery of the PETM against records of sustained acidification followed by rapid pH recovery in boron records, as well as the timing and depth of the CCD overshoot. Successful scenarios all require a sustained release of carbon over many tens of thousands of years following the onset (comparable to the mass released during the onset) and removal of carbon (likely as burial of organic carbon in addition to elevated chemical weathering rates) during the recovery. This sequence of events is consistent with a short-lived feedback involving the release of 13C-depleted C in response to initial warming followed by its subsequent sequestration during the cooling phase. Copyright (Copyright) 2018 The Author(s). Published by IOP Publishing Ltd
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Acidification; Atlantic Ocean; Carbon; Carbon cycle; Cenozoic; Chemical composition; Expedition 342; Foraminifera; Geochemical cycle; Geochemistry; Global change; IODP Site U1403; IODP Site U1409; Integrated Ocean Drilling Program; Leg 113; Leg 114; Maud Rise; Microfossils; North Atlantic; ODP Site 690; ODP Site 698; Ocean Drilling Program; Paleo-oceanography; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleogene; Paleotemperature; South Atlantic; Southern Ocean; Tertiary; Weddell Sea
Coordinates: N395636 N395636 W0514811 W0514812
S512731 S512730 W0330557 W0330558
S650938 S650937 E0011218 E0011218
Record ID: 2018082165
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by IOP Publishing Ltd., London, United Kingdom